I know many people on both sides are going to hate me for this one. But too bad because I am bringing you the straight facts and am drawing logical and obvious conclusions from these facts. I have seen so much arguing about RWHP numbers and ¼ mile time for both these cars that I had to add my two cents. Now, I will say this from the beginning, I am comparing STOCK cars here. Don’t come to me and say, "but this car does this with this mod",etc because it is completely out of the scope of this article.
I am using the same year for both cars (2003) and I have gone through the Dynoperformance data base and averaged all of our runs for both cars. Here are the results (FWHP - Fly Wheel Horsepower uses 15% DT loss).
Ford Mustang Cobra: 360 RWHP = 424 FWHP (factory spec 390)
Chevrolet Corvette Z06 345 RWHP = 406 FWHP (factory spec 405)
Now some of you will notice that the Z06 numbers are right on the money with what the manufacturer claims and the Cobra numbers are much higher. There has been a lot of debate about Ford underrating this car because of past power rating issues. This is NOT the purpose of this article. These are straight RWHP numbers, and in my opinion are the only ones that count. You can say but you should really use this Drivetrain loss for this car and this one for that car, but at the end of the day the RWHP number tells you what the car is putting down to the pavement. And at the end of the day, the Cobra puts down 15 more RWHP than the Z06. End of story.
That takes care of the power issue. Now what about the ¼ mile issue. The manufacturers claim the following:
Cobra = 13.1 sec. (3665 lbs curb weight)
Z06 = 12.4 sec. (3118 lbs curb weight)
An interesting note is that SVT does not provide performance numbers anymore. They leave it to the car magazines. So the “manufacturer’s” number above is an average of the published results I have seen from industry articles.
From our data base and track-side notes, we have seen these cars run in the following range (these numbers are from experienced drivers who frequently do ¼ mile runs):
Cobra = 12.7 – 13.3 sec.
Z06 = 12.2 – 12.5 sec.
The conclusion is that, despite the 03 Cobra putting down 15 more RWHP than the Z06, the vette beats it by about 0.5 sec in the 1/4 mile. As you may have guessed, it is the Cobra’s weight (and drag coefficient) that is killing it on the track. The 15 RWHP is not enough to overcome the 550 lb weight difference. The 550 extra pounds is in fact so much more that the 50 extra TRQ that the Cobra has at 3000 rpm (see graph) can’t even overcome it. Weight and drag are two aspects that are frequently forgotten and this comparison shows how important they are. The Cobra would need roughly an additional 50 HP to overcome this loss in a1/4 mile test.
Bottom line: Cobra outputs more power, Z06 is faster. Done.