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Track Test: 2008 Shelby GT-500KR

Story by Sam Haymart

We go beyond the headlines to see what makes this $79,995 Mustang tick.


05-01-08: The 2008 Shelby GT-500KR will be arriving soon to a dealer near you at a retail price of $79,995. The “King of the Road” is billed by Ford as the most powerful production Mustang ever with 540hp and 510 lb.ft. of torque from it’s revised 5.4 liter V8. Among the main things setting it apart from the rest are the unique Alcoa forged aluminum wheels, 1968 KR style snorkel hood, a host of carbon fiber add-ons, and of course the “KR” added to the stickers next to GT-500 on the front fenders. That’s what the headlines will say.

Headlines miss the point. One might ask, “You pay an extra 35-grand and all you get is an extra 40 horsepower?” Current Shelby GT-500 owners might already be patting themselves on the back having only spent $800-1000 to get well over 600hp with a pulley, cold-air-box, and a tune. Other automotive enthusiasts or casual observers might be writing off the GT-500KR as just one more special edition Shelby with a few visual tweaks, new graphics, and a mild software bump - hugely over-hyped and over-priced. That is the chatter, but like the headlines the point is missed.

TMN was invited to spend a couple of days behind the wheel of this ultimate Shelby in the mountain haven of Salt Lake City, Utah both around town and the closed course confines of Miller Motorsports Park. The goal? To see what truly sets this car apart from the garden variety Shelby GT-500. In the process of shredding tires, hitting rev-limiters and having a blast the big find is that what makes the GT-500KR special is far more than the sum of its parts. This car has a robust soul and a new set of limits that can only be communicated from behind the wheel.

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The first signal that things are different comes when you turn the key. The engine rumbles to life with a deeper and raspier tone than the base GT-500. You wonder if the sound level is street legal. A blip of the remapped drive-by-wire throttle sends the engine aflutter with a crisper urgency that makes shifting a game to play. As you shift into gear, you notice the delicate snick snick of a new short throw shifter mechanism that uses stiffer bushings and a shorter lever ratio. Before you even sample the extra 40 horsepower and 20 lb.ft. of torque, you know things have changed.

That extra power is transmitted to the ground with a more aggressive 3.73 axle ratio exclusive to the GT-500KR. It accelerates from 0-60 in 4.3 seconds, down from the GT-500’s 4.5. The quarter mile time is reduced over half a second to 12.1 from 12.8. The numbers while modestly improved only tell part of the story. The feel, responsiveness, and sound of the GT-500KR is where you really appreciate the improvements.

A revised exhaust system provides a significantly louder and sweeter resonance under full acceleration without giving a drone at cruising speed. Inside the car you get a pronounced growl that you feel as well as hear. On the outside you get a barking blast of vintage Ford racing bravado. A new X pipe design, 3” resonators, and revised mufflers were carefully massaged by SVT to give just the right sound only when you want it.

The engine is now breathing through a cold-air-box intake sealed snuggly to the bottom of the carbon fiber hood. It pulls outside air through the functional air inlets at the front of hood. Designed to match the 1968 Shelby GT-500 hood, this new generation design features a three-layer sandwich of carbon fiber panels to provide an integrated duct system that supplies fresh air to the filter box. The air extractor vents mounted further back on the hood are fully-functional as well, drawing heated air out of the engine compartment. No fakery here.

SVT engineers shared that this hood is likely one of the single most expensive components on this car. They created this high tech, eleven pound wonder to give the look and functionality of the 1968 design while providing a fit and finish expected in a car of this caliber. This is no ill-fitting or warping fiberglass Shelby hood from the 1960’s. There are diversion channels within the layers of carbon fiber that direct rain or carwash water away from the engine as well. Specially designed twist lock hood-pins have universal joints in them to assure proper alignment and action every time.

“This is our first-ever production application of carbon fiber, and it is fitting that we developed it with Shelby Automobiles,” said Ford SVT chief program engineer Jamal Hameedi. “It’s there purely for performance. It brings important aerodynamic and weight-reduction benefits that translate to enhanced performance for our new King of the Road”.

The wind tunnel has been a major part of the KR development. The carbon fiber air-splitter and unique rear-deck spoiler weren’t just styled and bolted onto the GT-500KR. The combination was strategically engineered to provide more frontal down force and less rear down force than with the standard GT-500. This moves the down force “center” further forward. At speed this adds a stability and balance that this new beast will truly be known for 20 years from now.

“You have to experience the new KR at speed in a curve to feel the difference,” said John Pfeiffer, SVT product design engineering specialist. “It has an absolutely minimal areo moment of just 54lb. Ft. at 120 mph, a 92 percent improvement versus the GT-500. That is central to its confident handling ability. Because it’s just as happy at 120 as it is at 60, the GT-500KR is a very special performance car”.

The balance in the new suspension is where the big story of the GT-500KR is really found. The handling of the standard GT-500 has been much maligned by the press and owners alike for being soft, wallowesque, and far beneath the expectations of a 500hp supercar. Rather than just bolt a suspension kit from the Ford Racing catalogue to the GT-500KR, SVT spent a year in development with a more holistic approach.

While the hardware is little changed, the tuning and tires have made the day. SVT started with a new generation of the 18” Goodyear F1 high-performance tires which will be exclusive to the GT-500KR. With a significantly softer compound and higher adhesion level, they tuned the suspension around this new tire by revising the shock valve rates and roll-bar stiffness. The result is a blistering 1G on the skid-pad while keeping a cruising ride virtually identical to the standard car. Spring rates increase 17% in the front and 7% at the rear.

