How to determine exhaust pipe size needed

Twist 2 Go · October 26th, 2005, 03:50 PM

here is a chart I found from Dynomax that lists how to determine the size of exhaust needed

DC97Cobra · October 26th, 2005, 04:27 PM

Cool! Looks like I'm in the right margin with 2 1/2" exhaust. Thanks for the info!

IcantDo55 · October 26th, 2005, 04:41 PM

I'm off the chart

347ci 700 hp?

Bill · November 11th, 2005, 05:25 PM

good info man

GTXRacing · April 24th, 2006, 12:51 AM

Originally Posted by IcantDo55

I'm off the chart
347ci 700 hp?

LOL you're not off the chart, you fall right into that last group on the bottom. You just have an overpowered lion beast LOL

AtlanticBlue99 · April 24th, 2006, 06:29 AM

Originally Posted by IcantDo55

I'm off the chart
347ci 700 hp?

wouldnt you be running just headers to a collection pipe? no exhaust needed unless you drive it on the street. do you drive it on the street lol?

WVSNS& · April 25th, 2006, 09:19 AM

I was under the improeeion that three inch pipes were a good starting point. At least that is what I liked on my old school svo mustangs.

99mustang232 · April 25th, 2006, 10:35 AM

back pressure can actually be a good thing in a n/a, nitrous, or blown setup... but not the same on turbo setups, where the exhaust drives the power adder and where exhaust scavaging is not an issue.

Sa-WaitNoMustang900Turbo · April 25th, 2006, 10:21 PM

I'm a turbo guy, but please explain to me how back preasure can help power

AtlanticBlue99 · April 25th, 2006, 11:05 PM

help torque. you lose low end power on n/a and non turbo cars without backpressure. but this is usually made up in the higher rpm's

Sa-WaitNoMustang900Turbo · April 25th, 2006, 11:12 PM

how does it help torque? doesnt the engine waste less energy (t and hp) if it is easier for it to expell exaust. I've always thought back preasure = preasue against piston as it strokes up to expell gasses

AtlanticBlue99 · April 25th, 2006, 11:17 PM

backpressure being higher pressure in exhaust pipe. a pipe that is too large has a lower pressure so the exhaust exits more slowly. remember that a smaller tube will make the same amount of air move at a higher pressue, thus more quickly. too small is too restrictive, too big is too free. there is a good compromise to be reached- thus the chart.

99mustang232 · April 25th, 2006, 11:27 PM

back pressure promotes low end torque... that is why you hear a lot of people complain about low end torque loss when changing from oem exhaust manifolds to long tube headers. also think about all these ricer's running around with a header and full 3 exhaust on a stock motor, most of them are actually losing power.

In a turbo setup the turbo is actually creating the backpressure.

99mustang232 · April 25th, 2006, 11:29 PM

Originally Posted by Sa-WaitNoMustang900Turbo

how does it help torque? doesnt the engine waste less energy (t and hp) if it is easier for it to expell exaust. I've always thought back preasure = preasue against piston as it strokes up to expell gasses

well in a good exhaust setup there is something called exhaust scavaging, where the exhaust pulse will actually help pull the next pulse away from the chamber

1slo5.0 · April 26th, 2006, 08:51 AM

You will never ever ever lose horsepower from running too big of an exhaust or open headers. You will lose low end torque but on a race car (circle or drag) it doesn't matter because the engine isn't ever in the lower rpm range. People that have exhaust on their race cars do it for the following reasons - 1. track restrictions 2. street car 3. because they can't stand the noise from no exhaust.

Zak · December 20th, 2006, 12:08 PM

Does anybody know if the stock exhaust pipe for 94 GT 5.0 is 2" or 2.25"?

I read in a book that it is 2-1/4"

when I measured the tailpipe, it was only 2"

I have to put the car on jacks but I'd appreciate it if somebody knows for sure who can tell me.

October 26th, 2005, 04:27 PM	#2
DC97Cobra Regular Join Date: Aug 2005 Location: Virginia Posts: 68 iTrader: 0 reviews	Cool! Looks like I'm in the right margin with 2 1/2" exhaust. Thanks for the info! __________________

October 26th, 2005, 04:41 PM	#3
IcantDo55 Enthusiast Join Date: Aug 2005 Location: Va Beach VA Posts: 590 iTrader: 0 reviews	I'm off the chart 347ci 700 hp? __________________ -Mike Link to My Site Want to Play Some Pool??? Stroked and Blown!

November 11th, 2005, 05:25 PM	#4
Bill Hardcore Enthusiast Join Date: Aug 2005 Posts: 1,327 iTrader: 0 reviews	good info man __________________ Too often, We lose sight of life's simple pleasures. Remember, when someone annoys you it takes 42 muscles in your face to frown, BUT, it only take 4 muscles to extend your arm and bitch-slap that Mother@#?!&! upside the head!!

