Help with deciding which piston cc to go with for new build.

[Quick Strike]

Or a .045" dish. Or a combination of dish and reliefs that add up to 4.5 ccs. The OP wanted to know what static compression would be needed with his particular cams to make 7.75:1 dynamic compression. So, we have to work the DCR calculator with the known values and adjust some piston values we can control to zero in on his answer. That just happened to be the dish/relief that works in this representation of the engine. Less piston relief/dish cc would be needed with thicker gaskets or less block decking as long as the quench was not dramatically reduced.


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[MalcolmV8]

Oh gotcha. I see what you were doing.

 

[Quick Strike]

I'm around .090" piston to valve clearance on the intakes in on a 115* CL with much less duration then the stage IIIs. That is with a 9 cc dish pistons .006" down the hole. OP will need intake reliefs unless he wants to risk bent valves.


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[MalcolmV8]

I'm around .090" piston to valve clearance on the intakes in on a 115* CL with much less duration then the stage IIIs. That is with a 9 cc dish pistons .006" down the hole. OP will need intake reliefs unless he wants to risk bent valves.


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Agreed. On my prior set of pistons that essentially had no valve reliefs (they did but Diamond cut them incorrectly so the valve was missing the pocket) I had to retard the Comp intake cams I had at the time to get clearance. I was actually able to degree them to the specs Comp wanted them at but not where I wanted them.