exhaust piping size...
05-28-2006, 09:49 AM
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exhaust piping size... i'm putting an ls1 into non ls1 car...i'll be running true dual exhaust...was wondering what is the optimal piping size for the exhaust...i've posted in the hybrid forum too...car will probably be slowly built to roughly 500/500...and i do mean slowly...like in years to get to that point...but for now i guess it'll be slightly modded...
05-28-2006, 10:25 AM
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I'm running dual 3"...always worked fine in the past. I saw a website a while back (while trying to find a weld up header kit) that had formulas and conversions to calculate optimum header primary size and lenght as well as exhaust pipe size and length.
05-28-2006, 11:46 AM
#4
Dual 3" will EASILY support 700 crank hp (580ish rwhp).
Take the cross-sectional area of the pipe, multiply it by 115. This gives you cfm for a piece of pipe. You need roughly 2.2cfm per hp, so devide the CFM# by 2.2 and you'll have the supported HP before it becomes a restriction.
Take the cross-sectional area of the pipe, multiply it by 115. This gives you cfm for a piece of pipe. You need roughly 2.2cfm per hp, so devide the CFM# by 2.2 and you'll have the supported HP before it becomes a restriction.
05-28-2006, 11:51 AM
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Originally Posted by TheBlurLS1
Dual 3" will EASILY support 700 crank hp (580ish rwhp).
Take the cross-sectional area of the pipe, multiply it by 115. This gives you cfm for a piece of pipe. You need roughly 2.2cfm per hp, so devide the CFM# by 2.2 and you'll have the supported HP before it becomes a restriction.
Take the cross-sectional area of the pipe, multiply it by 115. This gives you cfm for a piece of pipe. You need roughly 2.2cfm per hp, so devide the CFM# by 2.2 and you'll have the supported HP before it becomes a restriction.
wat do u mean by "cross-sectional area of the pipe"??? and would this number be in inches???
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05-28-2006, 06:06 PM
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right now i am running from the ory a single 3.5 / bullet exhaust and it works fine. my exhaust guy is about to fab up a 2.5" pipe to 2.5 x-pipe to 2.5 sweet thunders and we are going to try a side exit just in front of the rear tires.
05-28-2006, 07:58 PM
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Originally Posted by WS6nJAX
right now i am running from the ory a single 3.5 / bullet exhaust and it works fine. my exhaust guy is about to fab up a 2.5" pipe to 2.5 x-pipe to 2.5 sweet thunders and we are going to try a side exit just in front of the rear tires.
like the mustangs??? i think that's cool...
can someone show me exactly how to do the math as indicated above??? i don't understand what "cross-sectional" is...
05-28-2006, 08:48 PM
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Originally Posted by 2K2WS6TA
Figure the area of the circle, then multiply by 115
oh...ic...ain't the formula 2 pi r square??? lemme go look up the exact area formula and play around with the number to see if it turns out rite...i appreciate the input...
05-28-2006, 09:19 PM
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ok folks...i got another question...so for the number i get...i double that for the total amount hp it can support b4 it get restrictive since it's dual exhaust all the way???
3 inch pipe = 7.069 in area and multiply that by 115 and i get 812.935 and i divide that by 2.2 and i got 369.5159 hp...so since it's dual...i multiply that by 2 and get 739hp that a dual 3 inch pipe can handle is this correct???
3 inch pipe = 7.069 in area and multiply that by 115 and i get 812.935 and i divide that by 2.2 and i got 369.5159 hp...so since it's dual...i multiply that by 2 and get 739hp that a dual 3 inch pipe can handle is this correct???
05-29-2006, 12:00 AM
#13
Originally Posted by Yellowbrother
ok folks...i got another question...so for the number i get...i double that for the total amount hp it can support b4 it get restrictive since it's dual exhaust all the way???
3 inch pipe = 7.069 in area and multiply that by 115 and i get 812.935 and i divide that by 2.2 and i got 369.5159 hp...so since it's dual...i multiply that by 2 and get 739hp that a dual 3 inch pipe can handle is this correct???
3 inch pipe = 7.069 in area and multiply that by 115 and i get 812.935 and i divide that by 2.2 and i got 369.5159 hp...so since it's dual...i multiply that by 2 and get 739hp that a dual 3 inch pipe can handle is this correct???
Area is pi x (R squared), which you obviously figured out. 2 pi R is circumference.
For dual 2.5" exhaust, the R would be 1.25.
((1.25)^2 x 3.1415) x 115 = 564.488cfm for 1 PIPE. Which means you have 1129cfm for 2.
Divide 1129 by 2.2 and you get 513hp before it becomes a restriction.
What happens when you encounter a restriction can be thought about as this. Instead of using all of the power produced to propel the car forward, it must use some power to shove the exhaust gas through the pipe.
05-29-2006, 06:03 AM
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Originally Posted by TheBlurLS1
What happens when you encounter a restriction can be thought about as this. Instead of using all of the power produced to propel the car forward, it must use some power to shove the exhaust gas through the pipe.
but the reverse can be thought of a negative too can it not??? cuz if one goes too big u lose wat is called back pressure (which some article i read online a while back claim there's no such thing)...so according to the math i am good using anything from 2.5" to 3"...
05-30-2006, 10:48 PM
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I would use 3" to a X then 2.5" tails. That is what I built for the TA and it works great. I just wish I could run any muffler I wanted to like you can on a hybrid car.
When you are accually making 500 RWHP I would step up to a 3.5" with 3" tails.
When you are accually making 500 RWHP I would step up to a 3.5" with 3" tails.
05-30-2006, 11:58 PM
#16
Originally Posted by gearheads78
I would use 3" to a X then 2.5" tails. That is what I built for the TA and it works great. I just wish I could run any muffler I wanted to like you can on a hybrid car.
When you are accually making 500 RWHP I would step up to a 3.5" with 3" tails.
When you are accually making 500 RWHP I would step up to a 3.5" with 3" tails.
05-31-2006, 09:03 AM
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Originally Posted by gearheads78
I would use 3" to a X then 2.5" tails. That is what I built for the TA and it works great. I just wish I could run any muffler I wanted to like you can on a hybrid car.
When you are accually making 500 RWHP I would step up to a 3.5" with 3" tails.
When you are accually making 500 RWHP I would step up to a 3.5" with 3" tails.
05-31-2006, 10:14 AM
#18
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Originally Posted by fast377
I remember reading somewhere a while back that if you do the opposite (go from smaller pipe to larger pipe as you back) that you can pick up a few hp.
