Front bumper drag numbers?

[rdane]

Has anyone ever seen the numbers for down force and drag between the IROC, RUF Yellowbird, C2 front bumpers?

I assumed they were more effective in each version as listed.

Least effective to most effective.
IROC
Ruf
C2

But I have never seen that published.
Anyone have a list and numbers?

[masraum]

I think to get those numbers you'd have to take a car, put one of the setups on, test it in a windtunnel, then change the bumper on that car out and test again, etc... I can tell you that the 964 had pretty much 0 lift at speed, so from that point of view the 964 bumper is part of a package that makes 0 lift in the front, but I don't think you could say it was just due to the front bumper since so much of the 964 was designed just to minimize lift and drag compared to the earlier cars. Actually the 964, if I remember correctly had less lift than the 993 and 996.

[djmcmath]

Hmmm ... Paul Frere's got some numbers for lift and drag coefficients on the 964, but it's for the whole car, not just bumpers, or bumpers on an earlier car. Seems like the 964's are slightly different in a few other areas, aerodynamically. He doesn't list numbers for Ruf or IROC anywhere I've seen. Good question, now I'm curious.

Dan

[Lukesportsman]

I didn't know that the 964 had less lift, but it does also have less drag as a car than the bulky 993. Wouldn't you just assume that the aftermarket RUF is maybe the best since he was after top end speed. Porsche had to compromise drag, looks, safety, cost, durability and downforce.

Look at the compromises today with the turbo 996's bumper in comparison to their low drag aero front ends. Down force and cooling issues improved, but I bet a Turbo has more drag with all those openings.

In this compromise, I would think that Porsche was more interested in downforce than cd with the IROC's to balance out the spoilers on the bank'd ovals.

[rdane]

I am wondering as well. I first thought Ruf would have had the best set up available when he did Yellowbird with the high top end. But not sure that is true. It is just a guess.

Makes and easy marriage though with YB bumpers and a Carrera wing duplicating what YB had.

If you look at Peter Gregg's last RSRs they look more like Yellowbird bumpers than anything else. So I would think they would be pretty effective.

Nott specifically on point but I am thinking (this week anyway) of mating my current yellowbird set up to a duck tail and was trying to get some feel for how the car might handle at speed. My gearing tops out 135 and hit it often enough to not want any surprises.