LO PHAT

This is correct. There is also an interesting post around here about the factory body side moldings improving aerodynamics at speed as well.

Anyway ... Congratulations, David!

LO PHAT

Pfadt Racing

Hey everyone, new video here:

Corvette LSR prep

Pfadt Racing

cool, what top speed runs are you referring to? shoot me some info and I will forward it to him.

Pfadt Racing

Thanks! Speed isn't as easy as it may seem to come by. You have to remember, this are very specific timed miles you have to set the record. Davids exit speed was 265. It is a delicate balance of gearing, aero drag, rolling resistance, weight, horsepower, and very important is cooling. The power has to be reliable over miles of runs as well, as opposed to some hp numbers you see out of drag race cars etc that have shorter duty cycles. So, its all about tradeoffs and finding the right combo. I'd say he must be doing something right! Thanks for the comments

99C5JA1

GM itself states the coupe is more aerodynamic (.29 for the coupe and .31 for the FRC/Z06). Lingenfelter also chose a coupe for their top speed machine. Now how much difference this actually makes in reality I couldn't say.

KrispyZ06

Pfadt Racing

Ok, so where is this info? Saying something is "more aerodynamic" is ambiguous because it is usually a reference to L/D, which isn't the only target for top speed optimization. Or you could be referring to only downforce, or, only in terms of drag. What numbers are you quoting?

David's wind tunnel testing has shown that of all the configurations he has tested, the bodywork with the lowest drag value was a result of the FRC body being optimized.

Which LPE car are you talking about? Another member referenced a C4 Lingenfelter/Callaway effort that went 254!!!

99C5JA1

This was the Lingenfelter C5. I was referencing the C/D numbers in the post. Here's a blurb from http://www.corvettefever.com/techart...odynamics.html

For the C5, we tested two different models. The first was a standard-edition Vette owned by Mark Connolly. The second was a Z06 owned by Tommy Megremis. Surprisingly, the baseline Corvette produced better aero numbers both in terms of drag and lift. Because it has a greater frontal area, the C5 Z06 actually has slightly more drag than a C4 Corvette. Much of this apparently comes from the Z06's redesigned nose. It contributed to more aero lift on the front end versus the standard model, while the Z06 had considerably less lift at the rear end.

All the C5 articles I read over the years have stated the coupe is more aerodynamic. Some from various GM engineers. Some of the Vette sites may still have these up. I wish I could give you some links, but it's been long enough I frankly don't remember. The FRC was developed as a lower cost option originally. The FRC was rated for less top speed from the factory (same gearing, etc). The C5R factory race cars choose the coupe shell, again for aerodynamics. Maybe someone at Katech or Pratt and Miller would share some numbers. Frankly I've read it so many times over the years, I'm surprised it's being discussed.

Pfadt Racing

Again, you have to look at specific purposes of vehicle builds. Downforce is must less of a concern for a top speed car. PME choosing the coupe for basis of their bodies does not translate into why a top speed car would chose a body.

The article quoted that the Z06 actually had better "aero" on the rear axle, and worse front lift. Now consider that David is not running at stock ride heights/pitch values, and results will change. It is entirely conceivable, that due to the better rear values, and differences in set up, plus the removal of factory mirrors, that David could optimize the FRC body in lieu of the coupe.

Again, a lot of people bring up this one article. But you have to consider different goals (judging in terms of what is "better"), as well as differences in baselines that may result in values from David's wind tunnel tests, not correlating with a single magazines tests. We are not lying to anyone. As David has the fastest top speed Corvette, I would say he did a bit of homework first to make sure he chose wisely.

PME numbers would have nothing relating to OEM bodywork.