A/F for PE??
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Teching In
Joined: Nov 2005
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A/F for PE?? what is the Best A/F to shoot for on our V8 Fbody cars??
12.5 AFR up to peak torque....lean out to 12.8 at peak Horspower...richen back up a little to the rev limiter???
or just a flat value across the board...like 12.8 or 13.0 or 12.5??
just trying to figure this out as I am new to this tuning thing...
I have a basic understanding of what to do..I just want to know what the best PE settings are
12.5 AFR up to peak torque....lean out to 12.8 at peak Horspower...richen back up a little to the rev limiter???
or just a flat value across the board...like 12.8 or 13.0 or 12.5??
just trying to figure this out as I am new to this tuning thing...
I have a basic understanding of what to do..I just want to know what the best PE settings are
I'd be interested in hearing some responses to this question too from tuners with much experience.
I've done some road testing and seen extremely little performance difference between 12.2, 12.5, 12.8, and 13.1. In my testing 12.8 did seem to give the best performance at all rpm levels ...but I'm still a newb and am using the road, not a dyno, so my data has a lot of noise in it (wind, incline, etc.)
I've done some road testing and seen extremely little performance difference between 12.2, 12.5, 12.8, and 13.1. In my testing 12.8 did seem to give the best performance at all rpm levels ...but I'm still a newb and am using the road, not a dyno, so my data has a lot of noise in it (wind, incline, etc.)
TECH Fanatic
Joined: Mar 2003
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Depends too much on what you parts combo will let you get away with (without knock)... DCR, colder stat, cylinder head choice...blah blah blah... I have always made best power starting lean at low rpm (2000ish) and transitioning to richer at peak rpm. i.e. 14.4>---->13.7ish scaling in a gradient across the rpm range. BUT, this is for my specific setup... may not work for you... All my mods are in my sig...
I run timing in the same fashion... 30>---->27 (low rpm through high rpm) @WOT
I run timing in the same fashion... 30>---->27 (low rpm through high rpm) @WOT
TECH Enthusiast
Joined: Mar 2003
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From: San Diego
I figure you can do it either way, generally you don't need as much timing at higher maps but if you run a flat AFR curve or if you run slightly richer from peak torque up to peak hp you could probably run a tad more timing... probably something that would have to be played with on a dyno, making slight changes with the fuel/timing across the board. Just my thoughts, I've never actually played on the dyno with that, mostly since I'm broke. 
On the road dyno I actually found that more timing made less power. I could run as much as 50% more timing at high rpm-high load conditions with no KR, but it made slightly less power.
Now, my car is virtually bone stock, so it might be different for cars with cams/heads/higher compression, etc.
Now, my car is virtually bone stock, so it might be different for cars with cams/heads/higher compression, etc.
What I found works best for me is to keep the lower end of the rpm range fairly rich. I think I have mine set to start at 12.0 or so, lean out to 12.2 at peak torque, and then lean out further to 12.6~12.8 at peak horsepower, and then progressively richen slightly up to redline. Between peak torque, peak hp and redline actually looks like a perfect bowl (so if you folded it in half, the left side would lay on top of the right side perfectly). This fueling (along with 2-3* more timing between 4400-6400rpms) dropped 2 tenths and added 2 mph to my pass at the track.
