STS pressure drop
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Originally Posted by LSONE
Shouldn't temp drop and pressure drop be proportional?
Mike
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From: Cincinnati, Ohio
Mike, I'm not disputing what your saying and your equation is lost on me but I would like some clarification. If the system has boost pressure which would show the pressure is not completely vented off, wouldn't a cooler charge lower the pressure due to the air being denser? I would think if the air after the intercooler was denser it would make more room for air out of the compressor and thus lower the pressure.
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Originally Posted by 2001WS6Vert
I would think if the air after the intercooler was denser it would make more room for air out of the compressor and thus lower the pressure.
Originally Posted by engineermike
. . . but the wastegate closes off to force the turbine to speed up, and get back to the set boost level. With a supercharger, a good intercooler will actually reduce pressure even upstream of the cooler.
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Originally Posted by onfire
But if your boost reference is on the compressor it doesn't know about the pressure drop and will keep the wastegate the same.....and the pressure will drop along the way.
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I think 2 different concepts are getting confused here.
If you have 10 psi before the intercooler, and the intercooler drops the temperature of the air by 200 deg, and the intercooler has very little restriction, then you will also have 10 psi after the intercooler.
If you have 10 psi supplied by a supercharger, then add a good flowing intercooler that drops the charge by 200 deg, then you might only get 8 psi after the intercooler AND before it. It will move the compressor out on its curve and flow more air.
If you have 10 psi supplied by a turbocharger, then add a good flowing intercooler that drops the charge by 200 deg, then the turbo will speed up to maintain 10 psi and flow more air.
If you have a restriction in the piping, it has nothing to do with intercooling.
If you have 10 psi before the intercooler, and the intercooler drops the temperature of the air by 200 deg, and the intercooler has very little restriction, then you will also have 10 psi after the intercooler.
If you have 10 psi supplied by a supercharger, then add a good flowing intercooler that drops the charge by 200 deg, then you might only get 8 psi after the intercooler AND before it. It will move the compressor out on its curve and flow more air.
If you have 10 psi supplied by a turbocharger, then add a good flowing intercooler that drops the charge by 200 deg, then the turbo will speed up to maintain 10 psi and flow more air.
If you have a restriction in the piping, it has nothing to do with intercooling.
Originally Posted by onfire
But if your boost reference is on the compressor it doesn't know about the pressure drop and will keep the wastegate the same.....and the pressure will drop along the way.
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From: Dallas
Lemme try my hand at translation.
The smaller the pipe, the more velocity will have to increase to move the same volume of air.
Friction is a constant, and the higher the velocity, the higher the effect it has. This in turn would be compounded by turbulence that now disturbs the flow. Since its a smaller pipe, the impact of the turbulence and friction created drag is significant.
If your air is going through an intercooler really really fast and efficient, then it'll have less restriction, and less pressure as a result because "nothing is "holding" it back."
The moving air is not creating vacuums at areas of the pipe, so the volume throughout the pipe is effectively the same. And if it created vacuums, well, air would fill that void redonkulously quick as well.
For whomever was wondering about the temperature pressure relation, were you thinking of the basic PV=nRT idea?
A turbo breathing through a firehose does way better than a turbo breathing through a garden hose.
The way I'm visualizing it, is air not as a liquid, but as a solid highly deformable cohesive substance X, so to keep the volume the goal.
Does my post seem right? Or am I off?
The smaller the pipe, the more velocity will have to increase to move the same volume of air.
Friction is a constant, and the higher the velocity, the higher the effect it has. This in turn would be compounded by turbulence that now disturbs the flow. Since its a smaller pipe, the impact of the turbulence and friction created drag is significant.
If your air is going through an intercooler really really fast and efficient, then it'll have less restriction, and less pressure as a result because "nothing is "holding" it back."
The moving air is not creating vacuums at areas of the pipe, so the volume throughout the pipe is effectively the same. And if it created vacuums, well, air would fill that void redonkulously quick as well.
