Hey team, I'm rebuilding a 91 Civic (automatic since my girl has to drive too) for some cross country driving and I'm concerned more with fuel efficiency than power. The current engine is shot and since it has to come out anyway, I might as well check and see if we can put something more efficient in.

I've looked around for a couple days and I can't find any info on this swap. Can the engine from the CR-X HF be readily swapped into the Civic hatch? If not, what's stopping it?

 

it can be swapped in, but as far as full efficiency as the hf, not sure you will see it unless you do the full swap which is the the ecu, manifold and egr wiring. since your hb is a dx and auto, the hf ecu will not be compatible because the hf set up is mpfi from factory adn your auto hb is a dpfi.

 

Thanks for the knowledge drop. Hmmm, sounds like it'd be pretty straightforward swap if I had a donor car with all that already on and working. I dont though and I dont think I'll be able to get one before the road trip. I'll keep my eyes peeled for a junked CR-X HF and shelf the swap idea for now.

 

Do you already have the complete HF engine?

 

If I'm not mistaken, I don't think the HF ever came in an automatic. If that's true, you'd be hard pressed to find a stock ecu to run that engine correctly in your auto hatch. I think you'd be best trying to find a replacement D15B2, that's your next best engine for fuel economy.

 

ALL HF's are Manual and D15 MPFI with a HF intake manifold and camshaft and the ECU is what makes it HF . you could do a dpfi to mpfi conversion to use the hf motor and ecu but then it has no controller for the automatic transmission. If you already have the d15 HF motor you can pop your DX intake manifold on it and it would be a direct swap and plug and play but there would be really little to no gains as far as economy and at the end of the day its almost 2019 if you and your girl are having to share a ef dx standard base hatch id be looking at buying a 2nd beater and look into making some career/life changes lol

 

So it sounds like the consensus is that I'd basically need a complete donor engine and transmission to get some of that sweet sweet HF fuel efficiency. Even then it's be manual so I'd be have to drive those 8 hour sessions pretty much solo. That's gonna be a no. The DX doesn't get horrible fuel efficiency in automatic (even by today's standards) so the effort vs reward involved doesn't look favorable right now. Maybe after the road trip.

Side note that's consistent with the thread: Could I put just the HF head and manifold on? Or maybe just a cam swap? Even if it's a 10% gain that'll pay for itself across the length of the trip.

Side note that I hope doesn't derail the thread: Lemme throw some context on why I'm interested in the HF conversion. Tbh 2019/modern cars aren't really my thing. They're reasonably reliable and much more fuel efficient for the power that they give, but I dont really care about power. Cars like the og Honda Inisght and the HF hatch get me more excited. I think there's more freedom in knowing that I could quit my software job and still cruise, than in shaving seconds off the 0-60 time. I also dont like the interfaces on modern cars. Compare the 2019 VW interior to a bog standard 91 Civic. To me it looks like the VW is tryna be a spaceship (jesus how many buttons does it have). We dont drive old fuel efficient cars because we can't afford new ones, the old ones just match our priorities better, ya know?