2.5" vs 3" intake pipe...is their a performance advantage?
12-14-2011, 08:59 PM
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2.5" vs 3" intake pipe...is their a performance advantage? I have finished up my hot side and I still have a 180, 90, and 4' of straight aluminumized piping. My throttle body is a 4.25. I was thinking since I have this stuff and it should run cooler than my 3" steel piping, I could run it.
I am NOT running an intercooler so I was basically going to run a Y pipe right off the throttle body just before the fans. I was going to have it follow straight across the top of the radiator and into the compressor housing. It is 2.5" I was going to either make my own Y and trash the 3" one I did or buy a Y pipe that 71 Chevy posted a while back that has two outlets coming off the throttle body. It looks as though this would make the cold side very simple to do and keep it much cooler. I was just worried if being 2.5 inches instead of 3 inches would hurt any performance. FWIW my down pipe is 3"
Thanks.
I am NOT running an intercooler so I was basically going to run a Y pipe right off the throttle body just before the fans. I was going to have it follow straight across the top of the radiator and into the compressor housing. It is 2.5" I was going to either make my own Y and trash the 3" one I did or buy a Y pipe that 71 Chevy posted a while back that has two outlets coming off the throttle body. It looks as though this would make the cold side very simple to do and keep it much cooler. I was just worried if being 2.5 inches instead of 3 inches would hurt any performance. FWIW my down pipe is 3"
Thanks.
12-14-2011, 10:05 PM
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I have finished up my hot side and I still have a 180, 90, and 4' of straight aluminumized piping. My throttle body is a 4.25. I was thinking since I have this stuff and it should run cooler than my 3" steel piping, I could run it.
I am NOT running an intercooler so I was basically going to run a Y pipe right off the throttle body just before the fans. I was going to have it follow straight across the top of the radiator and into the compressor housing. It is 2.5" I was going to either make my own Y and trash the 3" one I did or buy a Y pipe that 71 Chevy posted a while back that has two outlets coming off the throttle body. It looks as though this would make the cold side very simple to do and keep it much cooler. I was just worried if being 2.5 inches instead of 3 inches would hurt any performance. FWIW my down pipe is 3"
Thanks.
I am NOT running an intercooler so I was basically going to run a Y pipe right off the throttle body just before the fans. I was going to have it follow straight across the top of the radiator and into the compressor housing. It is 2.5" I was going to either make my own Y and trash the 3" one I did or buy a Y pipe that 71 Chevy posted a while back that has two outlets coming off the throttle body. It looks as though this would make the cold side very simple to do and keep it much cooler. I was just worried if being 2.5 inches instead of 3 inches would hurt any performance. FWIW my down pipe is 3"
Thanks.
Why would you think that aluminized piping would run cooler than steel piping? They are both steel. The aluminized just has a coating on it to keep it from corroding.
In order to know if 2.5" vs. 3" is going to hurt anything, you need to know how much air you are moving first. When you know your CFM then you can calculate it into the size of the pipe. That will give you velocity. I believe anything over about 300 feet per second, and the pipe starts to become a restriction.
EDIT: I just checked... It is 450ft/sec, not 300ft/sec
Last edited by SATAN; 12-14-2011 at 10:13 PM.
12-15-2011, 12:01 AM
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Why would you think that aluminized piping would run cooler than steel piping? They are both steel. The aluminized just has a coating on it to keep it from corroding.
In order to know if 2.5" vs. 3" is going to hurt anything, you need to know how much air you are moving first. When you know your CFM then you can calculate it into the size of the pipe. That will give you velocity. I believe anything over about 300 feet per second, and the pipe starts to become a restriction.
EDIT: I just checked... It is 450ft/sec, not 300ft/sec
In order to know if 2.5" vs. 3" is going to hurt anything, you need to know how much air you are moving first. When you know your CFM then you can calculate it into the size of the pipe. That will give you velocity. I believe anything over about 300 feet per second, and the pipe starts to become a restriction.
EDIT: I just checked... It is 450ft/sec, not 300ft/sec
12-15-2011, 12:06 AM
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I really didn't think it would run cooler but I have heard it stated to me so many times that I should be running the aluminized steel to keep it cool. lol I guess I started to believe my own lie....if that makes sense. I have no idea of cfm but am guessing that I am no where near that 450ft per second.
Also, if you have no idea of the CFM, then you also wouldn't have any idea of the ft/sec.
600cfm = about 300ft/sec in a 2.5" I.D. pipe.
12-15-2011, 12:22 AM
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Your right. I am saying I have NO idea however, if it needs to be a certain number (x) before its a restriction, I was saying that I am probably safe to assume that I am not reaching such number since I have a modest build.
12-15-2011, 02:12 AM
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are you sure your not thinking acutal aluminum piping for the cold side rather than the aluminized steel piping?
being that you are not going to have a IC i would think the difference between 2.5 or 3 inch would be negligible since you will have less than a foot of piping on each side, your TB inlet would be simlar to 3.5 inch single pipe, so figure out that velocity and match that to the two pipes coming into the TB.
I dont have and #'s on hand though, you might be able to find some by searching
HTH
being that you are not going to have a IC i would think the difference between 2.5 or 3 inch would be negligible since you will have less than a foot of piping on each side, your TB inlet would be simlar to 3.5 inch single pipe, so figure out that velocity and match that to the two pipes coming into the TB.
I dont have and #'s on hand though, you might be able to find some by searching
HTH
