C5 Coupe Acceleration, W/ Top vs. Topless!!
Thread Starter
Melting Slicks
Joined: Sep 2005
Posts: 2,521
Likes: 146
From: Watertown CT
C5 Coupe Acceleration, W/ Top vs. Topless!!
OK here it is, I don't know how many of you saw my other post with the S4 vs. the modded C5 coupe but in a nut shell, out on the track, I had my top off, did a 70 to 140 pull against a 05 or 06 S4 and was pretty disapointed that I only beat him by a few car lengths. I and others seem to think that the top off is the big difference. SO this weekend I am going to go out on the track, with the top on, run a 70 to 140 mph pull and time it. I will go to the same spot on the track with the top off and do the same 70 to 140 mph run and time it. I want to see the time difference in acceleration. My guess is there will be a 2.3 second difference. The car in question is an 01 M6 with a cam, long tubes, high flow cats, x-pipe, 6" GHL's, underdrive pulleys, smooth coupler, black wing intake, MSD wires and dynoed 375 at the wheels. Lets see what you guys have for guesses. I will keep you all informed!!
Thanks, Dan 
Thanks, Dan
Race Director
Joined: Sep 2004
Posts: 17,786
Likes: 4
From: Redsox, Pats, Celts & Bruins !!! Redsox Nation !!!
St. Jude Donor '06-'07-'08-'09-'10-'11-'12
I would say the wind in the hatch slowed you down. The car is now not aerodynamic. Interested to see your results.
Thread Starter
Melting Slicks
Joined: Sep 2005
Posts: 2,521
Likes: 146
From: Watertown CT
Originally Posted by Dirty Howie
I would hope we would be much faster than an S4......
Are you sure he just wasn't getting better exit speed out of the turn before the straight???
DH
Are you sure he just wasn't getting better exit speed out of the turn before the straight???
DH
So i want to check that theory by actually timing it!! If this turns out to be the case that will be the last time my top comes off the car!!!
Thanks, Dan
Pro
Joined: Oct 2004
Posts: 514
Likes: 2
Originally Posted by SpeedyD
OK here it is, I don't know how many of you saw my other post with the S4 vs. the modded C5 coupe but in a nut shell, out on the track, I had my top off, did a 70 to 140 pull against a 05 or 06 S4 and was pretty disapointed that I only beat him by a few car lengths. I and others seem to think that the top off is the big difference. SO this weekend I am going to go out on the track, with the top on, run a 70 to 140 mph pull and time it. I will go to the same spot on the track with the top off and do the same 70 to 140 mph run and time it. I want to see the time difference in acceleration. My guess is there will be a 2.3 second difference. The car in question is an 01 M6 with a cam, long tubes, high flow cats, x-pipe, 6" GHL's, underdrive pulleys, smooth coupler, black wing intake, MSD wires and dynoed 375 at the wheels. Lets see what you guys have for guesses. I will keep you all informed!! Thanks, Dan
Thanks, Dan 
Instructor
Joined: May 2006
Posts: 244
Likes: 1
From: Paris, France
...
the all new S4 is 420 hp rated (V8), here in europe...
(just seen a review in a magazine)
Medias here say that's the new s4 can hang porsche and ferraries.
Never seen it on the road for the moment...
as for the top... : less weight but less aerodynamic.
My 2 cents : you're faster with the top
(just seen a review in a magazine)
Medias here say that's the new s4 can hang porsche and ferraries.
Never seen it on the road for the moment...
as for the top... : less weight but less aerodynamic.
My 2 cents : you're faster with the top
Thread Starter
Melting Slicks
Joined: Sep 2005
Posts: 2,521
Likes: 146
From: Watertown CT
Originally Posted by Brice
the all new S4 is 420 hp rated (V8), here in europe...
(just seen a review in a magazine)
Medias here say that's the new s4 can hang porsche and ferraries.
Never seen it on the road for the moment...
as for the top... : less weight but less aerodynamic.
My 2 cents : you're faster with the top
(just seen a review in a magazine)
Medias here say that's the new s4 can hang porsche and ferraries.
Never seen it on the road for the moment...
as for the top... : less weight but less aerodynamic.
My 2 cents : you're faster with the top
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Instructor
Joined: Dec 2003
Posts: 107
Likes: 0
From: Baltimore MD
Originally Posted by SpeedyD
Over 200 people look but there is only one guess!?!?!? What's up with that!!! No one is curious, how many of you own coupes?
Burning Brakes
Joined: Aug 2004
Posts: 783
Likes: 0
From: Phoenix Arizona
Top Off Top On
You will do much better with the Top on and I would guess 2.5 seconds. I have read hundreds of threads where a c5 out accelerated a higher horse powered car, because of it design. Take the top off and it is no longer aerodynamic, thereby losing one of its major advantages.
Would like to see the results.
Would like to see the results.
Team Owner
Joined: May 2004
Posts: 26,345
Likes: 232
From: SoCal
Originally Posted by SpeedyD
Over 200 people look but there is only one guess!?!?!? What's up with that!!! No one is curious, how many of you own coupes?
......there's probably a good reason for this
If rules allowed ...... keeping the windows up would also be better.
DH
Burning Brakes
Joined: Feb 2006
Posts: 899
Likes: 2
From: Ex BX... Ex NJ... Hello CT!!! CT
Were the sun visors "up" or "down"?!?!? 
Okay, how about trying to time it with the top off and the rear hatch propped open with "Ventmasters" spacers installed.
Seriously though..... I've found the acceleration seems to me, to be worse with the windows open, than with the top off....
Okay, how about trying to time it with the top off and the rear hatch propped open with "Ventmasters" spacers installed.
Seriously though..... I've found the acceleration seems to me, to be worse with the windows open, than with the top off....
Thread Starter
Melting Slicks
Joined: Sep 2005
Posts: 2,521
Likes: 146
From: Watertown CT
Sorry Guys, I wasn't able to go out and run this weekend, the weather really put a damper on evrything!! The rain up here has been terrible and I can't seem to catch a break, hopefully next weekend!!!
Burning Brakes
Joined: Jun 2006
Posts: 866
Likes: 0
From: Placerville Ca
Well, I'll bite.
Sure there is areodynamic drag at 100 mph, but appreciable wind resistance doesn't come into play until the race is past half over and 100 mph is just entering the area where it's a consideration. Your under constant acceleration the hp to overcome the difference in air resistance (top up/down) isn't going to materially affect your et. So, my guess is .030 slower with top down.
However your gas mileage with the top down will be awful... lol
Sure there is areodynamic drag at 100 mph, but appreciable wind resistance doesn't come into play until the race is past half over and 100 mph is just entering the area where it's a consideration. Your under constant acceleration the hp to overcome the difference in air resistance (top up/down) isn't going to materially affect your et. So, my guess is .030 slower with top down.
However your gas mileage with the top down will be awful... lol
