Honda B20A engine

Partially unrelated to the Honda B-series engines are the B20A and B21A. By some, these are not considered to be part of the B-series group of engines because they are not compatible with any of the other B-series parts or chassis.


There were 2 versions of the B20A

* The first generation of B20A engines was available in the 86-87 Prelude 2.0SI in Japan, the 86-89 Honda Vigor and Accord . It leaned towards the front of the car just like the A20A engine found in the same cars. This B20A produces 160 hp and 140 ft·lbf torque.

*
o There was also a similar engine named B18A for the 86-89 Accords. It was a destroked B20A powered by 2 Sidedraft Keihin carbs.

* The second generation of B20A was found in the 88-91 Prelude. The 88-91 Prelude B20A and B21A blocks are cast so they lay at an 18-degree angle leaning towards the firewall. This was done to please the exterior specifications for the 1988-1991 3rd Generation Prelude due to its ultra-low hoodline which Honda dubs the "engineless design".

The B20A, B20A3, and B20A5 engines consisted of closed-deck aluminum blocks with thicker-than-average iron sleeves where as the B21A1 had some special material.

The B21A1 was basically a re-worked B20A5 with an increase in bore to 83 mm. The external block dimensions had to stay identical to the B20A5 block so Honda called upon Saffil to create a thin but strong cylinder liner called FRM (Fiber Reinforced Metal) which basically consisted of a carbon fiber matrix, aluminum alloy, and aluminum oxide to make a very strong cylinder sleeve. These sleeves are so strong that they often do not lose their factory cross-hatching marks after 200,000 miles! A lot of B21A1 engines burn oil and have low cylinder compression numbers because the FRM material is so strong that it tears up piston rings. Good news though, you can usually replace the piston rings without any honing to the sleeves and go another 100,000+ miles without any sleeve wear.


B20A

(16-Valve, 4 Cylinder, DOHC, PGM-FI)

* Found in:
o Serial numbers 1000001~, 1500001~ and 1550001~ (Gold Valve Cover)
+ 1985-1986 Honda Prelude Non-U.S.
+ 1985-1986 Honda Accord Non-U.S.
+ 1985-1986 Honda Vigor Non-U.S.
o Serial numbers 1600001~ and 1640001~ (Black Valve Cover)
+ 1987-1989 Honda Accord Non-U.S.
+ 1987-1989 Honda Vigor Non-U.S.
* Displacement: 1958 cc
* Compression: 9.4:1
* Power: 160 hp @ 6300 rpm & 140 ft·lbf @ 5000 rpm
* Transmission: B2K5, F2K5


B20A

(16-Valve, 4 Cylinder, DOHC, PGM-FI)

* Found in:
o 1987-1990 Honda Prelude Japan Domestic Market
* This carries the same engine code as the original B20a above, but is actually a different engine.
* The serial number for these B20A will be: 5000001~


B20A2

(16-Valve, DOHC, PGM-FI)

* Found in:
o 1986-1989 Honda Accord Non-U.S.


B20A3

(12-valve, SOHC, dual side-draft carburetors)

* Found in:
o 1988-1991 Honda Prelude 2.0 S
* HorsePower: 104 @ 5800 (MT) 105 @ 5800 (AT)
* Torque: 111 @ 4000


B20A4

(12-Valve, SOHC, dual side-draft carburetors)

* Found in:
o 1988-1991 Honda Prelude Non-U.S.


B20A5

(16-valve, DOHC, PGM-FI)

* Found in:
o 1988-1991 Honda Prelude 2.0Si
* Power: 135 hp
* Engine cc: 1958.14
* Cylinder cc: 489.535
* Deck cc: 13.885
* Head cc: 47.3
* Compression Ratio: 9.0:1

engine using a pk-2 honda ECU based on oki83c154 processor (intel 8051 based with external ROM)


B20A6

(16-Valve, DOHC, PGM-FI)

* Found in:
o 1988-1991 Honda Prelude Non-U.S. New Zealand, and Australian Domestic Market

140hp@6000rpm 170nm@5500rpm KY model is one of them



B20A7

(16-Valve, DOHC, PGM-FI)

* Found in:
o 1988-1991 Honda Prelude Non-U.S. UK, France, Holland, Norway, South Africa
* Power 150 hp@6000 rpm
o Torque 180Nm@5500 rpm
+ Compresion ratio 10.5:1


B20A8

(16-Valve, DOHC, PGM-FI)

* Found in:
o 1988-1991 Honda Prelude Non-U.S. Russian, Swedish Domestic Market


B20A9

(16-Valve, DOHC, PGM-FI)

* Found in:
o 1990-1991 Honda Prelude Non-U.S. Finland, German, Norway, Netherlands, Russia, Argentina
* Power 140 hp@6000 rpm
o Torque 175Nm@4500 rpm
+ Compresion ratio 10.5:1


B21A

(16-valve, DOHC, PGM-FI)

* Found in:
o 1990-1991 Honda Prelude Si States
* Very rare, it was only produced for the "Si States" models in Japan
* Power: 185


B21A1

(16-valve, DOHC, PGM-FI)

* Found in:
o 1990-1991 Honda Prelude Si
* Power: 140 hp @5800 rpm
* Torque: 135 lb.ft @5000 rpm
* Engine cc: 2056.03
* Cylinder cc: 514.0075
* Deck cc: 10.191
* Head cc: 51.0
* Compression Ratio: 9.4:1

Torque (lb.ft. @ rpm): 135@5000