A few months back I created my first thread stating I wanted to build an USDM H23A1, but since then I've been informed that a JDM H23A would be a better choice. I'm creating this thread hoping I will be given enough knowledge to do this swap and have a complete guide for others wanting to do the same.

 

So far I've had trouble with this project because all of the sources out there are very unclear.
I know when when doing this swap I need 345cc injectors, a chipped ecu, my stock harness, distributor, altenator, and a new exhaust header.
Is there anything else I'm missing?

 

Are you talking about a non-VTEC JDM H23A or a VTEC JDM H23A ???

 

VTEC JDM H23A

 

Transmission

If you're going to tune chipped ecu anyway injectors doesn't matter since youre not using stock ecu

Just get ones which can give enough feed for your engine

 

Doing a manual swap isn't required but will definitely help get the most out of your new engine. Your current transmission will work fine with the H23A though.

Injectors do matter if you intend to run a stock P13. If you can source a stock automatic P13 ecu you will need to use injectors from a 92-96 Prelude VTEC. You would retain your stock TCU(transmission control unit). This will also be the simplest route.

If you plan to run a chipped ECU, the only way is to get a chipped automatic P75 ecu and use it in conjunction with your stock TCU. It must be that specific ECU. P06/P28/other chippable ECUs, etc do not have the internal circuitry required to communicate with the Prelude TCU and your transmission will not work with them at all. That would give you a tunable platform but also allows you to retain the factory functionality of the automatic transmission. There will likely be some re-pinning of the ECU/TCU harnesses required since the P75 uses a slightly different pinout.

 

So, is the P75 the only way to tune an engine which uses an automatic transmission?

 

For the OBD1 Accord/Prelude chassis that use a separate TCU, yes. OBD2A 96-97 can be done this way as well but there's a lot of wiring involved since you have to convert down to OBD1 at the same time. OBD1 cars it's relatively simple. The Accord/Preludes of this era had more shift solenoids than the same era Civics so the Civic ECUs can't control them or communicate with the standalone TCU. It was all integrated into the ECU on the P06/P28s because there were fewer solenoids and the ECU could handle it alone. The workaround with the P75 works because the OBD1 automatic Integras had a B series and also used a separate TCU but the ECU is similar enough to a Civic ECU to be chippable. It's as simple as getting a chipped automatic P75 and swapping a few wires around for OBD1 cars. I did this on my 95 Accord back when I had first turbo'd it(almost 10 years ago now...) and it worked great. Was easily tuned. Transmission didn't last long under boost though lol.

 

Thanks. I plan to stay with OBD1 cars, so this would work for me.