Balance was a major goal so in some cases stiffness was reduced where it meant better performance. “We reduced the diameter of the rear sway bar for just the right grip under power coming out of a corner, “ said Kerry Baldori, SVT chief vehicle engineer. “That is just one example of the amount of tuning that went into engineering the KR chassis”.

On a drive up some of Utah’s windy mountain roads over rail-road tracks and expansion joints we found the GT-500KR offers a day to day driving refinement that is honestly on par with many German sport sedans. There is no jarring, no pounding, and no harsh noise. It’s no softie however. On the track the inner demons are unleashed. The aggressive tire compound does need a lap to warm up, but once maximum adhesion temperature is achieved put on your eyeball straps because this thing drives like a glue-stick.

The new tires in concert with the revised suspension allow you to push this car all the way to the limits without any surprises. Body roll is reduced significantly. There is no more squirming or bobbing while cornering and there is no more confidence shattering buoyancy in transitions. What you do get is a progressive message of grip and balance as you increase your cornering speed. The tires make their noise but this baby isn’t gonna just let go without warning and launch you into the wall. Instead you get predictable and linear feedback that even a novice driver can relate to.

Put a professional road-warrior behind the wheel and you see a car that is as easy to drift control as they come. This is said because after a day of driving this car at white-knuckle speeds and feeling the love, we were taken on a shot-gun ride with the SVT suspension engineers themselves. They were able to truly demonstrate limits that were far beyond where we had taken it. The increase of grip, braking and power that the GT-500KR has within was most evident. This thing performs in ways that no price-tag or horsepower numbers can convey. When driven back-to-back with a standard GT-500, there is purely no comparison.

Braking of course is a huge part of the equation. Revised ABS software and functional brake cooling ducts from the Ford Racing catalogue combine to reduce stopping distance and brake fade under hard driving. Stopping distance from 60mph on the GT-500KR is reduced to 109 feet from 112. On the track there was no perceptible fade and the big brakes could be hammered hard at the end of straights and trail-braked without a single interruption from the ABS system. Because brake cooling ducts are very purpose oriented, they come boxed in the trunk and are an optional install of the owners.

There is more. In testing, they found that the high G-loads had produced a lot of differential fluid blow through at the rear axle vent. In normal situations, differential lubricant is allowed to slosh around in the rear axle assembly without issue. A vent cap allows pressure to be released when temperatures vary. In high speed G-intense cornering tests, it was found that the fluid wanted to escape, so they added an expansion tank connected with a flexible line just above the axle. A small touch, but further evidence that this car was built with a purpose in mind.

SVT has had a significant part in the development of the GT-500KR, though the common perception in enthusiast circles is that the Ford Skunkworks has been long gone. Nothing is further from the truth, the elite staff has brought this car to market in partnership with Ford Racing and Shelby Automobiles in less than half the time it takes to develop a new model. So to be fair, a good part of that $35,000 price bump comes from the year-long proving, research, and development bill from SVT which has to be divided into only 1746 cars. 1000 GT-500KR’s will be built for the 2008 model year, and only 746 for the 2009 model run.

The GT-500KR also differs from the standard GT-500 Mustangs in that it’s up-fitted by hand with all the go-fast goods at Shelby Automobiles in Las Vegas, NV. A process we wrote about a couple weeks ago when we toured the production facility, specially prepared batches of GT-500’s leave the line at Flat Rock, Michigan and then get shipped out west to Carroll Shelby himself for the final blessing of heart and soul. You are buying a genuine hand-stamped Shelby, and honestly that is another part of that price tag.

There will be a lot of talk about the new GT-500KR. Forums will be abuzz about how you can just buy a $300 pulley and blow this car away. There will be those who say it’s just another over-priced opportunity for dealers to rape and pillage with addendums - a car for the rich collector who will never drive it. The mainstream automotive press will likely write it off as a throwback to another time in a world that has gone smartly green or that for the same money you can buy a sophisticated BMW M5.

Given a chance however to drive the car at its limits on a race track it’s impossible not to come away with a different perspective on the GT-500KR. This thing rocks like Amadeus! It’s a Shelby in soul, an engineered wonder of SVT and a testament to Ford Racing‘s involvement in the development process. This car is at the top of the American Pony Car class and with even with Camaro and Challenger coming, that is unlikely to change. While those cars are looking impressive, Chrysler nor GM have the race engineering apparatus or the Mustang's gravitas to build on.

And did I mention fun as hell to drive? At the end of the day, you don’t buy this car because it's a Consumer Reports Best Buy. You don’t buy it because Edmunds says it's a good value. You don’t buy this car because it has Starbucks cache - though it will surely make even the snobbiest latte ladlers stop and question the coolness of their Prius.

You buy this car because it turns you on. And to that end, they will sell every one of the 1746 GT-500KR’s to some very turned on people whatever the price may be.

 
 
 

Additional Photos:

Carbon fiber hood features integrated ducts to channel cold-air to the sealed air intake box and also draw out heated engine compartment through top-mounted extrator vents.

Snow capped mountains provide backdrop to the Miller Motorsports Park in Tooele, UT.

Some of the unique parts to the Shelby GT-500KR include a Ford Racing cold-air box, differential fluid expansion tank, front brake cooling ducts, short throw shifter, specially valved shocks and carbon-fibert air splitter.

 

 
 
 
     
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