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Old 07-04-2014, 04:32 PM   #181 (permalink)
Too busy for gas stations
Superfuelgero's Avatar
Join Date: May 2013
Location: The intersection of TN/MS/AL
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Turtle - '92 Honda Civic Vx
Team Honda
90 day: 67.09 mpg (US)

Rolla - '10 Toyota Corolla Le

Beast - '91 Chevy V2500

Bus - '01 VW Eurovan MV

Speed - '93 Harley bored and storked Harley w/ turbo/ nitrous
90 day: 53.09 mpg (US)

Cal - '68 Ford Mustang GT/CS
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Originally Posted by The donkey CRX View Post
Thanks for the offer. I guess I was not thinking about the mods costing me power. The main reason I want to aero mod the CRX is it has more torque at lower speeds than the VX while in lean burn. I think I will wait til I can test the CRX with aero mods before I try any engine mods. But I will not give up on the idea that engine mods will help.

Based on driving both the CRX and VX prior to any modifications, I think the CRX has the potential to beat the VX by about 5 MPG. So my goal would be to get to tank MPG of 85 in the summer and 75 MPG in the winter with the completed CRX.
The stock motors are very good BSFC out of the box, there is no magic bullet. The only ways to improve it is to:
1) update materials/technology beyond what honda had available (not much).
2) upgrade on what Honda was willing to spend (not much either),
3) narrow the usable power band (cut high rpm and load) beyond what Honda thought customer would accept.
4) Reduce total power, which requires a total package (aero, friction and rolling resistance)
The last two are examples of where your WAI fits in by effectively reducing displacement, and also air flow conduits (effective intake and exhaust size) reducing power band (shifting VE towards the low end) and power levels.

The first two areas are much harder and expensive. You won't see many examples here, and I've yet to dive deeply into a build for it. When used in combination, they could have large gains, but you have to live with constant lower level of performance.

An overview would be to build more as a stationary motor (fixed rpm and load) than a gas powered car (wide rpm, wide load). This designing for narrow band is where increased efficiency can be built in. It is also why you view your HF as a higher efficiency motor, since it is a more narrowly focused engine. This can be done to the D15z1 with either more mpg, power, or power band depending on which way you lean.

So plan starting at #4, and we can work it backwards to get everything lined up. Just remember, the further you go, the less the ROI and the more you have to just view it as a hobby/challenge.

Shooting for 600 miles of range at 65-70 mph out of a vx.

Last edited by Superfuelgero; 07-04-2014 at 04:56 PM..
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