20 Ls cathedral intakes tested!
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From: Pompano Beach FL
not much... most motors dont need the flow of a 102 tb, you lose power with a 90mm tb when you mismatch it to a 102 intake and the step creates turbulence. when everything is properly matched the opening doesnt really matter too much past a certain point
Red, "the opening doesn't really matter too much" is open to debate. The smaller, shorter and smaller opening Edelbrock is at least as efficient as the taller, bigger opening Holley on this motor and the #'s prove it, just saying.
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The runners on the holley were also .25" longer and the plenum volume between the 2 was never displayed. 4hp could also be dyno variance. The runner length and plenum volume are really what determines power as long as the engine isnt choked for air. I can tell you through a lot of testing I did that a 92tb on a cam only car is NOT a restriction given the same intake I did many tests with both tbs and saw the same vacuum or lack thereof with each pull, yet I gained 7whp with the 102 over a 92tb and that was from the turbulence created from the step of having a 92tb on a 102 intake.
also 4hp on an engine dyno wouldnt even show up at the wheels. the motor doesnt care what size the tb opening is there it just has to be enough for it not to be a restriction which it is not. i pulled 99-101kpa with a 92tb on my cam only setup at wot then bolted a 102tb and again pulled 99-101kpa. repeated the same thing on my ls3 with the same results. both of those motors layed down 450whp.
also 4hp on an engine dyno wouldnt even show up at the wheels. the motor doesnt care what size the tb opening is there it just has to be enough for it not to be a restriction which it is not. i pulled 99-101kpa with a 92tb on my cam only setup at wot then bolted a 102tb and again pulled 99-101kpa. repeated the same thing on my ls3 with the same results. both of those motors layed down 450whp.
Last edited by redbird555; Aug 10, 2015 at 08:58 AM.
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From: indiana
I would Have like to seen them test the carb intakes with a throttle body EFI setup and not with carbs to go along with the other intake test with EFI.. It's ovious the camshaft is more a EFI friendly fit than for a carb setup as carb needs less LSA to shine more. Imo anyway..
Every high end carb intake on the market will demolish the lsxr, but then you're talking $3000 for an intake.
It would have been nice of they had included the Super Victor in this test as I think the cathedral port Victor Jr's runners are to small in cross sectional area to show the true high RPM benefit that a single plane can offer.
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If you are definining the street car's midrange powerband as something like 3000-6000, then I think you will find that the runner length in the FAST style intakes are perfectly tuned/optimized for that application. Runner length is crucial for tuning an engines powerband. When you shorten the runners as in most single plane carb intakes, you move the powerband higher in the RPM range. You can advance the camshaft's intake valve events to mitigate this characteristic, but the short runners will always prefer higher RPM.
It would have been nice of they had included the Super Victor in this test as I think the cathedral port Victor Jr's runners are to small in cross sectional area to show the true high RPM benefit that a single plane can offer.
It would have been nice of they had included the Super Victor in this test as I think the cathedral port Victor Jr's runners are to small in cross sectional area to show the true high RPM benefit that a single plane can offer.