My FE/Performance Project

[pgfpro]

Originally Posted by *************

So you decreased the compression ratio yet improved the overall mileage?? So tell me, how DID you achieve that 75mpg while cruising at 58mph? What kind of mpg can you get at 65mph? Any aerodynamic mods? Were you doing pulse and glide? The reason I ask is that it seems counter intuitive to go a lower compression ratio opposed to a higher one. Did you choose a lower compression ratio because you knew you couldn't modify the computer's programming? Or can you? I ask this because the Insight and the Geo Metro both have very high compression ratios (11:1) so you going the opposite direction seems strange. Yes I am aware that you have the low compression ratio for the turbo but 7.5:1 seems awfully low and usually cars run 8.5:1 when turbo equipped, maybe even 9:1.

Yes I decreased the compression ratio to 7.5:1. But there are a lot of other factors that are working with the lower compression. I can say if you just drop the compression ratio on any other engine and that's all you do you would lose efficiency.

My O2 is just along for the ride and does nothing other then give me real time readings and data logs.

The 75mpg was on a road trip over 500 miles of driving at a steady state cruise condition with no pulse a drive.

Yes I can and have altered my stock ecu settings using Neptune engine management. My engine runs in open loop all the time by running off my preprogrammed fuel and timing etc. maps.

My sons car has the same engine but with stock 9.8:1 compression and with him running at 17:1 A/F and me running at 17:1 his mileage is not as good as mine. But of course when I take it up to 22:1+ mine is way better.