H22A engine and gearbox
into Civic (from Prelude)
Yes: the H22A engine and gearbox from the Prelude (1992-1996) fits the Civic (1992-1995) — difficult difficulty, modifications required.
Installation notes
Required modifications
Chassis: the driver-side gearbox mount must be cut off below the suspension tower for the Hasport mount kit, and a clearance scallop cut into the body near the passenger headlight if the power steering pump is retained (alternatively a 1997-on Prelude pump and bracket clears without cutting). The shifter opening must be enlarged because the Prelude uses a cable shifter where the Civic uses shift rods. The complete exhaust must be replaced - Prelude headers are much longer than the Civic items. Wiring: the Civic engine harness is adapted to the H22A, including extending the alternator power wire, changing and extending injector wiring, a mandatory injector resistor box for the stock peak-and-hold injectors, and new circuits for the O2 sensor (Prelude connector, pins D14/A6/D22/A25 on an OBD1 Civic ECU), VTEC solenoid (A4), VTEC oil pressure switch (D6), knock sensor (D3), intake bypass solenoid (A25/A17) and EGR (A25/A11, A25/D22/D12 - only needed with a P13 ECU).
Important caveats
- Do not use standard Prelude engine mounts with relocated Civic brackets - documented installs done that way repeatedly break mounts from the added stress.
- The heavier H22A reduces ground clearance at the sump and headers; on 14-inch wheels clearance is unacceptable and springs must be chosen for the extra weight.
- The swap must be engineered/certified for road use (this build was mod-plated after completion in Queensland).
- A B18C is an easier swap into an EG with more aftermarket support, and total cost often ends up similar despite the H22A's cheaper purchase price.
- EGR wiring is only functional with a P13 ECU; P28/P72 and similar ECUs ignore it.
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Reference
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