Vapour lock

Vapor lock is a problem that mostly affects gasoline-fueled internal combustion engines. It occurs when the liquid fuel changes state from liquid to vapor while still in the fuel delivery system. This disrupts the operation of the fuel pump, causing loss of feed pressure to the carburetor or fuel injection system, resulting in transient loss of power or complete stalling. Restarting the engine from this state may be difficult. The fuel can vaporize due to being heated by the engine, by the local climate or due to a lower boiling point at high altitude. In regions where higher volatility fuels are used during the winter to improve the starting of the engine, the use of "winter" fuels during the summer can cause vapor lock to occur more readily.


Causes and Incidence

Vapor lock was far more common in older petrol fuel systems incorporating a low-pressure mechanical fuel pump driven by the engine, located in the engine compartment and feeding a carburetor. Such pumps were typically located higher than the fuel tank, were directly heated by the engine and fed fuel directly to the float tank inside the carburetor. Fuel was drawn under negative pressure from the feed line, increasing the risk of a vapor lock developing between the tank and pump. A vapor lock being drawn into the fuel pump could disrupt the fuel pressure long enough for the float chamber in the carburetor to partially or completely drain, causing fuel starvation in the engine. Even temporary disruption of fuel supply into the float chamber is not ideal; most carburetors are designed to run at a fixed level of petrol in the float chamber and reducing the level will reduce the air:fuel mixture delivered.

Carburetor units may not effectively deal with fuel vapor being delivered to the float chamber. Most designs incorporate a pressure balance duct linking the top of the float chamber with either the intake to the carburetor or the outside air. Even if the pump can handle vapor locks effectively, fuel vapor entering the float chamber has to be vented. If this is done via the intake system, the mixture is, in-effect, enriched, creating a mixture control and pollution issue. If it is done by venting to the outside, the result is direct hydrocarbon pollution and an effective loss of fuel efficiency and possibly a petrol odor problem. For this reason, some fuel delivery systems allow fuel vapor to be returned to the fuel tank to be condensed back to the liquid phase. This is usually implemented by removing fuel vapor from the fuel line near the engine rather than from the float chamber. Such a system may also divert excess fuel pressure from the pump back to the tank.

Most modern engines are equipped with fuel injection, and have a high pressure electric fuel pump in the fuel tank. Moving the fuel pump to the interior of the tank helps prevent vapor lock, since the entire fuel delivery system is under high pressure and the fuel pump runs cooler than if it is located in the engine compartment. This is the primary reason that vapor lock is rare in modern fuel systems. For the same reason, some carbureted engines are retrofitted with an electric fuel pump near the fuel tank.

Other solutions to vapor lock are rerouting of the fuel lines away from heat generating components, installation of a fuel cooler or cool can, shielding of heat generating components near fuel lines, and insulation of fuel lines.

A vapor lock is more likely to develop when the vehicle is in traffic because the under-hood temperature tends to rise. A vapor lock can also develop when the engine is stopped while hot and the vehicle is parked for a short period. The fuel in the line near the engine does not move and can thus heat up sufficiently to form a vapor lock. The problem is more likely in hot weather or high altitude in either case.


Incidence with other fuels

The higher the volatility of the fuel, the more likely it is that vapor lock will occur. Historically, gasoline (petrol) was a more volatile distillate than today and was more prone to vapor lock. Conversely, fuel for diesel engines is far less volatile than petrol and thus these engines hardly ever suffer from vapor lock. However, diesel engine fuel systems are far more susceptible to air locks in their fuel lines as standard diesel fuel injection pumps rely on the fuel being non-compressible. Air locks are caused by air leaking into the fuel delivery line or from the tank rather than the fuel evaporating in them. Eliminating such air locks requires an extended period of turning over the engine using the starter motor or manually bleeding the system.

Warm air intake

A warm air intake, or WAI, is a system to decrease the amount of air going into a car for the purpose of increasing the fuel efficiency of the internal-combustion engine.

All warm air intakes operate on the principle of decreasing the air density and therefore the amount of oxygen available for combustion with fuel. Warm air from inside the engine bay is used opposed to air taken from the stock intake which may pull in colder (and more dense) air.

It is similar to a cold air intake (CAI), which significantly differs by collecting air from a colder source outside of the engine bay where the air has a higher density and therefore more oxygen.

BMW M1

The BMW M1 is a supercar produced by the German automaker BMW from 1978 to 1981. It was the first and only mid-engined BMW. It employed a twin-cam M88/1 3.5 L 6-cylinder gasoline engine, a version of which was later used in the E24 BMW M6/M635CSi and E28 BMW M5. The engine had six separate throttle butterflies, four valves per cylinder and produced 277 PS (204 kW) in the street version, giving a top speed of 260 km/h (162 mph). Turbocharged racing versions were capable of producing around 850 hp.

The M1 coupe was hand-built between 1978 and 1981 under the Motorsport division of BMW as a homologation special for sports car racing. The body was designed by Giugiaro, taking inspiration from the 1972 BMW Turbo show car. Originally, BMW commissioned Lamborghini to work out the details of the car's chassis, assemble prototypes and manufacture the vehicles, but Lamborghini's financial position meant that BMW reassumed control over the project in April 1978, after seven prototypes were built. Only 456 production M1s were built, making it one of BMW's rarest models. The spirit of the M1 lived on in the first-generation M5, as both models shared the same (though slightly modified) engines.

Though the car never saw a great deal of racing success, the M1 is remembered as a refined and civilized supercar in the true BMW tradition, with great handling and stellar build quality. In 2004, Sports Car International named the car number ten on the list of Top Sports Cars of the 1970s.

Coffman engine starter

The Coffman engine starter (also known as a "shotgun starter") was a starting system used on many radial piston engines in aircraft and armored vehicles of the 1930s and 1940s. Most American military aircraft and tanks which used radial engines were equipped with this system. A derivation of the Coffman starter was also used on a number of jet engines, including those used on the Canberra B-57 light bomber.

The device used a blank gunpowder cartridge that, when fired, would cause the propeller to turn over and hopefully start the engine. The other systems used during the period were electric motors (such as those used in automobiles today) inertia starters (cranked either by hand or an electric motor) and compressed-air starters, which operate much like Coffman starters but are powered by pressurized tanks.

Shotgun starters are composed of a breech and a motor, which are connected by a metal line. The cartridge fits into the breech, and is triggered either electrically or mechanically. The expanding gases from the cartridge pressurize the line and cause the motor to spin and engage the starter ring on the engine, which is attached to the crankshaft.

The advantage of the cartridge system over electric starters is that the batteries of the time were weak and trouble-prone. Aircraft with electric motors often required the use of a battery cart and jumper cables, or large, heavy batteries carried in the plane. Inertia starters use a heavy wheel, usually made of brass, which is spun by a hand crank or electric motor, then the spinning wheel is made to engage the starter ring. The Coffman system weighs less.

The primary disadvantages of the shotgun starter are the need to keep a stock of cartridges, one of which is used for each attempt to start, and the short time that the motor is spun by each cartridge. Compressed-air starters, which use the same type of motor, are usually recharged by an engine-driven compressor, negating the need to carry cartridges. Hybrid systems can be made simply by adding a cartridge breech or an air tank to an existing system.

The Coffman starter was the most common brand of cartridge starters during the mid-1930s, and the name was used as a generic description. The starter became famous as a plot device in the movie "Flight of the Phoenix," when pilot James Stewart had a limited number of cartridges with which to start the makeshift aircraft's engine.

Some modern military diesels still use this device, but advances in battery technology have made shotgun starters obsolete for most uses.

Engine test stand

An engine test stand is a facility used to develop, characterize and test engines. The facility, often offered as a product to automotive OEMs, allows engine operation in different operating regimes and offers measurement of several physical variables associated with the engine operation.

A sophisticated engine test stand houses several sensors (or transducers), data acquisition features and actuators to control the engine state. The sensors would measure several physical variables of interest which typically include:

* crankshaft torque

* angular velocity of crankshaft

* intake air and fuel consumption rates, often detected using volumetric and/or gravimetric measurement methods

* air-fuel ratio for the intake mixture, often detected using an exhaust gas oxygen sensor

* environment pollutant concentrations in the exhaust gas such as carbon monoxide, different configurations of hydrocarbons and nitric oxides, sulphur dioxide, and particulate matter

* temperatures and gas pressures at several locations on the engine body such as engine oil temperature, spark plug temperature, exhaust gas temperature, intake manifold pressure

* atmospheric conditions such as temperature, pressure, humidity

Information gathered through the sensors is often processed and logged through data acquisition systems. Actuators allow for attaining a desired engine state (often characterized as a unique combination of engine torque and speed). For gasoline engines, the actuators may include an intake throttle actuator, a loading device for the engine such as an induction motor. The engine test stands are often custom-packaged considering requirements of the OEM customer. They often include a microcontroller based feedback control system with following features:

* closed-loop desired speed operation (useful towards characterization of steady-state or transient engine performance)

* closed-loop desired torque operation (useful towards emulation of in-vehicle, on-road scenarios, thereby enabling an alternate way of characterization of steady-state or transient engine performance)



Engine test stand applications

* Research and Development of engines, typically at an OEM laboratory
* Tuning of in-use engines, typically at service centers or for racing applications
* End of production line at an OEM factory


Engine testing for R&D

Research and Development activities on engines at automobile OEMs have necessitated sophisticated engine test stands. Automobile OEMs are usually interested in developing engines that meet the following three-fold objectives:

* to provide high fuel efficiency
* to improve drivability and durability
* to be in compliance to relevant emission legislation

Consequently, an R&D engine test stands allow for a full-fledged engine development exercise through measurement, control and record of several relevant engine variables.

