77CC LS6 Heads from WCCH.
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From: Forced Induction Heaven
77CC LS6 Heads from WCCH. Just wanted to say thanks to Richard for CNCing my LS6 Heads to 77cc. By using a .065 Cometic Gasket and the newly revamped LS6 Heads my CR will be below 9:1. My CR was 9.67:1 and when combined with 12-13lbs of boost could only run 10* of timing at WOT with 91 octane. Should be able to add around 20+* of timing now.
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Was this with a stock shortblock? I'm curious how much the CR can be changed by *just* changing the stock head CC size. I'd love to just throw a set of heads on and be blower friendly, or swap over and be NA on a whim.
I believe the short bolck on this one is forged pistons and aftermarket rods. Pistons are flat top with valve reliefs (approx. 2cc dish volume). C/R will get down to less than 9.25:1.
Richard
Richard
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From: Forced Induction Heaven
Originally Posted by jmX
Was this with a stock shortblock? I'm curious how much the CR can be changed by *just* changing the stock head CC size. I'd love to just throw a set of heads on and be blower friendly, or swap over and be NA on a whim.
When I put the motor together I had just gotten rid of the ProCharger and was looking at just doing H&C, my (our) friend Andy (A&A Corvette) had not built his own C5 Procharger kit yet (the best design sofar). So I just put in some Diamond Pistons with the -2cc Valve Reliefs. So when Turbo Tech came out with a kit and I was approached by a vendor for R&D purposes. I had the heads done to 73cc, used stock MLS gaskets and sent her on the way. My CR was 9.67:1 (-.014 Deck Height outta the hole). I noticed I was getting 4.5* of KR using 91 octane at 11.5-13lbs of boost...leaving me with only 10* total timing at WOT. So I asked Richard if he could see how much more he could take out safely...so my heads had been resurfaced (cleaned up) twice since I have had the car...a .005 and .004 resurface for a total of .009 all together. Richard CCd them after the clean up and they are 77cc. If they were a new GM casting being reworked they would be closer to 78cc.
Anyway if you have a stock LSx and wanted to reduce your CR with heads only. These heads with stock gaskets would give you a Compression Ratio of 9.2:1...just about right for any Turbo or SC application...and the availability to switch back over to NA with a Head Swap..to get back to a CR as high as 11:1....pretty good deal if you ask me.
