Over 10,000 lbs downforce at 200 mph....

[Tom and Vipers]

Found an incredible site.

http://www.mulsannescorner.com/toymkiii-1.html

Yes, the 91-93 Toyota Eagle MKIII GTP car developed over 10,000 lbs of downforce at 200 mph. ...and the lift to drag ratio was about 5:1.

Hubba Hubba...

[GTS Dean]

I love those pics! The IMSA P-cars of the mid-late 80's were the best looking e.g.: Jag & 962. However, the 300ZX-T began to lay waste to all comers with its slabby sides and sharper styling. The MkIIIs were not very attractive, but PJ Jones and JM FangioII just destroyed what was left of the competition with them.

I can still smell the VP and hear the wastegates popping off from the 4 races held here in San Antonio. Please - don't wake me up...

[GTS Dean]

Don Devendorf's goal was not merely to qualify and race, it was to race and WIN.

[Tom and Vipers]

I was just thinking about real basic things like spring rate and tire load carrying capacity when you are dealing with a downforce that ranges from 0 to 10k lbs!

Springs: Variable rate essential?

Tires: I haven't got a clue ...and what about tire pressure?

[jrkermode]

The tires are springs in a ground effects car. That's why the F1 paddock was all a tizzy when Ferrari got in bed with Bridgestone. All the other teams have to figure out the spring rate of the tire and hope their chassis will accomodate it. Ferrari, on the other hand, can specify the tire's spring characteristics and thus the tires are perfectly matched to the chassis. A BIG advantage.

As for variable rate... Race car suspensions (primarily push rod and pull rod) all have a provision for varying the wheel rate. However, the aero loading is usually transferred to a "3rd spring", a spring which only acts while pushing down on both wheels of an axle.

Also keep in mind aero loads vary with speed squared (that 10,000 pounds drops to 2,500 pounds at 100 MPH). So the car doesn't experience that 10,000 pounds very often.

[Tom and Vipers]

What else is interesting is that the drag force at 10k lbs was just under 2k so, for illustration, if the car weiged 2k lbs, with 2k drag, HP would have to be sufficient to drive car at 1G at 200 mph. ...which sounds like it might not be possible. (If I've got the analogy right.)

I suspect that the 10k at 200 mph is a windtunnel number and that 10k lb downforce is not even attainable at 200 mph in the actual car, however, I haven't gone over the numbers for 700 HP 1400 lb cars. (Actually, the weight of the car has nothing to do with it.)

Need a handy HP -v- (Thrust -v- Speed) formula...

[jrkermode]

It's actually a pretty simple thrust problem. The torque of the motor, working through the transmission, differential and the radius of the drive wheel must balance the drag.

If its just over beers (everyone knows not to drink and divide, right?), assume a drive wheel radius of 1 foot. Further, assume they had a 1:1 top gear and a 5:1 differential gear. Do the math (Motor x Trans x Diff / Wheel) and it appears they needed about 400 lbs-ft to keep things rolling along.

Anybody know the specs on that Toyota motor?

[j-rho]

oops, didn't mean to reply...

[dave6666]

Go check out the Vipair thread too, while waking up dead things.