Reason for the C5 ass end? Answer inside...

1437 Views 13 Replies 9 Participants Last post by 1fastdog, Apr 18, 2001

N4C5S

Discussion Starter · Apr 17, 2001

I saw this in another thread and thought I'd repeat it for everyone's benefit. I know alot of you already know this information, so forgive me for repeating....

The reason for the ass end of the vette is simple, and one I've heard repeated over and over. Mostly in articles from the engineers and wind tunnel guys.

Actually if you remember Cafaro's black car didn't have this abrubt 90 degree angle in the rear, and that's not the way he wanted it. However one of the critical goals that had to be met for the C5 was its aerodynamic slipperiness. To make a long story short, the wind tunnel and aero guys won this battle, you see, (I'm not an aero expert, just repeating) in order for a car (or any object) to demonstrate effective tunnel numbers air must cleanly enter the flow in the front of the car, travel relatively unimpeded over the surface, then make a clean exit off the rear.

This 90 degree angle was needed to reduce eddies and other stray currents when the airflow exited off the rear facia.

Short answer? Don't change your rear facia, unless it meets these requirements. And even then, ask for aero numbers...Unless you're all show and no go...or just want more flash than dash. /phpBB/images/smiles/icon_smile.gif

Feel free to step in and post your comments...or corrections....

The above information was gleaned from a taped interview I saw once with a GM engineer and from All Corvettes Are Red...

JC

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1fastdog

· #7 · Apr 17, 2001

On 2001-04-16 23:48, N4C5S posted this:

Short answer? Don't change your rear facia, unless it meets these requirements. And even then, ask for aero numbers...Unless you're all show and no go...or just want more flash than dash. /phpBB/images/smiles/icon_smile.gif

Feel free to step in and post your comments...or corrections....

The above information was gleaned from a taped interview I saw once with a GM engineer and from All Corvettes Are Red...

JC

I went with the GM Racing rear spoiler. More downforce above 90mph. It's the piece many of the hardtop teams have been running in World Challenge. I'm not going roadracing all that often, but it's a look with functionality I wanted.

Spectre's rear facia is to a great degree a similar profile but as it's a complete facia, therefore "built in" looking. Their's has a tad bit less overall area as the far left and right ends taper into the car more.

I believe wider tires are going to add more forward resistance to be overcome than a subtle tail flip.

Your point is well taken and agrees with my thought that every mod has a plus and some additional compromise. I weigh the balance and you can believe I'm really particular about what goes on my 'vette.

I researched this one pretty well with folks that have a better than average understanding of the car. I think I have a better than average understanding of the C5 as well, but that's another story.

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1fastdog

· #14 · Apr 18, 2001

On 2001-04-17 20:54, John Thawley wrote:

No..... the design comes from years of racing experience. If we tunneled that thing we'd have to charge twice as much as we do.

This is not rocket science. Really. The back end is too slippery at high speed. It needs a spoiler. Look at the World Challenge cars.... they run the GM Motosports aero package. I don't think they are running it because it simply looks good. Especially considering their spoiler goes on with two way tape!!! /phpBB/images/smiles/icon_biggrin.gif /phpBB/images/smiles/icon_biggrin.gif

The profile on your <John's > piece is quite similar to Racing's approved piece. The double sided tape comment is exactly right.

The latest WC rules allow for a similar wing approach that is reminiscent of the C5R piece. It does not translate well to a street car to my taste. I feel the hardtop looks a bit silly with a bonafide wing on the deck... to each his own.

John's piece is very integrated looking. The spoiler I am running is what it is... a racing piece. I'm an old roadracer. It looks just dandy to me and settles the rear nicely.

Both GM's and Spectre's look like they belong on the car to me.

I realize it's all a matter of taste, but for me the car looks better with a slight upturn at the rear. I'm just happy the look is good for me and the function is pleasing on two fronts.

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