STS pressure drop
Thread Starter
FormerVendor
Joined: Dec 2001
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From: WWW.SPEEDINC.COM
Just to clarify, I'm not looking for help, I was just curious if anyone had comparative results.
Tiger2o69- You can only definitively rule something out through testing, not assumptions.
Also, smaller tubing increases pressure drop as it has more resistance to flow, which will also be magnified at higher boost/hp levels. (though you are stating that larger tubing increases pressure drop????)
Tiger2o69- You can only definitively rule something out through testing, not assumptions.
Also, smaller tubing increases pressure drop as it has more resistance to flow, which will also be magnified at higher boost/hp levels. (though you are stating that larger tubing increases pressure drop????)
Originally Posted by Tiger2o69
I would give TRT a call.. They are very helpful and knowledgeable about these system.
sorry couldnt resist I dont know IMTMD8... I was giving you a comparison to mine.. w/o a front mount intercooler I lost 1-1.5.. To me I dont see how you could be losing so much more than me and the others guys with the same piping.. But thats just opinion because I have not tested your car.. Just mine.
I see you have a 9 second car so obviously if you did it you know what your doing.
I may be wrong about the pipe size... Seems to me like a larger pipe would create more area to fill which would cause a pressure drop... Also I see a smaller pipe creating a pressure drop.. I assume theres a point where above x'' pipe and below x'' pipe depending on psi ran there would be a bigger loss..
Anyway good luck with it
ddnspider
I see you have a 9 second car so obviously if you did it you know what your doing.
I may be wrong about the pipe size... Seems to me like a larger pipe would create more area to fill which would cause a pressure drop... Also I see a smaller pipe creating a pressure drop.. I assume theres a point where above x'' pipe and below x'' pipe depending on psi ran there would be a bigger loss..
Anyway good luck with it
ddnspider
Last edited by Tiger2o69; Mar 3, 2007 at 12:51 PM.
What's the air temp at the comp housing?
What's the air temp in the manifold?
Big delta = less pressure.
I've seen 1.5 to 2 psi drop through a screened maf at 17psi.
9psi through 2.25" pipe is pretty ugly. If the pipe is causing that much drop.....I'd try a 3.0
What's the air temp in the manifold?
Big delta = less pressure.
I've seen 1.5 to 2 psi drop through a screened maf at 17psi.
9psi through 2.25" pipe is pretty ugly. If the pipe is causing that much drop.....I'd try a 3.0
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Originally Posted by Tiger2o69
Seems to me like a larger pipe would create more area to fill which would cause a pressure drop...
TECH Addict
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Originally Posted by onfire
What's the air temp at the comp housing?
What's the air temp in the manifold?
Big delta = less pressure.
What's the air temp in the manifold?
Big delta = less pressure.
Mike
Originally Posted by ddnspider
INTMD8 is the equivalent of Chuck Norris for a car guy.....INTMD8 doesnt call TRT.....TRT calls INTMD8 for help sorry couldnt resist
sorry couldnt resist We dont know anyone. 
Last edited by trtturbo; Mar 3, 2007 at 05:21 PM.
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Originally Posted by trtturbo
We normally dont call anyone. We dont know anyone.
We dont know anyone. i have the 8psi spring and with my FMIC i saw just a little over 7psi @ WOT. i have an exhaust leak now and i barely see over 5, maybe 6 if im lucky
Originally Posted by engineermike
That's not right either. You can drop 300 deg F and still not see a pressure drop of more than 1 psi. When you condense air, the pressure does drop, but only if the system is closed. Intercoolers are not closed systems.
Mike
Mike
This car does not have an intercooler.
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From: Albuquerque NM - The Land of 8000ft DA
This should help explain what's going on.
I always wondered how much all that ducting at up in pressure. Thanks for posting your results. And to think that's just on the induction side of things, I wonder what's being lost on the exhaust side.
Last edited by SScam68; Mar 4, 2007 at 02:19 AM.
Staging Lane
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I arbitrarily picked some numbers:
Mass flow = 70 lb/min (a little high, likely 6x)
Turbo discharge pressure = 19 PSIG
Turbo inlet = 70 degrees F
Turbo outlet = 270 degrees F at 70% adiabatic efficiency
Density ratio = 1.6637:1
Pipe = cold rolled welded (roughness)
Pipe ID = 2.25 inch
Some pressure drop estimates:
Coupler Loss = 0.64 PSI
45 degree elbow (6 inch radius) = 0.34 PSI
90 degree elbow (6 inch radius) = 0.55 PSI
Straight pipe = 0.18 PSI/ft
Flow is predominantly turbulent at almost 350 ft/sec. Couplers are a larger variable then most expect.
Add all pipe segments together to estimate losses or pressure drop of complete system. As an example total linear length (ft * 0.18) + total couplers (coupler * 0.64) + elbows… equals theoretical total pressure drop. It adds up quicker then most expect.
My suspicion is one gauge is a bit on high side while other is on low side thus skewing delta P, but rear mount does come with penalties that most refuse to discus.
Mike
Mass flow = 70 lb/min (a little high, likely 6x)
Turbo discharge pressure = 19 PSIG
Turbo inlet = 70 degrees F
Turbo outlet = 270 degrees F at 70% adiabatic efficiency
Density ratio = 1.6637:1
Pipe = cold rolled welded (roughness)
Pipe ID = 2.25 inch
Some pressure drop estimates:
Coupler Loss = 0.64 PSI
45 degree elbow (6 inch radius) = 0.34 PSI
90 degree elbow (6 inch radius) = 0.55 PSI
Straight pipe = 0.18 PSI/ft
Flow is predominantly turbulent at almost 350 ft/sec. Couplers are a larger variable then most expect.
