cylinder wear

[Roger G.]

Is there any difference over time in cylinder wear for forged vs hypereutectic pistons? I've read that the forged piston rings are a little looser initially, and they expand to fit the cylinder when warmed up, and that there is "piston slap" during the warmup, which doesn' t sound good

Also is there any difference in engine temp between the two?

[Jim T.]

Re: cylinder wear

My 68 with 97,000 miles on it now has the L79 engine that was installed at the factory. The engine is original and has never been apart. Runs very good and the engine does not have the piston slap you mentioned and it has forged pistons. It has been maintained by me and not abused.

[John H.]

Re: cylinder wear

Also is there any difference in engine temp between the two?

No, there isn't - engine operating temperature isn't affected by piston design.

[Joe L.]

Re: cylinder wear

Is there any difference over time in cylinder wear for forged vs hypereutectic pistons? I've read that the forged piston rings are a little looser initially, and they expand to fit the cylinder when warmed up, and that there is "piston slap" during the warmup, which doesn' t sound good

Also is there any difference in engine temp between the two?

Roger-----


Forged pistons will wear faster than hypereutectic cast. This is partially due to the greater piston-to-cylinder wall clearance (even though the clearance is mostly taken up after warm-up) and partially due to the wear characteristics of the different aluminum alloys used. However, keep in mind that engines in old Corvettes are not likely to see the kind of miles at which point the wear differences become significant. In other words, the pistons in your engine, whichever type you use, are likely to last a lot longer than you will.

For me, though, hypereutectic cast are the way to go. The vast majority of modern high performance engines use them. I believe GM would have used them in the 1962+ applications in which forged pistons were used if hypereutectic had been invented then.