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Forged piston cylinder clearance?
speedster356 - January 6th, 2011 at 07:22 AM

JE forged piston 92mm / air cooled, what sort of cylinder clearance. This is on methanol and track only.

dangerous - January 6th, 2011 at 07:35 AM

They should have a spec sheet with them, but i would like to see min .005".
Boost? probably up to .010"

speedster356 - January 6th, 2011 at 07:49 AM

No boost Dave. Thanks for that.

Beetspeed - January 7th, 2011 at 11:09 PM

Quote:
Originally posted by dangerous
They should have a spec sheet with them, but i would like to see min .005".
Boost? probably up to .010"

Wouldn't you need to know first what type of forged JE it is? Excessive clearence (if its not needed, not saying it isn;t) would only give extra piston slap.
AFAIK, there are 2 kinds (material used), each with its specific expansion/clearence rate per mm or inch bore.
The manufactors (JE) info about those rates are on their website including the ring gaps, so no guessing needed.

dangerous - January 8th, 2011 at 07:05 AM

Yes.

vw54 - January 8th, 2011 at 07:46 AM

send us a link to the site and clearences

dangerous - January 8th, 2011 at 08:56 AM

Please.


Here are the specs required for the two different materials.
You can use the JE pistons website to work out what you have,
but as mentioned in my first response, it should all be in the specs sheet that comes in the box.

http://www.jepistons.com/PDFs/TechCorner/SCPDrawings/piston_instrc2618.pdf 

http://www.jepistons.com/PDFs/TechCorner/SCPDrawings/piston_instrc4032.pdf 

I always run a little more clearance with air cooled, or with boost as stated in the instructions.
But in a perfect world it should be fine with the recommended clearance they list.

The extra clearance can make it harder for the rings to do their job,
but a clearance that is too tight can be catastrophic(sp?).