thoght backpressure was a must on low mod (bolt on) cars

 

Sure isnt.... but you'll make more torque with a good catback or duals setup.

 

Backpressure is necessary for small displacement engines. In our cases, the less backpressure, the better. You will gain quite a bit on the top end that most people usually start thinking they lost some bottom end power. Good luck.

 

I'm running open TPiS LT's right now and I'm loving it! Gotta go get a a y pipe made some time today or tomorrow though...

 

heard some good numbers from open headers..Proven by back to back dyno pulls w/ and without open

 

At the dyno shop I go to they had a bolt-on LS1 Camaro loose hp by going to open headers. Of course they gained it back when they put the y-pipe back on, this was with LTs headers too. I don't remember the exact figures but the car was making around 340rwhp. Sometimes truth is stranger than friction.

 

I know when I open my Cut-out's I tend to lose some low end acceleration/torque because of the loss of back-pressure, but it definitely pulls stronger at higher RPM's.

 

 

with my cutout on, it feels like all the low end torque is gone, and its sluggish at low RPM's...but one i hit about 3-3 1/2 grand, the car just takes off

 

I think that its more of a trade off on lower HP cars. You may loose a little on the bottom end but once you get into the upper Rpms you gain a little more due to better flow. But you gotta figure that even though you may loose a little on the bottom that it sounds so damn gooooooooood


Later,
-JOhn

 

The only thing that may reduce peak power with open headers is possible false knock and also any fueling problems you may encounter if reversion hits the O2 sensors.

 

backpressure is a myth. YOU DONT NEED ANY..period


the key to a good exhaust system is how it flows in a constant diameter pipe. The reason people feel like they lose horsepower is that the higher RPM is so much better


here is a quote from sport compact car magazine's website

"To produce the most power, an exhaust should have the least amount of restriction to the exhaust flow. Restriction hampers the burned exhaust gases from exiting your engine, causing some charge dilution with the incoming fresh fuel/air mixture. (In other words, exhaust left in the cylinder is mixed with the fresh intake charge.) This causes a loss of power. With greater restriction, back pressure is generated, making the engine work harder to pump the exhaust out of the cylinders. This is one source of pumping losses."

the rest of the article can be read at
Article Link


there, read up. It is true from import to domestic. 1.3L to 8L motors.