Add all pipe segments together to estimate losses or pressure drop of complete system. As an example total linear length (ft * 0.18) + total couplers (coupler * 0.64) + elbows… equals theoretical total pressure drop. It adds up quicker then most expect.
My suspicion is one gauge is a bit on high side while other is on low side thus skewing delta P, but rear mount does come with penalties that most refuse to discus.
Mike
Staging Lane
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Originally Posted by SScam68
This should help explain what's going on.
I always wondered how much all that ducting at up in pressure. Thanks for posting your results. And to think that's just on the induction side of things, I wonder what's being lost on the exhaust side.
Mike
Not sure how much it matters, and I'm sure sombody will know for certain, but those calculations are for fluid flows. I believe for gas flows the numbers are different. I'm not sure which way that could sckew the numbers but I'd like to know.
I've got 15" straight pipe 15*.18= 2.7 psi and thats all I'm losing even through an intercooler. Plus 4 90* bends is 2.1 psi for a total of 4.8 then there are 3 or so 45* for another 1 psi total 5.8 and couplers 5 at .64 each 3.2 for a total of nine 9. Thats the loss he's seeing 19=10 but not mine i have 11=8. MAin difference is Im running 2.5" pipe which is about 1 more squre inch over the 2.25" pipe, also I've got am intercooler
I've got 15" straight pipe 15*.18= 2.7 psi and thats all I'm losing even through an intercooler. Plus 4 90* bends is 2.1 psi for a total of 4.8 then there are 3 or so 45* for another 1 psi total 5.8 and couplers 5 at .64 each 3.2 for a total of nine 9. Thats the loss he's seeing 19=10 but not mine i have 11=8. MAin difference is Im running 2.5" pipe which is about 1 more squre inch over the 2.25" pipe, also I've got am intercooler
Would cavitation cause large pressure drops? In fluid dynamics it can really lower flow which I would think raise pressure. Then beyond the components that are making up the cavitation issues the pressure would be reduced.
I would imagine that you could use a laser temperature guage and actually see the drop in temperature along the pipe and see where this is taking place. Course that means running the hell out of the car while you do all of this. LOL....
I would imagine that you could use a laser temperature guage and actually see the drop in temperature along the pipe and see where this is taking place. Course that means running the hell out of the car while you do all of this. LOL....
Staging Lane
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Originally Posted by 2002ws-6
Not sure how much it matters, and I'm sure sombody will know for certain, but those calculations are for fluid flows. I believe for gas flows the numbers are different. I'm not sure which way that could sckew the numbers but I'd like to know.
I've got 15" straight pipe 15*.18= 2.7 psi and thats all I'm losing even through an intercooler. Plus 4 90* bends is 2.1 psi for a total of 4.8 then there are 3 or so 45* for another 1 psi total 5.8 and couplers 5 at .64 each 3.2 for a total of nine 9. Thats the loss he's seeing 19=10 but not mine i have 11=8. MAin difference is Im running 2.5" pipe which is about 1 more squre inch over the 2.25" pipe, also I've got am intercooler
I've got 15" straight pipe 15*.18= 2.7 psi and thats all I'm losing even through an intercooler. Plus 4 90* bends is 2.1 psi for a total of 4.8 then there are 3 or so 45* for another 1 psi total 5.8 and couplers 5 at .64 each 3.2 for a total of nine 9. Thats the loss he's seeing 19=10 but not mine i have 11=8. MAin difference is Im running 2.5" pipe which is about 1 more squre inch over the 2.25" pipe, also I've got am intercooler
* Note used same variables from first example. With your car mass flow would be a bit lower. Also IC will increase density ratio thus slowing pipe velocity. Again following is estimate.
1ft straight pipe
2.00” = 437 ft/s, 49.01 lbw/sqft, 0.34 psi/ft
2.25” = 345 ft/s, 26.45 lbw/sqft, 0.18 psi/ft
2.50” = 280 ft/s, 15.27 lbw/sqft, 0.11 psi/ft
2.75” = 231 ft/s, 9.30 lbw/sqft, 0.06 psi/ft
3.00” = 194 ft/s, 5.92 lbw/sqft, 0.04 psi/ft
90 degree elbow (6” bend radius)
2.00” = 437 ft/s, 128.21 lbw/sqft, 0.89 psi
2.25” = 345 ft/s, 79.77 lbw/sqft, 0.55 psi
2.50” = 280 ft/s, 52.64 lbw/sqft, 0.37 psi
2.75” = 231 ft/s, 36.36 lbw/sqft, 0.25 psi
3.00” = 194 ft/s, 26.05 lbw/sqft, 0.18 psi
As you can see a considerable difference in just 0.25 inch ID increments. Another thing to consider is surface condition of piping i.e. how dirty it is. A very dirty pipe can add an extra PSI of drop on system like STS at high pipe velocities.
Mike
Last edited by Skunkworks; Mar 4, 2007 at 01:52 PM.
Originally Posted by engineermike
I don't think you guys can really go by the wastegate spring rating. I'm running a 10 psi spring in my Tial 40, but can't get the boost below 17 psi.
Mike
Mike
I'm in the same boat!!
Originally Posted by engineermike
That's not right either. You can drop 300 deg F and still not see a pressure drop of more than 1 psi. When you condense air, the pressure does drop, but only if the system is closed. Intercoolers are not closed systems.
Mike
Mike
Shouldn't temp drop and pressure drop be proportional?