D15Z1 Conversion Questions
 

Honda D15Z1 conversion questions.

I am currently driving a 89 Honda Civic Wagon.

My question is if their is anyone who has successfully installed a D15Z1 and a HF transmission into the Civic. I would like to know how successful this change would be in inproving the mileage of this car. I would also like to know if anyone has sucessfully been able to pass a California smog test, without going to a State referee and all of that baloney.

I know Matt converted his Civic, last year. However the last I heard, he was getting about 29 mpg and he had some electrical issues which he had become pretty frustrated with.

I currently get anywhere from 32 to 37 mpg, with the existing DPFI setup.

Any ideas, thoughts or suggestions would be appreciated.

I really think the 29mpg was due to a few things:

old o2 sensor, which I have since upgraded to a new one
timing - I never bothered to adjust my timing

The wiring issues are easy to track down, I'm sure. just need to take the time to figure it out.

My understanding is that you can put an engine in your car that comes from a NEWER year. Honestly, if your wiring is clean and all, no one would know any better. Wagon's came in MPFI as well as DPFI. You might want to find a valve cover though that doesn't say "VTEC-E" on it.

I think that with a d15z1 and HF tranny you could get 50mpg. I also think though that you could approach that with a HF transmission, which would be a much easier and cheaper upgrade.

Matt: On the transmission, do you know if anything pre 88 will fit without tremendous issues, or if I need to try to locate a 89-91, HF transmission? I know an 88 will fit, but I think the half-shafts have to be matched, or maybe it's just the number of splines on the clutch are different and would need to match the 88.

The transmission swap might be a good way for me to go, because the engine has a rebuilt head, with new rings, bearings, water pump, oil pump, timing belt and all of that stuff.

I think the issue is the axles and the clutch. I could be wrong though. I have honestly forgotten everything about honda's little compability issues. Perhaps someone else can chime in.

88 Honda transmissions had a different spline count in the differential and a smaller clutch area on the flywheel.

Given the state of your engine swapping in an HF transmission is a better and cheaper/easier way to go.

If you go to Autozone.com and set up your vehicle info (year make model) and also the potential donor vehicle info (year make model), you can look and see if the part numbers match up (search for axles, cltch disks etc.)

I am not endorsing Autozone- its just an easy way to see if the part numbers are the same for different vehicles

you coudl also just wait for a 88 HF transmission to show up.

What I should be looking for is a 89-91 HF transmission, it sounds like. I was partially trying to figure out if a 88 or possibly earlier would even work.

Since this isn't really a have-to sort of project, at least at the moment, it will probably be best for me to look for an 89-91.

Thanks for all of the help!

ah yes... I was assuming your wagon was an 88.

I found my 91 HF transmission on honda-tech for $50 plus shipping. I believe shipping was more than the transmission though.

Just remember, CA. HF tranny=3.25 final drive. 49 emission state emissions=2.954 final drive. i should have searched this before i bought my 88 CA. HF tranny :(