IC Piping Advice from Snickers
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Just in case any of you are not members of G20.net
Originally Posted by Snickers
people think you need to choose IC pipe size based on HP... which is NOT true.
If your motor makes 150hp NA and 300hp @ 15psi, and 450hp @ 30psi, and 600hp @ 45psi, you dont need larger piping just because your making more power. In the above scenario, you are making more power by increasing the boost pressure which is supplying a higher pressure more dense air/fuel mixture. This has nothing to do with the "flow" of air into the motor, as you are not making more power by increasing flow.
I made over 500whp on 2" and 2.25" piping and for many reasons i didnt have larger pipes. you would be suprised how small you can go with your IC pipes before losing power. Everyone thinks that because your Cold air intake has a 3" pipe, that your turbo motor does too... The reason why your CAI on your N/A motor is "so large" (relatively speaking) is because you dont want any pressure drop from the atmosphere to the engine. If the pipe is too small, then you have a pressure drop which means less actual air that can get into the motor before creating a lower than atmosphereic pressure in the intake manifold.
A SR20DE can actually run a 2.5" intake pipe wtihout any power loss, and it will actually make more midrange power with it too.. same goes with a VE motor. Run a 2.5" pipe from the T/B to MAF and you will be suprised.
NOW on a turbo motor, you are not relying on the Atmospheric pressure for the pressure differential that actually "fills" the engine with air.... you have a turbocharger which creates higher air flow levels than what your engine could do by itself. But wait! the turbo makes boost pressure right??!!! WRONG! the turbo creates air flow and pressure differential from the inlet to the outlet. Now you have this "higher than normal" air flow.. so how do you get boost? WELL remember this.... PRESSURE is RESTRICTION to flow. The restriction of the engine is what restricts air flow into the motor which builds up boost pressure.
SO HOW DOES ALL THIS relate to the size of my IC piping?
Well a given pipe diameter will only flow a given amount of air before being restrictive... now how do you know when its restrictive???
Turbo or NA its the same method of testing... Other than a dyno, you need a manometer which measures pressure differential.
Because you have a turbo on your engine, the turbo will "supply" the engine with air. You are not going from the engine "sucking" the air in to "forcing" the air in, but you are changing the pressure differential by which the engine's cylinders fill... Atmospheric pressure is always the same, roughly 14.7psi absolute. so when you have a slight pressure drop from the air filter to the intake manifold, you have no other means to "account" for that pressure drop and make up the different other than to find it and eliminate it.
With a Turbo, your wastegate or boost controller will see your boost pressure drop from say 10.00psi to 9.5psi, and thus the W/G will close slightly and the turbo will create more "flow" and thus with the same restriction you will have more "boost" have be back up to the same 10psi you were at.
The Charge piping is rarely too small. Because you have another "source" of "air flow" that is "constant" the minor pressure drop across the charge piping (most of it is from friction) is made up with minor power loss, maybe 2-3hp... but the decrease in lag is significant...
Also, side note.. The transition from the charge piping into the intercooler end tanks and core, and back into the charge piping has more effect on power loss than charge piping. The poor "flow path" of the charge piping/end tanks/core creates more restriction and turbulance which causes a larger pressure drop than smaller piping does.
Anyways, for most setups, like a T25, you could go with 1.75" and 2" and be plenty large enough, and on a GTIR turbo , probably just 2" and no more....
Also, if your charge piping is small enough and the air flows through it at a high rate, when it hits the throttle body or intake plenum and slows down, and there is a slight pressure drop, the air will actually drop in temperature and heat will dissapate...
Anyways, enough for you to stir on for a bit :smoke:
Just in case any of you are not members of G20.net
Originally Posted by Snickerspeople think you need to choose IC pipe size based on HP... which is NOT true.
If your motor makes 150hp NA and 300hp @ 15psi, and 450hp @ 30psi, and 600hp @ 45psi, you dont need larger piping just because your making more power. In the above scenario, you are making more power by increasing the boost pressure which is supplying a higher pressure more dense air/fuel mixture. This has nothing to do with the "flow" of air into the motor, as you are not making more power by increasing flow.
I made over 500whp on 2" and 2.25" piping and for many reasons i didnt have larger pipes. you would be suprised how small you can go with your IC pipes before losing power. Everyone thinks that because your Cold air intake has a 3" pipe, that your turbo motor does too... The reason why your CAI on your N/A motor is "so large" (relatively speaking) is because you dont want any pressure drop from the atmosphere to the engine. If the pipe is too small, then you have a pressure drop which means less actual air that can get into the motor before creating a lower than atmosphereic pressure in the intake manifold.
A SR20DE can actually run a 2.5" intake pipe wtihout any power loss, and it will actually make more midrange power with it too.. same goes with a VE motor. Run a 2.5" pipe from the T/B to MAF and you will be suprised.
NOW on a turbo motor, you are not relying on the Atmospheric pressure for the pressure differential that actually "fills" the engine with air.... you have a turbocharger which creates higher air flow levels than what your engine could do by itself. But wait! the turbo makes boost pressure right??!!! WRONG! the turbo creates air flow and pressure differential from the inlet to the outlet. Now you have this "higher than normal" air flow.. so how do you get boost? WELL remember this.... PRESSURE is RESTRICTION to flow. The restriction of the engine is what restricts air flow into the motor which builds up boost pressure.
SO HOW DOES ALL THIS relate to the size of my IC piping?
Well a given pipe diameter will only flow a given amount of air before being restrictive... now how do you know when its restrictive???
Turbo or NA its the same method of testing... Other than a dyno, you need a manometer which measures pressure differential.
Because you have a turbo on your engine, the turbo will "supply" the engine with air. You are not going from the engine "sucking" the air in to "forcing" the air in, but you are changing the pressure differential by which the engine's cylinders fill... Atmospheric pressure is always the same, roughly 14.7psi absolute. so when you have a slight pressure drop from the air filter to the intake manifold, you have no other means to "account" for that pressure drop and make up the different other than to find it and eliminate it.
With a Turbo, your wastegate or boost controller will see your boost pressure drop from say 10.00psi to 9.5psi, and thus the W/G will close slightly and the turbo will create more "flow" and thus with the same restriction you will have more "boost" have be back up to the same 10psi you were at.
The Charge piping is rarely too small. Because you have another "source" of "air flow" that is "constant" the minor pressure drop across the charge piping (most of it is from friction) is made up with minor power loss, maybe 2-3hp... but the decrease in lag is significant...
Also, side note.. The transition from the charge piping into the intercooler end tanks and core, and back into the charge piping has more effect on power loss than charge piping. The poor "flow path" of the charge piping/end tanks/core creates more restriction and turbulance which causes a larger pressure drop than smaller piping does.
Anyways, for most setups, like a T25, you could go with 1.75" and 2" and be plenty large enough, and on a GTIR turbo , probably just 2" and no more....
Also, if your charge piping is small enough and the air flows through it at a high rate, when it hits the throttle body or intake plenum and slows down, and there is a slight pressure drop, the air will actually drop in temperature and heat will dissapate...
Anyways, enough for you to stir on for a bit :smoke:
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