Curious to see what timing other people run or tune for on E85.

I have pretty much same timing as i had on pump gas on the bottom (around peak VE) and slightly more on top.
So for now its from 0* at 3500 to 18* at 7000. 25psi peak. AFR's are 11.5 to 11 (in gas numbers, obviousely)
Anything more on the bottom starts to knock.

IMHO that's the way it's supposed to be, but i want opinions. I also think that people have this concept that because E85 has higher octane it will take/needs more advance. I think this is wrong because higher octane gas requires more time to burn, therefore moving MBT, E85 on the other hand burns faster than pump gas, and does not need more timing because of that. Maybe i'm totally off


If you do not run E85 or do not tune other people for E85, or have good knowledge of how it works, please do not theorize as to what i "should" run. Thanks!

 

Your numbers are pretty close. E85 requires more timing to a point because it has a higher flashpoint, but if you have high enough intake air temps there is an amount (timing) of that ends up going away (just like gasoline). You can probably run more on the top end if you wanted to as is evidenced here:

https://www.evolutionm.net/forums/sh...ght=401whp+E85

Lucas is a good friend of mine (I have seen the car in action) and I can tell you that with even more boost as was used in that thread (he is up to 429whp and there is a thread on that one as well) his timing isnt too much different.

 

Did I read that right? 0* of timing at 3500 RPM and you're knocking? what kind of load are you seeing there?

 

Well, it does not at 0, but it does at 2*. Load is just over 280. My maps are rescaled for 280. So it's 0* at 280/25psi and then up to 18 or so.

 

It's completly possible. You see, every engine is different and ever set-up as well. What two identical engines will want will most always be different.

My engine on 93 octane does not like nearly the same amount of ignition most other 8's want at same boost with similar or identical mods, also on 93 octane. My power levels are actually above average, dispite this. Engine A, which likes more ignition timing, could make less power than engine B that wants less ignition advance. IT's really a toss-up due to factory tolerances. One engine could be built a lot tighter than the other..... one engine could be broken in properly and the other not..... like i said, it's a toss-up

This difference is very common in the internal combusiton engine world of tuning.

CJ

 

Thanks for the input, guys!
I've read some of LucasEnglish's posts, and i havent seen that thread. The timing does look pretty similar. And I do have a bunch more power after 4,4.5k to the top, like he does. The car just explodes with acceleration!

 

I know

 

what's your a/f when you bottom out at 0*?

 

I wanna say it is 11.5 or so on gas wideband, so 0.78 lambda, so 7.70 E85 AFR (with E85 stoich at 9.87)

If E85's sweet spot is in fact between lambda 0.71 ans 0.86, i'm right in between. Not too rich, not too lean.