5.0 Mustang & Super Fords
Testing the 2000 Mustang Cobra R
Driving The Wheels Off The Fastest Mustang Cobra Ever
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At 155 mph, just after I upshifted into Fifth, the wind flowing around the Cobra R's A-pillars suddenly took on a nasty, rumbling howl as it separated off the side windows--but that's all. The steering remained unwavering, the chop set up by the cracked, desert-baked heaves passing for pavement remained noticeable but unaggressive, and my right foot stayed on the floor. One hundred sixty miles per hour. One hundred sixty five and still pulling--amazing. One sixty-eight--laying down now, as the atmosphere inevitably has its way, but still some urge remaining. Two hands on the wheel, but one would do even over these bumps. I steal a last glance at the speedo--its needle nearly square on the 170 bug.
Thrilling as it is, I've learned what I needed to know. I breathe the engine down to 150 mph and linger there for several luxurious moments. What a pleasant cruising speed this is--the wind murmuring, the exhaust fluently singing its performance chord, tires rumbling over the pebbly pavement, and the nose responding now to a relaxed one-handed guiding. A mile blurs by. This is friend-to-friend motoring--a machine crafted by pro enthusiasts for their enthusiastic compatriots on the outside. No matter that money must change hands, or those friends may never be seen or even identified by name. This one is for us.
Ford's Special Vehicle Engineering and Special Vehicle Team get together only rarely to build R-model Mustang Cobras. SVT designed these specials to homologate a competitive package to various racing classes, and has produced but 657 of them, all told, since the first one in 1993.
Like three beautiful sisters, the R-models share compelling family traits, yet each remains uniquely individualistic. The first 107 '93 Rs are the rarest and most basic of the breed. They introduced the GT-40 engine parts to the 5.0 production line, along with the first serious brakes. Then came the '95 R, a voluptuous wonder bulging with 5.8 liters of Windsor muscle. Now the athletic 2000 Cobra R has brought 385 hp worth of 5.4L, super-tuned DOHC, Four-Valve, modular muscle to the family, along with a wholly unknown poise and sophistication. This is truly a class act, and Ford's first exotic car since the Total Performance era of GT40s and Boss 302s.
Indeed, there has never been a Mustang quite like the 2000 R. It boasts a unique modular powerplant--the largest ever put in a Mustang--and another first in its six-speed transmission, along with an aggressive aerodynamics package that is much more than a pretty fascia. Count the independent rear suspension (IRS), the big, ducted brakes, an equally large price, and an availability that can only be described as sold out before the first of the 300 were made, and you have a Mustang that defies swift categorization.
That's OK, as the 2000 R-model is really just a symbol of the future rather than a viable purchase option. It shows what the Mustang chassis is capable of, it showcases the modular families capabilities, and it promises to bring a veritable truckload of exciting new parts to eager tuner hands. The R-Model 5.4
From the beginning, the flagship 2000 R was going to fly the modular V-8 banner as proudly as possible. This meant a 5.4, but would it fit? Ford has always said the 5.4 won't go in the Mustang engine bay on its assembly line, but by using shorter engine mounts with harder bushings, a lowered crossmember, along with relaxing some of Ford's internal fit and accessibility requirements--and covering it all with a taller hood--the 5.4 was made to fit, even on the regular production line where the engine is offered up from beneath the chassis. All told, the Cobra R engine sits 12mm lower in the chassis than a simple 5.4 swap job would.
To get its 5.4 starting point, the SVE engineers reached into the Lincoln Navigator's engine bay for the largest, most sporting V-8 cammer in Ford's inventory. This brought on two excellent foundation parts--a durable, forgiving iron block and a stout forged steel crankshaft.
The modifications necessary to produce the R-model engine centered around durability, power production, and manufacturing. Ed Olin of Ford's Advanced Powertrain Engineering, and a two-time participant in our 4.6 Shootout, was the development engineer on the new engine.
The major issue was the 5.4's small bore (identical to the 4.6) and long-stroke layout. Without forced induction, elevated rpm had to play a role, and that meant blistering piston speeds. Define blistering? The engineers didn't have the exact number at their fingertips, but they said it was right next to the Jaguar Formula One racing engine, which has a short stroke but turns 18,000 rpm! For the R-model, this immediately disqualified the stock powdered-metal connecting rod, which was replaced by Carillo steel forgings.
