http://www.autoblog.com/2010/08/04/v...-shelby-gt500/

 

notice the mph is higher on the GT500 in the quarter? That means either a traction or driver issue with it.. The much larger engine in the Caddie should have creamed the Ford..

 

For the average person, the CTS-V Coupe auto will be faster. Probably same with the upcoming Z28. Traction with the Shelby IS the issue. It really sux that I have to either widen the stock rims or buy new rims to fit a decent width tire on the back. A 9.5in wide rim on a car like this is a joke. Sometimes I wonder if the Ford engineers want to hinder the Shelby's performance.

It doesn't take an engineering genius to figure out a 285 tire on a heavy car with 550HP doesn't make sense. God forbid I want to add more power.

 

The much larger engine only contributes to the higher torque numbers and better under the curve power. Both are tuned to almost identical power levels so engine size is irrelevant aside from that. It probably would have creamed it if they weighed the same but the added weight eroded some of the tq and curve advantages. I saw that in the video where the CTS made most of it's ground after gear changes.

 

I actually like the sedan better than the coupe.

 

I like them both(partial to the stang of course), but the ZR-1 motor that Caddy has, is incredible!!!!!

 

This is a common misconception, wider tires dont really do squat in a drag race on a street tire - the contact patch doesn't change compared to a narrower tire, it just changes the bias. A taller tire would do much better in that regard. Also the 9.5" rim width takes into consideration other engineering elements that constrain the car (remember the GT500 is based on the same lowly V6 that makes the GT and GT500 possible).

Contact patch = weight x pressure. Adding weight to increase the contact patch is obviously a no-go and unfortunately lowering the pressure is only so effective on a radial. Go down to far and it will buckle the tread further reducing the contact patch (when the ground is wet with standing water, a tire that is as little as 15-20% under inflated - 6 to 7 psi in most cases - will exhibit the same thing).

Not quite, the LSA uses cast pistons

 

And is an assembly line engine with smaller blower and intercooler. I'd love to stick one in the GTO for a daily driver though .

 

Yeah, can't argue with the results.

 

So you're saying a 2011 GT500 SVT Packaged car with widened stock rear wheels and (if they made them)325/30R-20 Goodyear Eagle F1 SuperCar G2s wouldn't do any better in a street race than the same car with the stock 9.5 wide wheel and 285/35R-20 Goodyear Eagle F1 SuperCar G2s? Just for clarification.

 

Thats what I'm saying, just hanging a wider tire on the car wont really do squat for traction. Hanging a taller tire on the rear will actually provide more traction under straight ahead acceleration (all things being equal)

A Bridgestone guy once showed me a pretty simple way to visualize this; Take a piece of paper 8.5 x 11, fold it length wise and width wise - which makes it about 4.25 x 5.5 and thats about the size of the contact patch holding most cars down on the road (roughly), he then held the piece of paper up so that the long part was verticle and rotated the piece of folded paper 90 degrees and said "Thats the difference between a passenger tire and a performance tire - the contact patch doesn't really change, just the bias"

The explanation is a bit simplistic, but it illustrates the basic premise. The difference comes in during a dynaimc state when you can increase the amount of weight on the tire (remeber weight x pressure = contact patch). The patch will get bigger under weight transfer, but once that weight transfer is minimized or eliminated that bigger tires isn't doing anything a smaller tire can do.

 

Gotcha So going to an 18 with more sidewall out back would provide more straight line traction, but I'd have to give up the look of the SVT PP 20. So you think widening the 20 to accommodate a 305 or 315 wouldn't really be worth it? Just trying to get ideas. I want to have the best traction I can in a street car without driving on slicks.

 

Single biggest problem with the Shelby is too much weight on the nose. Horrible for both a drag race and driving dynamics. I think if Ford wants to make a true supercar out of the Mustang use the smaller engine with a strong bottom end and blower and find ways to take weight off the front end. Perhaps shifting the wheels 2" forward, lightweight hood, lighter K-member, lowering the engine and shifting it back 2", relocating the cooling system, etc.

 

It can be done, but IMO Ford won't do it because the price wouldn't be worth it. Some of those ideas would result in something quite similar to the Corvette Z06...

 

Well they've probably gone as far as they are willing to go with that until the new model comes out.

I dont think they are interested in that, despite how people might see it, The GT500 is nothing more than a showboat, a halo model for Mustang, its the brand on an overdose of steriods. Not that its a bad thing, even with the iron block mill in my car, its a very entertaining car.

Of the things you've suggested only the hood and the k-member are easily feasible - the hood is already aluminum and the only thing I can think of that would lighter would be carbon fiber hood which would add some serious cost.

The k-member itself probably isn't worth replacing, its no where near the size and weight of the one employed in the previous chassis - apparently replacing the bulky motor mounts employed by the current car make an S-197 aftermarket k-member a good purchase (but would Ford do that given a possible increase in NVH)

Extending the wheelbase would require a significant reengineering of the chassis as well as certifying its crash worthiness again, also if one were to use the Camaro as an example, when they extended the wheelbase on that car over the G8 it added around 35-40 pounds of metal to maintain an acceptable level of rigidity in the chassis.

If Ford moved the cooling system (the Porsche 911 and Ferrari Testerossa being classic examples of cars where the cooling system was moved amidship, both for better weight distribution and better polar moment of inertia) it would require an extensive rework of the car, so much so that Ford might as well move the GT500 onto its own chassis (would it really be a GT500 anymore????? since it would no longer really be a Mustang).

If Ford wants to get back into the actual supercar business, they would be better served by creating a 3rd Gen GT40 - a vehicle that wouldn't be constrained by have to be based on a 20k "secretaries car".

 

what about the weight of these 2??

 

4222-4255 lbs for the CTS-V and 3820 lbs for the GT500

 

A caddy keeping up is impressive but does it handle well as in responsive to the road