D16y5 Turbo or D15Z1?

[ksa8907]

What kind of mileage are you wanting/expecting? Mid 30's may be all you'll get if you have to be aggressive. Maybe a larger 1.7 or 1.8 with a taller set of gears is what you're looking at. Power goes up as far as you can afford...

[rabbit640]

I don't have to be constantly aggressive. And after seeing people with turbos and low psi getting 64mpg, I definitely think my goals are possible:

City: 40 MPG*
Highway: 50 MPG*

*With occasional bad driving due to the nature of my travels...

[Shortie771]

Originally Posted by rabbit640

And after seeing people with turbos and low psi getting 64mpg

Would you mind sharing where you have gathered this information?

[Ryland]

There are plenty of people who have already ruined perfectly good civic VX's with engine swaps, so if you really want to go that route you might find exactly what you are looking for.
The difference between a VX and a CX once you pull the engine out for an engine swap is the VX has more wiring for the lean burn and the v-tec, if you are going to go with a 3 stage v-tec you are going to have to hack up the wiring anyway and you are not going to use the lean burn part of the wiring and you are going to pull the engine that the car was designed to use and that people get 50-60mpg with stock.

There are plenty of civics with engine swaps but finding one that is stock is rare.

It almost sounds like you need a motorcycle.

[rabbit640]

Originally Posted by Shortie771

Would you mind sharing where you have gathered this information?

Russell would be my source: d-series.org/forums/forced-induction/117099-i-did-some-fe-testing-64-8mpg dot html.

However, other people have done it, but not up to 64mpg. I see a lot of mid 40's though.

[rabbit640]

Originally Posted by Ryland

There are plenty of people who have already ruined perfectly good civic VX's with engine swaps, so if you really want to go that route you might find exactly what you are looking for.
The difference between a VX and a CX once you pull the engine out for an engine swap is the VX has more wiring for the lean burn and the v-tec, if you are going to go with a 3 stage v-tec you are going to have to hack up the wiring anyway and you are not going to use the lean burn part of the wiring and you are going to pull the engine that the car was designed to use and that people get 50-60mpg with stock.

There are plenty of civics with engine swaps but finding one that is stock is rare.

It almost sounds like you need a motorcycle.

Not looking to destroy a beautiful VX. I have respect for this car: honda-tech.com/showthread.php?t=1535304&highlight=turbo

From what I have been reading the 64 mpg turbo y5 is tempting, but most are unsuccessful and end up with a butchered VX getting 35 mpg combined. However, lots of engine swaps with the y5 are successful, yielding more power, but less mpg. Alternatively, I could just stick with a stock z1 and do very minor mods to increase power (very minor). 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).

So.... either boost the power of a z1 or boost the mpg of a y5. Which would be easier?

[niky]

From the thread at the forum, the guy is running a crazy set-up that enables him to do some very ultra-lean burn, using special plugs, cams and a fully programmable EFI.

You're not going to get that within a budget, not the kind of budget you'd throw at a daily beater... and in that state of tune, I doubt it'd pass NOx regulations.

-

Work on your current car. If you have the 2.0 with the manual, you can swap out fifth for an old 626 gear for some extra reach, and get taller tires. You can even chip it for more power and extra lean burn, if the idea of a special map to enable ultra-lean cruising is enticing, this is possible. The 2.0 is very resistant to detonation.

[rabbit640]

I agree with the "russell setup", almost anything is possible if you throw money at it (55 mpg fiero comes to mind). I'm definitely leaning towards a z1 and just trying to boost the power with a few very basic (and cheap) mods. I'll also try and cut weight where I can.

The y5 is not out of my mind yet though..it is very enticing given the 115 hp and the fact that the valves are much larger. I think there would be some serious mpg gain from a new intake and full exhaust (probably more power too).

[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.

[Shortie771]

Originally Posted by rabbit640

I'll also try and cut weight where I can.

Cutting weight will improve your mpg slightly but you would have to cut a lot of weight in order to see any noticeable changes in the environment you drive in. Weight reduction is far more effective in city driving, while aerodynamics play the largest role on the highway.

rrsussel aka dturbosol here on ecomodder, has did a lot more than work on his engine. He incorporated changing his driving habits, aerodynamic and other modifications.

"Try to run high IAT temps. I use a grill block"
"Run your tire pressure at 55psi to 60psi"
"Run with your windows up"
"If you do have AC turn it off"
lowered 2"

Here is his post on ecomodder of his build (link). This one is only 6 pages

I read in one of these posts that his goal was to keep it under $6,000 invested. With that much invested to make 64.8mpg, it will only take ummmm 117,108 miles (8 years to the average driver) to make his money back. Only after that will he begin saving money on gas. He has done an amazing job on that car and is getting great gas mileage, but in the end the upfront investment just isn't worth it