The forged aluminum piston was modified from the stout 5.4 Lightning slug with thicker walls and pin bosses, and with a higher flat-top to get the compression up to 9.6:1. A stronger piston pin and a unique harmonic damper were also developed.
Making the necessary horsepower meant Olin needed upgraded cylinder heads, and he came close with DOHC heads from the Rough Riders off-road racing program. As he put it, "That was a major help, and it really paved the way for our work. Initial development was a success, but because of tooling limitations, we had to design new heads for the Cobra R. They're similar to the 4.6 Cobra heads, but with a lot more flow through the intake and exhaust ports."
By reshaping both the intake and exhaust ports, redesigning the valve heads, and going to a 2mm larger exhaust valve than found in the 4.6, the engineers saw peak airflow increase 25 percent. We'll bet Olin's after-hours drag racing program didn't hurt at this stage, either. Keeping the heads in place are unique, high-strength bolts.
Funny cams with an extra 0.100 inch of lift over the Navigator's bump sticks were developed. Duration was kept relatively short for driveability, meaning the opening and closing ramps are good and aggressive. The production cam chains were micropolished to withstand the rpm.
Manifolding this special engine called for all new parts. The exhaust uses short-tube headers, a Bassani X-pipe, production catalytic converters, and unique side-exiting Borla mufflers. The side pipes create a forced route, as the IRS and 20-gallon Fuel Safe cell don't leave enough room to the rear. On the intake side, a K&N cylindrical air filter is used, along with a unique throttle body. It's oval, but instead of twin throttles, the R-model uses a single oval blade. It even has "Cobra R" etched into it.
SVE's big piston is John Coletti, a genuine hot-rodder and hardware junkie, and he is (justifiably) stoked about the big R's intake manifold. So he brought one to the press introduction so we would know what was inside, which is a good-sized patch of intake trumpets and intermeshing tapered runners. The whole looks like mating time at the Sousa-horn factory, and it's a real shame these sexy innards had to be enclosed in an aluminum bread box.
Another red light. Haven't they run out of tax money to put up these things? I push the Ripper shifter out of Sixth, and an unseen spring takes it to the center of the neutral gate. The R rolls toward the intersection's limit line. I lay the left half inch of my right boot on the brake pedal. The hood doesn't drop, and there's not a hint of jerk or stiction or breakaway effort in the pedal as the R gives up its momentum without any apparent effort. Stopped.
The 5.4 sits there mumbling muted V-8 mumbles. Photographer Thawley prattles on about photo locations or 8N tractors or something. It's a good time to talk, as the ever-present road noise hates red lights, too, but it can be gone during the wait. I play with the shifter, feeling the gates. That spring favors the 3-4 gate as it should for quick 2-3 shifts. It takes some to get over to the 5-6 gate. The clutch is light enough, and it feels just like the Cobra clutch it is. Still red.
Mumble, mumble. It sure mumbles evenly, similar to a stocker. I suppose it was just a minute ago that we were accelerating like a rocket sled, but now that rocket motor is idling like a ticking watch. Green, finally. Into first, the clutch is coming out all buttery, and we're going. The engine oomphs to its work, doing the chores. Hic. Hmmm, a solitary miss from underhood. Just felt.
It's the most minor hitch as the 5.4 gets running. Well, if that's all the driveability hiccups we're going to find, then that's worth $55 grand right there. Second. Roll the throttle almost to the floor, the exhaust comes up to drown out the tires, 4,000 rpm, and the engine starts to sing. The chores are finished by 4,000 rpm and it's happy. The rest is playtime, and the engine's noticeably new eagerness and exhaust's ever more powerful tenor make sure you know it. What a gorgeous wailer.
Transmission and Rear Axle
Behind the 5.4 is a McLeod aluminum flywheel and stock 11-inch Cobra clutch. Nothing more heavy-duty is required, says SVE, but the Cobra's glass-jawed T45 was replaced by Tremec's T56 six-speed manual. Its ratios are respectably close for racing, and the top gear makes an excellent highway cog. You can skip gears around town from time to time thanks to the 385 lb-ft of torque, and with near-seamless driveability, the 5.4 works fine below 4,000 rpm. Above that, it simply rips.
