how much of a restriction would a 90* angle coming of the turbo be?!?
08-31-2006 | 01:52 AM
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From: Fresno, CA
how much of a restriction would a 90* angle coming of the turbo be?!? well coming strait of my turbo where it blows into the intercooler there is a 90 degree silicone bend...... im going to be changing that shotly!! How much of a lag or hp loss would one think it is?? just a hypothisis
Last edited by TondSS; 08-31-2006 at 02:00 AM.
08-31-2006 | 01:55 AM
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Originally Posted by TondSS
well coming strait of my turbo where it blows into the intercooler there is a 90 degree silicone bend...... im going to be changing that shotly!! How much of a lag or hp loss would one think it is?? just a hypothisis
...sorry i forgot to tell you 
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08-31-2006 | 11:55 PM
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From: Houston, TX
I think that I would go with a more gradual 90 than what's in your picture. Maybe something along these lines http://www.stylinmotors.com/90Elbow-SME490-300.html where it's like a bent pipe, instead of 2 pipes cut at an angle then welded.
09-01-2006 | 12:29 AM
#12
I have the same question... Rob Raymer addressed this once way back..with back to back dyno sessions..wish I remembered the results... I think Pro-Chargers, on some cars at least, have 90 degrees bends. I am a beleiver in smooth... but I am chaning my ways, to just get things done and stop fighting so hard for 1 % gains.
Thats said, if its 5%, that could be 25 HP to a 500 hp car!
Heres what I once read:
Any bend in a charge pipe tube, or sudden change in a cross section must be viewed as a potential flow loss or source of increased drag. It would be reasonable to estimate that every time the airflow must turn 90 degrees, a loss of 1% of the flow will occur. three 30 degrees will add up to one 90 degree. ALWAYS USE THE LARGEST POSSIBLE RADIUS for any change or direction. A short radious 90 bend will lose more flow than a large 90.
Corky says.
Thats said, if its 5%, that could be 25 HP to a 500 hp car!
Heres what I once read:
Any bend in a charge pipe tube, or sudden change in a cross section must be viewed as a potential flow loss or source of increased drag. It would be reasonable to estimate that every time the airflow must turn 90 degrees, a loss of 1% of the flow will occur. three 30 degrees will add up to one 90 degree. ALWAYS USE THE LARGEST POSSIBLE RADIUS for any change or direction. A short radious 90 bend will lose more flow than a large 90.
Corky says.
Last edited by Jammer; 09-01-2006 at 12:37 AM.
09-01-2006 | 01:58 AM
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Okay, keep in mind this is summer and I just dusted off the fluid dynamics book....
According to Fox, McDonald, & Pritchard's Intro to Fluid Dynamics the "Le/D" (equivalent length divided by the pipe diameter) of a 90 degree bend is 30. This is the number used in calculating pressure drops for internal flow. Where this number is derived from I don't know - probably from testing on various bends using pipes of various diameters. Anyways, This means that if you had a pipe that was 2.25" in diameter (guessing from the pics, its the size that's used on my sts kit) it means that 2.25"*30=equivalent length of straight pipe that would cause the same pressure drop. So, that 90 degree bend is the same as the drop across 67.5" of pipe or 5.625' of straight pipe.
I tried to use a program to find the pressure drop. I used a worst case of 6000rpm, 2.25" piping and at 6psig (above atmospheric) along with an outside temp of 70*F and got about a 1# pressure drop through the 90 degree bend. I'm not really sure how accurate that is. It's been 3 months since I've touched that book and I just got off work soo...there may be some error. The loss won't be horrible but you definately want to limit the number of bends like that. Hope it helps.
According to Fox, McDonald, & Pritchard's Intro to Fluid Dynamics the "Le/D" (equivalent length divided by the pipe diameter) of a 90 degree bend is 30. This is the number used in calculating pressure drops for internal flow. Where this number is derived from I don't know - probably from testing on various bends using pipes of various diameters. Anyways, This means that if you had a pipe that was 2.25" in diameter (guessing from the pics, its the size that's used on my sts kit) it means that 2.25"*30=equivalent length of straight pipe that would cause the same pressure drop. So, that 90 degree bend is the same as the drop across 67.5" of pipe or 5.625' of straight pipe.
I tried to use a program to find the pressure drop. I used a worst case of 6000rpm, 2.25" piping and at 6psig (above atmospheric) along with an outside temp of 70*F and got about a 1# pressure drop through the 90 degree bend. I'm not really sure how accurate that is. It's been 3 months since I've touched that book and I just got off work soo...there may be some error. The loss won't be horrible but you definately want to limit the number of bends like that. Hope it helps.
09-01-2006 | 08:48 AM
#15
Haha thank you Corky Bell... I knew that sounded familiar.
Originally Posted by Jammer
I have the same question... Rob Raymer addressed this once way back..with back to back dyno sessions..wish I remembered the results... I think Pro-Chargers, on some cars at least, have 90 degrees bends. I am a beleiver in smooth... but I am chaning my ways, to just get things done and stop fighting so hard for 1 % gains.
Thats said, if its 5%, that could be 25 HP to a 500 hp car!
Heres what I once read:
Any bend in a charge pipe tube, or sudden change in a cross section must be viewed as a potential flow loss or source of increased drag. It would be reasonable to estimate that every time the airflow must turn 90 degrees, a loss of 1% of the flow will occur. three 30 degrees will add up to one 90 degree. ALWAYS USE THE LARGEST POSSIBLE RADIUS for any change or direction. A short radious 90 bend will lose more flow than a large 90.
Corky says.
Thats said, if its 5%, that could be 25 HP to a 500 hp car!
Heres what I once read:
Any bend in a charge pipe tube, or sudden change in a cross section must be viewed as a potential flow loss or source of increased drag. It would be reasonable to estimate that every time the airflow must turn 90 degrees, a loss of 1% of the flow will occur. three 30 degrees will add up to one 90 degree. ALWAYS USE THE LARGEST POSSIBLE RADIUS for any change or direction. A short radious 90 bend will lose more flow than a large 90.
Corky says.
