Wondering if anyone would know what the compression ratio would be for a set of jdm p72's oversized 0.50mm?

 

What block, crank and rods are they going with?

 

Also, is there any milling or decking of head and block?

 

I was trying to keep it basics for starters so we can get a baseline to work with. Don't overwhelm the guy lol

 

True. Although, he may learn something from the two posts and he may report back after doing research on his engine.

OP, rule of thumb, if going .50mm or .020" over bore on a cylinder this usually equates for roughly ~+.1 bump in static compression. (Example 10.6:1 STD vs 10.7:1 .020" overbore)

 

Yes I had the head milled and the block decked also. stock block, stock crank.

 

Stock gsr head, I replaced the valve stem seals.

 

head gasket is 81.5" .030" oversized

 

Forged h-beam scat rods w/ arp bolts... Lol

 

So roughly will I be running around 10.8:1-10.9:1?

 

Depends how much your stuff was decked and milled. Bone stock it will be 10.7ish.
Just curious...why the rods?

 

Boosting next summer.

 

I forgot what the machinist said already, it was a few weeks ago, said he basically barely skimmed the head and block that they were in good shape. The oversized head gasket will make up the difference in the machining so ur right prolly right in that range. I appreciate the advise/help. First build, testing stuff out.

 

If you're going to boost it and already have forged rods....why not do the pistons with them?

 

I did. The Jdm p72's 81.5mm bored .020".

 

I didn't go with forged pistons. Too expensive for this poor man build.

 

Everything's installed, just wanted a to get a rough estimate of the cp ratio

 

Nippon racing pistons and rings... the rods, pistons, rings came in a set for a decent price.