Quote:

---

Quote:

---

I mix Sonoco 112 with Sonoco Maximal 116 50/50 and add that 10% to 90% pure Ethonol. A/F on E85 was 9.6-1, and gas was 14.50-1.

the dyno owner operator said the A/F on his machine, should be 14.5 to one.

---

It is tough to say, but the engine builder that tore it apart thinks it was detonation, but maybe it was lean and burned them up (incorrect material for build). That does seem like a lot of CR for even a performance brewed E85, but judging by what they told you about A/F ratio, I can't even guess what the real A/F was and too lean could have detonated it. Especially on an engine dyno, some combos will make good power on the lean side, but that is pushing detonation, "lean is mean"

Is the dyno "14.5" based on an oxygen sensor or air and fuel flow measurements? He obviously doesn't care what the real A/F is and from his experience (on gas?) 14.5 was working for him. So when you ran E85 at "9.6" what does he think the actual A/F ratio was?
What I am getting at is that when people talk A/F on fuels other than gasoline (stoich 14.7), some people using oxygen sensors quote A/F on the gasoline scale rather than the actual scale of the fuel used.

E85 stoich is about 9.7 and E90 would be slightly higher
100% Ethanol 9.0
Methanol 6.4

I use an oxygen sensor, which by design indicates the ratio of A/F to stoich (called Lambda), so a stoich mixture is Lambda=1.0 and a typical power setting Lambda=0.85 (which is 0.85x14.7=12.5 actual A/F on gas). My engine is 13.5 CR and I have tried my E85 tune from 0.78 to 0.90 which is an actual A/F ratio of 7.6 to 8.7 (but on the gas scale it would read 11.5 to 13.2). So if your dyno run on E85 was an actual A/F of 9.6 that is way lean, basically stoich (ie from air and fuel flow measurements).

You obviously have had success with E85 for a couple years in your other motor with slightly less CR. Was it the E85 carb from that combo (ie known "good" E85 carb)?

---