Quoting myself from another thread, but still relevant...

The Yamaguchi 2nd gen bible states the base model w/ Cd of .31, its streamlined mirrors and 185/70-14 tires has a Cd X A of .56

So, I guess that is ~ 1.806452 sq Meters or ~2800 sq inches. I would think the slightly lower lip of the Aero kit and the wider tires of the sport (205/60-15?) would raise the frontal area a bit more, but the front lip's front tire deflectors may drop calculated frontal area...

Coefficient of lift is .08 front and .14 rear for standard model and .08 front, .07 rear for aero kit cars w/ .29 Cd.

Now the bummer,

Don't forget the hosepower needed to achieve the corresponding speed has to be available at that speed (and corresponding engine rpm) and gearing often won't allow for that.

For instance your peak HP may be 186hp, but even with the '87, '88 TII close ratio 5 speed you won't be able to do the 170MPH unless your engine peaks its HP at ~7,500rpm

In pracatice it takes closer to 300hp (peak) for TIIs to hit 170MPH since with the stock manifolds peak HP is ~6,500rpm ('87-88 TII) and drops from there.

 

I just want to say that the Cd is not a constant number but change depends on the speed. So you can not calculate the drag force at 100mph and 200mph with the same Cd.... So I wonder at what speed, was the measurment taken?

 

I'll bet if you dig around you'll find it's being done according to some SAE method for consistency.

Yes, Cd is definitely not a true constant. I messed around with the CdA numbers for the Veyron and it was not very close to its measured top speed. Whether that's due to gearing or nonlinear Cd I don't know.

 

Great thread.

Now I know I can go 200mph+ given enuf distance