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Posted by: Downunderman Oct 4 2018, 04:38 PM

Who makes forged pistons for a 1.7 with a compression ratio about 10.5:1 or thereabouts? I need to source some for my historic racer engine. TIA. Howie.

Posted by: ChrisFoley Oct 5 2018, 06:33 AM

JE or Wiseco

Posted by: Downunderman Oct 5 2018, 03:37 PM

JE have just said they dont have an off the shelf one but will do a custom one. Waiting to hear from Wiseco.

Posted by: Downunderman Oct 5 2018, 05:08 PM

What I want is probably what is used in F Production. What do you use Chris?

Posted by: Driver174 Oct 12 2018, 02:10 PM

JE made a custom set for my 914/4 - 2.0. It was an easy process and they pretty much had all of data required. They were simple flat tops and I machined to valve pockets. Fly cutting the head down to 45cc chambers gave me 10.5:1 compression ratio.

JIM

Posted by: ChrisFoley Oct 13 2018, 10:09 AM

I've seen popup pistons that someone else used to get high compression without flycutting the heads too deeply, but I think that much shape on the piston crown affects the flame path too much.
Cutting the heads has its drawbacks too. Mostly because one of the exhaust stud bores is very close to a combustion chamber and may break thru when trying to get below 40cc.
My pistons were made to order by sending them a set of dimensions to work with.
Pin height, ring groove widths, piston dia., dome height & dia.
I used a stock high compression 1.7L piston as my model.
I've had 91mm pistons made for 1.7L and 94mm pistons made for 1.8L.
I cut my own eyebrows for the valves after doing a full mockup.