IC pipping size?
IC pipping size?
Just wondered what most of you are using.. I need to fab inlet and outlet IC pipping. What size? Is 3 inch ok? Should I use 2.75? Gt40r turbo on Apexi FMIC. Thanks
WWFSMD
Joined: Jun 2001
Posts: 5,035
Likes: 4
From: SoCal
Stock piping is 2.75". Most turbos used on RX-7s have 2.5" compressor outlets. Measure the IC inlet and use that size, so long as you can clear the hood with it. You'll probably need a transition at some point to match the size of the turbo outlet.
Pressure drop comes from restriction, so a 3" pipe will have less pressure drop than a smaller one. Transitions add restriction, too, so it wouldn't make sense to go from 2.5" turbo outlet to 3" pipe to 2.75" IC inlet. Better to just transition once: 2.5 turbo outlet to 2.75" pipe to 2.75" IC inlet (or use 2.5" pipe). Bigger pipe adds volume but has lower restriction. Smaller pipe has less volume but is more restrictive.
-Max
Pressure drop comes from restriction, so a 3" pipe will have less pressure drop than a smaller one. Transitions add restriction, too, so it wouldn't make sense to go from 2.5" turbo outlet to 3" pipe to 2.75" IC inlet. Better to just transition once: 2.5 turbo outlet to 2.75" pipe to 2.75" IC inlet (or use 2.5" pipe). Bigger pipe adds volume but has lower restriction. Smaller pipe has less volume but is more restrictive.
-Max
Joined: Apr 2002
Posts: 4,232
Likes: 0
From: Rotaryland, New Hampshire
Corky bell says..
Now devide this # by 1100 to give you the speed of air in the pipe. If its higher than .4 then increase the pipes ID, if its substainatly lower, possibly decrease the ID.
-Jacob
Corky Bell's Maximum Boost - Pg 61 There is probably a magic number that airflow velocity in a tube should not exceed, for reasons of rapidly increasing drag and consequent flow losses. I suspect this number is around Mach .4 or about 450 feet per second, sience drag, and thereflore flow loss, is increases significantly after this.
Tube size can easily be checked by caluclating the maximum aireflow attainable, dividing that by the area of the tube in square feet, and dividing again by 60 to convert to feet per second. An approximate value for maximum aireflow can be obtained by muliplying the desired bhp by 1.5
Tube size can easily be checked by caluclating the maximum aireflow attainable, dividing that by the area of the tube in square feet, and dividing again by 60 to convert to feet per second. An approximate value for maximum aireflow can be obtained by muliplying the desired bhp by 1.5
Corky Bell's Maximum Boost - Pg 62 Resist the temptaion to use larger diameter tubes than neccessary, as little drag is created in smooth tubes with gental bends. larger tubes will only add to the volume of the IC system, and that is not a good thing to do
-Jacob
Last edited by CrackHeadMel; Jun 23, 2004 at 06:25 PM.
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WWFSMD
Joined: Jun 2001
Posts: 5,035
Likes: 4
From: SoCal
There was a thread about this very subject not too long ago. I ran some numbers with Corky's estimated speed limit and even 2.5" pipes seemed big enough unless you are building a super-beast of an RX-7. I don't remember the numbers, but a quick search would surely locate the thread.
-Max
-Max
not sure anymore
Joined: Aug 2003
Posts: 1,182
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From: leawood,kansas
i just got that book. its great. I will have to do the math on that and post back with some #'s for you guys to go off of. This will be with a stock turbo though as i ran out of money.
This will be used with Apexi FMIC, GT40R Turbo (if ever gets here) 16-18 psi for now. Once ported motor goes in then I will be running higher boost... The info I got from A-spec was 2.75 outlet on turbo. The IC has 2.5 in and out. Using Greddy elbow... ??????? What do you think?
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