14.3:1 on pump E85?
14.3:1 on pump E85? I’m in the process of rebuilding my engine as a 396 on E85, shooting for a target of 13.5:1 or so on compression with my 55cc AFR 210 heads. I’ve ran 13.4 before on ported stock heads when I first built a 385, and had no issues with that, but this is almost a full point higher. Unfortunately there aren’t a lot of off the shelf pistons that will give me near this target. 5cc flat tops give only 12.8 and 2.9cc flat dome gives me 14.3, there’s nothing in between. I know race E85 has no problem with this compression, but has anyone ran this high on pump E85?
Yeah I’ve got another block now, but it’s a 2-bolt block, I couldn’t find a 4-bolt block for it. My old block was a 4-bolt. So I’m going to have to pay extra for the conversion now.
Last edited by kgkern01; May 17, 2021 at 08:41 AM.
TECH Resident
Joined: Oct 2006
Posts: 993
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From: Euless, TX
Splayed cap 4 bolt is stronger than a factory 4 bolt.
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Joined: Sep 2014
Posts: 321
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From: Fort Wayne, IN
I never had a problem running E65 in winter here on my 12.5 385 LT1. Just had to go into the tune to richen it up. I ran 13:1 with smaller stock heads on it before I switched to the AFR heads as well.
Mite be one of those things you will just have to order a barrel from VP racing and can help mix with pump e85 to bump up the e content. That’s better then hurting a engine. But if it’s quality pump e-85 then it can be done.
I’m leaning towards having 2cc milled off the piston dome (its already a flat dome piston), which would put me at 13.9 instead of 14.3. Anyone ever have piston domes milled?
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Joined: Sep 2014
Posts: 321
Likes: 88
From: Fort Wayne, IN
I have a thread going over there as well. They are suggesting dropping it down a few tenths of compression to get it under 14. I know the LT1’s reverse cooling can handle a bit more than a typical SBC so I wanted to start a thread here too.
I never had a problem running E65 in winter here on my 12.5 385 LT1. Just had to go into the tune to richen it up. I ran 13:1 with smaller stock heads on it before I switched to the AFR heads as well.
I never had a problem running E65 in winter here on my 12.5 385 LT1. Just had to go into the tune to richen it up. I ran 13:1 with smaller stock heads on it before I switched to the AFR heads as well.