April 25th, 2006, 09:19 AM	#7
WVSNS& Regular 2001 Mustang Cobra Join Date: Dec 2005 Location: va beach Posts: 214 iTrader: 0 reviews	size of pipe I was under the improeeion that three inch pipes were a good starting point. At least that is what I liked on my old school svo mustangs.

April 25th, 2006, 10:21 PM	#9
Sa-WaitNoMustang900Turbo Regular Join Date: Jan 2006 Posts: 462 iTrader: 0 reviews	I'm a turbo guy, but please explain to me how back preasure can help power __________________ God... That Euro import guy is really starting to get on my nerves... my car can only beat his in a strait line(maybe)

April 25th, 2006, 10:35 AM	#8
99mustang232 MM Fanatic 1999 Ford Mustang V6 Join Date: Sep 2005 Location: newport news, va Posts: 3,745 iTrader: 0 reviews	back pressure can actually be a good thing in a n/a, nitrous, or blown setup... but not the same on turbo setups, where the exhaust drives the power adder and where exhaust scavaging is not an issue.

April 25th, 2006, 11:05 PM	#10
AtlanticBlue99 I Post Entirely Way Too Much 1999 Ford Mustang V6 14.79 @ 92.15 Join Date: Aug 2005 Location: University of Georgia Posts: 8,854 Blog Entries: 1 iTrader: 0 reviews	help torque. you lose low end power on n/a and non turbo cars without backpressure. but this is usually made up in the higher rpm's __________________ ModdedAutos 1999 Mustang V6 I used to list my mods here but stopped when I exceeded 255 characters.

April 25th, 2006, 11:12 PM	#11
Sa-WaitNoMustang900Turbo Regular Join Date: Jan 2006 Posts: 462 iTrader: 0 reviews	how does it help torque? doesnt the engine waste less energy (t and hp) if it is easier for it to expell exaust. I've always thought back preasure = preasue against piston as it strokes up to expell gasses __________________ God... That Euro import guy is really starting to get on my nerves... my car can only beat his in a strait line(maybe)

April 25th, 2006, 11:17 PM	#12
AtlanticBlue99 I Post Entirely Way Too Much 1999 Ford Mustang V6 14.79 @ 92.15 Join Date: Aug 2005 Location: University of Georgia Posts: 8,854 Blog Entries: 1 iTrader: 0 reviews	backpressure being higher pressure in exhaust pipe. a pipe that is too large has a lower pressure so the exhaust exits more slowly. remember that a smaller tube will make the same amount of air move at a higher pressue, thus more quickly. too small is too restrictive, too big is too free. there is a good compromise to be reached- thus the chart. __________________ ModdedAutos 1999 Mustang V6 I used to list my mods here but stopped when I exceeded 255 characters.

April 25th, 2006, 11:27 PM	#13
99mustang232 MM Fanatic 1999 Ford Mustang V6 Join Date: Sep 2005 Location: newport news, va Posts: 3,745 iTrader: 0 reviews	back pressure promotes low end torque... that is why you hear a lot of people complain about low end torque loss when changing from oem exhaust manifolds to long tube headers. also think about all these ricer's running around with a header and full 3 exhaust on a stock motor, most of them are actually losing power. In a turbo setup the turbo is actually creating the backpressure. __________________ ...even fire and single cammin 1986 Ford F-150 5.0L 2WD 1994 Toyota Pickup 2.4L 4WD 1999 Ford Mustang 3.8L V6 2002 Jeep Grand Cherokee 4.0L 2WD 2008 GMC Sierra Denali 6.2L AWD

April 26th, 2006, 08:51 AM	#15
1slo5.0 MM Ninjas! 1990 Mustang LX 9.36@143 mph Join Date: Jan 2006 Location: North Fond du Lac, Wisconsin Posts: 11,375 iTrader: 1 reviews	You will never ever ever lose horsepower from running too big of an exhaust or open headers. You will lose low end torque but on a race car (circle or drag) it doesn't matter because the engine isn't ever in the lower rpm range. People that have exhaust on their race cars do it for the following reasons - 1. track restrictions 2. street car 3. because they can't stand the noise from no exhaust. __________________ My daily driver has 16 cylinders and 4400hp @ 1000 rpm.... ***1988 Mustang GT - Stock....almost

December 20th, 2006, 12:08 PM	#16
Zak Regular Join Date: May 2006 Posts: 254 iTrader: 0 reviews	Does anybody know if the stock exhaust pipe for 94 GT 5.0 is 2" or 2.25"? I read in a book that it is 2-1/4" when I measured the tailpipe, it was only 2" I have to put the car on jacks but I'd appreciate it if somebody knows for sure who can tell me.

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How to determine exhaust pipe size needed

How to determine exhaust pipe size needed

size of pipe