i did i quoted it in a previous postboner;14525 wrote:Hey look at this
http://stlhondas.com/forums/showthread.php?t=354
2.5" or 3" exhaust?
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stolle
- Posts: 2241
- Joined: Wed Nov 08, 2006 5:47 pm
2.5" or 3" exhaust?
Team NOCO Crew Member #2
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b18b-t
- Posts: 376
- Joined: Thu Jan 11, 2007 6:20 am
2.5" or 3" exhaust?
I have 2 1/2 with e cut. I love it, but if i had more money to spend i'd go with 3 for sure.
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budget_crx
- Posts: 2722
- Joined: Wed Nov 08, 2006 9:49 pm
2.5" or 3" exhaust?
Ok finally busted out the math equations to figure this out, thanks corky!
bigger is not always better, exhaust gas velocity needs to stay at approx. 250ft/sec. tube size can be checked by calculating the maximum airflow atainable, dividing by the area of the tubing in square feet.
lets use 400hp and a 2.5in exhaust tubing with an approx. 600cfm of airflow
Velocity = Airflow / Area
[CENTER]= 600 cubicft/min X 1/60 min/sec
pi X [2.5/2][2.5/2] squarein. 1squareft/144squarein[/CENTER]
which comes out to 293ft/sec, more than what is suggested as a velocity rate for single tubing exhaust, and thats with 400hp.
The equation cannot be typed up to well, but evrything is there and it makes sense. the reason exhaust velocity should not exceed the number of 250ft/sec is because of rapidly increasing drag and cosequent flow losses. resist the temptation to use larger diameter tubes than neccesary, as little drag is created in smoothtubes with gentle bends.
All of the above info was quoted from Corky Bell, owner of Bell Engineering which makes turbo kits, intercoolers and specialty one off made cars and plane equipment. He also wrote the book maximum boost which is a good source for simplified Turbocharger understanding and design. needless to say the guys a legit source of information, so I will take his word on it. no more than 2.5in for me!
bigger is not always better, exhaust gas velocity needs to stay at approx. 250ft/sec. tube size can be checked by calculating the maximum airflow atainable, dividing by the area of the tubing in square feet.
lets use 400hp and a 2.5in exhaust tubing with an approx. 600cfm of airflow
Velocity = Airflow / Area
[CENTER]= 600 cubicft/min X 1/60 min/sec
pi X [2.5/2][2.5/2] squarein. 1squareft/144squarein[/CENTER]
which comes out to 293ft/sec, more than what is suggested as a velocity rate for single tubing exhaust, and thats with 400hp.
The equation cannot be typed up to well, but evrything is there and it makes sense. the reason exhaust velocity should not exceed the number of 250ft/sec is because of rapidly increasing drag and cosequent flow losses. resist the temptation to use larger diameter tubes than neccesary, as little drag is created in smoothtubes with gentle bends.
All of the above info was quoted from Corky Bell, owner of Bell Engineering which makes turbo kits, intercoolers and specialty one off made cars and plane equipment. He also wrote the book maximum boost which is a good source for simplified Turbocharger understanding and design. needless to say the guys a legit source of information, so I will take his word on it. no more than 2.5in for me!
