areodynamics
Race Director
Joined: Aug 2003
Posts: 16,270
Likes: 30
From: "It's 106 miles to Chicago, we've got a full tank of gas, half a pack of cigarettes, it's dark, and
St. Jude Donor '03-'04-'05-'06-'07-'08-'09-'10-'11-'12-'13-'14-'15-'16-'17-‘18-'19
NCM Sinkhole Donor
Obviously the back window and rear deck....what can you do about it?
You can either enjoy what you have and not worry about it or sell your car and buy a coupe.
You can either enjoy what you have and not worry about it or sell your car and buy a coupe.
Instructor
Joined: Jul 2004
Posts: 177
Likes: 0
From: Tampa FL
Any car without wings isn't going to generate much downforce though. Why do you care?
Race Director
Joined: Mar 2005
Posts: 14,440
Likes: 3
From: MD
St. Jude Donor '11
As someone else stated the roof line and longer rear deck gives the FRC a higher coeficient of drag. However, if I remember correctly, GM stated that the top speed of the FRC/convertible is only 5mph slower than the coupe. In everyday driving, you should not even notice. So what your car can only go 170mph...I wouldn't sweat it.
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Le Mans Master
Joined: Aug 2001
Posts: 6,725
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From: Colesville MD
Tech Contributor
Joined: Dec 2003
Posts: 19,384
Likes: 87
From: Horncastle Lincolnshire, England
2023 C5 of the Year Finalist - Unmodified
I hadn't realised the CD was different.
My guess would be that the steeper pitch of the rear window will cause the boundary layer to break away causing vortices and disturbed air. The airflow over the more "cigar" shaped rear of the coupe will cause less drag.
My guess would be that the steeper pitch of the rear window will cause the boundary layer to break away causing vortices and disturbed air. The airflow over the more "cigar" shaped rear of the coupe will cause less drag.
Team Owner
Joined: Jan 2002
Posts: 23,234
Likes: 4
From: All that glitters is Gold - Hockey Is CANADA'S game
Cruise-In VI Veteran
Cruise-In VII Veteran
St. Jude Donor '05-'06
Coupe is faster than the Z06 but Z06 is quicker
Safety Car
Joined: Jun 2006
Posts: 3,787
Likes: 2
From: Wildomar CA
it is caused by the downforce, but the handling at higher speeds is also improve slightly by this. Most track cars are more concerned with handling and downforce, than top speed.
Just keep modifying your car until it is redline limited. Then it won't matter whether you have a coupe or frc because they will both top out at the same.
Just keep modifying your car until it is redline limited. Then it won't matter whether you have a coupe or frc because they will both top out at the same.
Burning Brakes
Joined: Apr 2006
Posts: 940
Likes: 0
From: Surprise Arizona
The contours of the rear hatch lid produces less trailing vortices than the FRC does. As someone else pointed out, the differences are so minimal as to have no consequence in normal driving - even at interstate speeds. 
Drifting
Joined: Jan 2005
Posts: 1,496
Likes: 28
From: San Dimas Ca.
Yep if you put 4:88 gears or something in your FRC or Coupe then you will both top out or redline at say 125. No need for slick aerodynamics. For some reason the C-5R and the C-6Z and R are all Coupes.
Rick
Rick
Safety Car
Joined: Jun 2006
Posts: 3,787
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From: Wildomar CA
