Airflow velocity for different intercooler piping diameters (2.0 2.25 2.5 2.75 3.0 inches)
08-31-2005, 11:58 AM
#26
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Re: (mrx)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mrx »</TD></TR><TR><TD CLASS="quote">if the turbo is 2" you wont get a problem for the turbos flow capacity i guess... otherwise i would install the size of the turbo inlet
</TD></TR></TABLE>
My turbo compressor outlet is 2 inches, and I think that will be fine. The inlet is 3 inches and I know that is way too big. My piping expands throughout though, starts at 2 inch, intercooler (2.5 / 2.5), 2.25 lower charge, 2.5 upper charge.
Thanks for the response, I will stick with 2 inch out of the compressor.
</TD></TR></TABLE>
My turbo compressor outlet is 2 inches, and I think that will be fine. The inlet is 3 inches and I know that is way too big. My piping expands throughout though, starts at 2 inch, intercooler (2.5 / 2.5), 2.25 lower charge, 2.5 upper charge.
Thanks for the response, I will stick with 2 inch out of the compressor.
08-31-2005, 11:58 AM
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Re: (Rufus523)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Rufus523 »</TD></TR><TR><TD CLASS="quote">Sorry to bring this back. Does anybody know when 2 inches diameter (pre intercooler) becomes a restriction? Is there a horsepower number (like 400whp) that would require a larger pipe?
Is the downside that the air will be hotter in the smaller pipe? I think that's what I read above.</TD></TR></TABLE>
The numbers are above, you just have to guess what CFM would equal what HP out of whatever turbo. A very simple way of doing it is to multiply your engine's CFM by the pressure ratio at which your turbo will be operating.
If I had to gues what the boosted CFM out of a GSR at 15 psi would be I would say 245 x 2.02 = 494 CFM. That's a simple way of doing it, but it doesn't take into account how much actual CFM a specific turbo flows at 15 psi. A better way of figuring it out is to find out out how much CFM your turbo will flow at xx amount of psi that you want to run.
Is the downside that the air will be hotter in the smaller pipe? I think that's what I read above.</TD></TR></TABLE>
The numbers are above, you just have to guess what CFM would equal what HP out of whatever turbo. A very simple way of doing it is to multiply your engine's CFM by the pressure ratio at which your turbo will be operating.
If I had to gues what the boosted CFM out of a GSR at 15 psi would be I would say 245 x 2.02 = 494 CFM. That's a simple way of doing it, but it doesn't take into account how much actual CFM a specific turbo flows at 15 psi. A better way of figuring it out is to find out out how much CFM your turbo will flow at xx amount of psi that you want to run.
08-31-2005, 09:34 PM
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Re: (JSpin)
Wow, a lot of BS flying around in this thread. Only one guy has is right: <TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Def »</TD></TR><TR><TD CLASS="quote">
...the volumetric flowrate is going to change for a given inlet vdot(i'm getting lazy here) depending on the pressure.
...The negative side effect to too small charge piping is not heat, but head loss. This will be seen as an excessive amount of pressure drop through the pipes as the frictional losses require more energy to overcome due to the high velocities. Too large of charge piping has the disadvantage of a longer transient boost response since you're increasing the volume of space you need to pressurize.
</TD></TR></TABLE>
To expand on this, as far as your charge pipes go, you are only concerned with:
1.) pressure drop, and
2.) the time it takes to fill your volume of charge pipes and intercooler
Pressure drop will be the difference in pressure from your compressor outlet to your TB. Smaller pipes = more pressure drop = flow losses. You don't want this to be too high, 1.5 to 2 psig max. Here's a handy tool to calculate you pressure drop in your charge pipes (sorry, no intercooler included, you will have to look through a few texts to estimate this one (Kerns, etc.):
http://www.freecalc.com/gasfram.htm
More principles of pressure drop:
http://www.efunda.com/formulae...n.cfm
2.) the time it takes to pressureize your charge pipes. Large pipes = more time to fill = more lag. While some people claim they can feel the difference in lag when going from 2.25 to 2.5" piping, I'd have to call BS since the difference in volume isn't that great. Basically what's it take to fill an extra few tenths of a CF in volume when you are flowing 200 to 400 CFM? What, a tenth of a second? I'm too lazy to calculate, but maybe someone here will do it.