Typical tests include ones that:

* determine fuel efficiency and drivability: torque-speed performance test under steady-state and transient conditions

* determine durability: aging tests, oil and lubrication tests

* determine compliance to relevant emission legislations: volumetric and mass emission tests over stated emission test cycles

* gain further knowledge about the engine itself: engine mapping exercise or development of multidimensional input-output maps among different engine variables. e.g. a map from intake manifold pressure and engine speed to intake air flow rate.

Brake specific fuel consumption

Brake specific fuel consumption (BSFC) is a measure of an engine's efficiency. It is the rate of fuel consumption divided by the rate of power production. BSFC is specific for the piston engine known as the reciprocating engine. The general term is specific fuel consumption (SFC). There is also thrust specific fuel consumption (TSFC) for turbine and rocket engines.


The BSFC Calculation (in metric units)

To calculate BSFC, use the formula BSFC = Fuel_rate / Power
Where:

Fuel_rate is the fuel consumption in grams per hour (g/hr)
Power is the power produced in Kilowatts where kW = w * Tq / 9549.27

w is the engine speed in rpm
Tq is the engine torque in newton meters (N·m)

Note: The Power in the BSFC calculation is not weather corrected.


The resulting units of BSFC are g/(kW·h)
The conversion between metric and U.S. units is:

BSFC_US(Lbs/(HP*Hr)) * 608.277 = BSFC_METRIC(g/(kW·h))
BSFC_METRIC(g/(kW·h)) * .001644 = BSFC_US(Lbs/(HP*Hr))


To calculate the actual efficiency of an engine requires the energy density of the fuel being used.
Different fuels have different energy densities defined by the fuels lower heating value.

Some examples of lower heating values for vehicle fuels are:

Certification gasoline = 18640 BTU/lb = .01204 kW·h/g
Regular gasoline = 18917 BTU/lb = .0122225 kW·h/g
Diesel fuel = 18500 BTU/lb = .0119531 kW·h/g


Thus a diesel engine's efficiency = 1/(BSFC*.0119531)
and a gasoline engine's efficiency = 1/(BSFC*.0122225)

A typical cycle average value of BSFC for a gasoline engine is 322 g/(kW·h). This means the average efficiency of a gasoline engine is only 25%. A reciprocating engine achieves maximum efficiency when the intake air is unthrottled and the engine speed is at around 2000 rpm. For a gasoline engine, the most efficient BSFC is around 256 g/(kW·h) or an efficiency of 32%. Efficiency is worse at other operating conditions. As you can see above, lower values of BSFC mean higher engine efficiency. Diesel engines are more efficient than gasoline engines. A diesel engine can have a BSFC as low as 199 g/(kW·h) and around 42% efficiency.
See also Fuel economy in automobiles.

Diesel engine Glow Plug

Glow plugs are used to heat the combustion chambers of some diesel engines in cold conditions to help ignition at coldstart. In the tip of the glow plug is a coil of a resistive wire or a filament which heats up when electricity is connected.

Glow plugs are required because diesel engines produce the heat needed to ignite their fuel by the compression of air in the cylinder and combustion chamber. Gasoline engines use an electric spark plug. In cold weather, and when the engine block, engine oil and cooling water are cold, the heat generated during the first revolutions of the engine is conducted away by the cold surroundings, preventing ignition. The glow plugs are switched on prior to turning over the engine to provide heat to the combustion chamber, and remain on as the engine is turned over to ignite the first charges of fuel. Once the engine is running, the glow plugs are no longer needed, although some engines run the glow plugs for between 5 and 10 seconds after starting to ensure smooth and efficient running and sometimes to keep the engine within emissions regulations (combustion efficiency is greatly reduced when the engine is very cold). During this period, the power fed to the glow plugs is greatly reduced to prevent them burning out by overheating.

-injection diesel engines are less thermally efficient due to the greater surface area of their combustion chambers and so suffer more from cold-start problems. They require longer pre-heating times than direct-injection engines, which often do not need glow plugs at all in temperate or hot climates even for a cold start.

In a typical diesel engine, the glow plugs are switched on for between 10 and 20 seconds prior to starting. Older, less efficient or worn engines may need as much as a minute (60 seconds) of pre-heating.

Large diesel engines as used in heavy construction equipment, ships and locomotives do not need glow plugs. Their cylinders are large enough so that the air in the middle of the cylinder is not in contact with the cold walls of the cylinder, and retains enough heat to allow ignition.

automotive diesel engines with electronic injection systems use various methods of altering the timing and style of the injection process to ensure reliable cold-starting. Glow plugs are fitted, but are rarely used for more than a few seconds.

Glow plug filaments must be made of materials such as platinum and iridium that are resistant both to heat and to oxidation and reduction by the burning mixture. These particular materials also have the advantage of catalytic activity, due to the relative ease with which molecules absorbed on their surfaces can react with each other. This aids or even replaces electrical heating.


Model engines

In model aircraft, and similar applications , glow plugs are used for starting as well as continuing the power cycle. The glow plug consists of a durable, mostly platinum, helically wound wire filament, within a cylindrical pocket in the plug body, exposed to the combustion chamber. A small direct current voltage (around 1.5 volts) is applied to the glow plug, the engine is then started, and the voltage is removed. The burning of the fuel/air mixture in a glow-plug model engine, which requires methanol for the glow plug to work in the first place, and sometimes with the use of nitromethane for greater power output, occurs due to the catalytic reaction of the methanol vapor to the presence of the platinum in the filament, thus causing the ignition. This keeps the plug's filament glowing hot, and allows it to ignite the next charge. Since the ignition timing is not controlled electrically, as in a spark ignition engine or by fuel injection, as in an ordinary diesel, it must be adjusted by the richness of the mixture, the ratio of nitromethane to methanol, the compression ratio, the cooling of the cylinder head, the type of glow plug, etc. A richer mixture will tend to cool the filiment and so retard ignition, slowing the engine, and a rich mixture also eases starting. After starting the engine can easily be leaned (by adjusting a needle valve in the spraybar) to obtain maximum power.

Forced induction

Forced induction is a term used to describe internal combustion engines that are not naturally aspirated. Instead, a gas compressor is added to the air intake, thereby increasing the quantity of oxygen available for combustion. This compressed air is normally referred to as Boost or charge air.


Introduction

Forced induction can be used to increase the power of an engine or its efficiency, or both, without much extra weight. The ambient air that the engine is normally ingesting enters the compressor inlet of turbocharger or supercharger that is inline along the air intake tract. This effectively increases the pressure and density of the air, which allows for a much greater percentage of oxygen per volume of air intake to be added to the air/fuel mixture. The effects are an increase to the effective capacity of the engine without an increase in physical size. The forced induction approach has the advantage that the intake pressure may be regulated according to the engine speed, thus providing power from extra capacity at high speed, but without wasting fuel at lower speeds. A Nitrous Oxide system is also a form of forced induction. A simple oxidizer is injected either directly (direct port) or by a single fogger...with fuel(wet nitrous system) or without fuel(dry nitrous system).

Two of the commonly used forced induction technologies are turbochargers and superchargers. They differ mainly in the power source for the compressor. Turbochargers are driven by the exhaust gases of the engine, whereas superchargers are driven by a geartrain or belt connected to the crankshaft of the engine.


Comparison

Strengths and weaknesses vary according to the method of forcing induction largely based upon the inherent design functions of both. A turbocharger acts as an obstacle to exhaust gases due to its placement in the exhaust system tract. A supercharger uses torque generated from the rotational mass internal to the engine through the crank pulley. A turbo relies on the volume and velocity of exhaust gases to spool, or spin the turbine wheel. The turbine wheel is connected to the compressor wheel via a common shaft. The compressor wheel compresses the intake charge increasing the charge density by a large factor. The amount of time that it takes a turbocharger to reach the onset of boost is referred to as lag. A supercharger is 'on' all of the time, meaning that it is capable of producing a linear increase of boost up until redline. It is easier to target a desired boost with a turbocharger as there are many forms of boost controllers that allow a user to adjust to desired boost fairly easily. In order to achieve desired boost with a supercharger, a larger or smaller pulley must be installed.


Intercooling

A fundamental principle to forced induction is that compressing air raises its temperature. As a result, the charge density is reduced and the cylinders receive less fresh air than the system’s boost pressure prescribes. The risk of pre-ignition or "knock" in internal combustion engines greatly increases. These drawbacks are countered by charge-air cooling, which passes the air leaving the turbocharger or supercharger through a heat exchanger typically called an intercooler. This is done by cooling the charge air with an ambient flow of either air (air-air intercoolers) or liquid (liquid to air intercoolers), the charge air density is increased and the temperature is reduced.


Alcohol/Water Injection

Additionally, alcohol injection is an effective means of cooling the charge air. Methanol is the preferred alcohol due to its elemental properties, and is normally mixed with water to prevent evaporation. Methanol is typically injected pre throttle body. Methanol, unlike nitrous oxide or forced induction itself, doesn't add more oxygen to the charge, but by its low evaporation point changes from a liquid to a gas as its introduced into the air charge. The evaporation process uses the heat from the intake charge to complete the phase change. The alcohol is also a fuel in the charge which will cause a rich condition if used in excess. Due to the lower intake temperatures and denser air charge more power is exerted from the engine. Methanol is typically used in conjunction with poor quality fuel(pump gas) in order to run higher than normal boost pressures.

