Thread: NA air fuel ratios

just curious (since i'm gonna be doing a 10:1 de build) what a/f are you NA guys running?



also (and this might have already been asked before) but how lean is too lean?

Im in the 13.4 CR rang and im tuning to 13-13.5 for mild loads and around 13 even for hard loads.

Im also running a VE Head with N1 coated pistsons, so theres a few variables.


Your timing will determine a lot of how stoich an A/F you can run.

i'd like to run 19* timing but it all depends on weather or not we will get E85 here in az. (i heard the valero gas stations here are going start soon)

Well if your planning pump gas on a 10:1 motor id assume your going to make best powere around the low to mid 13:1 range. Usually with the higher cr set ups they like more fuel. Mine for example makes best power in the low 12s.

If your going to run e85 you'll probably shoot for a high 13 to mid low 14:1 afr. I really doubt you will see any gains from running e85 over 92oct. But I guess its always worth trying.

Same thing I have found here.

With SR16's pistons in my 20VE the motor favored mid to low 12's.

only reason i'd switch to e85 over 91 would be price (e85 is usually just a little cheaper than 87)

Ic. Well as you may or may not know, you will have to run somewhere around 30% more fuel with e85 so consumption will go down. You will see less miles per tank/gallon so it might not be much if any cheaper in the long run. Just some food for thought, so you can weigh the options.

it does take more fuel but e85 can run more timing and run leaner than pump gas so even though you are using 30 percent more fuel you can run both more timing and leaner fuel conditions resulting in more power and better gas mileage

Well higher oct does not always yield more power. More ign advance also does not always yield more power, when the cr is high enouth then yes but with a 10.0:1 de I highly doubt there will be much if any of a gain. Even the cammed itr motors didn't gain with e85 just saying..

true true to see gains it would also def need some good tuning and your right it might not yeild more power