Anyone ever use a set of these? Wondering about my compression ratio going up and octane vs computer's ability to function with a high compression ratio. I'm thinking 10:1 but not positive. They were custom made and I had rotating assembly balanced.

It depends on combustion chamber volume and piston-to-deck height. With a combustion chamber volume of 50cc and the pistons flush with the deck, you're looking at about 10.5:1. With a piston-to-deck height of 0.015", it's more like 10.2:1. And with a piston-to-deck height of 0.030", it's about 9.8:1.

Where can I get a set of flat top pistons for a 3.1 (3.2 with overbore)

Thanks

With what they call high octain these days, (I can still remember 100-104 at the pumps) I decided to not go over 9.5:1 when I rebuilt my 2.8.

Use the itronhead minivan 3.1 pistons. You can get factory overbore replacements.

So what I really want to know is what compression ratio is going to be the max before I can't use pump gas or the ecm will not be compatitble? I might consider a carb if I could still use pump gas.

I got 9.8 cr in my bored 3.4 . These are dished custom made pistons with zero piston height cause flat tops would have made it 12.? cr. To cut down on detonation I used 6" rods. So far no detonation problems. I use 91+ octane.

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85 GT 3.4
Auto 3.08
14.9 @ 90 1.9 60"