This guide provides detailed information on swapping a Honda B series OBD2 engine into an OBD1 vehicle. While focusing on 5-speed manual transmissions, it also touches upon key considerations for automatic to manual conversions.
Understanding the Basics
Before diving into the swap, familiarize yourself with these terms:
- OBD2a: Refers to 1996-1998 Civic and 1996-1999 Integra models.
- OBD2b: Refers to 1999-2000 Civic and 2000-2001 Integra models.
- EWH: Engine Wire Harness.
- VTS: VTEC Solenoid.
- VTPS: VTEC Pressure Switch.
- KS: Knock Sensor.
- IACV: Idle Air Control Valve.
- Dizzy: Distributor.
- PnP: Plug and Play.
Engine Installation: Mounts, Linkage, and Axles
96-98 Civic:
Ensure you have the correct mounts, shift linkage, and axles for your specific B series engine (B16, B18, B20 VTEC, etc.).
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Mounts/Brackets: For 96-98 Civics, using 99-00 Si or JDM EK4/9 engine brackets is recommended. These include the front transmission bracket, rear engine “T” bracket, and A/C bracket. For B18 engines, you’ll need a left-side (driver side) dual-post engine block mount. Consider Hasport mounts for upgraded performance and durability. Alternatively, you can use the front transmission bracket and A/C bracket from a 94-01 Integra. Reusing the top transmission mount and left-side dual-post bracket from your stock Civic is possible. For A/C compatibility, a “P54” 94-97 Del Sol DOHC VTEC or a CRV A/C bracket will support the smaller Civic compressor.
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Shift Linkage: A 99-00 Si or JDM EK4/9 shift linkage is highly recommended for 96-00 EK chassis for proper shift lever centering.
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Axles: Axles from 94-01 Integra (all 5-speed models), 99-00 Si, and 94-97 DOHC Del Sol are compatible.
99-00 Civic:
Engine installation information for 96-98 Civics generally applies to 99-00 models as well.
OBD2a/OBD2b Integra:
Generally, you can reuse your existing engine brackets, mounts, axles, and shift linkage.
Wiring the Honda B Series OBD2 Engine
This is arguably the most crucial aspect of the swap.
96-98 Civic:
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EWH: Reuse your existing EWH or a 96-98 EX 5-speed EWH. Do not use an OBD1 EWH in an OBD2 Civic due to incompatibility. If using a non-VTEC EWH, modifications are required for VTEC compatibility: add VTEC wiring, wire in the KS, and perform the IACV mod (converting the 3-wire IACV plug to a 2-wire plug). A 96-98 5-speed EX EWH simplifies the process as it includes these modifications, but might require manual wiring for the second O2 sensor if using a USDM OBD2 ECU.
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Distributor, Injectors, Alternator, IAT, CKF: Several components require modification or replacement for OBD1 compatibility. Options include using OBD2 components for plug-and-play compatibility or adapting OBD1 components through wiring modifications. For the CKF sensor, consider the CKF bypass trick to avoid costly oil pump upgrades.
99-00 Civic:
Wiring information is similar to the 96-98 Civic, but with some differences. The IACV mod is still necessary. Changing the distributor plug to a 99-00 Si, 96-98 Civic, or 96-01 Integra large-sized dizzy plug is required if reusing the SOHC EWH. A 99-00 Si EWH offers similar advantages to the EX harness in the 96-98 Civic.
OBD2a/OBD2b Integra:
Follow the wiring instructions for the corresponding Civic year (96-98 for 96-99 Integras, 99-00 for 00-01 Integras). Alternatively, utilizing a US OBD1 engine wire harness is possible due to backward compatibility. Ensure VTPS, VTS, and KS are wired in for non-VTEC Integras.
Choosing the Right ECU
You have several ECU options, each with its own pros and cons:
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JDM OBD2 ECU: Easiest installation (PnP for OBD2a chassis, requires adapter for OBD2b). Limited upgrade options, no smog legality in the US, speed limiter.
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OBD1 ECU: Requires a jumper harness. Widely reprogrammable, forgiving, no additional sensor requirements (2nd O2, CKF). No smog legality, VTPS wiring required.
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USDM OBD2 ECU: Smog legal with CKF bypass (Integra, Civic Si). Requires 2nd O2 sensor wiring and functionality. Specific ECU choices depend on the chassis and year.
Conclusion
Swapping a Honda B series OBD2 engine into an OBD1 car is a complex project requiring careful planning and execution. This guide provides a comprehensive overview of the process. Remember to research specific details for your application and consult reputable resources for further guidance. Understanding the wiring and ECU options is critical for a successful swap. Remember to consult with local regulations regarding emissions compliance.
