so, i had some JE pistons installed a while back which gave me compression test results of 135psi. this is on a stock IX engine.

i've since pulled them out and replaced with OEM which now reads 145psi (264 cams, which is why i'm assuming a bit lower than stock).

nothing else has changed so, based on the C/R of an OEM IX engine, can anyone make an educated guess on the C/R of the JEs?

or is it impossible without knowing all measurements and specs. i want to sell the pistons, but i'm sure the buyer would like to have an idea of what they are getting LOL.

 

Did you buy the Pistons without knowing the ratio? And post a picture if have one, so we can see the head/dish of the piston.

 

They were sold to me as "Buschur/JE drop ins" with stock comp. I sent them to Buschur for inspection. Buschur confirmed they are theirs, but no longer have info on the job number so they can't provide any specs.
They look identical to stock, but I can post a pic anyway.

 

I'm gonna guess they're 8.5:1.

 

That would make sense because I THINK the choices back then were 8.5 or 10.

 

Took a quick glance on their website and it seems the only two c/r's they offer for the 4G63 are 8.5:1 and 10.0:1. I would ditch those and get some 9.0:1's

 

i won't be using these. i took them out because i was disappointed in the power i was making. low comp is great when going for big power, but i have an HTA71 so can't really take advantage of a lower compression piston.
these are better suited for someone looking to run more than 25psi.