6.2L can I lower my compression ratio by

[mrbornery21]

Examples

I heard of guys milling the top off there stock pistons.

My question is why not just get a $100 set of custom copper head gaskets that are thicker than a stock compressed head gasket

My stock compressed head gasket is .040 inches thick 21.5:1 ratio specs

How thick of a headgasket is needed to drop ratio to 19:1
How thick of a headgasket is needed to drop ratio to 18:1

[mrbornery21]

I think I figured it out, ran some head gasket thickness ratios through a compression ratio calculator and this is what i found out.

For every .010 inch I add to the overall thickness off my head gasket it drops the CR about 1 point

so 21.5:1 = .040 inch compressed gasket thickness
20.5:1 = .050 inch
19.5:1 = .060 inch
19.1:1 = .065 inch
19.0:1 = .066 inch

[john8662]

Yep, roughly .010 per point.

Wasn't sure on your head gasket thickness number tho...

J

[mrbornery21]

Its not a perfect measurement but pretty close, If I end up going this route Ill do a better job and use the right tool, Not my redneck engineering way!

What kind of measurement numbers would sound about right for a used headgasket?

What way would you suggest to get an accurate reading?

I just picked up a used 6.2 head gasket and got my measurement from the steel cylinder rings. Came up with about .040 inch might be about 0.046inch

[arveetek]

The reason I had my pistons milled, was that I also got them ceramic coated at the same time....kind of like killing two birds with one stone, in some respects. It's one of those, "might as well while we're at it" kind of things.

Also, I didn't like the idea of setting the heads farther away from the block deck, and relying on thicker gaskets to keep a solid seal....didn't seem like the best solution in these high-compression engines.

Casey

[Robyn]

If you try to go with the copper gasket have the block O ringed and the heads reciever grooved.

The original gaskets have several specialty areas that I am not sure a solid copper will do well.

Someone will pop in here and add there two cents worth.

[john8662]

Yep, measure the gasket, that's the way I was going to check myself.

I wasn't sure on the number mainly because I haven't actually measured it, so you're likely on the money, just can't prove it ;)

J

[mstockton]

Don't mean to steal this thread, but can you o-ring the block and heads? How does that work with the stainless precups? Do you just machine the ring groove ino the precup as well as the rest of the head, would be interested to know in case I go the turbo route myself....


-Martin