Quote:
Originally Posted by cmitchell17
I am curious as well, I told TSP I wanted as much taken off as they could give me considering PTV, I have a similar size TSP cam 228/236-.635/.635-114. They told me they took off .030 but I didn't see it marked or engraved on the heads anywhere so just took their word for it (which honestly doesn't seem that good of a word with TSP)
I calculate now I have 12.25:1 compression, I want as much as I can get because I run 100% E85, if I had my choice I would be at 14:1, but I don't see anyway to get to that much compression even with an aftermarket rotating parts. I also don't like the idea of messing up the factory piston shape given that supposedly 5 million hours or something like that of CFD time was spent by GM on getting the piston top shape for correct mixture motion, although I suspect a lot of it was optimizing for emissions considerations so there is probably some room to reoptimize it for airflow capacity and detonation resistance maybe.
So by my calculations the .028 with .010 milling would be 12.65
with the .040 ones it would be 12.21
and with a stock .052 it would be 11.80
I am using the SBC spec that is about 1cc per .0055 inches milled. I have no idea how much the piston and valve relief volumes are but I back calculated and iterated until I got to the stock compression ratio of 11.5, which for some weird reason ends up being 0 cc for piston dome volume and 1.17 cc for valve relief volume so I'm not sure what's going on there. I am also assuming the pistons are .008 below deck.
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I'm glad I'm not the only one looking into this, with all these big na cars chasing records and shops putting out cars idk why more information on this isnt published. My next question is will I have adequate piston to valve or will I have to flycut? I prefer to not go down that road also as this is a procharger oriented cam I'm just having fun in the meantime to see what I can get out the car for now. I've raced a couple hefty na set ups and my car does very well considering cam and converter size.