D16y5 Turbo or D15Z1?

[AntiochOG]

I used to have a 95 Civic CX with a D16A6 swap. It made 100 whp with an intake and exhaust and was plenty fast. I got 40 mpg all day long driving like an idiot.

[California98Civic]

Originally Posted by oil pan 4

I did some FE testing 64.8mpg - D-series.org

Seems to be a lot more leget than some of the others I have seen out there, mainly because this guy gives actual detals of his setup.

I have seen that link before. But thanks for the reminder! That car's owner established an ecomodder fuel log at one point: 1993 honda del sol s Gas Mileage (dturbosol) - EcoModder.com. And in a couple log entries he reported about 70mpg across full tanks with average speeds of 55mph and 58 mph (during summer). But he did really extensive and complex engine mods, it seems, including designing his own lean burn "prechamber".

Check out his first fuel use gauging method: I did some FE testing 64.8mpg - Page 5 - D-series.org

Here is the fuel map he discusses, in post 50. The highlighted blue is the lean burn zone:


I did some FE testing 64.8mpg - Page 3 - D-series.org

And here's a pic of some aeromods he reports in post #63, reporting over 70mpg:



In post #71 he promotes ecomodder, as he suggests he wants to build a kamm back. In a later post he seeks a CX transmission from a guy.

Here he is designing and prototyping a huge boattail:


Quite an amazing thread. Skills and motivation like few have. Amazing.

[Ryland]

Originally Posted by rabbit640

One mod that comes to mind would be a 2.25 inch piping catback exhaust. I would get better mpg and more power since the motor would be able to exhale at full capacity (emissions standards are non-existent in my city).

The Z1 engine and o2 sensor do not handle over sized exhaust or exhaust leaks without burning out the $300 o2 sensor within a few months, if you get a new o2 sensor you need to fix the exhaust to stock or you've just wasted money.

[rabbit640]

Originally Posted by Ryland

The Z1 engine and o2 sensor do not handle over sized exhaust or exhaust leaks without burning out the $300 o2 sensor within a few months, if you get a new o2 sensor you need to fix the exhaust to stock or you've just wasted money.

Shouldn't be a problem as long as I don't go too far beyond 2 inches. People have gone all the way up to 2.5. I'm just going to 2.25 inches.

[Sven7]

Is your Mazda a manual or automatic? If it's automatic, ditch it.

If it's manual, you could...

-work on your driving habits
-start aggressively aero-modding it for the freeway
-get some used lightweight wheels and remove the rear seats
-build a kammback or boat tail
-buy the VX and trade me for my DX D16 which has plenty of power and 40+mpg highway

But I do recommend that you get some coroplast and do a grille block, wheel covers, rear skirts and a passenger mirror delete immediately (air dam if you feel like throwing $20 at it). Combine that with improving your driving technique and you might be surprised at what you get.

The first tank out of my '92 Ford Probe (with the Mazda 2.2L rated at EPA 21/28mpg) was 38mpg. Nothing special other than some aero work and hypermiling. The car later got a 40-inch boat tail and achieved 41mpg over 400 miles just driving a steady 60 mph.

Your car's EPA figures are comparable to my old Probe, so you can definitely average 40mpg if you try.

[Ryland]

Originally Posted by rabbit640

Shouldn't be a problem as long as I don't go too far beyond 2 inches. People have gone all the way up to 2.5. I'm just going to 2.25 inches.

1.75" exhaust was enough to burn out 2 of the 5 wire o2 sensors on my old civic vx and both my brother and I had the 5 wire o2 sensors burn out on our current vx's from exhaust leaks, it's a common pattern with people who have 5 wire o2 sensor problems to have them burn out after an exhaust leak or switching to a non stock exhaust.

but if you like buying exhaust systems that haven't been proven to increase mileage but that do have a pattern of killing expensive sensors, then go for it.

The stock engine on the VX has some weird sensitivities and it works great in stock form.

[hamsterpower]

Not to discount all the other advice but with the modest goals and performance desired, skip the highway cruiser models (cx-vx) and go straight to the common-man DX. I had a DX take me from NH to FL and back with NO hypermiling or mods @ 35mpg. A stock DX should be close to your goals and a few mods will get you closer for far less money than a VX + turbo.

Swap in the VX 5th gear and adjust the driver, should exceed the goals stated.

[California98Civic]

Originally Posted by hamsterpower

Swap in the VX 5th gear and adjust the driver, should exceed the goals stated.

The fifth and sixth gen d-series DX, VX, CX, and possibly other trim level trannys all had the 0.702 fifth gear. It was the final drive that made the big difference in fwy cruising rpms. Swap the CX/VX final drive into a DX and you get very similar gearing (not the same, but similarly tall).

But I think hamsterpower has a good point too.

Happy father's day to all who might be celebrating right now...

[pgfpro]

Thanks Guys for the kind words.

That car was a major learning experience for me. It was kinda of a love/hate adventure. It was fun in that it was a success but it came with a ton of broken parts and labor hours and lots of $$$. In the end I sold it for a nice new house. So I can't complain to much.

My advice would be on a budget, is to get a nice fuel efficient platform to start with. Then work on the aero. Its by far the most bang for your $$$ that you can do. Plus of course the driving techniques is number one.

[Jakins]

dude get this. i ran my d16y5 civic hx with a little turbo back in high school with an open down pipe. like 4 inches of exhaust just dumping in my engine bay. at first i ran 310cc RC injectors but it wasnt running to nice. and i didnt tune it. i was just running an FMU to manage the fuel. so i went 240cc integra gsr injectors. it ran better and got a little better gas milage. if i remember correctly i was getting like 320-340 to the tank. i got like 400-440 before (before i was a real hypermiler) so i was averaging about maybe 28-34 mpg in my un tuned turbo set up driving the piss out of it. it was quick to. kept up with some v8's. impressed the chicks. but i eventually took it back apart. 40k miles later running stock (with my engine killing dad driving it) the bottom end of my engine kind of totally died. probably because it leaked a quart of oil every 100 miles and it was running lean as hell. but if it wasnt done by an idiot high schooler it probably could have turned out pretty sweet. just needs to be tuned properly.

oh and another thing. my primary o2 sensor. even though it was treated like crap for like 160k miles and is currently 270k old is just now showing signs of failure.