Time with E85
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We have been finding that 12.0 seems to work best, but out to 12.5 or so doesnt seem to make anymore power. I have heard (not confirmed) that even all the way to 13.0 makes the same power. Thats more than I want to push it though. For what its worth, when Lucas made the 506 I think that was 11.0 flat as I recall.
EvoM Guru
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From: Tri-Cities, WA // Portland, OR
Maximum lean power lambda for E85 is about 1.15. In terms of gasoline AFR, this is about 12.25:1. Maximum rich power lambda for E85 is 1.40 which is 10.5:1 AFR on a gasoline scale. So it would seem that the optimum target AFR (gasoline scale) should be around 11.5-12.0:1 AFR. The neat thing about E85 is that it allows us to actually tune right in this maximum power AFR range while this would never be possible with pump gas.
You've used some kind of equivalence ratio numbers, which is Stoich/AFR. Whereas Lambda is AFR/Stoich.
Last edited by mplspilot; Aug 20, 2008 at 01:57 PM.
I think the richer than 11.5 will sputter/misfire would be true with stock plug gap at high boost with stock timing numbers.
There are lots of tricks to make it fire, one is adding timing (assuming no knock), tighter gap, hotter spark, more dwell in the coil (more charge time before firing), etc.
There are lots of tricks to make it fire, one is adding timing (assuming no knock), tighter gap, hotter spark, more dwell in the coil (more charge time before firing), etc.
Yes sir, I was afraid to go over 12 to 1 but since our conversation I have been trying different things..It's weird because I was hitting knock and not getting anywhere before taking Warrtalons advice. Now I have found myself a nice little afr tuning window for my car that it seems to be happy in..Thanks again Clay!
Petey, I see you took some of my tips to heart, or at least I think you started messing with those AFRs and timing after our conversation. Nonetheless, your numbers are where I'm getting the best results. I thought my timing was high, but Razorlab's is higher even with much higher sustained boost on the top-end. My boost is way low, which allows me more timing with ease. I couldn't run that much timing with way higher boost sustainment at sea level.
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E85 maximum power AFR rich on a gasoline AFR scale is 10.5:1
E85 maximum power AFR lean on a gasoline AFR scale is 12.75:1
I was trying to do the calculations but they look non-linear. Does anyone know the max power leavel Rich/Lean AFR for E70?
EvoM Guru
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From: Tri-Cities, WA // Portland, OR
I wouldn't bother too much with trying to calc those. E85 is good at about 12:1 (gasoline scale). If I were running E70, I'd start with 11.5:1 and work my way up. I hadn't mentioned it before but I suspect that it might be possible to make more power on E70 than E85 because the burn time will be a little longer and perhaps can make more of a push on the piston and a little less of a jab.
Last edited by mrfred; Nov 14, 2008 at 02:10 PM.
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