Honda B20A engine

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title: "Honda B20A engine" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["honda-engines", "1985-introductions", "straight-four-engines"] topic_path: "general/honda-engines" source: "https://en.wikipedia.org/wiki/Honda_B20A_engine" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::data[format=table title="Infobox automobile engine"]

Field	Value
name	Honda B20A engine
image	B20A GoldTop.jpg
manufacturer	Honda
production	1985–1991
configuration	DOHC and SOHC inline-four
successor	Honda B engine
::

The Honda B20A engine series, known as the B20A and B21A, was an inline four-cylinder engine family from Honda introduced in 1985 in the second-generation Honda Prelude. Also available in the contemporary third-generation Honda Accord in the Japanese domestic market, along with the Accord-derived Vigor, the B20A was Honda's second line of multivalve DOHC inline four-cylinder engines behind the "ZC" twin-cam variant of the ordinarily SOHC D-series, focused towards performance and displacing 2.0 to 2.1 litres.

The third-generation Prelude was exclusively powered by the B20A engine family and production of the B20A engine family ended with the conclusion of the production of the third-generation Prelude in 1991.

History

The B20A would be succeeded by the Honda B engine family. Although sharing similar nomenclature and some design elements, the earlier B20A substantially differs from the later B-series in architecture enough to be considered two different engine families and is also not to be confused with the B20B, a 2.0 liter DOHC engine introduced alongside the Honda CR-V in 1994.

There were two versions of the B20A:

The first generation of B20A engines was available in the 85–87 Prelude 2.0SI in Japan and in Europe, 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 PS and 140 lbft torque in Japan. In Europe this is called B20A1, producing 137 hp and 127 lb.ft (172 Nm).
The second generation of B20A was found in the 87–91 Prelude. The 87–91 Prelude B20A and B21A blocks are cast so they lie 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 hood line which Honda dubs the "engineless design" and also for handling reasons; placing the engine at an angle gives it a lower center of gravity (similar to straight 6 designs in older BMW's).

There was also a similar engine named B18A for the 86–89 Accords and Vigors. It was a de-stroked B20A powered by two side-draft Keihin carburetors.

All B20A engines consisted of closed-deck aluminium blocks with thicker-than-average iron sleeves whereas the B21A1 had FRM (fiber reinforced metal) cylinder liners.

The B21A1 was basically a re-worked B20A5 with an increase in bore to 83 mm. The external block dimensions had to stay identical (although there was increased external strengthening and webbing on the B21) to the B20A5 block so Honda called upon Saffil to create a thin but strong cylinder liner using FRM (fiber reinforced metal) which consisted of a carbon fiber matrix, aluminium alloy, and aluminium oxide to make a very strong cylinder sleeve. The sleeve is so strong, in fact, that it wears out the piston rings, causing low compression numbers, severe smoking, and high oil usage. It is possible in many situations to merely replace the worn rings in order to revive the motor's former output. Many machine shops will not attempt to re-hone or re-bore the FRM sleeves, as this type of sleeve will de-laminate during machining operations.

B18A

The original B18A is a short-stroked version of the B20A. It is not considered to be part of the modern B-series family, despite sharing its dimensions with the later B18A1.

(16-valve, DOHC, dual side-draft carburetors)

Found in:
- 1986–1989 Honda Accord Aerodeck LXR-S/LX-S (Japan)
- 1986–1989 Honda Accord EXL-S/EX-S (Japan)
- 1986–1989 Honda Vigor MXL-S (Japan)
  - Displacement: 1834 cc
  - Compression: 9.7:1
  - Bore x Stroke: 81x89 mm
  - Dual Keihin carburetors
  - Power: 100 PS at 6100 RPM & 128 lbft at 4700 RPM
  - Transmission: A2N5, E2N5

{{anchor|B20A1}} B20A, B20A1

(16-valve, DOHC, PGM-FI)

"Honda" logo in center of valve cover – Filler cap on left side of cover.
Found in:
- Serial numbers 1000001~, 1500001~ and 1550001~
  - 1985–1987.03 Honda Prelude Non-U.S.
  - 1985.06–1987.04 Honda Accord Non-U.S.
  - 1985.06–1987.04 Honda Vigor Non-U.S.
- Serial numbers 1600001~ and 1640001~
  - 1987.05–1989.08 Honda Accord Non-U.S.
  - 1987.05–1989.08 Honda Vigor Non-U.S.
Displacement: 1958 cc
- bore: 81 mm
- stroke: 95 mm
Compression: 9.4:1
Power:
- (JDM GOLD TOP B20A 1985.06–1987.04) 160 PS at 6300 rpm & 137 lb.ft (186 N·m) at 5000 rpm (!JIS Gross data), using PH3 ECU
- (JDM BLACKTOP B20A 1987.05–1989.08) 145 PS at 6200 rpm & 127 lb.ft (173 N·m) at 4000 rpm (!JIS Net data with new dual-stage intake manifold), using PH3 ECU
- (EDM, B20A1 Gold Top) 137 PS at 6000 rpm & 127 lb.ft (172 N·m) at 4000 rpm, using PJ5 (602,603,752), PJ7, PH3 ECU w vac. advance
Transmission: B2K5(86–87), F2K5(88–89)

