E85 vs E70

[SnakeBoostE85]

They don't change blends here in Colorado year round. There are two chains that carry E85, one is 70% year round and there are tons of stations around town and very close to my home. The other has consistent 87% year round but its pretty far and not as plentiful.

I've been thinking about just changing the stoich setting in my tune to run 70%, but I am worried I will have to pull some timing to compensate for the lower octane.

Are their any real octane or performance differences between 70% and 85% blends?

 

[Bdubbs]

I don't think there's a huge difference. Both my e70 and e85 tunes peak total timing at 23*.

 

[SnakeBoostE85]

cool thanks for the info... based on some rough calculations IF the 87% blend is about 105-106 Octane, that makes 70% approximately 102 Octane. Obviously when your dealing with 87-93 - 6 octane points is a big difference in timing.

 

[MG0h3]

According to our resident specialist, the octane doesn't drop until you near E50.

 

[InvisibleBlade]

I'll preface my statement by saying I'm not very well read in the subject. I was tuned on E64 (what the pumps have for "E85") and my tuner was able to get to 23 degrees of timing safely. I have another tune for if it's E80+ but it makes no difference in power, just evening out the mixture.
I've heard that as long as it's above E55, then you're good to go.

 

[SnakeBoostE85]

wow - so there is literally no performance difference between E85 and E70.

 

[InvisibleBlade]

wow - so there is literally no performance difference between E85 and E70.

Based on my experience, no.

 

[biminiLX]

According to our resident specialist, the octane doesn't drop until you near E50.

I believe the DETONATION RESISTANCE doesn't drop from E85 to around E50.
This is from my research and makes me less anal about testing all the time. We tend to stay closer to E87-89 except for the very coldest months at most gaas chsins.
-J

 

[04sleeper]

You can still make a ton of power on E70. I wouldn't worry at all. Just change the stoich to whatever the fuel is so your fuel trims will be in line and you should be good to go.