Backpressure?

[Nomad707]

im running stock piping on a 87 5spd NA with an Afrermarket cat. ..anyways my question is, if im running my stock header, the cat and my precat.. and i have just straight tubing after my cat with no muffler or resonator.. (2 and 1/4" piping)

Is this enough backpressure for an NA or should i add a flange or something to the open pipe?

 

[amichie]

You will get more gains by upgrading the headers than any other exhaust component.

On an NA engine a cat back system will just make your car louder and may feel a little stronger up top.

 

[Ma70.Ent]

Read N/A mod FAQ. There's a whole lot of stuff to read in it...especially talks of "backpressure". Most would say N/As don't NEED it, and I agree, but you can read and find out for yourself

 

[HommerSimpson]

Run strait out to back... if you dont like.. cut and put muffler...

 

[Poodles]

"backpressure" is a myth

It's a function of the velocity and scavenging effects that make the difference in low end torque. The velocity causes section and will actually pull the exhaust out of the cylinder so you get a better charge of air/fuel.

Go to small, and it won't flow enough up top. Go too big and lose the low end power.

On a turbo car it's irrelevent post turbo, the bigger the better.

 

[Nick M]

Poodles with a good post! You don't want any backpressure, but to big, and you lose velocity.

Such as more than 60-65mm on a stock 7M.

 

[webbs7mgte]

:thumbup: poodels back pressure is somethign everyone thinks you need or have oto much of or worries about it but like he said thats why many like newer camaros and everythign dump out very soon to gain that low end torque keep a decent size on it just full exhaust with aobut 2 3/4" or 3" if you cazn get away with it drop that cat and run a test pipe