...the volumetric flowrate is going to change for a given inlet vdot(i'm getting lazy here) depending on the pressure.
...The negative side effect to too small charge piping is not heat, but head loss. This will be seen as an excessive amount of pressure drop through the pipes as the frictional losses require more energy to overcome due to the high velocities. Too large of charge piping has the disadvantage of a longer transient boost response since you're increasing the volume of space you need to pressurize.
</TD></TR></TABLE>
To expand on this, as far as your charge pipes go, you are only concerned with:
1.) pressure drop, and
2.) the time it takes to fill your volume of charge pipes and intercooler
Pressure drop will be the difference in pressure from your compressor outlet to your TB. Smaller pipes = more pressure drop = flow losses. You don't want this to be too high, 1.5 to 2 psig max. Here's a handy tool to calculate you pressure drop in your charge pipes (sorry, no intercooler included, you will have to look through a few texts to estimate this one (Kerns, etc.):
http://www.freecalc.com/gasfram.htm
More principles of pressure drop:
http://www.efunda.com/formulae...n.cfm
2.) the time it takes to pressureize your charge pipes. Large pipes = more time to fill = more lag. While some people claim they can feel the difference in lag when going from 2.25 to 2.5" piping, I'd have to call BS since the difference in volume isn't that great. Basically what's it take to fill an extra few tenths of a CF in volume when you are flowing 200 to 400 CFM? What, a tenth of a second? I'm too lazy to calculate, but maybe someone here will do it.
09-01-2005, 04:33 AM
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Re: (turncoat)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by turncoat »</TD></TR><TR><TD CLASS="quote">Wow, a lot of BS flying around in this thread. Only one guy has is right:
I'm too lazy to calculate, but maybe someone here will do it.</TD></TR></TABLE>
Maybe you guys should quit being lazy and come up with a better write up.
I didn't want to go too much into detail with my original post. My main goal was to show the the changes in flow rate when going with different piping sizes and I wanted to show this in the easiest way possible. I knew that factoring in things such as temperature, actual boost pressure, compressor size and pressure drop would have made the whole process a lot more complicated, which is why I didn't do any of that. The reason I originally made the thread was to show why a 3" charge pipe would have been a bad idea for a low-medium boost build.
I'm too lazy to calculate, but maybe someone here will do it.</TD></TR></TABLE>
Maybe you guys should quit being lazy and come up with a better write up.
I didn't want to go too much into detail with my original post. My main goal was to show the the changes in flow rate when going with different piping sizes and I wanted to show this in the easiest way possible. I knew that factoring in things such as temperature, actual boost pressure, compressor size and pressure drop would have made the whole process a lot more complicated, which is why I didn't do any of that. The reason I originally made the thread was to show why a 3" charge pipe would have been a bad idea for a low-medium boost build.
09-01-2005, 02:02 PM
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Re: (BlueShadow)
Okay then, let's see how much the charge pipe size (and thus volume) affects lag time:
Every foot of 2" x 0.065" tube will hold 0.095 CF.
If you can flow 400 CFM from 0 to 15 psig (please excuse the simplification of the transient, it's just a quick estimate), you can pressurize the charge pipe from 0 to 15 psig in 0.014 seconds. (Note this is not spool time, just the time it takes to fill a pipe given a certain flow which is what we are trying to isolate)
Change to 3" charge piping, your volume increases to 0.22 CF and for the same scenario, the time to fill increases to 0.033 sec..
So the question is can you feel the extra 0.019 sec it takes to get to 15 psig when you increase your charge pipe size from 2" to 3"? Not likely.
Please don't pick at that the calculations were massively simplified, it was just to verify the hunch that charge pipe volume is not a very sensitive factor in the common sizes.
The problem with the first post is velocities are calculated for a given pipe size and flow, which is relatively insignificant. What you want is pressure drop as the main component in sizing the charge pipe. Use the link in my previous post to calculate pressure drop.
Why is pressure drop a big deal? Well, to keep the same flow if charge pipe pressure drop is increased (smaller and smaller diameter charge piping), the turbo will have to operate at a higher pressure ratio, in a less efficient range on the compressor and turbine maps. All this will equate in less power due to higher charge temps and EM pressure.
