Mythbuster: LT headers/PP on forced induction. Gain or no gain?

o0Dan0o said:

It shouldn't get easier with boost, it should get harder.

Think of an exhaust this way, it's essentially a parasitic loss. The engine has to force the exhaust gases through the exhaust which is power lost. The reason why we don't just run the things through the hood as open headers is we need back pressure at lower RPM for exhaust scavenging. As you gain RPM you need a similar amount of back pressure but a less restrictive exhaust to produce it (at 6K RPM you're forcing roughly twice as much gas through the exhaust compared to 3k RPM). The same is true when you up the HP in general (if its N2O or FI), you pushing more exhaust gas through the exhaust so you don't need a system capable of producing the same back pressure, thus you want a freer flowing exhaust.
Dan

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o0Dan0o said:

That brings up a question I had, does the 500 RWHP on the stock bottom end rule of tumb stay with ported heads and cams? Those combined with headers should lower you boost readings a decent amount, but I'm guessing it would still increase cylinder pressures beyond what the stock rods can take.
Dan

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stangzilla100 said:

i have a friend w/ a whippled terminator and stock exhaust except for borla catback. he put in some LT's and o/r x pipe. he gained 10 rwhp and lost 2 psi, went from 17 to 15. he has less compression and less strain on the engine w/ a slight increase in power. i would say that is a good deal, more efficient and less wear on the engine.

i already had LT's and o/r x pipe when my whipple went on. i have the 3.5 pulley which is supposed to be 10 psi but i only see 9 on the gauge. i will take better efficiency over more psi any day. cam and heads would make it even more efficient.

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NastyStang113 said:

WTF !! I said the same thing !!

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