cali4sun

I saw this printed somewhere online? Anyways, thought that this was interesting. I would not have guessed such a difference between 928 models.

"Despite its sleek contours, the 928's coefficient of drag was a mediocre 0.41
(0.38 for an S model, with spoilers). The 1987 S4 model introduced a new, longer front clip that cut Cd to 0.34, a more creditable figure."

'89 S4 GP White/Black
'912E Silver/Black sunroof

Objects in mirror are losing

Lopez

well, it WAS designed in the 1970's, I don't think there was much emphasis on wind tunnel optimization for the sake of fuel economy then (certainly before CAFE laws and the like).

mark kibort

and once you put wings and splitters on , that goes right out the window!

PorKen

The Engineers must have realized the original shape was not perfect.

Note the air dam and whale tail on a prototype car in this scan from Project 928.

goodspeed928

.34 is a brick!
My ECHO is .29
The avg car today is .33, Good cars are in the .27-.29

http://www.mayfco.com/tbls.htm

goodspeed928

By the way, you NEED drag to go around corners!

http://www.madabout-kitcars.com/kitcar/kb.php?aid=327

Gtaebr

Even a brick can go fast with enough ooomph!

Imo000

And it needs needs every bit of the .29 to make it to 100.

tedward515

I think the original Lotus Elite had a cd of .29 if I remember right. Not to bad for the late 50's.

RKD in OKC

The 928 was designed back when aerodynamic downforce was generally considered a good thing. I vividly remember my 90GT taking an aerodynamic set as I passed about 115mph. It felt like I was flying the car on the road instead of rolling the weight of the car. Comparatively the lower drag less downforced BoxsterS would just start getting twitchy and felt a bit loose at speeds over 110mph.

mark kibort

No, only into corners!

drag is a factor that goes up with the square of speed, so when it comes to acceleration and deceleration at moderate speeds, it barely has an effect.

For example, the wing I have puts out 250lbs of downforce at 100mph, but that is less than 5ft-lbs of torque at the engine and also drives up the drag coeff. to over .4 vs the stock .34 Cd.

goodspeed928

"And it needs needs every bit of the .29 to make it to 100."

That little cars go's like HELL , I have got her up to 118, and at 100 is no problem at all.

dr bob

Slippery little cars are great at most legal speeds here in the US. Over the years I've experienced the joys of flying in slippery cars at super-legal speeds. eg: I have a (pair of) early 1960's Lotus 23 model, a somewhat road-worth little sports racer. At 70 MPH it's a blast. By 100 it's a kite. Add a small splitter at the front, or even a couple inches of chin spoiler, and it's glued to the ground at 100. In original condition it won't go a whole lot faster than maybe 115, and that little chin spoiler costs about 5 MPH of top speed when combined with a little wicker at the rear. The difference in driveability is amazing. Fast-forward to the 928, which just hunkers down harder as the speed goes up. Must be the front spoler and that monster S4 rear wing thing...

DonS

Wasn't it in Projekt 928 that I read that the drag co-efficient was better going backwards?

goodspeed928

YES it's true