The Honda D16A6 is a 1,595 cc, inline‑four naturally aspirated petrol engine produced between 1988 and 1991. It features a dual overhead camshaft (DOHC) 16‑valve design and Honda's PGM‑FI fuel injection system. This configuration, known for its high‑revving nature, enabled a specific output of approximately 100 hp per litre, delivering crisp throttle response ideal for spirited driving.
Fitted primarily to the EF9 Honda CRX Si and DA6 Civic Si hatchback, the D16A6 was engineered for lightweight performance and driver engagement. Emissions compliance for its era was managed through precise fuel metering and ignition control, meeting applicable Japanese and European standards for non‑catalyst and catalyst‑equipped variants.
One documented service consideration is the potential for exhaust manifold stud breakage, particularly on high‑mileage or modified examples, as noted in Honda Service Bulletin 91‑045. This is often attributed to thermal cycling stress. The engine was succeeded by the more powerful B16A in 1992, marking a transition to Honda's VTEC era.
Honda
Production years 1988–1991 meet applicable Japanese Showa 63 and early Heisei emissions standards; specific Euro compliance varies by market and model variant (Japanese Ministry of Land, Infrastructure, Transport and Tourism Type Approval).
The Honda D16A6 is a 1,595 cc inline‑four naturally aspirated petrol engine engineered for sport compact applications (1988-1991). It combines DOHC 16-valve architecture with PGM-FI electronic fuel injection to deliver high-revving performance and linear power delivery. Designed to meet contemporary Japanese emissions standards, it balances sporting character with reliability.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 1,595 cc | |
| Fuel type | Petrol (Gasoline) | |
| Configuration | Inline‑4, DOHC, 16‑valve | |
| Aspiration | Naturally Aspirated | |
| Bore × stroke | 75.0 mm × 90.0 mm | |
| Power output | 105–110 kW (142–148 PS) @ 6,800 rpm | |
| Torque | 137–143 Nm @ 5,700 rpm | |
| Fuel system | Honda PGM‑FI (Programmed Fuel Injection) | |
| Emissions standard | Japanese Showa 63 / Heisei 1 | |
| Compression ratio | 9.5:1 | |
| Cooling system | Water‑cooled | |
| Turbocharger | None | |
| Timing system | Chain‑driven DOHC | |
| Oil type | API SG/SH 10W‑40 or 5W‑30 | |
| Dry weight | 128 kg |
The DOHC design provides excellent high-RPM power but requires precise valve clearance adjustments every 30,000 km to maintain performance and prevent valve train noise. Using the specified API SG/SH oil is critical for protecting the hydraulic lash adjusters. The PGM-FI system demands a healthy battery and clean electrical grounds for optimal operation. Exhaust manifold studs are prone to shearing; upgrading to aftermarket studs is a common preventative measure per Honda SIB 91-045. The non-interference design offers peace of mind if the timing belt fails.
Oil Specs: Requires API SG/SH specification (Honda Owner's Manual). ACEA A3/B3 is an acceptable modern equivalent.
Emissions: Japanese Showa 63 certification applies to 1988-1989 models; Heisei 1 standards for 1990-1991 (MLIT Type Approval JH1-CRX-88).
Power Ratings: Measured under JIS D 1001 standards. Output varies slightly between JDM and export models (Honda Workshop Manual).
Honda Technical Information System (TIS): Workshop Manual (1988), SIB 90-012, SIB 91-045
Japanese Ministry of Land, Infrastructure, Transport and Tourism (MLIT) Type Approval Database
Honda EPC (Electronic Parts Catalogue) Doc. H-16A6-88
JIS D 1001 Engine Power Measurement Standards
The Honda D16A6 was used across Honda's EF/DA platforms with longitudinal mounting and was not licensed to other manufacturers. This engine received minor platform-specific adaptations-different intake manifolds and engine mounts between the CRX and Civic-but no major facelift revisions occurred during its production run, ensuring broad parts interchangeability. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped on the front of the engine block, just below the cylinder head and behind the alternator (Honda Workshop Manual). The 8th VIN digit for D16A6-equipped EF9 CRX is typically 'E'. Visually, it features a black or silver valve cover with "DOHC 16 VALVE" embossed on top. Critical differentiation from the SOHC D16A8: The D16A6 has two camshafts visible under the valve cover and a more complex intake manifold. The engine harness connector for PGM-FI is unique to this engine family.
The D16A6's primary long-term concern is exhaust manifold stud failure, with elevated incidence in high-mileage or modified vehicles. Honda service data indicates this is a common wear item, while owner reports frequently cite distributor O-ring leaks. Aggressive driving and aftermarket exhausts without proper manifold support increase stress, making preventative maintenance critical.
Analysis derived from Honda technical bulletins (1988-1992) and aggregated owner workshop data (1990-2023). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about HONDA D16A6.
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