im building a 383. i have scat forged crank, and 5.7 eagle forged rods. i dont have pistons or heads yet, but im looking hard at just some stock vortecs. i have a edelbrock 2201 cam with comp cams roller hydro lifters. ive been doing alot of research but there doesnt seem to be alot of real world expirience. ive read go 12-12.5:1, and ive heard keep it @ 11:1. hit me with some knowledge.

 

Search for "E85" on the Carb forum. There's a big info-filled thread there.

You could also Google it. There are a few forums dedicated to it.

 

I'm in an internal combustion class right now for my Engineering Degree, i can tell you that you would be able to run anywhere from about 11:1 to about 15:1 and have no chance of detonation. The efficiency of the engine is proportional to the CR, therefore, the higher your CR, the better mileage you will get. That's the reason diesels, even though they burn less efficiently, since they run at such high CR ratios, they are more efficient per se by output. Just a little FYI.

 

Stay in school pinto
Diesels are a whole different ballgame, compression ignition kinda changes things.
He could set his 15:1 engine on a stand and run it on E-85 all day long. However real life has a way of raining on our respective parades
Once the engine gets warm (granted not all that warm with E-85), and heavily loaded, it'll still want to knock.
"They" say that E-85 has an effective motor octane of what... 102 or so? So compare it to 100 ish octane fuel. You can get away with 11-12:1 on that, but any higher and that's when guys are running pure methanol or 114 octane leaded race gas.

You do gain some HP by going to higher CR, but there's nothing worse than having to pull timing to keep it from knocking. You lose MORE HP by pulling timing than you gain from raising the CR.

 

Yes, 12:1 is about the max for E85 that I've heard, a little higher if you carefully control everything in a "purpose-built" engine.

Reported octane is in the 105 range. Interestingly, the pumps don't post it, that I've seen.

The turbo Buick guys love E85. I just talked to a good-ol'-boy fellow racer yesterday who makes his living building performance engines. He's run a '37 Chevy pickup with roots 383 for years, and been very successful with it. Over the winter, he built a 400 with a little more compression because he heard someone who's run E85 for the last couple of years really likes it.

mr.southtown73, that cam has a lot more lift than stock Vortecs can handle. I haven't heard much about the Edelbrock roller cams, but if it's just their RPM grind modified for roller, you can do a lot better with something else.

 

yes, ive researched this topic outside of thirdgen and saw the good thread in the carb section. i guess theres no you can run this and be ok. it must depend on you combo as to what will complement each other or not. i just wondered if there was new info or if someone is running 13:1 or so and what is the combo. its interesting to me that with the mention of diesel is that the new duramax is running 17:1 (i believe, and im supposed to know) but diesel has a octane rating of 104. i might be one phd short of comprehending all this, but one nice thing i did hear about running e-85 is its supposed to increase your gas mileage to 60-65 per gallon. prius owners can f off!

 

no dude, you will actually lose mpg with e85. It takes more of it to make the same power.

 

Well, that 60-65 MPG of gasoline, not "fuel".

 

point well made. At only 15% gasoline per gallon. it just may.

 

No, i'm sorry but that's stupid. Diesel works on compression ignition. It doesn't really have an octane rating. It's like having an octane rating of zero. It has a cetane rating. Google cetane rating for more information. It runs on compression ignition, completely different ballgame. You can have a 20:1 diesel engine with 40psi of boost as long as the block holds together. That's the reason diesel engines weigh twice as much as a gas engine, they're so thick. They knock normally, that's how they run.
There's no comparison between a compression ignition engine and a spark ignition engine when we're talking about SCR, knock, boost, etc etc etc. Just leave diesel out of the discussion to avoid major headaches and confusion.

And yea, E85 stoich is what... 11:1 or something? Significantly richer than gasoline. Wasn't the quoted number 30%? So, much much much much worse mileage. But it's a tad cheaper, and has more octane, so to us it's still win-win

 

geico, so easy sonix could do it. why wouldnt that make sense, cause your smart? just kidding.