1996 Hond Civic DX Hatch with d15z1 results

[steffen707]

Well 2 years ago I bought a 92 civic vx with 200,000 miles without title for $900. Several months ago I swapped the motor into my 96 dx hatch. The car has manual windows and locks. No power steering, but the AC blows ice cold. Before doing the swap i replaced the clutch and flywheel, spark plugs, timing belt and water pump.

After first doing the swap i had horrible hesitation coming off lean burn, after consulting with some fellow moders I discovered that the factory sugested spark plugs perform much better than the crappy aftermarket junk sombody else had in there. After putting a set of the right plugs in, I gained 10 mpg on the highway, from 30-40mpg. This was only on a 5 mile test using a mpguino, but the hesitation went away. ONLY USE THE PROPER PLUGS.

I was going to swap in an HF final drive, but decided to just try it with the VX gearing first. Boy am I glad i did that. With such a heavy vehicle, I don't think i would get better gas mileage with the HF final drive. I may try it out someday, but for now i'm enjoying the stock VX gearing.

Good news is that the exhaust bolts right up to the center section of the exhaust without any modification.

To compliment my motor, i bought Honda Insight Bridgestone RE92 tires and mounted them on my 10.8 pound miata 14" wheels. What a light weight combo.

After the first 2500 miles I was severely disapointed in the setup. I assumed that my car was much too heavy for the lean burn power output. I was rarely able to maintain 70mph with A/C, usually couldn't maintain 65mph with A/C. Quite frustrated with the car, i decided to try things without A/C, and what a difference this made. I was getting 35 mpg combined city/highway, and after turning off the AC i was up to 49-51mpg average.

This car loves 55-60mph. My girlfriend and I loaded the car up with camping stuff and 2 coolers. With both of us in the car and a full tank of gas the car weighed 2940 lbs. We took a 1400 mile trip through the U.P. which is almost only 2 lane 55mph roads. We averaged 52mpg verified at the pump and was within 1mpg of my mpguino. I put 50psi into the tires before the trip.

I drafted a modern airstream RV for 16 miles at about 55mph maintaining about 2 car lengths distance and was able to achieve 72mpg for those 16 miles. The best i got was going 14 miles down the porcupine mountains which was mostly coasting in 5th gear with 0 throttle, i was able to get 89mpg.

In normal 4 lane highway driving I try to maintain 65mph unless there is a SUV or semi in front of me. Giving as much as 3-4 length of space I can still draft and get 66mpg while drafting at 70mph.

I have noticed that even though I can get into lean burn mode relatively quickly, it likes being fully warmed up before giving the best mileage. For instance, if i drive to my friends place on a cold engine I can get 50mpg for the 2 mile drive. With it fully warmed up from driving around then doing the 2 mile drive, I can get 70mpg. My jaw almost dropped yesterday when I got 75mpg driving 3 miles through town.

Of course limiting the number of full stops is crucial and also coasting to stops yields free miles of travel with 9999999mpg.

Anyways, very long post by me, but hopefully this helps some fellow ecomodders out there with their projects. If you are skeptical that your car is too heavy for a d15z1 swap, use my experience of 2940 lbs civic achieving 52mpg for 1400 mile trip and GO FOR IT!

[Daox]

Great results! Next mod you might want to look into a warm air intake. I believe that that engine really likes them.

[California98Civic]

Originally Posted by Daox

Great results! Next mod you might want to look into a warm air intake. I believe that that engine really likes them.

I have to agree with Daox that the sixth gen motors seem to like WAIs, but I also have to wonder if your fifth gen engine would. Does it have the same sensors? And be aware, I think the WAI might be reducing power, though I can't tell for certain. Still tests for my car, which Daox helped me understand, showed better than a 1% improvement. That's significant at this level of MPG. My design has evolved a lot, and so I'd be happy to offer what I have learned. Might write it up eventually too.

BTW, thanks very very much for the update. I have been considering something exactly like this--in the distant future when I have more skills, tools, and experience.

One suggestion: my 1998 DX Coupe has a stock curb weight of 2262lbs. I have stripped it down almost to about 2016 or something close to that. I think weight reduction matters when you start to pile up the subtractions. I have managed a 10% weight reduction. You could benefit from your own reduction program, I'm sure.

Thanks again!
james

[steffen707]

Do people make intake tubes that mount near the headers for extra heat, or do they just get a short ram that stays under the hood? I was also thinking about doing a partial grill block and a higher temp thermostat. I replaced the old thermostat, but I believe I just got a normal one.

[steffen707]

Originally Posted by California98Civic

One suggestion: my 1998 DX Coupe has a stock curb weight of 2262lbs. I have stripped it down almost to about 2016 or something close to that. I think weight reduction matters when you start to pile up the subtractions. I have managed a 10% weight reduction. You could benefit from your own reduction program, I'm sure.

Thanks again!
james

Definately reducing the weight of the car would yield better mpg, and in daily form it weighs about 500 lbs less than the 2940 figure. Which was full of cargo and another person. I think I weighed it before and with me and full tank of gas it weighed 2500. Stock weight of a 96 dx manual hatch is 2242 lbs.

I love good gas mileage, but i'm not willing to sacrifice things to achieve it in my current car. I like all 4 seats, the carpeting, the A/C when its really hot, though I havn't been using it nearly as often because of the huge 13-17mpg increase.

I have 2 gutted CRX's that I could have put the VX engine in to get ultimate gas mileage, and maybe someday I'll put it in one to feed my curiosity, but for now, 50mpg is awesome, and more than double what my CRV gets.

[California98Civic]

Originally Posted by steffen707

Do people make intake tubes that mount near the headers for extra heat, or do they just get a short ram that stays under the hood? I was also thinking about doing a partial grill block and a higher temp thermostat. I replaced the old thermostat, but I believe I just got a normal one.

I made mine with black plastic plumbing tubing that just barely clears the heads with the trunk closed. My goal was to get the line close to the exhaust manifold--a trick I learned here on EM. The function is the reduce the air density, which the ECU will adjust the fuel air mix in order to keep a stoichiometric balance. The result seems possibly to be an FE benefit through reduced pumping losses. I should write-up my current design, but I'm still trying to figure out an easy way to switch from hotter to cooler air according to season/conditions.

Originally Posted by steffen707

I love good gas mileage, but i'm not willing to sacrifice things to achieve it in my current car. I like all 4 seats, the carpeting, the A/C when its really hot, though I havn't been using it nearly as often because of the huge 13-17mpg increase.

I hear you. My AC was almost never used, even when I lived in the South. It never worked well and I don't like AC, anyway. I have not missed the back seats, but that's because I needed cargo more than seating. Without those deletes and others in the interior you have to go for other things to get closer to the 2094 stock curb weight of the 1992 VX. You took out the PS hardware? How about spare tire? Lighter battery? Rear window glass plexi/lexan substitution? Fiberglass or carbon fiber replacements for body panels?

But here's another thing... considered a SMALL turbo for low end power, like the super sipper TDIs have?

[basjoos]

Originally Posted by steffen707

I drafted a modern airstream RV for 16 miles at about 55mph maintaining about 2 car lengths distance and was able to achieve 72mpg for those 16 miles.

Do a thorough aeromod on your car and you'll be able to get that 72mpg in all of your high speed driving, not just when drafling.

[mugen]

Steffan
just PM'd you about your setup
im working on a similar one