02-07-2019, 05:21 AM
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CC Member
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Join Date: Dec 2001
Location: Louisville,
KY
Cobra Make, Engine: I'm Cobra-less!
Posts: 9,417
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I think it all depends on the application and engine. For the most part I've seen a tighter LSA make more torque, but a tighter LSA also can increase overlap, which decreases vacuum, etc.
You can't really make a generalization though that changing from a 112 LSA to a 108 LSA will get you this, that, this, and that. It doesn't work that way. It all depends on the displacement, cylinder heads, intake, rest of the cam specs, etc. You can generally say that changing nothing else, going from a 112 LSA to a 108 LSA will increase overlap, which will decrease engine vacuum, and could make the engine inefficient.
A couple of random notes....
I run a 119-120 LSA on my pulling truck engines that need to pull hard up to 8500-9000 rpm.
On a small displacement engine with a big fat intake port (think 351C or 427 Tunnel Port), a tighter LSA is necessary to make big power at all. It's not because we're trying to juggle horsepower or torque curves, but we need overlap to scavenge the intake charge.
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