Lapping the tight West Track on the Firebird Raceway complex in Phoenix, we found the 1-3 gears nicely spaced, with just a hair more gap than optimum going into Fourth. The Ripper shifter is precise, although when all heeled over in the twisties, we missed the Third shift three or so times in two days. It was probably our fault.
Of course, in back is the Cobra IRS, but this time with a Visteon-supplied hydro-mechanical differential that is both speed- and torque-sensing. Speed sensitivity is achieved with a gerotor pump, which is activated when the halfshafts rotate at different speeds. Then the pump applies hydraulic pressure through a piston to compress the clutch pack, thereby transferring torque to the other wheel. The torque sensitivity is achieved by beveled helical gears, which produce an axial force that tries to separate the gears. This compresses the clutch pack as well. All this seemed to work great in all our thrashing and lapping. The R never peg-legged in the traditional sense, and when provoked by overeager editorial throttle feet, the R smoothly and controllably slid its rear wide on corner exits. Only the most extreme acceleration from extremely tight corners would produce blue smoke off the inside rear tire, and this was still accompanied by hard acceleration. If the differential were set up any tighter, power-on understeer would likely be a complaint.
Gearing is 3.55 instead of the Cobra's 3.27. Furthermore, the halfshafts are unique, being induction-hardened bits from GKN. The shaft diameter is stock Cobra, but the inner splines have increased from 28 to 31. Also different are the inner tulips, which are a tripod design, and the right halfshaft is shorter because the differential is a bit wider thanks to the pump and such.
The only failures we heard of during the 24-hour durability testing were from the differential. (The engine threw its tantrums on the dyno.) These were cured with an optional differential cooler system. This isn't necessary on the street, but on the track, the differential temperature can become excessive. The optional cooler uses an automatic temperature-activated pump to circulate the differential fluid through an oil-to-air cooler. Air is drawn through a Plexiglas rear 3/4 side window on the passenger side. The replacement window features an NACA duct and SCAT tubing to get the air to the trunk-mounted cooler.
Brakes, Suspension, and Steering
Road racing a Mustang is all about getting the front-heavy chassis to quit dragging its front tires into the corners while, at the same time, trying to keep the rear tires in the same zip code when the throttle is down coming out of the turn. Anything that makes the front end lighter during quick transitions and keeps the rear axle from tramping while powering out of tight turns is good, too. The 2000 R-model has taken care of all these issues.
The first step was fitting way-sticky 265/40ZR18 BFGoodrich g-force KD tires all around. These are soft, grippy tires, which is a godsend when trying to get an inherently unbalanced chassis to behave.
Next, the suspension was given a careful bushing, shock, and spring tune-up. The control arm and IRS rear subframe bushings are stiffer, while the outer pivot of the upper control arm was relocated to increase camber. The carefully valved shocks are low-pressure Bilsteins, the 30- and 40-percent stiffer springs (compared to the production Cobra) are from Eibach. Interestingly, the stabilizer bars are stock Cobra.
The steering is stock Cobra, but with a revised power-assist curve, a stiffer T-bar, reduced steering angle (turning circle), and the tie rods are 4mm lower at the steering knuckle. These changes increase steering feel, prevent the wider front tires from rubbing the inner fender, and reduce bumpsteer. Also, the power steering received a two-step cooling system. An air-to-air cooler and a water-to-air cooler are fitted to all R-models.
What's most amazing about this chassis refinement is how SVE and SVT got the R-model track-ready, but with a street-friendly ride. Thank the IRS for much of this because the heavy spring rates aren't felt by your spine as would occur with a live axle. SVE also got the R to stick, claiming more than 1.0 g on the skidpad. We saw 1.25 g on the track in one of the prototypes fitted with a Pi Research data system. Brake dive was well managed, the IRS never tramped, body roll was minimal, and high-speed stability was as stable as your living room couch--all in an enthusiast's daily-driver ride. That's quite an accomplishment.
