Swapping a B18C engine into an older Honda Civic can seem daunting, especially when dealing with different OBD generations. One common question revolves around the distributor: Do you need to modify it when using an OBD2 B18C engine in an OBD1 chassis? This guide clarifies the process, focusing on utilizing the readily available OBD2 distributor for a plug-and-play experience.
OBD2 Engine Harness: The Key to a Seamless Swap
Forget the outdated methods of using OBD1 parts or splicing harnesses. The most efficient approach involves sourcing a complete OBD2 USDM Integra engine harness (from a 1996 or later model). Crucially, avoid using a Civic harness as it’s a one-piece design. The Integra harness is two-piece, featuring separate plugs on the strut towers, mirroring the OBD1 Civic setup. This compatibility eliminates the need for alternator, injector, or distributor modifications—it’s truly plug and play. Simply connect the OBD2 Integra harness to your OBD1 Civic harness at the strut towers. You’ll have one extra connector on the OBD2 harness, which can be safely tucked away. This setup allows you to retain the B18c Obd2 Distributor.
ECU Options: Choosing the Right Brain for Your B18C
With the harness sorted, you have several ECU options:
OBD1 ECU Options:
- Option 1: OBD1 Manual P72: This classic choice requires sourcing a manual P72 ECU (which can be challenging and expensive), plugging it into your Civic harness, and adding wiring for knock, VTEC, and Intake Air Bypass System (IABs).
- Option 2: OBD1 Automatic P72 Conversion: A more budget-friendly alternative involves converting an automatic P72 to manual operation, offering similar functionality to option 1.
OBD2 ECU Options:
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Option 3: Chipped/Flashed P06 or P28: This route provides tunability advantages. A chipped P06 or P28 (which already has VTEC provisions) can be flashed with a B18C1 tune and modified for IAB control. Professional tuning is recommended for optimal performance. This allows for dyno tuning, a significant advantage.
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Option 4: OBD2 Manual P72 with Conversion Harness: Utilizing an OBD2 P72 with an OBD1 to OBD2 conversion harness (available from suppliers like Rywire) offers a readily available and cost-effective solution. Minor modifications are required, including bypassing the Crankshaft Fluctuation Sensor (CKF) and adding wiring for knock and a secondary O2 sensor. This option is often considered the most straightforward and compliant with emissions regulations.
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Option 5: JDM OBD2 P72 with Conversion Harness: While potentially the cheapest option using a JDM P72 with a corresponding conversion harness, it might not comply with stricter emissions regulations in certain regions like California.
OBD2 Engine Harness
Conclusion: Embracing the Simplicity of OBD2
By leveraging the compatibility of the OBD2 Integra engine harness and the readily available B18C OBD2 distributor, swapping a B18C engine into your OBD1 Honda becomes significantly simpler. Choosing the right ECU to manage your engine will depend on your budget, tuning goals, and local regulations. With careful planning and execution, you can enjoy the performance of the B18C in your classic Honda.
