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Lost Boost with Headers!

2.3K views 22 replies 13 participants last post by  03_StangGuy  
#1 ·
Here's some thing kinda funny and wanted to know if this is true. I was at the shop talking to a guy there about getting long tube headers and an o/h pipe. The guy told me it's kind of a trade off. He told me with forced induction he has seen cars loose about .5-1.0 lb boost with headers and o/r set up but they did gain hp? Any one ever heard of this?
 
#8 ·
why would you want to? Running less boost making more power is a good thing. Sure slap a smaller pulley on there but your gonna make power that will probably start pushing your luck.
 
#14 ·
Just think about how you measure boost. Where ever you have the most restriction thats where boost builds up. You free up your exhaust and flow more air then you will be less restrictive and lose boost pressure.

However your supercharger is still pumping out the same amount of air that it was before. You will still make a little more horsepower and say you're running less boost than that other guy with shorty headers.
 
#15 ·
Less Restriction = Less Boost = More Power
 
#17 ·
Exactly. The headers create less restriction so more air can flow out and in turn more air can flow in. More air means more power. Air flow is measured in CFM, air restriction is measured in boost. Less restriction (boost) mean more air flow (CFM).
 
#16 ·
When I went to longtubes I went from about 11.5 max psi to about 10.5 max psi. The low end torque suffered a bit but the peak hp went up. I went to a smaller pulley and brought the boost back up to 11.5 or so. Whoa - that made a big diff :) I got to the boost level I was at before long tubes but was now pushing much more air through the engine and making more power. I think that's the main advantage of long tubes - allows you to make more power at a given boost level.

I'm in "not too concerned if the motor blows" mode now so am willing to push it a bit further and have actually gone down a pulley size and see 12 - 12.5# boost now with the longtubes.
 
#20 ·
this is why LT's are a very good mod for FI
on my Whipple gen 1, i have a 3.5 pulley which I rate at about 9 psi since its 10 with a gen 2.
i see about 7 psi on my gauge, i get about 449 rwhp/419 tq. i figure i lost a couple psi but picked up a few ponies.
less restriction and more power is what you want.
friend of mine with a terminator put in LT's, lost 3 psi but gained about 10 psi without retuning and no pulley change.
you dont gain a ridiculous amount of power but its better on your engine, and it sounds good too.