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Team Tool
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2,514 Posts
Discussion Starter #1
I kinda know what overlap is, but what are the effects on the engine and turbo when running boost?

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Russ Knezic
Place Racing CAI,JWT S4 cams and JWT ECU with S4 program, hotshot gen3 header, greddy SP exhaust, KYB AGX's and Ground Controls, Konig Traffiks with Nitto NT555's

Turbo soon!
N/A is not enough
 

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sleeper
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5,445 Posts
Well, overlap is when the intake and exhaust vavles are open at the same time. Now, the more boost you try to make by spinning the turbo faster, the greater the backpressure the turbo creates. At some point, there will be so much back pressure that the exhaust is forced backwards back into the cylinder when you have overlap(called reversion). As you would think, this is very bad for power. Messes up the intake mixture into the cylinder, increases the temp in the cylinder making it more prone to detonation. I think that's all correct...

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'96 SE-R.... a few tweaks here and there :)
 
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