yeah, well, a lot of people also swear by the TTDA, and a lot of people swear by those 'tornado' sheetmetal things that are supposed to go in your intake, or putting 93 octane in a car designed for 87, so whats your point?

Think of it like this... you exhaust is a long steel pipe (wild stretch of imagination, I know) your exhaust is actually wet cement. If your diameter is too big, your velocity is gonna be too low, and the cement will start getting hard before it exits the end of the pipe. Reduce the diameter, velocity increases, and the cement leaves the pipe before it hardens up. Your exhaust gasses do the same thing, they get dense as they cool, and act as their own restriction near the end of the pipe. Reduce diameter, keep flow up, restriction stays low.

Page 286 of Forced Induction Performance Tuning...

'because exhaust gases cool and contract as they get towards the rear of the car, it is in order to reduce the pipe diameter after the rear axle. This won't have much effect on power output and it may help reduce noise, thereby allowing the use of a less restrictive silencer (muffler).'

 

Ill take your word for it. But honestly, i have seen WAY to many dynos of turbo cars showing increasing the diam of the piping improving power and significantly. This is on evo, wrx/sti, sr20det, skylines, etc. Its nice when you have a subscription to Import Tuner and their tuner pages. Its basically dyno, install part, dyno, install part, dyno. They do 3-4 parts and overlap the dynos. I have yet to see any exhaust increase not make more hp on a turbo car.

Again, i do see your point and theory.

 

Isn't it funny that the newShelby GT500 has a beam for a rear suspension? Crazy Americans... when will they learn [>:]

 

I'm not arguing that an increased diameter makes more power, yes, obviously, it'll flow more. It's the end of the pipe that everyone ignores. Theres some math to it if you want to get it perfect, most likely why its skipped.

 

I guess the other option is to exhaust wrap cat-back... maybe I'll do that.... ; )

 

Or you can be like some and heat wrap the dp and it should keep the heat in all the way through the exhaust. Plus you can keep some of the heat out of the engine bay.

 

I'm glad this has sparked some debate. Actually what I was thinking was (dons flame suit) to have an electric exhaust fan in the stock exhaust. If I cooled the air before the fan it would reduce stress on the fan and would make the air denser and increase the fan's efficiency. Just a thought, I haven't tested or bought anything.

 

What you think you would gain in flow would be restricted by the fan. You need the live by the KISS philosophy.

 

Heatwrap + heatspray on a DPis underated. not only does it function to keep exhaust flowing quickly and keep engine bay temps down. but its a great way to make those really annoying rattles go away when clearance is really tight [8D]

 

Dont forget the ceramic coating on the manifold.