I've started tuning my car, which has a lot of n/a mods. Anyways a few questions. I don't have a wideband O2, although we have been datalogging with HP Tuners, while changing a few things.
What's a good AFR target to set for PE mode for N/A Ecotecs? Has anyone out there found the "sweet spot"? I've set it to 12.0, but I have a feeling this might be too rich for optimal power in a n/a car.
We've advanced the timing graduated over 4k rpm and upwards in PE mode, and noticed some nice power gains. Does anyone have any spark tables for a dyno tuned n/a car that I could compare it to? Yes we have been checking for detonation, so far there is none in the logs, but I'd like a better idea of the "sweet spot", again, some definite numbers to try. So far we've been gradually adding advance, and testing, but without a dyno it's a bit of guessing involved. This would be running 92 octane, with a mildly shaved head(slight c/r increase). Any helpful feedback welcome.
12 is way to rich for n/a. I'd say between 13.0-13.5 would be the best range. However, without a dyno you can't really find a "sweet spot".
First of all I wouldn't tune anything w/o the use of a wideband.
With that being said, 15-18% rich is widely known as the best possible range for making power w/ gasoline. Stoicheometric value based upon the fuels that are blended 90% gasoline, 10% alchohol is actually 14.08. Which would make the optimal afr 11.96 at 15% rich. Anyone who wants the excel spreadsheet to prove this point I'll be more than willing to email it to you. Just pm me and I'll be more than happy to share.
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4 Cams...32 Valves...5 Liters...This Could Get Fun!
Skunk v.2K4 wrote:First of all I wouldn't tune anything w/o the use of a wideband.
With that being said, 15-18% rich is widely known as the best possible range for making power w/ gasoline. Stoicheometric value based upon the fuels that are blended 90% gasoline, 10% alchohol is actually 14.08. Which would make the optimal afr 11.96 at 15% rich. Anyone who wants the excel spreadsheet to prove this point I'll be more than willing to email it to you. Just pm me and I'll be more than happy to share.
I agree tuning fuel without a wideband is not a good thing.
11.96 AFR is too rich for a N/A car.
FU Tuning
upgrade your injectors, i can asure you they're clipping and you're running lean.
you won't be able to tune your afr until you put larger ones in. lsj injectors would be good. I was using 440cc and they're way overkill.
you may want to think about an adjustable fuel pressure regulator and a fuel pressure gauge to keep an eye on the pressure there.
if I were you, I'd put your spark tables back to stock, throw it on a dyno and tune your AFR first.
I've *HEARD* that ecos like it rich, however when I ran my fastest times last year I didn't have my wideband set properly so I believe I was running a 12:1 AFR for a while...
I want to say 13:1 should be ideal for n/a but I can't back it up with quantifiable proof.
throw her on a dyno or install a wideband and do some runs. tuning with HPT is a bit hard on an n/a eco since a lot of our tables run out before peak power.
once your AFR is set, then go back and futz with timing.
here's a bit of a secret... see if you can do something with the factory intake. you'd be VERY surprised how much of a bottle neck the little hookshot that connects to the t body mouth is.
^Listen to him, PJ knows his stuff when it comes to n/a ecotec.
BTW PJ, nice to see you'll be joining the boosted ranks shortly
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4 Cams...32 Valves...5 Liters...This Could Get Fun!
Some good advice, thanks. Although if you read my mods list, you'll see that I'm running 310cc GM s/c injectors, and have a modified AEM CAI installed already, amongst other things.
I looked too! damn i skimmed right over them
o well lookin good get a wideband and kick some arse!
Its great to see reading paying off...one less "What AFR should I aim for thread?" on the forums today since I read. lol...just wish more people would do that.
from my experience, 12.5-13.0 works well. when i went as lean as 13.5, the car was noticably slower.
as far as my spark advance goes, its set at 26* at 6400 rpm on 95-105kpa. Any higher and I would start to see knock but it could be false knock. From 4k down its 21,22,23,24....
