Another Civic

[EF Civic]

Hello... I've been on many different forums over the years, but never thought I'd join one about getting higher MPG out of a car Although it wasn't until last year that I started a job that's a good 45 minute drive one way, so I decided it was time to get a car with better mileage.

Last year I almost bought a 1st gen Honda Insight. Price wasn't quite right though sometimes I wish I had just gone with that. But a friend gave me a 1991 Civic hatchback shell, which I had been storing for him for a few years. He was going to make a project out of it, but changed his mind. Instead of getting rid of it, I'm going to clean it up and make it drivable. I plan on doing some aero mods, as much as I reasonably can.

I picked up a D15Z1 along with its transmission from someone I know. I'll be using an adapter kit for the VX trans since it uses a hydro clutch and the EF is set up with a cable clutch. The Z1 was rebuilt last year, turbocharged & tuned with a Hondata S300 to get better MPG (and a little bump in HP) than stock.

He also had a D15B8 with a very small GT15 turbo, and got crazy good MPG from that setup (I believe upper 60s). He was selling both engines, and it was a hard choice between the two, but the Z1 was rebuilt while the B8 was not.

My current hangup is finding the right turbo, then getting it tuned. The guy who built & tuned this setup hasn't answered all my questions about buying the right turbo. He was using a "GT2554," but the ones I've found aren't clockable. So my project car won't be going anywhere for a while.

[Daox]

Welcome to the site.

My MPG research also started when I got a job far from home. Even though I'm only 7 miles from work now, I still keep it up because I enjoy it.

[sandras]

I'm interested in engine with small turbo's for better mpg. I'll be watching you.

[California98Civic]

Welcome! A turbo with hondata software for FE in a D15 sounds like a fun and interesting project.

I have watched Hondata run its civics at El mirage and Bonneville, and I was aware of this fuel economy hack from them... will be fun to finally see someone using it.

[EF Civic]

So like most of my projects, this a slow moving one. I need to finish making the 1991 shell usable, as it has water leaks, and who knows what condition the gas tank is in after sitting for 5 or so years.

I ended up getting a 1988 CRX HF swap, and a 1990-1991 DX transmission. The HF engine & trans were sitting outside, so I wanted to get that trans rebuilt before using it. The engine I may rebuild someday, but for now it's sitting in my garage safe from mole crickets (one of which was found inside the HF trans ). Under the valve cover, that D15B6 looks fine. It was sitting under a cover, but the trans was not.

The 1988 Civic transmissions aren't so great because they used that-year-specific clutch & flywheel (input shaft splines are different than the 1989-2000 D series). So I picked up the 90-91 DX trans to have a hybrid one made up: DX 1st thru 4th gear, HF 5th gear & 2.95 final drive, DX casing (better condition), DX input shaft (can use newer/better clutches & flywheels). The DX gears will shorten up driving around town a little bit. The 5th gear will be fantastic at higher speeds on the highways -- about 80 MPH at 2400 RPMs.

I ended up swapping the D15Z1 engine & trans into one of my other cars, a del Sol. Since I didn't have the OEM wideband O2 or EGR wiring, I just used a California spec D15Z1 fuel map from pgmfi.org and put that on a chipped ECU. I'm sure it's mostly due to my driving style, but I'm getting 34 MPG at best. I do have a lot of highway driving in the 70-80 mph range. I get the VTEC-induced 16 valve mode at 2700 RPMs.

I just ordered my GT2554 turbo, finally, and I now have the fuel map the previous owner of the engine had used. I can't wait to get it set up the way he had it and see what improvements there are in mileage. The Sol is heavier than the 91 Civic, but I should be able to get the engine set up & running properly before the 91 shell is ready.

More to come in the coming months.

[Gasoline Fumes]

Originally Posted by EF Civic

The 1988 Civic transmissions aren't so great because they used that-year-specific clutch & flywheel (input shaft splines are different than the 1989-2000 D series). So I picked up the 90-91 DX trans to have a hybrid one made up: DX 1st thru 4th gear, HF 5th gear & 2.95 final drive, DX casing (better condition), DX input shaft (can use newer/better clutches & flywheels). The DX gears will shorten up driving around town a little bit. The 5th gear will be fantastic at higher speeds on the highways -- about 80 MPH at 2400 RPMs.

Good idea! I hate the HF 3rd gear, it's too tall for climbing some hills where I live. I should've made a hybrid transmission, but instead I installed a junkyard HF transmission with a bad bearing.