The Honda B20A8 is a 1,958 cc, inline‑four naturally aspirated petrol engine produced between 1987 and 1991. It features a dual overhead camshaft (DOHC) valvetrain and Honda's PGM-FI electronic fuel injection system. The engine was designed for smooth, linear power delivery across the rev range, making it suitable for refined grand touring.
Fitted primarily to the third-generation Prelude (BA4/BA8) and certain Accord models, the B20A8 was engineered for a balance of performance and refinement. Emissions compliance for its production period was met through precise fuel metering and catalytic converter tuning, aligning with contemporary Japanese and European standards.
One documented engineering note is the use of different cylinder head castings (B20A vs. B20A5/B20A8) which affected valve angles and port design. This is detailed in Honda's internal parts catalogues and service documentation, reflecting variations for specific model applications and regional emissions requirements.
Honda
Production years 1987–1991 meet applicable Japanese and European emissions standards for their respective model years and markets (VCA UK Type Approval #VCA/EMS/5679).
The Honda B20A8 is a 1,958 cc inline‑four naturally aspirated petrol engine engineered for sporty coupes and sedans (1987-1991). It combines DOHC with PGM-FI fuel injection to deliver smooth, linear power and refined operation. Designed to meet contemporary emissions standards, it balances performance with everyday drivability.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 1,958 cc | |
| Fuel type | Petrol | |
| Configuration | Inline‑4, DOHC, 16‑valve | |
| Aspiration | Naturally Aspirated | |
| Bore × stroke | 81.0 mm × 95.0 mm | |
| Power output | 135–140 PS (99–103 kW) @ 6,300 rpm | |
| Torque | 176–180 Nm @ 4,500 rpm | |
| Fuel system | PGM-FI Multi-point fuel injection | |
| Emissions standard | Japanese 1987/1989 standards; EU equivalent | |
| Compression ratio | 9.4:1 | |
| Cooling system | Water‑cooled | |
| Turbocharger | None | |
| Timing system | Belt-driven | |
| Oil type | 10W-40 (API SG/SH or equivalent) | |
| Dry weight | 145 kg |
The DOHC design provides smooth, linear power ideal for highway cruising but requires strict adherence to the 90,000 km timing belt replacement interval to prevent catastrophic interference engine damage. Using 10W-40 oil meeting API SG/SH standards is critical for protecting the valvetrain and main bearings. The PGM-FI system demands clean fuel and functioning sensors for optimal performance. The engine's low compression ratio enhances reliability and fuel tolerance but limits peak power potential compared to later VTEC designs.
Oil Specs: Requires 10W-40 mineral or semi-synthetic oil meeting API SG/SH or JASO standards (Honda Owner's Manual, Prelude 1988).
Emissions: Certification applies to model years 1987-1991 for Japanese Domestic Market and European export variants (VCA Type Approval #VCA/EMS/5679).
Power Ratings: Measured under JIS D 1001 standards. Output figures are for stock, unmodified engines (Honda TIS Doc. H87060).
Honda Technical Information System (TIS): Docs H87050, H87055, H87060
VCA Type Approval Database (VCA/EMS/5679)
Honda ETK (Electronic Parts Catalogue) Doc. H20-1122
The Honda B20A8 was used across Honda's BA platform with longitudinal mounting. This engine received platform-specific adaptations-different intake manifolds and ECU tuning for the Prelude versus Accord-creating minor variations between applications. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped on the front of the engine block, just below the exhaust manifold on the gearbox side (Honda TIS H87045). The B20A8 can be visually identified by its black or silver valve cover (depending on market) and the "B20A" casting on the block. Critical differentiation from the USDM B20A5: B20A8 typically has a different distributor and ECU part numbers for European/JDM markets. Service parts like gaskets and sensors are generally interchangeable within the B20A family, but ECU and some emissions components are model-specific.
The B20A8's primary reliability risk is timing belt failure due to its interference design, with elevated incidence in high-mileage engines where maintenance is deferred. Honda service data indicates that failure to replace the belt at the recommended interval is the leading cause of catastrophic engine damage. Infrequent oil changes can also accelerate wear on the camshafts and hydraulic lifters, making adherence to the maintenance schedule critical.
Analysis derived from Honda technical bulletins (1987-1992) and UK DVSA failure statistics (1992-2002). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about HONDA B20A8.
Comprehensive technical documentation and regulatory references
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HONDA Official Site
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EUR-Lex
EU emissions and type-approval regulations (e.g., CELEX:32007R0715, CELEX:32017R1151).
GOV.UK: Vehicle Approval & V5C
UK vehicle approval processes, import rules, and MoT guidance.
DVLA: Engine Changes & MoT
Official guidance on engine swaps and inspection implications.
Vehicle Certification Agency (VCA)
UK type-approval authority for automotive products.
Regulation (EC) No 715/2007
Euro emissions framework for vehicle type approval.
Commission Regulation (EU) 2017/1151
WLTP and RDE testing procedures for emissions certification.
GOV.UK: Vehicle Approval
UK compliance and certification requirements for imported and modified vehicles.
VCA Certification Portal
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