Supercharged111
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11.5:1 will produce more torque than 12.5-13:1 and provide more cooling.
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I still don’t understand GM’s logic behind setting the delay on PE to 60 seconds and then when PE does come in it dumps fuel at 11.5:1 afr which is way below optimal power afr. It makes no sense, but surely they have their reasons. It’s not like the optimal afr for power wasn’t figured way before the 1990’s.
11.5:1 will produce more torque than 12.5-13:1 and provide more cooling.
What I'm not getting here is that you guys seem to know when it goes PE while driving - or do you just know it will?
This is age old. When radiators were still made of soldered brass (read expensive) under-specifying the cooling capability and 'fuel cooling' was the norm. It still is to some extent principally to pull in-cylinder temps down to resist detonation. The cooling of the incoming air by giving up heat to vaporise the additional fuel will increase its density which can increase power.
The only way I could see 11.5 creating more torque is if you ran more timing and actually needed the fuel to hit MBT timing.11.5:1 will produce more torque than 12.5-13:1 and provide more cooling.
The only way I could see 11.5 creating more torque is if you ran more timing and actually beeded the fuel to hit MBT timing.
Interesting...I have never seen this on a dyno. On E10 I usually find peak torque around 12:1 and higher rpm around 12.6 on Chevy small block heads. The 8.1 is said to run best around 13.4:1 at high rpm although I have it in the 12.6 range as well for cooling.It's in a tuning book, I can get a snapshot when I get home. I run mine in the 11s because of the heat of the blowers. I know timing is a part of it.
My trucks have widebands and they're both programmed to enter PE before a downshift from 4th.
If I understand your question correctly, I think the answer is we know when it goes into PE because we've looked into the factoring tuning and/or modified the tune.
I wonder if this holds more true for carbs and TBI's vs multi-port. Multi-port doesn't have as much runner length to vaporize the fuel and more relies on the atomization of the injector.
So now I'm feeling really guilty for dragging this so far off topic. Maybe start a new thread?