https://ls1tech.com/forums/showthrea...ght=e85+sweden

Thats a total explination of E85 and also how to tune for it.

 

so quick question...

my truck can run E85. If I did a performance tune for like 91 octane vs. E85, would there be a big diff?

 

A 91 octane tune on 91 octane gas should outperform an 87 octane tune. A 104 octane tune on E85 should outperform the 91 octane tune. Of course, you have to have injectors big enough to handle the extra flow requirements of E85.

 

Dont the E85 trucks have bigger injectors? I do know that you have a couple of different tables for ethanol on EFI Live

 

The price difference with E85 is negated since you get less miles per tank. The performance is better since you can run much more timing. The tuning is different since stoich on E85 is ~9:1.

 

Yes, they come with 38lb hr injectors stock.

 

They come with larger injectors and a bigger fuel pump from what I understand. and then a few extra sensors and tuning to detect and run e85. I think if you had vehicle running on e85 alone you could boost the compression to well over 11:1. I would think you could get more effiecency back so you wouldnt burn throught the fuel as fast, since power increases with compression.

 

Any SCT tuner can make you an E85 tune. Basically they will turn off your O2 sensors on the tune, and tune it purely MAF. As soon as we get E85 here, I have some 60lb injectors going in

It really helps with forced induction- and not just because of the higher octane. The Ethanol has a cooling property much like running meth injection, allowing even more timing.

 

You don't even have to do that in these GM pcm. Basically, all you really have to is tell the computer that stoich is 9.7 to 1 and it will correctly calculate the fuel based on the that. The stock narrow band sensors will work just fine. They don't read 14.7 to 1, they read lambent, or complete combustion which will be around 9.7 to 1 for the e85. Add some timing to take advanage of the increase in occtane and go.

 

The SCT tuners I have talked to say they have had problems with O2 sensors reading correctly with an E85 tune on non e85 vehicles- so they tune MAF to be safe. But, these guys are tuning race cars that only rely on O2 data a very small portion of the time.

True, the oxygen sensor reads lambda, and you have to interpret that into which fuel you are using. Target the computer to e85 stoich and you are usually set.