Every foot of 2" x 0.065" tube will hold 0.095 CF.
If you can flow 400 CFM from 0 to 15 psig (please excuse the simplification of the transient, it's just a quick estimate), you can pressurize the charge pipe from 0 to 15 psig in 0.014 seconds. (Note this is not spool time, just the time it takes to fill a pipe given a certain flow which is what we are trying to isolate)
Change to 3" charge piping, your volume increases to 0.22 CF and for the same scenario, the time to fill increases to 0.033 sec..
So the question is can you feel the extra 0.019 sec it takes to get to 15 psig when you increase your charge pipe size from 2" to 3"? Not likely.
Please don't pick at that the calculations were massively simplified, it was just to verify the hunch that charge pipe volume is not a very sensitive factor in the common sizes.
The problem with the first post is velocities are calculated for a given pipe size and flow, which is relatively insignificant. What you want is pressure drop as the main component in sizing the charge pipe. Use the link in my previous post to calculate pressure drop.
Why is pressure drop a big deal? Well, to keep the same flow if charge pipe pressure drop is increased (smaller and smaller diameter charge piping), the turbo will have to operate at a higher pressure ratio, in a less efficient range on the compressor and turbine maps. All this will equate in less power due to higher charge temps and EM pressure.
06-06-2007, 11:19 AM
#32
Re: (turncoat)
Can anyone help me calculate the amount of CFM Im going to need to make 600hp from a 2.0L GSR reving to 8500rpm?
From my crude method, I estimate I'd need about 60lbs/min to support 600hp (Garretts website says apprx 9.5-10.5HP are generated for every 1lb/min). 10 lb/min is equal to 144.7178 cfm so 60lbs equals 868CFM. I rounded up to 900CFM. According to this chart, 2.5" piping will provide the fastest velocity at 900 CFM.
Am I way off base on my calculations?
From my crude method, I estimate I'd need about 60lbs/min to support 600hp (Garretts website says apprx 9.5-10.5HP are generated for every 1lb/min). 10 lb/min is equal to 144.7178 cfm so 60lbs equals 868CFM. I rounded up to 900CFM. According to this chart, 2.5" piping will provide the fastest velocity at 900 CFM.
Am I way off base on my calculations?
06-21-2008, 01:52 PM
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Re: (Astig)
ok... bringing this back from the dead. I have been debating wether to run 2.25 or 2.5 inch piping,
a t3/t04e, .57 trim, flows about 49 lb/min, at 700 CFM, 2.25 inch piping would be ideal right? you would have better spool then 2.5 yet it would not hinder any performace?
i'm having a hard time understanding and figuring this out. help is appreciated, i was thinking 2 inch piping from the turbo to the intercooler, then 2.25 from the intercooler to the throttle body?
motor is stock d16y8 if that helps.
a t3/t04e, .57 trim, flows about 49 lb/min, at 700 CFM, 2.25 inch piping would be ideal right? you would have better spool then 2.5 yet it would not hinder any performace?
i'm having a hard time understanding and figuring this out. help is appreciated, i was thinking 2 inch piping from the turbo to the intercooler, then 2.25 from the intercooler to the throttle body?
motor is stock d16y8 if that helps.
06-22-2008, 08:40 AM
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Re: (EJ8 944)
Since this thread has been reborn, after skimming through it the glaring error is that the speed of sound (and hence mach number) will change dependent on the temperature of the air. It looks like Mach 0.4 @ 304mph is at ambient temperatures. The speed of sound will actually rise (V = sqrt(k*R*T): k=specific heat ratio, R=gas constant, T=abs temperature) after the compressor outlet as the temperature greatly increases... so Mach 0.4 is probably at closer to 330-340mph in your pre intercooler pipe.
We could keep picking at small details but I doubt it's worth agonizing over. Personally, I would err on the side of too large piping (~2.5 min) before I would go too small. I think any extra lag observed by going to larger piping is probably in the driver's head. It's not like the piping is evacuated every time the throttle is released
We could keep picking at small details but I doubt it's worth agonizing over. Personally, I would err on the side of too large piping (~2.5 min) before I would go too small. I think any extra lag observed by going to larger piping is probably in the driver's head. It's not like the piping is evacuated every time the throttle is released
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