[N4C5S]

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

 

[Redshift]

Same as what I heard and read. But I've got you FRC and Z06 guys beat with my slippery 0.29 Cd, whereas you have a paltry 0.31 (I believe that is right). Good thing you have better gearing and more power to get you there faster? /phpBB/images/smiles/icon_smile.gif

 

[fcalmes]

On 2001-04-16 23:56, Redshift spewed forth this drivel:
But I've got you FRC and Z06 guys beat with my slippery 0.29 Cd, whereas you have a paltry 0.31

You'll still get your ass thumped!! /phpBB/images/smiles/icon_biggrin.gif

 

[Redshift]

Sure I will, but I'll have fun getting whipped. Can't blame a guy for trying. I'll take my roof off so I can enjoy some sunshine and breeze while getting whipped, too /phpBB/images/smiles/icon_razz.gif

 

[JZ]

Great idea!! (the roof off), you will really get to hear that Ti Exhaust better as it blows by you !! (hehe) /phpBB/images/smiles/icon_biggrin.gif /phpBB/images/smiles/icon_biggrin.gif /phpBB/images/smiles/icon_biggrin.gif

I Love my Z!! /phpBB/images/smiles/icon_biggrin.gif /phpBB/images/smiles/icon_cool.gif

 

[Redshift]

What did you say? I couldn't hear you over my CD changer. /phpBB/images/smiles/icon_biggrin.gif

Touche'!

 

[1fastdog]

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.

 

[hcvone]

Redshift, I will have you covered in a few months, CD changer, convertible and most important Z06 power and then some. /phpBB/images/smiles/icon_biggrin.gif

 

[Redshift]

Carl, I know - but my funds run out well before yours /phpBB/images/smiles/icon_wink.gif

I will, like the rest of the folks here, drool and dream. /phpBB/images/smiles/icon_smile.gif

 

[John Thawley]

On 2001-04-16 23:48, N4C5S spewed forth this drivel:
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

Partially correct. I believe the real winners of the battle was the MARKETING people. They want to be able to BOAST of the lowest drag of any production car on the road.

Hence, all the World Challenge guys run the stick-on spoiler because the car is so freaking squirrely at high speed.

In performance handling there is no ONE answer. It is always a question of balance. Balancing the handling is the key. Wind tunnel is only one factor. Just like weight is only one factor and horsepower is only one factor.

Obviously, if you stuck a C5R wing on the back of your car you'd probably have a blow-over. /phpBB/images/smiles/icon_biggrin.gif /phpBB/images/smiles/icon_biggrin.gif And, you're probably not "cruising" at an average of 185mph either. The point is, between the front splitter and the wing, they are able to establish the "balance" they need to make the car handle.

Regarding the stock C5's low drag number.... what percent of the time does it really effect the handling of the majority of the average C5 driver? Probably .001% of any given Sunday? /phpBB/images/smiles/icon_smile.gif

 

[c5xdup]

John T,

Are there any down force numbers available for your rear facia? I'm in the market for some functional pieces (front and rear).

John

 

[CorvetteSS]

All I can say is the Spectre Werkes fascia may add a bit of drag, but it looks damn good. Since I stay below 170 mph most of the time, I'll take the show rather than the go for this mod.

 

[John Thawley]

On 2001-04-17 11:46, c5xdup spewed forth this drivel:
John T,

Are there any down force numbers available for your rear facia? I'm in the market for some functional pieces (front and rear).

John

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

But, our design is for the street. And as Corvette SS said...... it looks awfully good!

 

[1fastdog]

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.