For whomever was wondering about the temperature pressure relation, were you thinking of the basic PV=nRT idea?
A turbo breathing through a firehose does way better than a turbo breathing through a garden hose.
The way I'm visualizing it, is air not as a liquid, but as a solid highly deformable cohesive substance X, so to keep the volume the goal.
Does my post seem right? Or am I off?
Originally Posted by Zombie
Before I added the intercooler to my car my waste gate was referenced off the compressor outlet. The wastegate spring allowed me to run 6psi. It would build to 6psi and maintain 6psi until 6700 rpms. After then added an intercooler without changing any of the setup. It would build to 6psi initially and then drop to 3.5 psi as it got closer to 6700. The pressure drop was solved by changing the reference point of the wastegate from the turbo outet to a manifold source. 6psi all the way through to 6700. Adding the intercooler, extra piping and couplers caused me to see a 2.5 psi drop.
Exactly.
If you have 10 psi supplied by a supercharger, then add a good flowing intercooler that drops the charge by 200 deg, then you might only get 8 psi after the intercooler AND before it. It will move the compressor out on its curve and flow more air.
Also, I didn't think it was possible to get a properly sized IC with zero pressure drop under boost.
Jim
Originally Posted by engineermike
No. In a close system, the equation is T2/T1=(P2/P1)^((k-1)/k). In the case of an intercooler or a long pipe, ALL of the pressure drop is due to frictional losses and NONE is due to cooling of the charge. You see, as the air cools, it condenses and more air comes in behind it to displace it. Think of an oven. When you turn on an oven, the air inside heats up, but the pressure does not rise because the excess air is allowed to purge out and keep the pressure at or near atmospheric. That's because it's an open system.
Mike
Mike
Oh I see... I was thinking P=nRT/V IU suppose that is a bit simplistic for such a complex system.
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Originally Posted by DeltaT
engineermike - that makes no sense to me. I have a supercharger and have measured (with the same gauge) 8.1psi right before the IC and 7.3 right after, with like a 90 degree temp drop.
Also, I didn't think it was possible to get a properly sized IC with zero pressure drop under boost.
Jim
Also, I didn't think it was possible to get a properly sized IC with zero pressure drop under boost.
Jim
I usually try to shoot for 200 ft/s or less pipe velocity when possible to minimize losses.
As far pressure drop across IC, yes you will always have one. A good intercooler will reduce velocity down to 20-50 ft/s to increase resonance time (cooling). But surface area drastically increases resulting in frictional losses even with modest velocities. No way around this and I agree no such thing as 0 loss IC.
Onto Mike’s earlier point an efficient IC will allow centrifugal supercharger/turbo to flow more if not on raged edge of compressor map. If compressor is in map sweet spot flow will increase with little output pressure loss do to increased density ratio.
Mike
Originally Posted by DrTurbo
Jim that is common. Call Jose about it....he can share some info on this. This is part of the reason why Jose says the turbos max out so quickly on the rear mounts, and power falls off.
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Originally Posted by DeltaT
engineermike - that makes no sense to me. I have a supercharger and have measured (with the same gauge) 8.1psi right before the IC and 7.3 right after, with like a 90 degree temp drop.
Also, I didn't think it was possible to get a properly sized IC with zero pressure drop under boost.
Also, I didn't think it was possible to get a properly sized IC with zero pressure drop under boost.
Of course, flow is caused by deltaP, so any time you have flow (through a pipe or intercooler), you will have a pressure reduction. However, this pressure drop can approach zero.
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Originally Posted by Skunkworks
Different Mike – first you will have no flow without a pressure differential so you will always see a pressure gradient from compressor discharge to intake manifold. The goal is to minimize this.
I usually try to shoot for 200 ft/s or less pipe velocity when possible to minimize losses.
I usually try to shoot for 200 ft/s or less pipe velocity when possible to minimize losses.