matmag89

Your gonna burn your engine out, because there isnt enough back pressure

hamhead

... ^^^ ...

What are you referring to? Backpressure, while needed to some extent, is bad for the engine. It keeps burned, hot gas in the combustion chamber, increasing heat inside your engine. Cooler is better...

OdessitPashka

<div class='quotetop'>QUOTE (hamhead)</div><div class='quotemain'>... ^^^ ...

What are you referring to? Backpressure, while needed to some extent, is bad for the engine. It keeps burned, hot gas in the combustion chamber, increasing heat inside your engine. Cooler is better...</div>

not always. you want to have high velocity of the gases.

hamhead

Well this thread is back from the dead isn't it OP? LOL. You need a happy medium of hot but not too hot inside the engine, and as hot as possible outside through the exhaust path.

With the stock exhaust, it keeps the insides of the engine hot, and the material the exhaust is made of makes the exhaust relatively cold. The stock exhaust also has a habit of expanding and "ticking." You can hear it when you turn the car off. This is because of all the hotness that leaves the engine and has no where to go because of the horrible material and constrictive exhaust.

With an aftermarket, 2.25-2.5, you reduce strain on the combustion chamber, yet still have a happy medium with hotness. The better material (mild steel, stainless steel) keeps the heat in, and the better bends help the exhaust leave faster than stock, while retaining the same velocity.

If you went 3inch (n/a), the loss of backpressure on the combustion chamber would probably cause a loss of low-end, and the large piping would be too big and the velocity wouldn't be as good, making it worse than the general 2.25-2.5inch setup.

OdessitPashka

good stuff man, but I still think that 2.5" is a little too big for mild N/A mods. 2.25" is plenty.

You want to be able to get gases out with the highest velocity possible, therefore you need to be able to get an exhaust that will be not too big to be loosing gas velocity, nor too small to be restricting any flow.

hamhead

I agree it might be a little too big. Maybe 2.39 or something would be perfect LOL. Maybe thats why my exhaust seemed to do more than KRD cat-backs and such to other people. My exhaust is 2.37inches in the bends. tongue.gif That and I didn't go over the axle like most.

Kiltman

<span style="font-size:10pt;line-height:100%">So what kind of exhaust do you have? Mandrel bent aluminized steel? Do you have headers, and if so what kind and what are they made of? What muffler do you have? Do you have a cat? I want an exhaust that will give me more power without throwing a cel.

</span>

hamhead

An exhaust won't throw a CEL no matter what size or if you eliminate the second cat first of all.

I'm running 2.5inch press-bent (difference between a good press and mandrel on a N/A setup is negligible) stainless steel from the cat to the axle, then 2.5inch press-bent mild steel from the axle to the muffler. I don't know what brand muffler it is, but its straight through non-perforated... sounds great. My exhaust doesn't go over the axle, it goes under it, like the Apexi. It has two 90 degree bends, and two 50ish degree bends.

Currently not running headers, that might have to wait since that Air-Ram/BBTB groupbuy tempts me.