Like was stated above, adding forced induction increases the amount of air an engine can use for combustion, in effect allowing more fuel to be used with the available oxygen. Further, it increases an engine's dynamic compression ratio. As compression ratio increases, so does the threat of knock and therefore the need for higher octane fuel.

Motronic

Bosch Motronic was one of the first digital engine-management systems. The idea behind it was to fully integrate and regulate all major engine system parameters, thereby enabling fuel delivery and spark timing control functions to be controlled by the same unit, in an attempt to achieve optimum efficiency, driveability and power output potential.

The early Motronic systems integrated spark timing control with existing Jetronic fuel injection systems, such as L-Jetronic, LH-Jetronic, K-Jetronic, and in some cases Mono-Jetronic. It was originally developed and first used in the BMW 7 Series, before being implemented on several Volvo and Porsche engines throughout the 1980s.

The components of the Motronic 1.x systems for the most part remained unchanged during production, although there are some differences in certain situations. The electronic control unit (ECU) receives information regarding engine speed and position, crankshaft angle, coolant temperature and throttle position.

An air flow meter is used to measure the volume of air entering the induction system, and a charge air temperature sensor monitors the temperature of the inducted air after it has passed through the turbocharger and the intercooler, in order to accurately calculate the overall air mass.

A separate constant idle speed (CIS) system monitors and regulates base idle speed, depending if an interior electrical component is in operation. A cold start (5th) injector is used to provide extra fuel enrichment during different cold-start conditions.

1. ^ 25 years of Bosch Motronic: Think tank under the bonnet, Bosch, may 2004

Napier Nomad engine (aircraft engine)

The Nomad was a complex Diesel cycle aircraft engine from Napier & Son of the UK. The Nomad used a turbine to recover power from the exhaust of the otherwise conventional Diesel engine, resulting in a specific fuel consumption that remains unmatched by an aircraft engine 50 years later.


History

In 1945 the Air Ministry asked for proposals for a new 6,000 horsepower (4,500 kW) class engine with good economy. Curtiss-Wright was designing an engine of this sort of power known as the "turbo-compound", but Sir Harry Ricardo, one of Britain's great engine designers, suggested that the most economical combination would be a similar design using a diesel two-stroke in place of the Curtiss's petrol engine.

Prior to World War II Napier had licensed the Junkers Jumo 204 diesel design to set up production in the UK as the Napier Culverin, however the start of the war made the Sabre all-important and work on the Culverin was stopped. In response to the Air Ministry requirements they dusted off this work, combining two enlarged Culverins into an H-block similar to the Sabre, resulting in a massive 75 litre design. Markets for an engine of this size seem limited however, and instead they returned to the original Culverin-like horizontally opposed 12 cylinder design, resulting in the Nomad.

Design

The Nomad design was incredibly complex, essentially two engines in one. One was a supercharged Diesel similar to the Culverin. Below this was a complete turboprop engine, based on their Naiad design. The output of the turboprop was geared to a shaft running inside the Diesel's, driving the front propeller of a contra-rotating pair. As if that were not enough, during takeoff additional fuel was dumped into the rear turbine stage for additional power, and turned off once the plane was cruising.

The compressor and turbine assemblies of the Nomad 1 were tested during 1948, and the complete unit was run in October 1949. The prototype was installed in the nose of an Avro Lincoln bomber for testing, and first flew in 1950. In total the Nomad 1 ran for just over 1,000 hours, and proved to be rather temperamental, but when running properly it could produce 3000 hp (2,200 kW) and 320 lbf (1.4 kN) thrust. It had a specific fuel consumption (sfc) of 0.36 lb/(hp·h) (0.22 kg/(kW·h)).

Even before the Nomad 1 was running, its replacement, the Nomad 2, had already been designed. In this version an extra compressor stage was added, replacing the original supercharger. This stage was driven by an additional stage in the turbine, so the system was now more like a turbocharger and the compressed air for the Diesel was no longer "robbing" power. In addition the propeller shaft from the turbine was eliminated, and geared using a hydraulic clutch into the main shaft. The result was smaller and considerably simpler, a single engine driving a single propeller.

While the Nomad 2 was undergoing testing, a prototype Avro Shackleton was lent to Napier as a testbed. The engine proved bulky, like the Nomad 1 before it, and in the meantime several dummy engines were used on the Shackleton for various tests. By 1954 interest in the Nomad was dropping, and after the only other project based on it was cancelled, work on the engine was ended in April 1955.


Specifications (Nomad 2)

General characteristics

* Type: Twelve-cylinder liquid-cooled horizontally opposed Diesel combined with a turboprop aircraft engine
* Bore: 6 in (152 mm)
* Stroke: 7.375 in (187 mm)
* Displacement: 2,502 in³ (41 L)
* Dry weight: 3,580 lb (1,624 kg)

Components

* Cooling system: Liquid-cooled

Performance

* Power output: 3,135 ehp (2,338 kW) max take-off at 89 psia (614 kPa) including thrust power from the turbine
* Specific power: 1.25 ehp/in³ (57.0 kW/L)
* Compression ratio:
o Engine 8:1
o Turboprop compressor 8.25:1
* Specific fuel consumption: 0.345 lb/(ehp·h) (0.210 kg/(kW·h))
* Power-to-weight ratio: 0.88 ehp/lb (1.44 kW/kg)

Wright R-3350 engine

The R-3350 Duplex-Cyclone was one of the most powerful radial aircraft engines produced in the United States. It was a twin row, supercharged, air-cooled, radial engine with 18 cylinders. Power ranged from 2,200 to over 3,700 hp (1,640 to 2,760 kW), depending on the model. First developed prior to World War II, the R-3350's design required a long time to mature before finally being used to power the B-29 Superfortress. After the war, the engine had matured sufficiently to become a major civilian airliner design, notably in its Turbo-Compound forms.

In 1927 Wright Aeronautical introduced their famous Cyclone engine, which powered a number of designs in the 1930s. After merging with Curtiss to become Curtiss-Wright in 1929, an effort was started to redesign the engine to the 1,000 hp (750 kW) class. The new Wright R-1820 Cyclone 9 first ran successfully in 1935, and would become one of the most-used aircraft engines in the 1930s and WWII.

At about the same time Pratt & Whitney had started a development of their equally famous Wasp design into a larger and much more powerful two-row design that would easily compete with this larger Cyclone. In 1935 Wright decided to follow P&W's lead, and started to develop much larger engines based on the mechanicals of the Cyclone. The result were two designs with a somewhat shorter stroke, a 14 cylinder design that would evolve into the Wright R-2600, and a much larger 18 cylinder design that became the R-3350.

The first R-3350 was run in May 1937, but proved to be rather temperamental. Continued development was slow, both due to the complex nature of the engine, as well as the R-2600 receiving considerably more attention. The R-3350 didn't fly until 1941, after the prototype Douglas XB-19 had been re-designed from the Allison V-3420 to the R-3350.

Things changed dramatically in 1940 with the introduction of a new contract by the USAAC to develop a long-range bomber capable of flying from the US to Germany with a 2,000 lb (900 kg) bomb load. Although smaller than the Bomber D designs that led to the B-19, the new designs required roughly the same sort of power. When preliminary designs were returned in the summer of 1940, three of the four designs were based on the R-3350. Suddenly the engine was seen as the future of Army aviation, and serious efforts to get the design into production started.

By 1943 the ultimate development of the new bomber program, the B-29, was flying. However the engines remained temperamental, and showed an alarming tendency to overheat. A number of changes were introduced into the aircraft production line in order to provide more cooling at low speeds, and the planes were rushed to operate in the Pacific in 1944. This proved unwise, as the overheating problems were not completely solved, and the engines had a tendency to burst into flame after takeoff.

Early versions of the R-3350 were equipped with carburetors, which led to serious problems with inadequate fuel mixture distribution. Near the end of World War II, in late 1944, the system was changed to use direct fuel injection, where fuel was injected directly into the combustion chamber. This change improved engine reliability immediately. After the war the engine became a favourite of large aircraft of all designs, most notably the Lockheed Constellation and Douglas DC-7.

Following the war, in order to better serve the civilian market, the Turbo-Compound system was developed in order to deliver better "gas milage". In these versions of the engine, three separate power recovery turbines were attached to the exhaust piping of each group of 6 cylinders, using the power not to deliver additional boost as in a normal turbocharger, but geared directly to the engine crankshaft by fluid drives in order to deliver more power. This recovered about 20% of the heat of the exhaust, (something around 500 hp) which would otherwise be wasted. This is not without cost, however, for those devices are also nicknamed "Parts Recovery Turbines" (and worse), and were another source of failures.

By this point reliability had improved, with the mean time between overhauls at 3,500 hours, and specific fuel consumption on the order of 0.4 lb/hp.hour (243 g/kWh). Engines still in use are now limited to 52 inches of manifold pressure and 2,880 HP with 100 octane fuel (100LL) instead of the 59.5 inches and 3,400 HP possible with 115/145 fuels, which are no longer available.

Maserati Quattroporte

Vehicle Overview
Changes for Maserati's 2007 Quattroporte include suspension modifications intended to soften the car's ride, a stronger climate control system, stronger brakes and reduced emissions courtesy of an updated catalytic converter. Inside, the steering wheel and handbrake stitching no longer contrasts with the surrounding leather, and folding tables for backseat passengers are no longer available.

For the 2005 model year, Maserati introduced a full-size four-door luxury sedan called the Quattroporte. Designed by Pininfarina, the rear-wheel-drive Quattroporte competes against the Audi A8, BMW 7 Series and Mercedes-Benz S-Class.

