E85 and boost, what compression ratio could I run?
 

I've run 38 PSI boost on my 9:1 motor without any detonation on E85.

My previous motor was 10.5:1 compression, and had a lot more low end, and I swear even more top end at a given boost level. Admittedly, I never ran that motor past 22-23 PSI though.

Just wondering, I have a spare motor and was curious how much higher I could go on compression with E85 and the same high boost? 11:1? 12:1? more?

Hahah, you are NUTS dude. Nuts.

9:1 static at 38psi is 32.27:1

11:1 static at 38psi is 39.44:1

12:1 static at 38psi is 43.02I was trying to find information on the flash point and other info on E85 to help you further, but I suck. I could only find anecdotal evidence for static compression ratios used succesfully on E85.

12.5 or more if you can find the pistons

There was a guy selling some 13:1 pistons here a while ago. Idk if they ever sold.

Ive got 2 builds at just under 12:1 at over 25psi.

Both are awesome and not even close to knock.

Dann

I could even share timing tables if anyone wanted.

Dann

Off the shelf 11:1 pistons plus a couple of quarters per cylinder should get you 14:1.

--Ian

Yes please share. I've been trying to find a timing map of a high comp turbo e85 setup to see if I'm running anywhere near what someone else is running. I know no two engines are the same but it would still be nice to see what others are running. I'm only running 10.5 wisecos and I think I still have plenty of room to go on timing.

10:1 and 25psi is 20 degrees safe as houses.

Could you post a screen shot of your timing table

When I get to work.

Ok thank you sir

I'd love seeing some spark tables you guys are running. I had no idea you could get away with those kind of compression ratios with that much boost on E85.

corn loves compression. and there's rarely any knock, if ever. and you can run astronomical boost and timing.

but

you really have to keep in mind that despite not being det limited, there is such a thing as too much timing, and that you are putting crazy stress on your engine when you're well past MBT.

But yeah, this might be a good place to discuss/share spark maps on e85

I feel sad that I am sitting here with an 8.6:1 motor with dreams of e85/flex

Not to mention making less power. You really need a dyno to tune it.

--Ian

Ok here is my map currently. This is by no means a good or great map, it is not dyno tuned and it needs work in several places and needs smoothing out I'm sure. I am not a tuning expert but trying my best to learn. It's what I've come up with based on other e85 maps and also driving around with electronic det cans and monitoring knock via MS3. I have not seen or heard any knock at all and I think that this timing map is still somewhat conservative and has plenty of room for improvement, thus why I'd like to see what others are running with high compression, high boost and e85. I'll get it to a dyno someday. But for now I'd just like to see if I'm somewhat close to what others are running. Any help and feedback is welcome. This is with 84mm 10.5:1 wiseco pistons, diy ported and polished 99 bp4w head and a relatively big turbo that hits late.

https://cimg0.ibsrv.net/gimg/www.mia...366c844589.png

Can't speek on the boosted cells, but that is less agressive in the 100KPa and under cells than I am running on my 1.6 with 87 octane....

Yeah, you can run way more.

19kpa cruise should be 40*
taper to
100kpa should be at least 27-30*
taper to
230kpa 16* is ok but should not be dropping, should be ramping up to redline, to at least 20*

Assuming built engine, competent setup, and at least e70 actual in tank, preferably 80+