The Pittsburgh Thread

[Seer]

Originally Posted by tahseenmahmood

umm.. if i knew why would i ask.. and it has nothing to do with common sense.. most common ppl dont mess or know about pipes in their cars.. the only time i even looked under my car is when some one installed the exhaust an year ago..
But thanks anyways

yes, most enthusiasts do know about their exhaust.

Although a 4" whistle tip adds tons of HP

[demonspeed]

Originally Posted by Seer

yes, most enthusiasts do know about their exhaust.

Although a 4" whistle tip adds tons of HP

Thanks for the blast down memory lane...

[Swacer]

Originally Posted by Seer

yes, most enthusiasts do know about their exhaust.

Although a 4" whistle tip adds tons of HP

He's gonna yell at you....

[tahseenmahmood]

"most" not me
I am considering changing my exhaust from MRT to pypes with 4 inch tips this summer

Originally Posted by Seer

yes, most enthusiasts do know about their exhaust.

Although a 4" whistle tip adds tons of HP

[PittPaz]

Originally Posted by Swacer

He's gonna yell at you....

You're a douche.

[Swacer]

Originally Posted by PittPaz

You're a douche.

Ouch....right thru the heart...

[tahseenmahmood]

Originally Posted by PittPaz

You're a douche.

Originally Posted by Swacer

Ouch....right thru the heart...

[PittPaz]

Originally Posted by Swacer

Ouch....right thru the heart...

Yep.

[demonspeed]

Let's move forward with one of these:

[Witt]

Originally Posted by demonspeed

I've stood by this post for nearly a decade...

Hey guys I just got done reading a good article in the May 2005 issue of Popular Hot Rodding Magazine. The article was written by David Vizard who seems to be one of the most accredited and respected people in the automotive performance world. In the article he stated that CFM is a great way to help develop a zero loss exhaust system. For zero loss a exhaust must flow 2.2 CFM per horsepower(This means less than 1% of total power produced by the engine is lost due to back pressure.). From reading the article I think that a lot of people that see gains when going from a 2.5” exhaust system to a 3” dual system see them because the muffler on the 2.5” system didn’t flow enough for their application. David stated that per square inch of exhaust tubing there is 115 CFM of flow. So plugging some numbers into the good ole TI-89….. ((3.14 * radius^2)*115[*2 for a dual exhaust system])/2.2 = Max hp supported with zero loss

A 2.75” (stock) single system is good for a 310hp engine with zero loss…
A 3” Single system is good for a 370hp engine with zero loss…
A 3.5” Single system is good for a 503hp engine with zero loss…
A 4” Single system is good for a 657hp engine with zero loss…
A 2.25” dual system is good for a 457hp engine with zero loss…
A 2.5” dual system is good for a 513hp engine with zero loss…
A 3” dual system is good for a 812hp engine with zero loss…

Now these numbers are assuming that everything else is set up perfectly. The muffler must flow as much as the open pipe or more to get zero loss at the listed hp levels. He also states that using a muffler with a larger inlet/outlet diameter than your exhaust pipe is a great way to get more out of a smaller diameter system since the muffler flow will be able to match the straight pipe flow. Now there are many other things to consider when designing an exhaust system but I figured this would give a great foundation to build on.

Just a side note that he stated that I thought was neat... “Just as fish don’t feel the weight of water, we don’t readily appreciate the weight of air. Just to set the record straight, a cube of air 100 feet square will weigh 38 tons!”

Hopefully I’ll get some more understanding of flow in a closed space in my fluid dynamics class next semester.

- OldSchoolSS

While the math is somewhat correct, something like that isn't very useful imo. While zero loss is fine, on an NA application I think we all agree that you want a system designed for best scavenging relative to the engine in question. A supercharged engine, specifically on a positive displacement setup, not much of that really matters because your blower dictates the amount of airflow in and out of the engine. Exhaust upgrades on a supercharged engine do very little relative to an NA setup contrary to what some people might think.

If you have the time, this link is a good read with a little math behind the action.

[demonspeed]

I attempted to read through that like, Al. My head started to get all

[Swacer]

Originally Posted by Witt

While the math is somewhat correct, something like that isn't very useful imo. While zero loss is fine, on an NA application I think we all agree that you want a system designed for best scavenging relative to the engine in question. A supercharged engine, specifically on a positive displacement setup, not much of that really matters because your blower dictates the amount of airflow in and out of the engine. Exhaust upgrades on a supercharged engine do very little relative to an NA setup contrary to what some people might think.

If you have the time, this link is a good read with a little math behind the action.

A lot of assumptions in there, but in general really good back of the napkin calc there.

Just wish the author would cite where he got the equations from.

[Trav2SS]

Originally Posted by Swacer

A lot of assumptions in there, but in general really good back of the napkin calc there.

Just wish the author would cite where he got the equations from.

Well as with a lot of Internet Facts and Equations.. lol

[Swacer]

Originally Posted by Trav2SS

Well as with a lot of Internet Facts and Equations.. lol

hahaha Gotta love your day when Sheldon is included.

I have one of those shirts at home.