Can someone help me understand the importance of backpressue?

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Rafs-T-Type

Not so Senior Member
Joined
Mar 8, 2009
Messages
2,766
Why couldn't you run your car with no headers at all? assuming a NA car ;). It just seems like the less restrictions the better it should move.
 
I cringe every time I see the word 'backpressure'.


If you run a cam that's why too damn big with too much overlap, corking up the exhaust will get you back a little of the power you lost from over-scavenging. The better of the scenarios is to run a correctly sized cam with as little flow restriction as possible. That way the scavenging effect you get from a set of headers can actually help instead of just letting raw air/fuel run out the exhaust pipe. That doesn't apply turbo engines.

On a turbo car the exhaust manifolds are pressurized so you can't make a low pressure pulse at the exhaust valve. Same negativity comes from too much overlap on our engines though. We don't need an exhaust snatch during over lap to pull air/fuel across the combustion chamber, we've got boost to do that job. Too much overlap just blows it right out the cylinder.
 
Why couldn't you run your car with no headers at all? assuming a NA car ;). It just seems like the less restrictions the better it should move.


most people would prefer not to melt their inner fenders and raise their under hood temps 1000 deg.
 
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