The Honda H23A1 is a 2,259 cc, inline‑four petrol engine produced between 1993 and 1997. It features a single overhead camshaft (SOHC) with 16 valves and Honda's PGM-FI (Programmed Fuel Injection) system. This design prioritized smooth, linear power delivery and low-end torque for larger Honda coupes, producing 118 kW (160 PS) and 214 Nm of torque.
Fitted primarily to the fourth-generation Honda Prelude (BB4/BB6) for the North American and Japanese markets, the H23A1 was engineered for refined, comfortable cruising with a sporty character. Emissions compliance for its production period was met through electronic fuel injection and a catalytic converter, allowing it to meet US EPA Tier 0 and Japanese 1993 standards.
One documented engineering characteristic is its use of a balance shaft to reduce vibration, detailed in Honda Service Bulletin 93-035. This feature enhanced refinement in the Prelude coupe, distinguishing it from the performance-oriented H22A which lacked this component and featured VTEC.
Honda
Production years 1993–1997 meet applicable US EPA Tier 0 and Japanese emissions standards for passenger vehicles of that era (Honda Internal Emissions Certification Docs).
The Honda H23A1 is a 2,259 cc inline‑four naturally aspirated petrol engine engineered for sporty coupes (1993-1997). It combines SOHC 16-valve architecture with PGM-FI fuel injection and a balance shaft to deliver smooth, linear power and refined cruising. Designed to meet early-1990s emissions standards, it prioritizes drivability and mechanical simplicity.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 2,259 cc | |
| Fuel type | Petrol | |
| Configuration | Inline‑4, SOHC, 16‑valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 87.0 mm × 95.0 mm | |
| Power output | 118 kW (160 PS) @ 5,800 rpm | |
| Torque | 214 Nm @ 4,800 rpm | |
| Fuel system | PGM-FI (Programmed Fuel Injection) | |
| Emissions standard | US EPA Tier 0 / Japanese 1993 Standards | |
| Compression ratio | 9.8:1 | |
| Cooling system | Water‑cooled | |
| Turbocharger | None | |
| Timing system | Belt-driven | |
| Oil type | 10W-30 (API SH) | |
| Dry weight | 145 kg |
The balance shaft provides exceptional smoothness for a large four-cylinder engine but adds complexity. Strict adherence to 90,000 km timing belt replacement intervals is critical to prevent catastrophic failure. The PGM-FI system requires clean fuel filters and properly functioning sensors for optimal performance. The distributor-based ignition system should be inspected for wear. Regular oil changes with the correct viscosity protect the valvetrain and balance shaft bearings.
Oil Specs: Requires 10W-30 meeting API SH specification (Honda Owner's Manual 1994 Prelude).
Emissions: Certification applies to 1993-1997 models for North American and Japanese markets (Honda Internal Emissions Certification Docs).
Power Ratings: Measured under SAE J1349 standards (Honda Group PT-1995).
Honda Technical Information System (TIS): Workshop Manual 1994 Prelude, SIB 93-035
Honda Electronic Parts Catalogue (EPC): Doc. H-H23A1-93
Honda Owner's Manual: 1994 Prelude
The Honda H23A1 was used across Honda's BB platform with transverse mounting. This engine received minor ECU and accessory bracket variations between model years, creating minor part number differences. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped on the front of the engine block, near the timing belt cover (Honda Workshop Manual 1994 Prelude). Visually, it can be identified by its SOHC valve cover and the presence of a balance shaft housing at the bottom of the engine block. Critical differentiation from the H22A: The H23A1 has a longer stroke (95.0 mm vs 90.7 mm), no VTEC system, and includes a balance shaft for refinement. The distributor is mounted at the rear of the cylinder head.
The H23A1 is renowned for its durability, with the primary long-term concern being timing belt failure if replacement intervals are neglected. Honda service data indicates that failure to replace the belt at 90,000 km can lead to catastrophic engine damage due to its interference design. The distributor and balance shaft seals are also common wear items after 150,000 km.
Analysis derived from Honda technical bulletins (1993-1997) and aggregated workshop repair data. Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about HONDA H23A1.
Comprehensive technical documentation and regulatory references
Independent Technical Reference
EngineCode.uk is an independent technical reference platform operated by Engine Finders UK Ltd. We are not affiliated with HONDA or any other manufacturer. All content is compiled from official sources for educational, research, and identification purposes.
Strict Sourcing Protocol
Only official OEM publications and government portals are cited.
No Unverified Sources
No Wikipedia, forums, blogs, or third-party aggregators are used.
Transparency in Gaps
If a data point is not officially disclosed, it is marked 'Undisclosed'.
Regulatory Stability
EU regulations are referenced using CELEX identifiers for long-term stability.
HONDA Official Site
Owner literature, service manuals, technical releases, and plant documentation.
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
Type-approval guidance and documentation.
Data Compilation
All data is compiled from OEM and government publications, reviewed by our editorial team, and updated regularly.
Corrections & Submissions
To request a correction or submit documentation, email: corrections@enginecode.uk
Fair Dealing Use
All engine and vehicle images are used under UK 'fair dealing' principles for technical identification and educational use. Rights remain with their respective owners.
Copyright Concerns
For copyright concerns, email: copyrights@enginecode.uk
GDPR Compliance
EngineCode.uk complies with UK GDPR. We do not collect personal data unless explicitly provided.
Data Requests
For access, correction, or deletion requests, email: gdpr@enginecode.uk
Trademark Notice
All trademarks, logos, and engine codes are the property of their respective owners. Use on this site is strictly for reference and identification.
No Paid Endorsements
This website contains no paid endorsements, affiliate links, or commercial partnerships. We do not sell parts or services.
Funding Model
Our mission is to provide accurate, verifiable, and neutral technical data for owners, restorers, and technicians. This site is self-funded.
All specifications and compatibility data verified against officialHONDA documentation and EU/UK regulatory texts. Where official data is unavailable, entries are marked “Undisclosed“ .
All external links open in new tabs. Please verify current availability of resources.
