When tuning with e85 @ 30psi and about 625hp.

Tuning on a dyno, as timing is slowly increased, does max torque occur before of after detonation?

 

it depends...i have tried it around 16-20 @ 30psi. after doing a plug read, there is no hint of detonation...however, it depends since on the dyno, the engine is kept cold/iats are monitored and kept on the coldest possible. i also run on low 11s AFR at that boost levels.

on the track its a different story.

 

Detonation hurts power. Not increases. If you have exceeded your ignition advance for the fuel octane or other reasons why an engine detonates, it doesnt matter about torque. Pull timing until it stops detonating regardless what the power is doing.

Your question is too open ended though. At 30psi, a detonating chamber will kill itself in no time. Regardless of what fuel is used to tame it.

 

Ill also run low 11 AFR on the regular scale.

At the track when the engine and IAT increase.
Do you add a fuel to keep the AFR at 11?
I assume you advance timing till you were close to max torque, Do you retard the timing a little more for the track?

Thanks

 

exactly...
yes.... during dyno, i try to keep the engine running ta 90-95C when doing a pass..and say my fuel multiplier is 0 on the fuel trim. but at the track when I open my logs, I see 100-103. fortunately AFR log is still at low 11s.

yes tuning mbt is a bit tricky. even after reading so much on tuning mbt, you can only learn through your own experience. try adding 1-2deg on each pass on the dyno. if it loses power, then go the other way...

 

In 2012 I built an engine with 13.5:1 static compression designed to run E85 and high boost from a GT3076R.

At 9psi we made 385hp observed. We pulled 1* of timing and made 388hp. Zero sign of detonation even though we were beyond MBT timing with extremely high cylinder pressure. This engine went on to make 540hp observed (597hp Std CF) at 18.3psi (20.2psi peak). The knock resistance of E85 is amazing.

https://honda-tech.com/forums/showpo...&postcount=253

 

That is amazing. Thanks