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Aluminium air intake pipe

Immortality

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There's a lot more to this than simply the heat conduction and convection through the pipes.

Stainless and Aluminium pipes can be much more highly polished which can SIGNIFICANTLY reduce heat gain due to friction of the air passing over the surface of the pipe, and if you think that this friction is nothing to worry about, you would be quite wrong. The rate that the air passes through these pipes is VERY fast, and the faster you go, the faster the air flow is through the pipes, which means greater and greater heat gain due to friction.

In a stainless or aluminium pipe, these frictional effects would be mostly transferred to the pipe, and then convection heat transfer would remove the heat energy from the pipe to the air blowing under your bonnet.

So, with a plastic pipe, not only is your friction effects greater, but the friction energy is transferred more to the air inside the pipe than to the pipe itself since the pipe does not conduct heat as readily as metals.

There is a method in the madness.

correct in the fact that the aluminum/stainless intakes are smoother and therefor would create less turbulance in the intake but a good plastic intake like K&N do for the LS1/LS2 would do that also. the heat from the engine/exhaust under the bonnet would heat the intake more then the heat caused by the friction of the air passing through intake itself. this is the reason that on racing cars so much effort is made to insulate the entire intake system from heat under the bonnet. look at the V8 supercars, there entire intake from the front intake to the inlet manifold is one huge carbon fibre box
 

Hwarang

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Your right about the hot air under the bonnet from the engine. However it really depends how fast you are going in your car. At fast enough speeds the hot air under the bonnet will be removed at a rate fast enough for the air to be cooler or as cool as the air in the intake.

In which case, once you have been driving around for a while and your plastic intake has heated up, it will then take longer to cool down at faster speeds too.

Also, no matter how smooth a good aftermarket intake is, plastic is plastic, and manufacturing processes limit the level of smoothness a plastic pipe can reach.
 

cracker

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i doubt ull be able to tell the difference which ever way you go.
what max it will make maybe 1rwkw
you wont notice it lol
 

Jon Z

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yeh id say you will feel a bit more responsiveness if you go the steel option with smooth mandrel bends but yeh it will make some difference as well as improving looks. :thumbsup:
 

VN Commy

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The level of smoothness (within reason ofcourse) will have little or no effect on the air passing through the pipe. There will be negligable friction caused by fast moving air also. The reason for this is that air speed is zero at the boundary between the air and the pipe. The air speed increases the further towards the centre. This means while air in the middle of the pipe can be travelling very fast, air very close to the pipe will be travelling slow (ie no friction, no advantages in terms of air speed of a polished pipe).
 

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The level of smoothness (within reason ofcourse) will have little or no effect on the air passing through the pipe. There will be negligable friction caused by fast moving air also. The reason for this is that air speed is zero at the boundary between the air and the pipe. The air speed increases the further towards the centre. This means while air in the middle of the pipe can be travelling very fast, air very close to the pipe will be travelling slow (ie no friction, no advantages in terms of air speed of a polished pipe).

In terms of boundary layers your right. Basically there will be very minimal gains from this i think its more a placebo effect.
 

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In terms of boundary layers your right. Basically there will be very minimal gains from this i think its more a placebo effect.

probably correct except the factory plastic intake pipe is far from smooth to begin with with all those ridges in the plastic and the flexible boots used to connect it to the TB and airbox are really crap as well. changing to a smooth setup whether it be plastic/stainless or aluminum got to reduce the turbulance in the intake. this is probably more off an advantage however on higly modified engines/turbos etc that flow much more air.
 

Hwarang

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The level of smoothness (within reason ofcourse) will have little or no effect on the air passing through the pipe. There will be negligable friction caused by fast moving air also. The reason for this is that air speed is zero at the boundary between the air and the pipe. The air speed increases the further towards the centre. This means while air in the middle of the pipe can be travelling very fast, air very close to the pipe will be travelling slow (ie no friction, no advantages in terms of air speed of a polished pipe).

Uhh... where do you think the zero velocity boundary condition comes from?...

Friction my friend. In an ideal world there would not be zero velocity. The further you move out from the surface, the faster it gets until the fastest point is in the centre, yes. But rougher edges means more friction which inversely affects the total speed at the centre of the air.
 

VN Commy

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Stainless and Aluminium pipes can be much more highly polished which can SIGNIFICANTLY reduce heat gain due to friction of the air passing over the surface of the pipe, and if you think that this friction is nothing to worry about, you would be quite wrong.

No matter how smooth or rough the finish of the pipe is the boundary velocity is going to be zero everytime. We don't live in an ideal world. There is no such thing as a significant heat gain generated in a pipe from fast moving air. Friction only produces heat when it does work. Because the air has zero velocity no work is being done. It's like when you park on a hill, the friction between the tires and the road hold the car in place, but the friction isn't doing any work, therefore no heat is generated (unlike if you do a skid for example).

Rough edges have no effect on the total speed at the centre of the air. The ridges ofcourse are another story. :thumbsup:
 
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