Lets talk aero!
- Thread starter ga41
- Start date
Probably the best downforce generator in a road car at higher speeds would be provided by a Bernoulli plate - basically a flat floor pan that is inclined upwards from front to back. Combine this with vertical fences from front to back to prevent cross-flow as far as possible. The biggest problem is ground clearance, as you need the plate height to be about 50-75mm between the front wheels and about 100-150mm at the rear wheels, with smooth entry and exit at the front and rear. This would give a reasonable venturi effect to accelerate the air under the car.
To put aerodynamics into some sort of perspective that we can understand, Ross Brawn says that a current F1 car can run upside-down at 80mph. In other words, by the use of appropriate aerodynamic devices, a vehicle with a minimum weight of 640kgs (F1 car) can be develop more than 640kgs of downforce at a speed as relatively slow as 80mph! Therefore, as I see it, all appropriate aerodynamic devices on road cars can generate some additional downforce which can be useful at speeds seen on a trackday.
The Z4MC already has a series of OEM undertrays which leaves the underside of the car pretty tidy and the differential has its own cooling provision in the OEM undertrays and there is a rear diffuser arrangement in the rear bumper. The car has a natural rake angle (front lower than rear) which helps to create low pressure under the car, which assist higher speed stability. There is also the little flexible "airdam" beneath the front bumper which reduces the amount of air getting under the car, which additionally helps.
IMO, the Z4 MC could be discretely aerodynamically improved by the provision of some larger front splitters beneath the "fangs", which will add downforce at the front and sharpen the steering response. Likewise, the fitting of the OEM rear CF tailgate lip-spoiler (Gurney flap/wickerbill) would increase rear downforce and also assist the rear diffuser to perform better.
The Z4MC already has a series of OEM undertrays which leaves the underside of the car pretty tidy and the differential has its own cooling provision in the OEM undertrays and there is a rear diffuser arrangement in the rear bumper. The car has a natural rake angle (front lower than rear) which helps to create low pressure under the car, which assist higher speed stability. There is also the little flexible "airdam" beneath the front bumper which reduces the amount of air getting under the car, which additionally helps.
IMO, the Z4 MC could be discretely aerodynamically improved by the provision of some larger front splitters beneath the "fangs", which will add downforce at the front and sharpen the steering response. Likewise, the fitting of the OEM rear CF tailgate lip-spoiler (Gurney flap/wickerbill) would increase rear downforce and also assist the rear diffuser to perform better.
exdos said:
It's been suggested by some who have this lip spoiler that it does indeed act like a Gurney flap, leading to front end lift and a "floaty" steering feel at very high speeds. I don't have one, so I cannot comment from experience - I know tomscott loves his, but I suspect that is all about cosmesis!
BMWZ4MC said:
I'm sure it will be very effective. I certainly wouldn't fit any rear spoiler device without putting some flippers at the front to keep the front end down and preserve the rake angle.
Here are a couple photos of the aero bits on my Z3MC. The front flippers and Rear roof wing are AC Schnitzer parts. I've fitted small rubber airdams beneath the flippers. Additionally, I've completely gutted a pair of OEM silencers to make them "straight-through" and I've also made the underside of the silencers flat so that they incorporate with other flat sections that I've made and fitted behind the rear axle, so that with the vertical strakes they form part of a rear diffuser. I've also made the small diffuser wing that fits between the exhaust pipes. The rear diffuser works in conjunction with the rear roof wing and the car is extremely "planted" at all speeds.
Doesn't the GT3 RS 4.0 have an innovative aero solution on the front bumper? There is also the flexible arrangement on the grill on the 458 Italia). On my phone at the moment so can't post any pics but will do later if someone hasn't beaten me to it.
No those on the side of the bumper near the wheels GA41. I might be wrong but I think they are active aero
I know about the flexible winglets on the 458's front bumper but i've not read anything about active aerodynamics on the 4.0. Only thing mentioned in the press releases is about those little flics on the front bumper which "make their first appearance on a production Porsche". http://press.porsche.com/news/release.php?id=644
Yes that's them. I'm sure they are flexible and as the press release states, are there to increase downforce. I can't remember for sure but I think a Chris Harris video shows him checking them out at close quarters. 