NA car, WOT, how lean is OK
My target AFRs are 12.8-13.1 at 89-101 kPa on my track only NA car.
I see other folks with as high as 14.7 (although they are boosted) at the same map levels?
I am looking for max power thus the 12.8 to 13.1 numbers but am just curious as to how lean is OK before I need to start worrying should it magically start running leaner on track... (and it seems to vary based on what gear I am in and high RPM/high gears have not seen much action on the street).
I see other folks with as high as 14.7 (although they are boosted) at the same map levels?
I am looking for max power thus the 12.8 to 13.1 numbers but am just curious as to how lean is OK before I need to start worrying should it magically start running leaner on track... (and it seems to vary based on what gear I am in and high RPM/high gears have not seen much action on the street).
Your AFR values sound reasonable to me. I generally don't recommend 14.7:1 at 100 kPa, boosted or not.
Would that mean hitting 17plus while off, or slighty pressing the throttle is really bad. Under load, I'm below 13.4, but often when off throttle (Understandably) or just barely pressing the gas I'm getting 16-17 plus
that's fine for cruising speeds, it's only heavy throttle and wide open throttle that you need to stay a bit rich at.
Running 16:1 without an egt gauge to verify safe temps could cause burned valves. 17:1 can cause burned valves with a perfect timing table depending on the engine. 17+ you're gonna break your ****. And rebuilding a head is not exactly economical.
Joined: Jun 2006
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From: Republic of Dallas
Their are 3 of us around here now? BTW, my VE Table shows whole numbers nothing with a decimal, or anything that I recognize as a A/F Ratio Hustler where did you go to get that table?
Last edited by apariah; Oct 19, 2008 at 01:06 PM.
Last night may have been more eye opening than I thought it was, I found out I have to remove my A/F gauge, and I based on what I just read in regards to burnt valves I think I may have to rebuild my head. We noticed last night my car sometimes smells of raw fuel, I thought this was because I was running rich, but I never even considered a burned valve could allow raw fuel into the exhaust. This could suck.