The Quattroporte has Brembo all-disc brakes and a Skyhook automatic-damping suspension. A V-8 engine works with Maserati's DuoSelect sequential transmission, which can be shifted using paddles mounted on the steering column. Maserati says the Quattroporte can accelerate from zero to 60 mph in a swift 5.2 seconds. For optimum weight distribution, the engine sits aft of the front axle and drives a rear-mounted transmission.

Two versions of the Quattroporte arrived in late 2005: an Executive GT and a Sport GT. The Executive GT has polished 19-inch wheels and heated, ventilated and massaging rear seats. A wood and leather steering wheel also is installed.

The Sport GT features 20-inch wheels, carbon fiber trim, racing pedals, and a black grille and side air vents. Maserati's Skyhook suspension system has been modified for use in the Sport GT, and the car has a sport exhaust system.

Exterior
Recognizable Maserati styling cues include its long hood, prominent grille and headlights. Low-slung front fenders, short front overhangs, a swept-back profile, a high belt line and a steeply raked windshield also help establish what the company calls an "authoritative persona [and] predatory appearance."

A broad horizontal-bar grille contains Maserati's Trident badge. The headlights sit slightly back, and a wide air intake is installed below the grille. Three portholes adorn each front fender. Standard wheels measure 18 inches in diameter. Built on a relatively long 120.6-inch wheelbase, the Quattroporte is 198.9 inches long overall and 56.6 inches tall.

Interior
Five people can luxuriate inside the Quattroporte, where handcrafted leather complements the premium wood trim. Rosewood is standard, but buyers can specify mahogany, burl walnut, a titanium-style trim or piano black finish.

Standard features include power front and rear seats, a power rear sunshade and a cooled compartment in the front armrest. Touching a button in the center rear armrest moves the front passenger seat forward, supplying additional legroom. The Bosch-Blaupunkt Multi Media System includes a navigation system, Bose stereo and TV tuner.

Under the Hood
The Quattroporte's 4.2-liter V-8 engine generates close to 400 horsepower and 333 pounds-feet of torque. The six-speed sequential transmission can be shifted using paddles mounted on the steering column, but it also includes a fully automatic mode. A Low Grip mode is included for driving in poor weather.

Safety
All-disc antilock brakes, an electronic stability system, side-impact airbags for the front seats and side curtain airbags are standard.

Rear disc brakes are larger for 2007 — growing from 12.4 to 13 inches. Maserati says this reduces the Quattroporte's stopping distance from 62 mph by 5 percent.

Whats a Stationary engine

A stationary engine is an engine whose framework does not move. It is normally used not to propel a vehicle but to drive a piece of immobile equipment such as a pump or power tool.

This article concentrates on oil-burning or internal combustion engines;
steam-powered engines are described separately in stationary steam engine.


Overview

Stationary engines come in a wide variety of sizes and use a wide variety of technologies. These include:

* Power stations of all sizes.

* Beam engines used in mills and factories before the widespread use of electric power.

* Winding engines used at mine pitheads.


Railways

In Victorian era railway engineering, many attempts were made to replace locomotives by stationary engines, on the grounds that it was inefficient to move something as large and heavy as a steam engine around. These attempts only succeeded where short distances were to be covered, where various kinds of cable railway were successful, particularly for steep inclines (where the inefficiency of moving the engine up and down a hill is particularly significant). A heroic failure was Isambard Kingdom Brunel's attempt to construct an atmospheric railway from Exeter to Plymouth in Devon, England.

Cable haulage did prove viable where the gradients were exceptionally steep, such as the 1 in 8 gradients of the Cromford and High Peak Railway opened in 1830. Cable railways generally have two tracks with loaded wagons on one track partially balanced by empty wagons on the other, to minimise fuel costs for the stationary engine.


Farms

Small stationary engines were frequently used on a farm to drive various kinds of power tools and equipment such as circular saws, pumps, and hay elevators. The engine was fitted to a wooden trolley with steel wheels so that it could be moved to where required, and was then coupled to the equipment by means of a flat belt.

The engines were usually powered by gasoline, but in some cases for economy it was possible to switch over to run on paraffin after the engine had warmed up - to achieve this required a part of the inlet tract to be heated by exhaust gases in order to vaporise the less volatile fuel. Very large stationary engines ran on a heavier type of fuel oil, but this type of engine was usually too large to be moved; typical applications were electricity generation and large-scale pumping.

Initially, such engines mirrored steam engine design in having the piston move horizontally, with the crank and valve gear exposed and employed a drip-feed total loss lubrication system. Later for safety, cleanliness and longevity the design moved towards enclosing the working parts and using sump lubrication.

The four-stroke cycle design was by far the most common, but Petter, a British manufacturer, developed a successful two-stroke cycle design.

A centripetal governor system was usually incorporated to regulate the engine's speed under varying loads. This is a simple negative feedback control system. The engine speed is sensed by a pair of weights that rotate with the crankshaft. As the speed increases, centripetal force causes the weights to move outward against the pressure of a retaining spring. This outward movement is used to restrict the engine power to limit the speed. If the engine slows down, the centrifugal force reduces and the weights are pulled inward by spring pressure, and this movement is used to increase the engine power to maintain speed under increasing load.

The governor can use one of two techniques for controlling speed. Today, most governors open and close a butterfly valve to control the amount of fuel-air mixture entering the engine. However, in earlier engines, the governor would cut off the fuel air mixture completely. These engines are often called "hit and miss" (variously called "hit or miss") because they do not fire on every available power stroke. When the engine is running above a certain rpm, the exhaust valve is held open, and the magneto is prevented from generating a spark. Once the speed drops, the governor allows the exhaust valve to close and the magneto to fire. The engine fires and speeds back up, causing the governor to keep the exhaust valve open again.

On a medium size engine such as a 6hp, the engine can be adjusted so that it only fires every 10 seconds or so when it is not under load. These engines generally drove a wide flat belt to run a firewood cutoff saw, a pump, a reciprocating log saw, etc.

Eventually such engines were rendered obsolete by the development of electrically powered tools, and by newer gasoline engines that were small and economical enough to be permanently built in to each piece of equipment.

Live steam models of stationary engines are popular among collectors and hobbyists.

Harmonic balancer

A harmonic balancer (also called crank pulley damper, torsional damper or vibration damper) is a device connected to the crankshaft of an engine to reduce torsional vibration.

Every time the cylinders fire, torque is imparted to the crankshaft. The crankshaft deflects under this torque, which sets up vibrations when the torque is released. At certain engine speeds the torques imparted by the cylinders are in synch with the vibrations in the crankshaft, which results in a phenomenon called resonance. This resonance causes stress beyond what the crankshaft can withstand, resulting in crankshaft failure.

To prevent this vibration, a harmonic balancer is attached to the front part of the crankshaft. The damper is composed of two elements: a mass and an energy dissipating element. The mass resists the acceleration of the vibration and the energy dissipating (rubber/clutch/fluid) element absorbs the vibrations.

Over time, the energy dissipating (rubber/clutch/fluid) element can deteriorate from age, heat, cold, or exposure to oil or chemicals. Unless rebuilt or replaced, this can cause the crankshaft to develop cracks, resulting in crankshaft failure.

There has been a trend at times by some "performance enthusiasts" to remove the harmonic balancers on their cars. The argument is that they aren't necessary and their mass reduces the performance of the engine. Others argue that this is not worth it, because the danger of damage to the engine from the vibrations the damper is intended to prevent is too high.

While net engine output can be increased without harmonic balancers, in professional race cars harmonic balancers are still commonly equipped, for reasons ranging from safety concerns to regulations. Almost all modern car manufacturers, even "performance" car makers and specialty tuners, include a harmonic balancer on their vehicles, and removal voids vehicle warranty.

Reverse-flow cylinder head

A reverse-flow cylinder head is a cylinder head that locates the intake and exhaust ports on the same side of the engine. The gasses can be thought to enter the cylinder-head and then change direction in order to exit the head. This is in contrast to the cross-flow cylinder-head design. This term is used for engines which have only one intake and one exhaust valve per cylinder.

The reverse-flow design is accepted to be inferior to a cross-flow design in terms of ultimate engineering potential, however, the reverse-flow design has been shown to be a more practical and economical manufacturing proposition and has similar potential in forced induction applications (where overly-large valves and "through flow" of gasses on cam overlap are not as desirable as under normally-aspirated conditions).

The real problem is that of temperature. With the exhaust ports on the same side as the intake ports, the intake air gets some of the heat, which reduces efficiency.

Why buy a Hybrid Car

1. - Gas Savings -
Hybrid cars can get up to 60 mpg (miles per gallon), due to their advanced aerodynamics, engine efficiency, tire technology (which is so different to the standard cars) just to mention some of its characteristics.

2. - Environmental Issues -
Reduced gas emissions equals less air pollution because a hybrid car has an electric motor and batteries to rely on when the gasoline engine is not in use. They can reduce smog up to 90%.

3. - Better engine efficiency -
Reducing the overall weight of the hybrid car is a way to increase its efficiency, smaller engines equals better efficiency. Another way is how the hybrid cars recharge they batteries, the hybrids battery pack never needs to be charged from an external source, every time you hit the brake, the brake system stores some of the energy to the batteries (this is known as regenerative braking). Also the batteries get recharged by the gasoline engine when necessary.

4. - Low Maintenance costs -
The electrical motor and the batteries dont require any maintenance; they have the same life span as the car itself. The gas engine doesnt require any more maintenance than any other normal car.

Autogas

Autogas is the common name for liquified petroleum gas when it is used as a fuel in internal combustion engines in vehicles. The same equipment is also used for similar engines in stationary applications such as generators.

