Aerodynamics

[BUD]

On my 98RT I have a factory hard top, factory spoiler and a Venom front air dam. After all this should I be just as aerodynamic as a stock GTS?

 

[Tom and Vipers]

When you say "as aerodynamic" you might want to be more specific.

The 2 major issues are downforce -v- drag.

You could have very low drag with now downforce which would be very dangerous if you ever wanted to take advantage of your drag coefficient.

Other than this comment, I have no idea how your car would compare to a GTS.

Others may.

Good luck
Tom

 

[Paul Fischer]

No. The airdam alone will change the entire configuration. You'll notice that's the first piece that's pulled when HMS takes a car to the strip, the rear wing comes off too. My car hit a wall around 170 once the aero was tacked on (though it really stuck to the ground with wing, splitter and lowering). Getting into a stock bodied car at the track after getting out of mine was an eye opener, they pulled much stronger above 120.

The shape of the cockpit greenhouse is quite different between the GTS and a hardtopped RT as well. If anyone has done a tunnel test for coefficients please post.

You are trading forward energy for downforce with aero, there is no free lunch. I remember a slab sided NASCAR outrunning a 917 in a magazine article, the difference was the Porsche was shaped to stick in corners and the stock car wasn't, there was a 20 mph+ difference in top speed.

 

[jrkermode]

Its pretty easy to mess about with a car's Cd, most notably by folding the mirrors and altering the car's rake, so be skeptical about the second digit in a Cd number. That said, here are some numbers for stock Vipers:

RT/10: .45/.52 (top up/top down)
SRT10: .40/.43 (top up/top down)
GTS: .35

Common aero mods, such as you have made, are aimed at increasing downforce, not reducing drag, meaning you made your Cd worse, not better.

 

[Paul Fischer]

Makes me wonder what the CD of the production SRT hardtop will be. Thanks jrkermode.

 

[joe117]

How about some kind of covering for the underside of the car to make for smooth flow? Cover up all the open spaces on the underside.

 

[Paolo Castellano]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by joe117:
How about some kind of covering for the underside of the car to make for smooth flow? Cover up all the open spaces on the underside.

<HR></BLOCKQUOTE>

I know Ron Adee made an undertray for the car and he said the car ran too hot in the summer from what I remember. Paolo

 

[jrkermode]

An undertray is a very expensive and complicated mod with little performance benefit. Most of the drag on a modern car is simply the hole it leaves in the air as it passes through (base pressure). So, unless you're prepared cut-up the car, you're basically stuck with what you have.

Perhaps the best you could ever do with a stockish Viper is to remove the windshield from an RT and fit a tonneau around the driver.

 

[Lee00blacksilverGTS]

Jrkermode...those are interesting numbers, and the first time I've seen them quoted, what's your source?

 

[joe117]

If you took off the stock windshield and replaced it with a small wind deflector in front of the driver, then put a metal tonneau around the driver, the car would look like an old D Jaguar from the early 60's. That would be cool, I always liked them. Of course you would need the fin behind the driver.

 

[jrkermode]

Lee,

No single source, rather a sort of average from numerous publications and web sites. In any single source you'll likely find a different number. Little things like ride height and rake can change the number .01 or .02, so differences of that magnitude aren't really significant.

 

[BUD]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by jrkermode:
Its pretty easy to mess about with a car's Cd, most notably by folding the mirrors and altering the car's rake, so be skeptical about the second digit in a Cd number. That said, here are some numbers for stock Vipers:

RT/10: .45/.52 (top up/top down)
SRT10: .40/.43 (top up/top down)
GTS: .35

Common aero mods, such as you have made, are aimed at increasing downforce, not reducing drag, meaning you made your Cd worse, not better.

<HR></BLOCKQUOTE>Thanks everyone for the great answers! I am still glad I did it for the looks as I don't road race, only street play.