2.25" piping, why?
03-30-2002, 10:48 PM
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Re: 2.25" piping, why? (Muglit)
Why does the Drag and Rev-Hard kit come with 2.25" piping when intakes for NA integras are 2.5"(AEM) or 3"(Injen)?
going with a 3" IC piping would probably make the turbo LAG more noticeable.
03-30-2002, 11:05 PM
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Re: 2.25" piping, why? (BlueShadow)
I just thought that since the turbo is pushing more air into the engine than an NA car that it would at least have the same diameter piping.
03-30-2002, 11:08 PM
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Re: 2.25" piping, why? (Muglit)
I just thought that since the turbo is pushing more air into the engine than an NA car that it would at least have the same diameter piping.
03-31-2002, 12:11 AM
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Re: 2.25" piping, why? (BlueShadow)
I just looked in Maximum Boost, and it's a lot more complicated than I thought.
It also has to do with air velocity, air velocity drag, and piping diameter.
page 61-62 Maximum Boost by Corky Bell
It also has to do with air velocity, air velocity drag, and piping diameter.
page 61-62 Maximum Boost by Corky Bell
03-31-2002, 02:01 AM
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Re: 2.25" piping, why? (BlueShadow)
I just looked in Maximum Boost, and it's a lot more complicated than I thought.
It also has to do with air velocity, air velocity drag, and piping diameter.
page 61-62 Maximum Boost by Corky Bell
It also has to do with air velocity, air velocity drag, and piping diameter.
page 61-62 Maximum Boost by Corky Bell
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03-31-2002, 02:56 AM
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Re: 2.25" piping, why? (LsTurbo91)
well it goes into speed of sound (MACH), CFM, and calculating the max airflow.
I quote page 61-62 of the book Maximum Boost by Corky Bell.
the calculation seems simple enough but there are a lot of fractions that need to be divided by other fractions. and after the whole formula is drawn out it looks kinda complicated, the formula is:
Velocity = airflow divided by area
(It's a lot more complicated than it seems)
I dont know of any other way to put that in laymans terms so I just copied it word for word. I can also sketch out the formula in JPEG format if someone can host it for everyone else to see.
but basically the "book" says a large tube is bad, so who am I to argue?
[Modified by BlueShadow, 11:58 AM 3/31/2002]
I quote page 61-62 of the book Maximum Boost by Corky Bell.
Tube Sizes and Shapes
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 0.4 or 450 feet per second, since drag and therefore flow loss, increases significantly after this. Tube size can easily be checked by calculating the maximum airflow attainable, divided 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 airflow can be obtained by multiplying the desired BHP by 1.5.
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 0.4 or 450 feet per second, since drag and therefore flow loss, increases significantly after this. Tube size can easily be checked by calculating the maximum airflow attainable, divided 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 airflow can be obtained by multiplying the desired BHP by 1.5.
Velocity = airflow divided by area
(It's a lot more complicated than it seems)
continued from above
Resist the temptation to use larger diameter tubes then necessary, as little drag is created in smooth tubes with gentle bends. Larger tubes will only add to the volume of the IC system, and that is not a good thing to do.
NOTE: A large tube is not necessarily better than a small tube.
Resist the temptation to use larger diameter tubes then necessary, as little drag is created in smooth tubes with gentle bends. Larger tubes will only add to the volume of the IC system, and that is not a good thing to do.
NOTE: A large tube is not necessarily better than a small tube.
but basically the "book" says a large tube is bad, so who am I to argue?
[Modified by BlueShadow, 11:58 AM 3/31/2002]
03-31-2002, 07:46 AM
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Re: 2.25" piping, why? (94hondahybrid)
Not always bad, if you boost more you should get a bigger pipe. To find out exactly what MORE is use the formula
the formula was Velocity = airflow divided by area
the numbers used in the example are:
-400 BHP
-600 CFM (airflow)
-2.5" (area)
now the formula is supposed to tell us if 2.5" is going to be the right size for a goal of 400 BHP.
the velocity comes out to 293 ft per second (velocity) they took that and divided it by 1100. the speed of sound is 1100 feet per second (MACH).
293 / 1100 = 0.27
The book doesn't say why .27 is good or bad it just says based on that number that 2.5" is adequate.
or maybe it's cause the velocity in the 2.5" tube didn't go over 450 feet per second (0.4 MACH), which as stated in my previous post is the point after which the air starts to get increased drag and increased drag leads to flow losses.
03-31-2002, 09:42 AM
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Re: 2.25" piping, why? (BlueShadow)
Not trying to question the book because he is far more knowledgeable than I, but just trying to throw ideas out there.
If the problem is too much velocity then doesn't velocity increase with smaller and longer pipes but decrease with larger and shorter pipes. So if the pipes are longer like you said won't making them bigger cut down on velocity?
If the problem is too much velocity then doesn't velocity increase with smaller and longer pipes but decrease with larger and shorter pipes. So if the pipes are longer like you said won't making them bigger cut down on velocity?
03-31-2002, 02:56 PM
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Re: 2.25" piping, why? (Muglit)
If the problem is too much velocity then doesn't velocity increase with smaller and longer pipes but decrease with larger and shorter pipes. So if the pipes are longer like you said won't making them bigger cut down on velocity?
03-31-2002, 03:25 PM
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Re: 2.25" piping, why? (BlueShadow)
Yeah I two have to work out the size of my intake also…
As many of you know, im doing the Max rev turbo thing.. but of course it did’t come with a intake tube, I was going to hack open my 3” CAI and make that my intake tube from the IC.
But that was one of my problems my IC pipes are 2.25” where as my CAI is 3”
I figured.. having a 3” intake pipe would be fine. .but now I wonder if I should make it all 2.25”
So drag intake pipe is 2.25’ ? to the tip of the throttle body ???
Also what size is the throttle body on engine intake? ( im 2 lazy to go outside and rip off my CAI and measure the size of the intake )
Regards James
As many of you know, im doing the Max rev turbo thing.. but of course it did’t come with a intake tube, I was going to hack open my 3” CAI and make that my intake tube from the IC.
But that was one of my problems my IC pipes are 2.25” where as my CAI is 3”
I figured.. having a 3” intake pipe would be fine. .but now I wonder if I should make it all 2.25”
So drag intake pipe is 2.25’ ? to the tip of the throttle body ???
Also what size is the throttle body on engine intake? ( im 2 lazy to go outside and rip off my CAI and measure the size of the intake )
Regards James
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