Autogas is widely used as a "green" fuel as it decreases exhaust emissions (less 20 % CO2) . It has an octane rating (MON/RON) that is between 90 and 110 and an energy content (higher heating value—HHV) that is between 25.5 megajoules per litre (for pure propane) and 28.7 megajoules per litre (for pure butane.)

In countries where petrol is called petrol rather than gasoline, it is common for autogas to be simply referred to as gas. This can be confusing for people from countries where petrol is called gasoline, as they often use the abbreviation gas to refer to petrol. In the United States, autogas is more commonly known under the name of its primary constituent, propane.


Vehicle manufacturers

Toyota made a number of LPG engines in their 1970s M, R, and Y engine families.

Currently, a number of automobile manufacturers—Citroën, Fiat, Ford, Hyundai, General Motors (including Daewoo, Holden, Opel/Vauxhall, Saab), Peugeot, Renault, Toyota and Volvo—have OEM bi-fuel (dual fuel) models that will run equally well on both LPG and petrol. See list of LPG cars.

Vialli have OEM LPG powered scooters and LPG powered mopeds that run equally well on LPG. Ford Australia have offered an LPG-only variant of their Falcon model since 2000.

MAN AG produces LPG buses.

Countries

Autogas enjoys great popularity in Australia, The Netherlands, Italy, Serbia, Poland, Hong Kong and Korea. The former Soviet republic of Armenia may, however, be the world leader in autogas use. The Armenian transport ministry estimates as much as 20 to 30% of vehicles use autogas compared to traditional gasoline, once again due to the fact that it offers a very cheap alternative to both diesel and petrol, being less than half the price of petrol and some 40% cheaper than diesel. The recent rises in oil-derived fuels has sharply raised the difference.


Europe

The european standard is EN 589


Australia

LPG is popular in Australia, in part due to it being less than half the price of petrol in urban areas. The four major local manufacturers (Ford, Holden, Mitsubishi and Toyota) offer it in some models of their locally made large cars. All factory autogas vehicles are dual fuel vehicles, with the exception of the E-Gas Ford Falcon model, which runs on autogas only.

Autogas is especially popular with taxis, except in remote areas where transportation costs make autogas prices uncompetitive.

Whilst LPG is currently excise-free, an excise on LPG starting at 2.5 cents per litre in 2011 will be placed, which will increase incrementally to 12.5 cents per litre (as opposed to the 38 cpl excise on petrol) by 2015. This will be offset somewhat by a AU$2000 subsidy that was implemented in 2006 for private motorists to convert their cars to LPG.The subsidy does not presently apply to business vehicles or vehicles with a Gross Vehicle Mass of over 3500 kilograms but lobbyists are trying to get that changed. On top of the subsidy to be provided by the Australian federal government, the Western Australian government will also provide motorists with a AU$1000 subsidy under the long-running LPG subsidy scheme.


System types

The different autogas systems generally use the same type of filler, tanks, lines and fittings but use different components in the engine bay. Some injection systems use special tanks with circulation pumps and return lines similar to petrol fuel injection systems.

There are three basic types of autogas system. The oldest of these is the conventional converter-and-mixer system, which has existed since the 1940s and is still widely used today. The other two types are known as injection systems, but there are significant differences between the two.

A converter-mixer system uses a converter to change liquid fuel from the tank into vapour, then feeds that vapour to the mixer where it is mixed with the intake air.

Vapour phase injection systems use a converter in much the same way as with a mixer, but have a series of electrical shutoff solenoids and nozzles (collectively referred to as injectors) that are controlled by a computer. The computer works in much the same way as a petrol fuel injection computer. This allows much more accurate metering of fuel to the engine than is possible with mixers, improving economy and/or power while reducing emissions.

Liquid phase injection systems do not use a converter, but instead deliver the liquid fuel into a fuel rail in much the same manner as a petrol injection system. These systems are still very much in their infancy. Because the fuel vapourises in the intake, the air around it is cooled significantly. This increases the density of the intake air and can potentially lead to substantial increases in engine power output, to the extent that such systems are usually de-tuned to avoid damaging other parts of the engine. Liquid phase injection has the potential to achieve much better economy and power plus lower emission levels than are possible using mixers or vapour phase injectors.


System components

Filler

The fuel is transferred into a vehicle tank as liquid by connecting the bowser at the filling station to the filler fitting on the vehicle.

The type of filler used varies from country to country:

* The type used in Australia and the USA has an ACME threaded fitting onto which the bowser nozzle is screwed before the trigger is pulled to establish a seal then transfer fuel.
* The type used in other countries is the Bajonett.

The fill valve contains a check valve so that the liquid in the line between the filler and the tank(s) does not escape when the bowser nozzle is disconnected.

In installations where more than one tank is fitted, T-fittings may be used to connect the tanks to one filler so that the tanks are filled simultaneously. In some applications, more than one filler may be fitted, such as on opposite sides of the vehicle. These may be connected to separate tanks, or may be connected to the same tanks using T-fittings in the same manner as for connecting multiple tanks to one filler.


Hoses, pipes and fittings

The hose between the filler and tank(s) is called the fill hose or fill line. The hose or pipe between the tank(s) and the converter is called the service line. These both carry liquid under pressure.

The flexible hose between the converter and mixer is called the vapour hose or vapour line. This line carries vapour at low pressure and has a much larger diameter to suit.

Where the tank valves are located inside an enclosed space such as the boot of a sedan, a plastic containment hose is used to provide a gas-tight seal between the gas components and the inside of the vehicle.

Liquid hoses for LPG are specifically designed and rated for the pressures that exist in LPG systems, and are made from materials designed to be compatible with the fuel. Some hoses are made with crimped fittings, while others are made using re-usable fittings that are pressed or screwed onto the end of the hose.

Rigid sections of liquid line are usually made using copper tubing, although in some applications, steel pipes are used instead. The ends of the pipes are always double-flared and fitted with flare nuts to secure them to the fittings.

Liquid line fittings are mostly made from brass. The fittings typically adapt from a thread in a component, such as a BSP or NPT threaded hole on a tank, to an SAE flare fitting to suit the ends of pipes or hoses.


Tank

Vehicles are often fitted with only one tank, but multiple tanks are used in a some applications.

The tanks have fittings for filling, liquid outlet, emergency relief of excess pressure, fuel level gauge and sometimes a vapour outlet. These may be separate valves mounted into a series of 3 to 5 holes in a plate welded into the tank shell, or may be assembled onto a multi-valve unit which is bolted into one large hole on a boss welded into the tank shell.

Modern fill valves are usually fitted with an automatic fill limiter (AFL) to prevent overfilling. The AFL has a float arm which restricts the flow significantly but does not shut it off entirely. This is intended to cause the pressure in the line to rise enough to tell the bowser to stop pumping but not cause dangerously high pressures. Before AFLs were introduced, it was common for the filler (with integral check valve) to be screwed directly into the tank, as the operator had to open an ullage valve at the tank while filling, allowing vapour out of the top of the tank and stopping filling when liquid started coming out of the ullage valve to indicate that the tank was full. Modern tanks are not fitted with ullage valves.

The liquid outlet is usually used to supply fuel to the engine, and is usually referred to as the service valve. Modern service valves incorporate an electric shutoff solenoid. In applications using very small engines such as small generators, vapour may be withdrawn from the top of the tank instead of liquid from the bottom of the tank.

The emergency pressure relief valve in the tank is called a hydrostatic pressure relief valve. It is designed to open if the pressure in the tank is dangerously high, thus releasing some vapour to the atmosphere to reduce the pressure in the tank. The release of a small quantity of vapour reduces the pressure in the tank, which causes some of the liquid in the tank to vapourise to re-establish equilibrium between liquid and vapour. The latent heat of vapourisation causes the tank to cool, which reduces pressure even further.

The gauge sender is usually a magnetically coupled arrangement, with a float arm inside the tank rotating a magnet, which rotates an external gauge. The external gauge is usually readable directly, and most also incorporate an electronic sender to operate a fuel gauge on the dashboard.



Valves

There are a number of types of valve used in autogas systems. The most common ones are shutoff or filterlock valves, which are used to stop flow in the service line. These may be operated by vacuum or electricity. On dual-fuel systems with a petrol carburettor, a similar shutoff valve is usually fitted in the petrol line between the pump and carburettor.

Check valves are fitted in the filler and on the fill input to the fuel tank to prevent fuel flowing back the wrong way.

Service valves are fitted to the outlet from the tank to the service line. These have a tap to turn the fuel on and off. The tap is usually only closed when the tank is being worked on. In some countries, an electrical shutoff valve is built into the service valve.

Where multiple tanks are fitted, a combination of check valves and a hydrostatic relief valve are usually installed to prevent fuel from flowing from one tank to another. In Australia, there is a common assembly designed for this purpose. It is a combined twin check valve and hydrostatic relief valve assembly built in the form of a T-fitting, such that the lines from the tanks come into the sides of the valve and the outlet to the converter comes out the end. Because there is only one common brand of these valves, they are known colloquially as a Sherwood valve.


Converter

The converter (also known as vapouriser) is a device designed to change the fuel from a pressurised liquid to a vapour at around atmospheric pressure for delivery to the mixer or vapour phase injectors. Because of the refrigerant characteristic of the fuel, heat must be put into the fuel by the converter. This is usually achieved by having engine coolant circulated through a heat exchanger that transfers heat from that coolant to the LPG.

