standard air

been looking at this and has anyone got a idea what all the holes in the intake are for.thought i might tape them up to stop the hot air,but they are there for a reason.
 
Hmmmm could think that the holes are there for a reason. Wonder how the air flows through the pipe...maybe these holes are there so the small amount of air that is sucked in by them "twists" (this is not the right word but can't remember it right now) the incoming air in the pipe so more air gets in the engine :huh:
 
like you say ^^^^ surely they are there for a reason,

i shall be leaving mine just the way they are tbh, :biggrin:
 
Hmmmm could think that the holes are there for a reason. Wonder how the air flows through the pipe...maybe these holes are there so the small amount of air that is sucked in by them "twists" (this is not the right word but can't remember it right now) the incoming air in the pipe so more air gets in the engine :huh:

you mean a type of "vortex" generator

think it will just pull in hot under bonnet air to be honest - thats why i blocked mine up
 
Yeah a vortex. Something in the way the BMC CDA works with deflecting the incoming air. The intake hole is smaller as an air deflector is in the middle of the box but by altering the airflow (so that it deflects/twists/.....) more air gets in the engine - Click

As for the hot air you got to think a in different dimension. As the car doesn't move....yes it probably sucks in hot air but such a small amount that it really doesn't matter. You would get far better result if the pipe would be made of carbon and it wouldn' get so hot.

Back to the heat-sucking thing :biggrin: as the car is moving there is such a vast amount of air going through the engine bay that the air that's beeing sucked in by those holes is probably the same temperature as the air in the pipe. The exhaust manifold is on the other side so a big source of heat is "far" away as for the temperatures of the air inside the intake and I think that even if the holes would suck a small amount of hot air in there wouldn't be any difference since the inlet manifold is preheated by the engine etc. and the air still gets warmer.....but as I said before the air that is sucked in is probably already the same temperature as the one in the pipe.

Look at this pic and you'll see what I mean by the air flow around the pipe
01_2006cliors.jpg

A tuner/racer in Croatia tuned his Alfa GT 1.9JTDm over 190hp and 400Nm and tried this from Novitec - http://img510.imageshack.us/img510/4750/14318847rd1.jpg - think that it actually gave some gains iirc
 
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you forgot about the radiator at the front so hot air is still getting under bonnet and the pipe bends right in front of it so those holes will drag in some hot air
 
you forgot about the radiator at the front so hot air is still getting under bonnet and the pipe bends right in front of it so those holes will drag in some hot air

Yeah but when going over, let's say 70-80km/h?, the air flow is at such a high rate that it doesn't really matter. As the intake pipe is near the radiator and the inlet manifold which are both hot. I'd presume the air inside is warmed by it's surroundings so it could easily be that the air inside the pipe is actually warmer than the one that is sucked in by those holes because the air around the holes is constantly moving/changing when driving.

Would be nice to test it and see what's what :smiley:
 
I would have to disagree with the "vortex" idea. To me, those holes are for air to partially escape from the pipe. The reason is the "near-to-wall" regions in the pipe which cause substantial instabilities in the flow field due to friction (a good example is a Couette flow). This ultimately changes the velocity fields and thus the vortical behaviour of the flow itself (vorticity is just the gradient of velocity). In this pipe you need the air to be as smooth as possible (low Reynolds number laminar-like flow). The holes help the flow to naturally stabilize itself.
 
I would have to disagree with the "vortex" idea. To me, those holes are for air to partially escape from the pipe. The reason is the "near-to-wall" regions in the pipe which cause substantial instabilities in the flow field due to friction (a good example is a Couette flow). This ultimately changes the velocity fields and thus the vortical behaviour of the flow itself (vorticity is just the gradient of velocity). In this pipe you need the air to be as smooth as possible (low Reynolds number laminar-like flow). The holes help the flow to naturally stabilize itself.

Thought of that too. Similar to the intake manifold which is better when it's a little "rough" so huh the air is circulating at those "hills" inside the manifold and by that creating a really smooth passage for the air so the air flow is laminar and not turbulent.
 
we could be to clever for our own good here....

the holes probably just let a bit of under bonnet warm air in on cold morning starts :wink:

as for inlet air being rammed in - RML RACING did some testing on the primera touring cars (BTCC) and at maximum speed they gave very little in-let ram effect to their cars from front mounted air trunking