Verification of L98 Engine Compression numbers please?
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Joined: Jul 2010
Posts: 97
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Verification of L98 Engine Compression numbers please?
So, I've researched some numbers and crunched them, and would like verification from someone whom has worked on and measured the L98 engine as installed in my 1987 Corvette.
Bore and stroke = 4.00 x 3.48
Cylinder head volume = 58cc
Head gasket = .051"
Deck height = .025" (Probable?)
Valve reliefs = 6 cc
My engine is still assembled and installed, so I can't verify that deck height, but that's fairly common, and those numbers crunch to 9.99:1, which corresponds to the Vette's advertised compression ratio of 10:1. Can someone that's had one apart verify any of those numbers, but especially the stock deck height??
If correct, that correlates to a quench of .076" which is no bueno and will need addressed when I go through this motor. A simple change to a .026" head gasket would help a lot...
That would also be helpful in keeping up the compression ratio when going to 64cc aftermarket heads, though milling would likely still be necessary.
Thanks,
Vettepilot
Bore and stroke = 4.00 x 3.48
Cylinder head volume = 58cc
Head gasket = .051"
Deck height = .025" (Probable?)
Valve reliefs = 6 cc
My engine is still assembled and installed, so I can't verify that deck height, but that's fairly common, and those numbers crunch to 9.99:1, which corresponds to the Vette's advertised compression ratio of 10:1. Can someone that's had one apart verify any of those numbers, but especially the stock deck height??
If correct, that correlates to a quench of .076" which is no bueno and will need addressed when I go through this motor. A simple change to a .026" head gasket would help a lot...
That would also be helpful in keeping up the compression ratio when going to 64cc aftermarket heads, though milling would likely still be necessary.
Thanks,
Vettepilot
Thread Starter
Advanced
Joined: Jul 2010
Posts: 97
Likes: 12
I have always basically gone by this: milling the heads up to .030", intake fitment should be ok. More than that, and the intake surfaces should be milled.
However, the engine ALWAYS needs mocked up and fitment checked.
I once knew a guy that blew TWO engines in his jet boat. Water at the poorly fitting intake leaked into the oil, and diluted the oil and destroyed the engines.
Vettepilot
However, the engine ALWAYS needs mocked up and fitment checked.
I once knew a guy that blew TWO engines in his jet boat. Water at the poorly fitting intake leaked into the oil, and diluted the oil and destroyed the engines.
Vettepilot