There are two distinctly different basic types of converter for use with mixer type systems. The European style of converter is a more complex device that incorporates an idle circuit and is designed to be used with a simple fixed venturi mixer. The American style of converter is a simpler design which is intended to be used with a variable venturi mixer that incorporates an idle circuit.

Engines with a low power output such as; scooters, quad bikes and generators can use a simpler type of convertor (also known as governor or regulator). These convertors are fed with fuel in vapour form. Evaporation takes place in the tank where refrigeration occours as the liquid fuel boils. The tanks large surface area exposed to the ambient air temperature combined with the low power output (fuel requirment) of the engine make this type of system viable. The refrigeration of the fuel tank is proportional to fuel demand hence this setup is only used on smaller engines. This type of convertor can either fed with vapour at tank pressure (called a 2 stage regulator) or be fed via a tank mounted reguator at a fixed reduced pressure(called a single stage regulator).


Mixer

The mixer is the device that mixes the fuel into the air flowing to the engine. The mixer incorporates a venturi designed to draw the fuel into the airflow due to the movement of the air.

Mixer type systems have existed since the 1940s and some designs have changed little over that time. Mixers are now being increasingly superceeded by injectors.


Vapour phase injectors

Most vapour phase injection systems mount the solenoids in a manifold block or injector rail, then run hoses to the nozzles, which are screwed into holes drilled and tapped into the runners of the intake manifold. There is usually one nozzle for each cylinder. Some vapour injection systems resemble petrol injection, having separate injectors that fit into the manifold or head in the same manner as petrol injectors, and are fed fuel through a fuel rail.


Liquid phase injectors

Liquid phase injectors are mounted onto the engine in a manner similar to petrol injectors, being mounted directly at the inlet manifold and fed liquid fuel from a fuel rail.


Electrical and electronic controls

The are four distinct electrical systems that may be used in autogas systems - fuel gauge sender, fuel shutoff, closed loop feedback mixture control and injection control.

In some installations, the fuel gauge sender fitted to the autogas tank is matched to the original fuel gauge in the vehicle. In others, an additional gauge is added to display the level of fuel in the autogas tank separately from the existing petrol gauge.

In most modern installations, an electronic device called a tachometric relay or safety switch is used to operate electrical shutoff solenoids. These work by sensing that the engine is running by detecting ignition pulses. Some systems use an engine oil pressure sensor instead. In all installations, there is a filterlock (consisting of a filter assembly and a vacuum or electric solenoid operated shutoff valve) located at the input to the converter. In European converters, there is also a solenoid in the converter to shut off the idle circuit. These valves are usually both connected to the output of the tachometric relay or oil pressure switch. Where solenoids are fitted to the outputs of fuel tanks, these are also connected to the output of the tachometric relay or oil pressure switch. In installations with multiple tanks, a switch or changeover relay may be fitted to allow the driver to select which tank to use fuel from. On dual-fuel systems, the switch used to change between fuels is used to turn off the tachometric relay.

Closed loop feedback systems use an electronic controller that operates in much the same way as in a petrol fuel injection systems, using an oxygen sensor to effectively measure the air/fuel mixture by measuring the oxygen content of the exhaust and control valve on the converter or in the vapour line to adjust the mixture. Mixer type systems that do not have a closed loop feedback fitted are sometimes referred to as open loop systems.

Injection systems use a computerised control system which is very similar to that used in petrol injection systems. In virtually all systems, the injection control system integrates the tachometric relay and closed loop feedback functions.


Converter-and-mixer system operation

The designs of converters and mixers are matched to each other by matching sizes and shapes of components within the two.

In European style systems, the size and shape of the venturi is designed to match the converter. In American style systems, the air valve and metering pins in the mixer are sized to match the diaphragm sizes and spring stiffnesses in the converter. In both cases, the components are matched by the manufacturers and only basic adjustments are needed during installation and tuning.

An autogas carburettor simply consists of a throttlebody and a mixer, sometimes fitted together using an adapter.

Cold start enrichment is achieved by the fact that the engine coolant is cold when the engine is cold. This causes denser vapour to be delivered to the mixer. As the engine warms up, the coolant temperature rises until the engine is at operating temperature and the mixture has leaned off to the normal running mixture. Depending on the system, the throttle may need to be held open further when the engine is cold in the same manner as with a petrol carburetor. On others, the normal mixture is intended to be somewhat lean and no cold-start throttle increase is needed. Because of the way enrichment is achieved, no additional choke butterfly is required for cold starting with LPG.

The temperature of the engine is critical to the tuning of an autogas system. The engine thermostat effectively controls the temperature of the converter, thus directly affecting the mixture. A faulty thermostat, or a thermostat of the wrong temperature range for the design of the system may not operate correctly.

The power output capacity of a system is limited by the ability of the converter to deliver a stable flow of vapour. A coolant temperature lower than intended will reduce the maximum power output possible, as will an air bubble trapped in the cooling circuit or complete loss of coolant. All converters have a limit, beyond which mixtures become unstable. Unstable mixtures typically contain tiny droplets of liquid fuel that were not heated enough in the converter and will vapourise in the mixer or intake to form an excessively rich mixture. When this occurs, the mixture will become so rich that the engine will flood and stall. Because the outside of the converter will be at or below zero degrees Celsius when this happens, water vapour from the air will freeze onto the outside of the converter, forming an icy white layer. Some converters are very suceptible to cracking when this happens.


Performance

The Yellow-Checker-Star taxi fleet of Las Vegas, NV is a well known propane user. These taxis are mostly production gasoline Crown Victoria conversions. When the larger propane fuel tank replaces the smaller gasoline tank, about 1/8 of the trunk space is lost. Maximum distance varies between 250 to 320 miles on one full tank. Fuel capacity varies a great deal with ambient temperature. In the coldest desert winter nights taxis might travel up to 400 miles or more. But in the hotest summer days taxis might achieve only 180 miles. When it is very hot, refueling requires extra time. This can cause long lines to form at refueling stations, particularly during shift changes.

It's a common rule of thumb in Australia that a dual fuel car will use about 20-30% more fuel than an equivalent petrol car, and has about 20-30% less power. Modern injection systems are making the gap smaller, however, as do dedicated LPG systems, since they don't have to be able to run both LPG and petrol.


LPG injection for diesel vehicles

The performance, economy and emission profile of diesel engines can be improved by injecting a small quantity of LPG into the inlet manifold. It is claimed that the LPG increases the burning efficiency of the diesel fuel from typically 75-85%, to 95-98%.

The systems typically operate by metering a small quantity of LPG, at a pressure slightly above atmospheric, into the intake manifold, where it enters the combustion chamber and is ignited with the diesel. LPG flow is regulated to ensure smooth operation, and will typically only deliver LPG under power.

Some companies claim a 10% to 20% increase in power and torque, and a reduction in overall fuel costs. Any actual savings are dependent on the relative cost of diesel versus LPG. In Australia, where diesel costs substantially more then LPG, savings of 10 to 20% are claimed.

Automotive Accessories : Spark Plug Voltage Stabilizer

* for Petrol/Gasoline vehicles

The spark [at the spark plug] is fundamental to cause ignition and thus combustion of the Air/Fuel mixture.

Spark at the spark plug is created by a high voltage that comes from the ignition coil.

The +12 Volt car battery is the main power source to many users of a vehicle; i.e.

* air conditioner
* head-lights
* wipers
* hi-fi and radio
* other electrical items, etc

As such, consistent supply cannot be guaranteed to the ignition coil via the +12 Volt Car Battery. When this happens, the spark may be too small to cause burning of the Air/Fuel mixture, or mis-firing, causing 100% unburn fuel to be released to the environment through the exhaust system.

This is also true when the vehicle is running at high rpm, and sparkings has to take place in shorter interval. So, when the car battery is not able to consistently supply the same power to the ignition coil, smaller or no sparking will occur.


Concept of Work

The Spark Plug Voltage Stabilizer is installed at the front of the ignition coil(s).

The Spark Plug Voltage Stabilizer concept of work is to take residual energy from the car and make it into good use. It relies less of the car battery in supplying the require power to the ignition coil. Revolutionary circuit design allows more Sparks.And this is achieved through a much higher Voltage delivery to the spark plugs.

* Impact of Optimized sparks
o Reducing unburn fuel will improve Fuel Consumption; because of less wastage [unburn fuel].
o The result of better burning improves car response, increasing power to the vehicle.


Types of Ignition Coils

The Spark Plug Voltage Stabilizer works on all different types of Ignition Coil Designs.

Earlier car design has the ignition coil as a separate unit. It is then connected to a 'distributor unit' which will sequence the high voltage generated to the respective spark plug.

Current design for single ignition coil system is called the 'Built-In Coil'. This houses both the Ignition Coil and Distributor as one unit.

* Single Coil - works with a separate Distributor unit
* Built-In Coil - Ignition Coil and Distributor unit in one
* Multi Coil; may be
o 2 Ignition coils
+ 1 Ignition coil to 2 spark plugs, or
+ 1 Ignition coil to 3 spark plugs [V6 engine]
o 3 coils
+ 1 Ignition coil to 1 spark plug, [3 cylinders engine eg. Perodua [Malaysia] or
+ 1 Ignition coil to 2 spark plugs [V6 engine]
o 4 coils
+ 1 Ignition coil to 1 spark plug [DIS - Direct Ignition Coil System, or Distributorles Ignition Coil System]
o More than 4 Coils, such as 6 coils (V6 engine), etc


Factors to better Fuel Consumption

There are many websites giving advice to improve fuel economy. Beside ensuring the vehicles at tip top conditions, the right foot is key! However, to attack the problem at the source; the Spark Plug Voltage Stabilizer has its merit.

