track with lip

[Brent Dalton]

Originally Posted by Melchior

Lips, even typical "show" lips, sit lower to the ground which reduces the amount of air flowing underneath the car. This results in lower pressure under the car, and reduced drag because the air under the car doesn't have to flow around all the suspension/exhaust/diff components. Depending on how low the lip is (height from the ground), this can produce significant downforce. I went from wing/no lip ---> wing/oem lip on my RX7 race car and had to add wing to balance the car back out. I then went from wing/oem lip with custom splitter and hand to add even more wing to balance the car out. The splitter was worth more front grip, but the OEM lip did make a decent difference.

Lip and splitter mounting isn't as critical as most people think on low downforce setups. The overall donwforce isn't achieved through the lip or short splitter surface, but actually primarily from the underside of the car. That's a lot of sq-ft to distribute the pressure, and only a very small amount on the actual lip itself. I ran a Mode Carbon V2 setup on my M3 and had to dial in a fair amount of wing to get the car balanced. The lip/splitter combo was only bumper mounted. I've even run a 1/4" plywood splitter which was bumper mounted and it still produced a fair amount of front grip, and I don't think either of these arrangements would have gained much from chassis mounting.

If the splitter goes back (centerl ine of front axle) further, extends further forward, and is designed to produce higher downforce, then it should be mounted to the chassis. The splitter should also be rigid to prevent deflection at speed. Splitters extending further back are more critical because the pressure will be distributed across the spilltter, as opposed to the underside of the car.

best post in the thread.

[bigjae1976]

I think 95% would never know the difference with a typical lip.

[M3 Number 86]

Thanks for all the replies!

When at Autoclub Speedway, I do a decent speed around the bowl - faster than the non-fast guys with full aero

But, when I took a ride in a friend's car with full aero, it was 5000% obvious that the car was much more planted at higher speeds - I felt the car literally squat opposed to mine getting a little light.

NT01s are my next mod. RS3 can't handle my aggressive foot.