Quote:
Originally Posted by LT7A
Gregski, do you feel like you've noticed any benefit with regards to the lighter weight of the aluminum over the cast iron other than lifting them over the fender? You said the performance feels about the same and, so maybe it's not enough weight change to feel a difference. The owner of the local high performance shop that does some of my work has cautioned me that aluminum heads actually pull energy out of the combustion event in the form of heat. He says that installing aluminum heads without increasing the compression ratio about a point will actually net a drop in performance. If that theory holds, then maybe you have increased flow etcetera, but then were balanced out by that factor.
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That is a good question, the weight difference is negligeable on a 2 ton truck, it's like throwing a pool chair off of a Titanic, ha ha.
I think I may have actually decreased compression by following Edelbrocks instructions and mounting a .041 compression head gasket rather than the .028 the General had me install for the Vortec heads. But again very small potatoes. I recon Edels reasoning is if you buy these new heads most likely you had a block rebuilt and they decked it a few mil so the gasket is to compensate for piston height / quench area etc. I'm no expert just regurgetating what I read on the InterWebs.
I have not tunned the bejezus out of this new engine top end configuration yet on the account of the valve train noise, I think once I have proper rocker/pushrod geometry I will feel more comfortable pushing the engine a bit more.
Stay tuned a Dyno Test is on the horizon.