Long shot here, but does anyone know if the Cosworth H22a pistons are the same specs as the Jun pistons? I picked up a set on ebay and the only thing I know is that they are 87.25mm bore with 35.375 compression height(according to Cosworth). The guy I bought them from advertised them as Jun pistons soo I bought them thinking they were. I emailed Cosworth and they did'nt have any more specs on them. I'm really more concerned if these things are gonna work on the stock frm sleeves like the Jun ones were designed for.
Does anyone know how to figure compression ratio with this info used with stock stroke and head gasket?

 

not sure.

Jun did order their Pistons from Cosworth in England, but they were made to a specification that Jun requested. If they are made the same exact specs as the Jun pistons, including whatever coating they use then yes they will work

 

yeah,
Thats the problem, Jun has'nt replied to my email and Cosworth does'nt seem to know **** about em. Soo I'm kind of wondering what to do with these things.
Also, I know you can't tell by looking at pistons, but these don't look to be the 12.3:1 compression that Jun pistons are supposed to be.

 

they look about right to me. and yes, cosworth doesn't seem to know aobut them. i even asked them at SEMA.

but if you want to unload those, come see me

 

Jeff's got a compression calculator on his site
http://www.importbuilders.com
Try that!

 

just a side note about jun, they will get back to you, it may take a week or two, but when they do they will cover what you need to know