I'm having difficulty finding anyone with real world experiences building a dedicated E85 engine. Any idea what the max compression E85 could tolerate in a big block chevy would be? Reason being is that I have a AFR headed tall deck 610 with coated pistons and chambers, but the compression is 14:1. Anyone out there with an opinion on whether E85 would handle it?

should be fine with a big cam, but just check out the timing curve and back out if there's pinging. E85 likes a warmer motor as well.

sorry to tap the tread, can you run E85 in any gas motor?

not unless you burn the prom for it on a efi motor. Or it's a newer flex fuel vehicle. There is no benefit unless you're running the extra compression to somewhat makeup for the more fuel needed.

Five7 kid runs E85 in his big block 396 car, at the track mostly.

I agree though, 14:1 is still a fair bit, you'll want a big cam to bleed some of that off.

i've heard that E85 is max, 105 octane..

Yea, it's hard to base it's burning properties solely on octane rating though. Since it's an ethanol blend it has some properties akin to water, ie, when it vaporizes it cools a lot. It needs a warmer motor to properly vaporize, but the cooling effect also helps add to the "octane" value. etc etc. So it's hard to quantify.

Yeah, all alcohols are supposed to cool the intake charge quite a bit more than gasoline does. Which is a real plus when it comes to preventing detonation. But, finding the true octane rating of E85 seems rather difficult at best. Online sources state its' octane is somewhere between 100 and 111, which is the highest number I've found. But, on some of the E85 websites I've been to they state 12:1 is about the highest compression ration E85 will support. I've seen a fair amount of 11:1 engines running on premium unleaded though, which is only 91-93 octane. So I would think E85 would have to be good up to at least 13:1 wouldn't it??? Even if it's only truly a 100 octane fuel.

it's really all in how it is built. if you knew your tuning you could get prem gas to run on 12-13:1 compression without detonation. again if you know what you are doing. and yet I have had cars that would ping like hell even using 8:1 compression unless I retarded the timingso far back that it would hardly idle.

Member IHI has done a lot more research and is building an engine for it. Check out the E85 thread on the Carb forum, starting about post #99.

Way old thread, but read this...Ohio Crank has it in a 15:1 555 and it is working fine.

http://www.yellowbullet.com/forum/sh...ad.php?t=88332

my buddys 13.5-1 412ci is running it all year with no problems, and it's pretty consistent.