compression Questions

[Immeraufdemhund]

I was reading that fuel burns more fully with less compression. would it be better economically (not power wise) to get smaller injectors, retard the timing, and somehow decress the compression like with shorter rods, or smaller pistons?? I know we already get good MPG, but if it bumps it up to like 40mpg instead of 30...man that would help me alot. like for instance dropping the compression from 9.1 : 1 to maybe 8.9 or 8.5... not a bunch, just a little bit.

['A20A3']

Dude I don't know what you're talking about but my compression sucks ass and as a result my car is running WAY too rich.

[Ludi Mali]

i'm not sure on this, but it makes sense seeing as, if you raise compression and tune it right you get more power, i'd assume that if you lowered compression and tuned it right you'd get lower power but better economy, not sure tho.

[Immeraufdemhund]

Dude I don't know what you're talking about but my compression sucks ass and as a result my car is running WAY too rich i thought about that, if you get smaller injectors though it wouldn't be so rich. You'd have to retard the timing also because it will take longer (i think) to burn up the more fuel...there by making it more efficiant.... or you could fool your O2 sensor and make it think that your running rich then it will automatically tell your computer to lean it out.

[accordlxi2.0]

ummm if you retard your timing, it still would'nt burn properly, if anything it'll ruin your economy somewhat.....

[Immeraufdemhund]

Keep the timing the same then? i figured you'd ahve to mess with the timing because of the lower compression and less fuel.

[FoX]

try getting a different MAP sensor. depending on what you get you can lean out or richen up a motor.

[AccordEpicenter]

itd be most economical to keep the compression where it is or higher with stock ignition timing. Getting rid of some of that compression will let the engine require less fuel but also put out substantially less power, therefore youd have to burn more fuel to get it back to what it was putting out originally, so thats defying the point

[Oyvind Ryeng]

Good mileage:
-As high as possible compression; higher compression gives a more "powerful" burn, even though the engine has to work more to compress the air/fuel-mix further.
-Extremely good intake and exhaust system creating a higher-, and moving the peak volumetric efficiency to between 2500-4000 RPM and always stay in that powerband to save the most fuel.
-Tuning, tuning and more tuning on an load-dependant Eddy current dyno. This includes mapping ALL the load and RPM points to even leaner than LBT (Leanest Best Torque). On a dyno like this you can hold the car at for example 40% throttle and 4000 RPMs to optimize the burn in this point; and then go over ALL the other points in the map (from like 10% throttle 1000-6000 RPMs, 20% throttle 1000-6000 RPMs and so on). You can read out in realtime what torque the engine puts out right there, so you can adjust fuel and ignition timing to the best possible compromise between power output and fuel consumption.