Hypereutectic vs Forged piston to bore clearances..

[JLaw]

Hi,

I am having a set of ductile iron barrels made for me and I need to specify what piston to bore clearance I would like. What are your thoughts regarding clearance per inch of bore for both a hypereutectic mahle and a forged piston in this application? Any ideas would be great to help me settle on a size.

Cheers,

John.

[mr horsepower]

Once had that problem
And then i put the piston and cilinder in the oven
To heat it up and then i could measurre it dynamic .
Gr henri

It give s you a good indication for the final hone

[Taylor]

There are too many factors to give you a recommendation.   Is it a naturally aspirated,  turbo or nitrous?  Is it a street car or racing only?  Who made the pistons? 

[JLaw]

Hi,

Thanks for the replies, its a turbo street motor running 18psi. The pistons are an older hypereutectic mahle design that are turbo specific.

Cheers.

[Taylor]

I would think you could get away with .005-.006"  as a low and high clearance.   But if they are ductile iron, do they have fins?   If you like to fire it up and stomp on the gas you might shoot for the high side.  Look up Mike Lawless or run a search for clearances run with AA "forged" pistons as I believe they are of similar construction.

[Taylor]

.....One more thing.  If you don't have the manufacturer's specs sheet in front of you, you will want to find out how big the skirt on your piston is to start with before calling out a spec to the honer on bore size. $.02