Because SVT has always done a good job with the binders, we expected the Cobra R to impress us in braking, and we weren't disappointed. The R uses Brembo 13-inch front rotors and four-piston aluminum calipers. They are cooled by air drawn through the foglight holes and delivered around the rotor by carbon-fiber ducts. These were developed by Multimatic Motorsports last year in the Motorola Cup series. The rear brakes are stock Cobra fitted with special, 1mm-thicker racing pads. We can say we gave the brakes a comprehensive, red-hot whipping at the press introduction, and they hung right in there with an extra-firm, linear, easy-to-modulate pedal. This is with the hydraulic assist, which seems to have gained considerable feel throughout the years.
Chassis, Aerodynamics, and the Cockpit
Cobra Rs use standard Mustang unibodies for three reasons: It would be too expensive to do otherwise, the stock unibody is stiff enough for street work, and racers will fit a full, chassis-stiffening cage anyway.
Weight savings were realized by deleting the sound system, the air conditioning, all chassis-dampening material, the trunk trim, the spare tire cover, the rear seat, and the rear interior trim. This does not mean there is no sound-deadening in the car. The doors are stock and fully insulated, the headliner provides some dampening, and there's at least some carpet front and rear. The effect is just right. You can hear all the car you'd ever want to hear--especially road noise from the rear--but the sound isn't so overpowering that it would drive away the dedicated enthusiast. Instead, the constant mechanical patter--and especially the luscious 5.4 song--is a continuous incitement to hit the gas. Street-bound Cobra R pilots had better have plenty of self-restraint.
Note also that the Cobra R has power locks, power mirrors, and power windows, along with remote keyless entry. This is because there are no manual substitutes for them in the Mustang line, so it would be too expensive to replace them with manual versions.
R-type pilots and passengers will also find living with their hot rod easygoing. The seating is supplied by Recaro buckets, and these wonderfully supportive seats have enough side bolstering to provide cornering support, yet they pose little restriction when entering or exiting the cockpit. For long trips, some drivers may want to spread out a little more around the thighs than the seats allow, but that would only be on true cross-countries. The adjustable seat backs and manual fore and aft adjustment were otherwise all we needed in such a minimalist sportster. With the seat back set a bit upright, we found the Recaros excellent for open-track or slaloming work. Pure road racing would, of course, call for an all-out racing seat.
The instrumentation is standard Cobra fare, although we guarantee you'll have great fun with the 180-mph speedometer. The shifter is a hair forward, and the throws are perhaps a tad long, so long-legged folks find themselves reaching for Third and Fifth occasionally. Bending the upper shift lever rearward should cure that.
Outside, there is little compromise in the bodywork. The bulging hood is a requirement, although we could do without the phony Hot Wheels louvers. In back, the base V-6 Mustang rear fascia is used because it does not have exhaust pipe cutouts.
The real bodywork news, however, is the aggressive front air dam, valance--or splitter (depending on how old you are)--and the rear wing. The aerodynamics of these parts were determined in the wind tunnel, and then the job of making them look like something, along with turning them into manufacturable parts, went to Darrell Behmer, a chief designer at Ford. With previous work on the '94 Mustang and '99 Cougar, Behmer was primed for the racey R--a job that went from napkin sketch straight to clay. "Basically, we short-circuited the usual system," Behmer said. "There wasn't time for development work on computers."
Testing shows the splitter and wing are the good guys in the R's one-handed, high-speed stability. The combination produces a 10-fold reduction in front-end lift, along with a 3-fold increase in rear downforce. The drag penalty turned out to be about 5 mph--from approximately a 175-mph top speed down to 170. Even for racing, this is an excellent trade.
So, Really, What's It Like?
It's way cool. The Cobra R gets major looks on the street. All the young turks wanted to challenge it, but they weren't sure enough to make a move. Their conservatism was well-founded.
As a race car, the R should be quite successful; as a street car, it's a fabulous street car in the minimalist tradition. The lack of understeer, tenacious grip, eager engine, siren exhaust, excellent seating, and easily liveable ride are what matter then--not the missing air conditioning, lack of tunes, or all that road noise. If you like to drive without a bunch of toys between you and the road, then you'll love it.