Standard R8 Airbox breathes HOT Air!!

[bz888]

Whilst removing my Air filters today I was disappointed to find the R8 V8 OEM Airbox is not the beautifully design Cold Air Intake we would like to think!

It's actually got a 10cm x 10cm mesh cut-out in the airbox that breathes hot air from the engine bay! So, Audi designs these Cold Air intakes from the side blades and then they go a screw it all up by allowing hot air to enter from engine bay via this mesh cut-out! Seriously, they have no idea.

So annoying..we spend all this time/$$$ upgrading and enhancing our cars for more performance, all the while, it breathes HOT AIR from the engine bay!

Has anyone seen this? Maybe I should block it and see what happens??
Pics to come.

[bz888]

Pics attached!

[PDE491]

There's a lot of turbulence & fluid flow going in in the engine bay, and my guess is that, under normal non-stationary operation, the temp of the air at intake is much lower than you think. I once accidentally offended my clutch & filled the engine compartment with smoke at about 100 km/hr. Was interesting to see how violent the fluid flow was with the smoke swirling around. It was only about 8-10 seconds for all of the smoke to be gone. How much can ambient air heat in under 10 seconds? I'm sure these engineers perform FEA/CFD computer simulations plus live tests and know what's going on... or they're making pretty good guesses :-)

[desperado]

FWIW, here's a diagram of the airflow in the engine compartment. The colors indicate the relative speed of the airflow:

[SteveR]

I assumed the side intakes fed radiators on the way to the engine bay? If not, it looks like it would get plenty of flow to keep things cool.

[bz888]

Sideblade intakes are dual purpose. Bottom half does Engine Oil cooler. Top half does engine air intake.

I think allowing hot air from engine bay into airbox is a compromise of some sort.

[desperado]

There is a transmission oil cooler on one side, and an engine oil cooler on the other side. While there is plenty of excess flow through the sideblades as well as the air entering through the NACA vents in the undertrays, it's hard to say what the temperature of the air circulating around the airbox would be. I agree with bz888 that it probably gets pretty hot in there!

What I am not so sure of is how much air will actually enter through the little screen. It is pretty fine. With air being forced in from the side blades it seems likely, at least while the car is moving, that very little air from the engine compartment would enter the airbox. It probably only breathes hot air when standing still.

[harrison]

Thanks for the second set of images !

[M3R8]

I've took tabs of temperatures around the bay for a special project, its really not hot in there during normal and spirited driving, there's plenty of air to cool things down. Granted I'm testing in cold weather.

Anyway, I think we can trust Audi to know what they are doing. If you think you know better, go ahead and modify your car. I just don't see the benefit of doing any modifications in the intake air temperature department unless you're actually having real issues with it.

One might get close to the limits when the the outside air temp is 50 degrees celsius (122f) and you're racing around very curvy roads at relatively low speeds but high RPMs. Probably not even then, these things get tested for.

[Europrice]

Be aware that this type of port may be to help cold running. When the ambient temp is cold, the engine is cold and you are gently driving the car there isn't much airflow (or idling and there is likely not any air flow) and the warmer air coming from that intake actually helps the engine run better until the engine comes up to temp. Even if you are up to a hot temp and stop for a bit it doesn't hurt anything for the engine to ingest some hot air, the second you get moving again I bet there is plenty of air moving through the engine bay and being fed to the airbox.