Thread: Mahle pistons,the coatings

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i used many sets of mahle rings have 4 more to file fit for a 427 today and JE for big bore 4.600+.I use the hell fire for Nos use for mild use and oem i like hasting.theres i new line of rings re box i am sure that use a steel top ring for the 043 ring looks to use the vent flex 3mm oil expander like mahle

During looking at the Mahle pistons which are the part number SBC425030I26 I was concerned with making the wrong choice and ending up with too low of a compression ratio.<it's a dished piston>.Still wanting to run 87 gas threw it because it is basically a towing van for my business(costs of gas is a concern somewhat),but wanting to have some fun with it when the trailer isn't behind the van.

Mahle suggested the following:

-0- deck with a .040 gasket

RHS 64 cc heads cast iron with a 180 cc intake runner and a cut of 12 to 15 thousands to get to a ratio of 9.21.About 62cc end results after the cut.

Well I was talking to the machine shop telling them the costs was $693.95 for these pistons.They checked their cost and it wasn't much different.

The machine shop called back suggesting these TRW pistons with 5/64's rings.Part number L2256F30.With a 64cc head would be 9.6 compression ratio.
Man,I keep going back and forth on the compression ratio.I am thinking to cross over the line of 9.5 is a point where 87 gas isn't in play any longer.Yep,I know I could cam it to work,but I am thinking a smooth idle is also apart of my intension.

The cam is a GM roller part number14097395 that is:

288/308 duration @ .050 tappet lift

196/206 max lift 1.51 rocket ratio

431/451

center line of 109.