Other products are available in the car accessories market to help in this area. Some of them, notably are :

*
o Voltage Stabilizer
o Magnet systems on the fuel line
o Fuel additives
o Cold Air Intake
o Special Air Filters
o Special Engine Oils
o Special Spark Plugs
o Highly Conductive Spark Plug Cables
o Your Right Foot, artificial or otherwise

*
o Latest product in the market : Patented composite material 'Titanium Ceramic' that influence the breaking up of clustered Air Molecules that allow easier combustion in the cylinder.

Cleaning a car engine

start the engine, let it warm up for a few minutes then shut it off, in order to soften up collected grease and grit in your engine compartment.

correct cleaning temperature for the engine to be is warm but not hot- you should be able to hold your hand to the engine without burning it.

Before cleaning the engine with water, it's imperative to cover electrical and mechanical components beneath the hood to protect them from water damage.

The air intake/air filter, the distributor, the coil and the oil dipstick/breather should be covered using plastic baggies sealed with rubber bands.

It's a good idea to also check the tightness of the
1) oil filler cap
2) power steering filler cap
3) windshield washer fluid cap
4) oil dip stick
5) battery filler caps


Spray all over the engine and engine compartment with non-petroleum based degreaser,

starting from
the bottom and working up.

Citrus degreasing products will not harm the paint or finish on aluminum components and are biodegradable.

After 3-5 minutes use a soft cotton towel or brush to carefully scrub the heavy dirt. Re-spray and re-scrub any areas that need additional cleaning.

Once the whole engine and engine compartment has been cleaned, rinse thoroughly with water.

Try to avoid getting the degreaser on any exterior painted areas as it will strip the wax from your finish. If this happens, it's okay, but you'll have to give those areas a good wax job when you're through.

Once clean, right away take off all the plastic baggies.

Dry any collected water, especially on aluminum parts, with a soft cotton towel.

Using paper towels, dry the battery.

Start the engine and let it warm up, in order to dry the remainder of the engine and evaporate any moisture in sensitive components. Once everything is dry and cooled off is a good chance to put a coating of rubber protectant on your rubber hoses, plastic shields and rubber gaskets.

If the battery terminals are dirty, disconnect the cables and clean both the cable terminals and battery posts with a wire brush.

Reconnect the terminals and retighten. Get some battery terminal spray and spray on the connected terminals to protect them from corrosion.

A thin coating of non-silicone lubricant should be applied to any hinges, throttle cables, cruise control cables and similar moving parts. Now check and top off fluid levels.

Key Engine Parts

key components inside an engine

Spark plug
The spark plug supplies the spark that ignites the air/fuel mixture so that combustion can occur. The spark must happen at just the right moment for things to work properly.

Valves
The intake and exhaust valves open at the proper time to let in air and fuel and to let out exhaust. Note that both valves are closed during compression and combustion so that the combustion chamber is sealed.

Piston
A piston is a cylindrical piece of metal that moves up and down inside the cylinder.

Piston rings
Piston rings provide a sliding seal between the outer edge of the piston and the inner edge of the cylinder. The rings serve two purposes:

* They prevent the fuel/air mixture and exhaust in the combustion chamber from leaking into the sump during compression and combustion.
* They keep oil in the sump from leaking into the combustion area, where it would be burned and lost.

Most cars that "burn oil" and have to have a quart added every 1,000 miles are burning it because the engine is old and the rings no longer seal things properly.

Connecting rod
The connecting rod connects the piston to the crankshaft. It can rotate at both ends so that its angle can change as the piston moves and the crankshaft rotates.

Crankshaft
The crankshaft turns the piston's up and down motion into circular motion just like a crank on a jack-in-the-box does.

Sump
The sump surrounds the crankshaft. It contains some amount of oil, which collects in the bottom of the sump (the oil pan).

Operation and working cycle for Hot bulb engine

The hot-bulb engine shares its basic layout with nearly all other internal combustion engines, in that it has a piston inside a cylinder connected to a flywheel via a connecting rod and crankshaft. The flow of gases through the engine is controlled by valves. The majority operate on the standard 4-stroke cycle of an Induction Stroke, a Compression Stroke, a Power Stroke and an Exhaust Stroke.

The main feature of the hot-bulb engine is the vaporiser or hot-bulb, a chamber usually cast into the engine block and attached to the main cylinder by a narrow opening. Prior to starting the engine from cold, this vaporiser is heated externally by a blow-lamp or slow-burning wick (on later models sometimes electric heating or pyrotechnics was used) for as much as half an hour. The engine is then turned over, usually by hand but sometimes by compressed air or an electric motor.

Air is drawn into the cylinder through the intake valve as the piston descends (The Induction Stroke). During the same stroke, fuel is injected into the hot-bulb by a mechanical jerk-pump through a nozzle. Through the action of the injector and the heat of the hot-bulb, the fuel instantly vapourises. The air in the cylinder then forced through the top of the cylinder as the piston rises (The Compression Stroke), through the opening into the hot-bulb, where it is compressed and therefore its temperature rises. The vaporised fuel mixes with the compressed air and ignites due to the heat of the compressed air and the heat applied to the hot-bulb prior to starting. The fuel ignites, driving the piston down (The Power Stroke). The piston's action is converted to a rotary motion by the crankshaft which drives the flywheel, to which equipment can be attached for work to be performed. The flywheel also conserves momentum to turn the engine over the three strokes when power is not being produced. The piston rises again and the exhaust gases are expelled through the exhaust valve (The Exhaust Stroke). The cycle then starts again.

Once the engine is running, the heat of compression and ignition maintains the hot-bulb at the necessary temperature and the blow-lamp or other heat source can be removed. From this point the engine requires no external heat and requires only a supply of air, fuel oil and lubricating oil to run. The fact that the engine could be left unattended for long periods whilst running made hot bulb engines popular choices for powering generators and pumps.

Hot bulb engine Differences from the Diesel Engine

The hot-bulb engine is often confused with the diesel engine, and it is true that the two engines are very similar. Aside from the obvious lack of a hot-bulb vaporiser in the diesel engine, the main differences are that:

* The hot-bulb engine uses both compression-ignition and the heat retained in the vaporiser to ignite the fuel.

* The diesel engine uses just compression-ignition to ignite the fuel, and it operates at pressures many times higher than the hot-bulb engine.

Due to the much greater and longer-term success of the diesel engine, today hot-bulb engines are sometimes called 'semi-diesels' or 'semi diesel' because they partly use compression-ignition in their cycle.

There is also a detail difference in the timing of the fuel injection process:

* In the hot-bulb engine, fuel is injected into the vapouriser during the Induction Stroke as air is drawn into the cylinder.

* In the diesel engine, fuel is injected into the cylinder in the final stages of the Compression Stroke.

However, Diesel's original engine design used compressed air to blast the fuel into the cylinder. This complex and heavy system limited the speed the engine could run at and the minimum size a diesel engine could be built to. This was needed to inject fuel under sufficient pressure for it to enter the highly compressed air in the cylinder. In hot-bulb engines fuel is injected before compression takes place, allowing a lighter, more accurate injection system to be used. Only when Akroyd-Stuart's mechanical pump-and-injector system that he developed for his hot-bulb engine was adapted by Robert Bosch for use in diesel engines (by making the system run at a much higher pressure) were high-speed diesel engines practical.

Swashplate engine

The swashplate engine is a type of reciprocating engine that replaces the common crankshaft with a circular plate (the swashplate). Pistons press down on a circular plate in a circular sequence, forcing it to nutate around its center. This motion can be simulated by placing a CD on a ball bearing at its centre and pressing down at progressive places around its circumference. The plate, also known as a wobble plate, is typically geared to produce rotary motion. An alternate design replaces the plate with a sine-shaped cam, and is thus known as a cam engine.

The key advantage of the design is that the cylinders are arranged in parallel around the edge of the plate, and possibly on either side of it as well, and are aligned with the output shaft rather than at 90 degrees as in crankshaft engines. This results in a very compact, cylindrical engine. For this reason the design is also known as a barrel engine.

The arrangement also allows the compression ratio of the engine to be changed whilst running by adjusting the distance of the plate from the cylinders.


Applications

Swashplate engines are particularly interesting in the aircraft engine role, where their compact size is valuable. However, it appears no swashplate engine has ever been widely used in this role, although there have been numerous attempts to introduce one. This may not be any fault of the design, but the designers themselves. It appears that anyone working on these "oddball" engine designs seems to try to include every advanced feature known at the time, instead of using known technology where possible. The result are designs that never seem to mature.

A more successful application is in torpedoes, where the cylindrical shape is desirable. For example, the modern Mark 48 torpedo is powered by a swashplate engine.

Other applications include pneumatic and hydraulic motors and hydrostatic transmissions. Also some Stirling engines use swashplate arrangement.


History

The first known swashplate engine design was introduced by Statax-Motor of Zurich, Switzerland in 1913. Only a single prototype was produced, which is currently held in the Kensington Museum in London. In 1914 the company moved to London to become the Statax Engine Company and planned on introducting a series of rotary engines; a 3 cylinder of 10 hp, a 5 cyl of 40 hp, a 7 cyl of 80 hp, and a 10 cyl of 100 hp. It appears only the 40 hp design was ever produced, and installed in a Caudron G.II for the British 1914 Aerial Derby but was withdrawn before the flight. Hansen introduced an all-aluminum version of this design in 1922, but it is not clear if it was produced in any quantity. Much improved versions were introduced by Statax's German division in 1929, producing 42 hp in a new sleeve valve version known as the 29B. Greenwood and Raymond of San Francisco acquired the patent rights for the US, Canada, and Japan, and planned a 5 cylinder of 100 hp and a 9 cylinder of 350 hp.