The B20A installed in 1988–1991 Preludes have the following specifications:

(16-valve, DOHC, PGM-FI)

Found in:
- 1987–1991 Honda Prelude 3rd gen Non-U.S.
Power: 145 PS at 6000 rpm
Torque: 128tq at 4500 rpm
Compression ratio: 9.4:1

B20A2

(16-valve, DOHC, PGM-FI)

Found in:
- 1987–1989 Honda Accord (CA5), Europe
Power: 137 PS at 6000 rpm

B20A3

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

Found in:
- 1987–1990 Honda Prelude 3rd gen 2.0 S
Power: 109 hp at 5800 rpm (MT) with catalytic converter, 115 hp at 5800 rpm without catalytic converter
Torque: 111 lbft at 4000 rpm
It was PGM-CARB microprocessor controlled (pk-1)

B20A4

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

Found in: 1987–1991 Honda Prelude 3rd gen Non-U.S.
Fuel system: 2 carburetors
Displacement (cm3): 1958
Bore x Stroke (mm): 81 x 95
Compression ration: 9.2:1
Maximum power: 114 hp at 5800 rpm
Maximum torque: 116 ft lb at 4500 rpm
Catalytic converter: no
ECU: no

B20A5

(16-valve, DOHC, PGM-FI)

Found in:
- 1987–1991 Honda Prelude 3rd gen 2.0Si
Power: 135 hp at 6200 rpm
Torque: 127 lbft at 4000 rpm
Engine cc: 1958.14
Cylinder cc: 489.535
Deck cc: 13.885
Head cc: 47.3
Compression Ratio: 9.0:1

B20A6

(16-valve, DOHC, PGM-FI)

Found in:
- 1987–1991 Honda Prelude 3rd gen Non-U.S. and Australian Domestic Market 142 hp at 6000 rpm 174 Nm at 4500 rpm KY model is one of them

B20A7

(16-valve, DOHC, PGM-FI)

Found in:
- 1987–1991 Honda Prelude 3rd gen Non-U.S. UK, France, Holland, Norway, South Africa, New Zealand
Power 150 PS at 6000 rpm
Torque 132tq (180 Nm) at 5500rpm
Compression ratio 10.5:1
Bore 81 mm
Stroke 95 mm
Engine capacity 1958 cm3 or 119.5 cu-in

B20A8

(16-valve, DOHC, PGM-FI)

Found in:
- 1987–1991 Honda Prelude 3rd gen Non-U.S. Russian, Swedish Domestic Market
- 1988–1989 Honda Accord Non-U.S.
Power 133 PS at 6000 rpm

B20A9

(16-valve, DOHC, PGM-FI)

Found in:
- 1990–1991 Honda Prelude 3rd gen Non-U.S. Finland, Germany, Norway, Netherlands, Russia, Argentina
Power 139 hp at 6000 rpm
Torque 129tq (175 Nm) at 4500 rpm
Cylinder cc: 489.535
Deck cc: 13.885
Head cc: 47.3
Compression ratio 9,3:1

File:B20a9stamp.jpg| B20A9 engine code stamp

B21A

(16-valve, DOHC, PGM-FI)

Found in:
- 1990–1991 Honda Prelude 3rd gen Si States
Very rare, it was only produced for the "Si States" models in Japan
Power: 145 PS
Torque: 186 N·m (137 lb·ft)
Compression Ratio: 9.4:1 engine using a pk-3 honda ECU

File:B21a.jpg| B21a File:B21Astamp.jpg| B21A engine code stamp

B21A1

(16-valve, DOHC, PGM-FI)

Found in:
- 1990–1991 Honda Prelude 3rd gen SI USDM
- 1990–1991 Honda Prelude 3rd gen SR Canadian Market
Power: 140 hp at 5800 rpm
Torque: 135 lbft at 5000 rpm
Engine cc: 2056.03
Bore 83 mm
Stroke 95 mm
Cylinder cc: 514.0075
Deck cc: 10.191
Head cc: 51.0
Compression Ratio: 9.4:1

File:B21a1front.JPG| Block casting – FRONT File:B21a1rear.JPG|Block casting – REAR

Sources

References

"Honda Prelude 3G 1988–1991 – Specyfikacje".

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