Louvres

[Osella]

what do the louvres above the front wheels do on sportscars exactly? eg the Zytek

are they to equalise the air pressure in the wheelarch with the air over the front of the car, or to drain the brake cooling air, or what?

[imull]

yes tkey arepoof presoor =ing

[imull]

im gussing thats meant to say that they are for dealing with pressure in the wheel well afaik.

dont even remember writing that last night

[shiny side up!]

for imull...

[zefarelly]

ha ha . . . post of the month !

at a guess I'd say they help draw air from the brakes which is forced in through cooling ducts, therefore eliminating any turbulence or poressure in the arches ? and guiding it over the rest of the body to help down force ???

a complete guess, they might just look racy

[Morris 1100]

The slots spoil the airflow over the top of the mudguard and reduce lift.

[zefarelly]

MOrris . . .thats far to simple . . .sure ly you can think of something more elaborate?

[imull]

Surely the drag created would outweigh the disadvantage of the lift.

only finish uni once. now my head rually hurts

[Tim Falce]

Surely they are to make the car go faster in a similar way that stripes down the sides in the 70s made cars go faster

[hush]

hi to let the high pressure air out the top of wheel arch
and not down the side and under the car as this would reduce the downforce

[Speck]

I read somewhere acouple of years ago that there is a high pressure area at the top of the wheel well. Putting the louvres there is meant to get rid of this, at the very least.

[Cameron Winton]

The louvres are purely for lift reduction. The rotating wheels/tyres in the wheel well create all sorts of undesirable airflow conditions and when enclosed can act like a weak air pump. Dealing with pressure rise in the wheel well is an issue that creates a lot of aero features on sports cars and keeping it seperate from the front diffuser is concern as well. Look at the R8 Audi over the years and you will see a variety vents, louvres and fences to help manage airflow in this area. Even in GTS, you will see vents and louvres attempting to do something about this. You end up with a trade off between lift reduction and drag and I think optimising this needs a lot of experimentation in a moving floor wind tunnel.
Airflow through the brakes is normally from the duct in the front of the car into the hub and then radially out through the disk vents with the airflow being exhausted through the spokes of the wheels. That's why the Group 5/6 and Group C cars of the late seventies and early eighties had "hub caps". The best visualisation of this air flow is watching a modern F1 car under heavy braking and you will see most of the dust blowing outwards from the wheel.

[HiRich]

Yep, it's to alleviate a high pressure point between wheel and arch. At 200mph, the lift created is pretty significant.

A distant memory, but I think the first instance was on the 917s - I am pretty sure I read about it in John Wyer's autobiography. Wherever I read it (and whichever car), I clearly remember the reason being pressure release.

[Morris 1100]

If you look at the Can Am cars of the 60s you will see vents and holes in a lot of cars.