Experimental barrel engines for aircraft use were built and tested by Mr J.O. Almen of Seattle, WA in the early 1920s, and by the mid-1920s the water-cooled Almen A-4 (18 cylinders, two groups of nine each horizontally opposed) had passed its United States Air Corps acceptance tests. It however never entered production, reportedly due to limited funds and the Air Corps' growing emphasis on air-cooled radial engines. The A-4 had much smaller frontal area than water-cooled engines of comparable power output, and thereby offered better streamlining possibilities. It was rated at 425 horsepower (317 kW), and weighed only 749 pounds (340 kg), thus giving a power/weight ratio of better than 1:2, a considerable design achievement at the time.

Indian motorcycle also introduced a swashplate engine, the Alfaro, in 1938. The Alfaro is a perfect example of the "put in everything" design, as it included a sleeve valve system based on a rotating cylinder head, a design that never entered production on any engine.

Stephen DuPont in 2006 wrote a small book, A 1911 Spanish Pilot and MIT Aeroengineer and his 1938 Aeroengine Upgraded for Today, ISBN 0-9777134-0-7, which details the development of a barrel engine for aircraft and contains a brief biography of its inventor, Heraclio Alfaro. DuPont was the son of the founder of the Indian motorcycle company; Alfaro was one of his professors at MIT. DuPont later worked further on developing the barrel engine, particlarly for a helicopter, the Doman.

Some small barrel engines were produced by the H.L.F. Trebert Engine Works of Rochester, New York for marine usage.

Perhaps the most refined of the designs was the British Wooler motorcycle engine of 1937. This design used two pistons per cylinder, moving in opposite directions (see the Junkers Jumo 205 for details). The connecting rods attached to a tilting plate through ball joints, and the plate in turn drove a swashplate for power.

More recently, Axial Vector Engine Company has been attempting to re-introduce the concept, although with limited success to date. Their engine, like many of the others on this list, also suffers from the "put in everything" problem, including piezoelectric valves and ignition, ceramic cylinder liners with no piston rings, and a variety of other advanced features.

Axial piston pump

An axial piston pump is a positive displacement pump that has a number of pistons in a circular array within a cylinder block. It can be used as a stand-alone pump or as a hydraulic motor.


Description

An axial piston pump has a number of pistons (usually an odd number) arranged in a circular array within a housing which is commonly referred to as a cylinder block, rotor or barrel. This cylinder block is driven to rotate about its axis of symmetry by an integral shaft that is, more or less, aligned with the pumping pistons (usually parallel but not necessarily).

* Mating surfaces. One end of the cylinder block is flat and wears against a mating surface on a stationary valve plate. The inlet and outlet fluid of the pump pass through different parts of the sliding interface between the cylinder block and valve plate. The valve plate has two semi-circular ports that allow inlet of the operating fluid and exhaust of the outlet fluid respectively.

* Protruding pistons. The pumping pistons protrude from the opposite end of the cylinder block. There are numerous configurations used for the exposed ends of the pistons but in all cases they bear against a cam. In variable displacement units, the cam is movable and commonly referred to as a swash plate, yoke or hanger. For conceptual purposes, the cam can be represented by a plane, the orientation of which, in combination with shaft rotation, provides the cam action that leads to piston reciprocation and thus pumping. The angle between a vector normal to the cam plane and the cylinder block axis of rotation, called the cam angle, is one variable that determines the displacement of the pump or the amount of fluid pumped per shaft revolution. Variable displacement units have the ability to vary the cam angle during operation whereas fixed displacement units do not.

* Reciprocating pistons. As the cylinder block rotates, the exposed ends of the pistons are constrained to follow the surface of the cam plane. Since the cam plane is at an angle to the axis of rotation, the pistons must reciprocate axially as they precess about the cylinder block axis. The axial motion of the pistons is sinusoidal. During the rising portion of the piston's reciprocation cycle, the piston moves toward the valve plate. Also, during this time, the fluid trapped between the buried end of the piston and the valve plate is vented to the pump's discharge port through one of the valve plate's semi-circular ports - the discharge port. As the piston moves toward the valve plate, fluid is pushed or displaced through the discharge port of the valve plate.

* Effect of precession. When the piston is at the top of the reciprocation cycle (commonly referred to as top-dead-center or just TDC), the connection between the trapped fluid chamber and the pump's discharge port is closed. Shortly thereafter, that same chamber becomes open to the pump's inlet port. As the piston continues to precess about the cylinder block axis, it moves away from the valve plate thereby increasing the volume of the trapped chamber. As this occurs, fluid enters the chamber from the pump's inlet to fill the void. This process continues until the piston reaches the bottom of the reciprocation cycle - commonly referred to as bottom-dead-center or BDC. At BDC, the connection between the pumping chamber and inlet port is closed. Shortly thereafter, the chamber becomes open to the discharge port again and the pumping cycle starts over.

* Variable displacement. In a variable displacement unit, if the vector normal to the cam plane (swash plate) is set parallel to the axis of rotation, there is no movement of the pistons in their cylinders. Thus there is no output. Movement of the swash plate controls pump output from zero to maximum.

* Pressure. In a typical pressure-compensated pump, the swash plate angle is adjusted through the action of a valve which uses pressure feedback so that the instantaneous pump output flow is exactly enough to maintain a designated pressure. If the load flow increases, pressure will momentarily decrease but the pressure-compensation valve will sense the decrease and then increase the swash plate angle to increase pump output flow so that the desired pressure is restored. In reality most systems use pressure as a control for this type of pump. The operating pressure reaches, say, 200 bar (2 MPa or 3000 psi) and the swash plate is driven towards zero angle (piston stroke nearly zero) and with the inherent leaks in the system allows the pump to stabilise at the delivery volume that maintains the set pressure. As demand increases the swash plate is moved to a greater angle, piston stroke increases and the volume of fluid increases, if the demand slackens the pressure will rise and the pumped volume diminishes as the pressure rises. At maximum system pressure the output is almost zero again. If the fluid demand increases, beyond the capacity of the pump's delivery, the system pressure will drop near to zero. The swash plate angle will remain at the maximum allowed and the pistons will operate at full stroke. This continues until system flow-demand eases and the pump's capacity is greater than demand. As the pressure rises the swash-plate angle modulates to try to not exceed the maximum pressure while meeting the flow demand.


Design difficulties

Designers have a number of problems to overcome in designing axial piston pumps. One is managing to be able to manufacture a pump with the fine tolerances necessary for efficient operation. The mating faces between the rotary piston-cylinder assembly and the stationary pump body have to be almost a perfect seal while the rotary part turns at, maybe, 3000 rpm. The pistons are usually less than half an inch (13 mm) in diameter with similar stroke lengths. Keeping the wall to piston seal tight means that very small clearances are involved and that materials have to be closely matched for similar coefficient of expansion.

The pistons have to be drawn outwards in their cylinder by some means. On small pumps this can be done by means of a spring inside the cylinder that forces the piston up the cylinder. Inlet fluid pressure can also be arranged so that the fluid pushes the pistons up the cylinder. Often a vane pump is located on the same drive shaft to provide this pressure and it also allows the pump assembly to draw fluid against some suction head from the reservoir, which is not an attribute of the unaided axial piston pump.

Another method of drawing pistons up the cylinder is to attach the cylinder heads to the surface of the swash plate. In that way the piston stroke is totally mechanical. However, the designer's problem of lubricating the swash plate face (a sliding contact) is made even more difficult.

Internal lubrication of the pump is achieved by use of the operating fluid—normally called hydraulic fluid. Most hydraulic systems have a maximum operating temperature, limited by the fluid, of about 120 °C (250 °F) so that using that fluid as a lubricant brings its own problems. In this type of pump the leakage from the face between the cylinder housing and the body block is used to cool and lubricate the exterior of the rotating parts. The leakage is then carried off to the reservoir or to the inlet side of the pump again. Hydraulic fluid that has been used is always cooled and passed through micrometre-sized filters before recirculating through the pump.


Uses

Despite the problems indicated above this type of pump can contain most of the necessary circuit controls integrally (the swash-plate angle control) to regulate flow and pressure, be very reliable and allow the rest of the hydraulic system to be very simple and inexpensive.

Axial reciprocating motors are also used to power many machines. They operate on the same principle as described above, except that the circulating fluid is provided under considerable pressure and the piston housing is made to rotate and provide shaft power to another machine. A common use of an axial reciprocating motor is to power small earthmoving plant such as skid loader machines. Another use is to drive the screws of torpedoes.

Land Rover 2008 LR2

Type:
Five-door,
all-wheel drive luxury small SUV

Retail price:
$34,700 to $40,350

Engine:
3.2-liter inline six-cylinder, 230-hp; 234-pound-feet torque

Transmission:
Six-speed automatic, with clutchless shifting

EPA mileage:
16 mpg city / 23 mpg highway

Notes:
Hits showrooms in April.


Exterior:
Excellent. A distinctive, boxy Land Rover.

Interior:
Good. Luxurious and comfortable, even in the back. Only the cluttered center console kept the rating from being excellent.

Safety:
Excellent. Stability control and roll over control standard. Full set of front, side, and side curtain airbags are standard.

Performance:
Excellent. Performs well on the highway and trails. Engine is powerful and handling is crisp when taking tight mountain turns or making sandy donuts.

Notes:
The LR2 is an excellent vehicle and the price is very competitive when comparing it to other high-end compact SUVs such as the Acura MDX and BMW X3.