Raising compression/e85

You are going to be directed to the RJC head gaskets. I bet you can mill the heads down from 48cc to 46cc. I wouldn't go too much because the intake will need to be milled as well. More work than needed since you can simply turn up the boost! Now if you were to build a new short block you can order pistons to do this without all the milling.

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runs with scissors
Cometic will custom make you some .027" gaskets. Odds are they won't seal against your used unmachined deck though.

And like mentioned above, shaving the hell out of the heads and running thinner gaskets will require the intake to be milled too. The machine shop costs halfassing a stock shortblock will probably cost more than a set of new slugs.

Nick Micale

Tech Advisor
Staff member
What's the maximum milling of stock heads coupled with the thinnest head gasket to raise comp. Ratio and allow me to run e85?
A stock turbo engine will run fine with e-85.

If you are building a performance engine, raising compression is a good idea using gasoline or e-85.

The main concern in this conversion is that you must supply 25-30% more fuel at WOT when using e-85 so your fuel pump and lines are adequate for the performance you desire.


runs with scissors
Earlbrown tell me more about the custom pistons

Basically you move the piston up in the bore. That way you can leave that meat on the decks, the heads, and run shelf gaskets.

That's a much better option than decking the block, shaving hell out of the heads, custom ordering gaskets, and shaving the intake. ESP if you're buying pistons anyways.


runs with scissors
Earl I gotta hit you up for a set on an old 109 I have that could use a compression bump.
I'm about to do the same thing. I dug out my original block that spun overheated a main when my car was stolen. I've got all the parts needed to longblock it except a set of pistons. And some steel to start making main caps. For years I've had a mental image of a better mousetrap as far as caps go. I think I'm going to make a high compression ground pounder that'll stay sideways and abuse tires with it. :)

.....since any money I spend before dec 31 I can write off on my taxes. lol

dank GN

BlackArts Automotive (661)993-8277
I'm still amazed those slugs were possible with both a stroker crank AND a 6.500" rod.
Yea they ended up perfect and even with the deck . I’m switching to my stage heads so I’m going to have ether get some new slugs or notch these ones for valve reliefs. Idk though im thinking if I notch these I will gain to much volume and my compression will be to low . I’m right at 10.5:1 right now so what do you think ?


runs with scissors
Depends on how much notching you'll need. The only way to know for sure is to mock it up with light test springs and see. With any luck all you'll need is a small triangle taken out of the edge of the inverted dome.

With your skills, it'd be easy to convert an old valve into a piston crown cutter. After that all you'd need is a clamping shaft collar to act as a stop. I'm guessing you're lose 1 or 2 CCs at the most.

What was our quench distance again?