For most of us, the terms "e.t." and "horsepower" go hand in hand. If you want to go faster, you simply add more power-an easy solution in an age where aftermarket heads, cams, and superchargers are just a mouse-click away. But now imagine that the only things you have to work with are the parts that Henry Ford gave you-the stock heads, cam, and intake. No porting. No power adders. No kidding. If you can picture trying to make beef stew for six with four ounces of meat, one potato, and one carrot, you're starting to get the idea; you don't have a lot to work with, so everything you do-everything-must count if you want to be competitive.
This is what makes Shawn Johnson's '99 Cobra all the more impressive. The car has not only captured the NMRA Factory Stock (F/S) record with an amazing 11.41 at 120 mph (on drag radials with full exhaust, mind you), it has done so against a sea of more-experienced 5.0-powered cars-and in a span of less than 12 months. Of course, the fact that Shawn hooked up with Modular Performance (www.modularperformance.com) within months after purchasing his car in August 2003 didn't hurt his efforts. Mike and the gang at Modular Performance had just completed an F/S legal Cobra short-block and were looking for a car to try it in. On went a set of stock '99 heads and a stock intake, and soon the car was running 11.60s.
With little more than a Wolf Products eight-point cage installed by Anthony Jones Engineering, weld-in subframe connectors, and reinforced torque boxes, Shawn was off to the races, or so he thought. Rule revisions for 2004 allowed a few more tweaks, so a second motor was put together with better-flowing '03 cylinder heads and aftermarket valves, which were now legal. The stock transmission was replaced with a Tremec T5 modified by Pro Motion with G-Force internals for added strength, and testing commenced until the Joliet, Illinois, NMRA event in July 2004. There, Shawn got his first lesson in chassis dynamics. "Matt Wirt from Race Fab Engineering [Virginia Beach, Virginia] took a look under my car, and told me everything I had done was wrong," Shawn recalls. "Wrong pinion angle, wrong suspension pieces, wrong ride height, and so on."
With the next NMRA event in Atco, New Jersey, only three weeks away, a major thrash session ensued. "We stripped everything out of the car and started from scratch," Shawn says. "We removed all unnecessary weight; lowered the ride height of the car [for better aerodynamics], which entailed readjusting drivetrain angles as well as the instant center. We also tried different lower arms, upper arms, and stuff like that." It was worth the effort. Shawn's 60-foot times were pared down from 1.80 to 1.54. "We did all that just so we could go to Atco and get rained out," Shawn says laughing. "But we did get in one pass at 119 mph-and that made everyone nervous."
The car was making progress. Two more engine combinations were tried, the second of which allowed Shawn to lay down his record e.t./mph at the Martin, Michigan, NMRA event at U.S. 131 Dragway. The current engine is a derivative of that combo, with a 0.030-over Cobra block, factory steel crank, Manley Sportsman rods, and Diamond forged pistons wrapped in a tightly guarded ring combo. Under NMRA rules, the heads can be milled and the pistons can be changed from dish to flat-top, which produced a compression ratio of around 12:1, according to Shawn.
That's all fine and dandy-but everyone knows that a bump in compression does not an 11-second car make. The cams, heads, and intake are where the power is-and those may not be replaced with aftermarket components, nor molested with a die grinder. "You've got to get what you can get from testing factory intakes and heads," Shawn explains. "In any casting, there is always one that is just a little bit better than another-the key is to find it. We're also able to use aftermarket valve springs and valves, but that's about it."
Shawn soon learned that tuning would be a big part of his performance equation. "We found out that we were overloading the fuel system at 5,000 rpm," Shawn says. Ordinarily, this wouldn't pose much of a problem-but, remember, these cars use a returnless fuel system controlled by the EEC V. "You can't just throw in a bigger fuel system," Shawn says. "The computer drivers won't interact with the pump." This is where MD Performance of Cincinnati entered the picture. Using one of its fuel systems and Superhips Custom Tuning software, the fuel system woes and subsequent tuning issues were resolved simultaneously. "The new fuel system and tuning allowed us to make the engine very efficient-let's put it that way," Shawn allows.
Resting on your laurels is a luxury you can ill afford when competing in a stock class-especially when you're defending a title. "We're testing new parts from pistons to clutches all the time," Shawn says. "Diamond is helping us try different piston designs, and RPS Performance Products is working with us right now with its Cyn-R-G Segmented Flywheel and Max Series clutch. I really like it-it's an aluminum flywheel with steel pucks in it that don't warp like a steel ring insert." Another change for the better, Shawn says, is a new antiroll system by Gun Lake Performance that helps keep both wheels planted during a launch. Passing through the trunk, it doesn't interfere with the full exhaust system required in F/S.
As you might have guessed, constant change requires constant evaluation to determine if you are on the right path to improvement-however tiny that improvement may be. As such, Shawn has amassed a team that would make any Top Fuel driver envious. "Matt Wirt has been hired on as my chassis consultant, and he datalogs every launch, analyzes tire spin and suspension movement, then provides chassis setup recommendations. MD Motorsports does all our engine tuning and dyno testing. I've also got a crew chief, Ian Mullane, and he takes all of the info from the chassis guy and tuning guy and decides what changes should be made between rounds, plus fine details like launch rpm and shift rpm. All that varies depending on track conditions, weather conditions, and so on. They tell me what changes to make, and I do it. I like to remain hands-on."
Persistent protested teardowns (it's inevitable when you're the record holder) have also necessitated a dedicated engine builder. "It takes so long to tear down and reassemble one of these engines," Shawn says, "so now we're putting together a spare engine that we can put in the car while the other one is being torn down for protest."
So now here comes the million-dollar question: Is it all worth it? "If I break even, it's a good year," Shawn laughs. "But I don't have any other bad habits-I don't drink or smoke-racing is my only habit. And my wife, Christine, keeps me grounded so I don't get too carried away." Fortunately, racing is a habit the whole family can enjoy-in fact, Shawn recently purchased a motor home so both his wife and 9-year-old son, Tyler, can go to the races in comfort.
As of this writing, Shawn had just returned from Bradenton, Florida, where he won the class again-but just by the seat of his pants. "In the semifinal, I won with an 11.73 to an 11.61, and in the final, I won with 11.79 to an 11.77," he says. "Everyone was slow during eliminations-it was a lot hotter on Sunday and the track was getting greasy. But our mph was down to around 115, so now we're tearing everything apart to find out why the car is slowing down. The team I'm working with is never satisfied with 'good enough.' We'll analyze everything, put the car back together, and head to the next race."
And that, ladies and gentlemen, is what it takes to be a champion in the competitive world of Factory Stock racing.
5.0 tech specsEngine And DrivetrainBlock'99 Cobra, 0.030 overDisplacement285 ciCylinder Heads'03 CobraCamshaftsStockIntake ManifoldStockThrottle BodyStockPower AdderNoneExhaustJBA Shorty headers, SLP full exhaust w/X-pipeFuel SystemMD Motorsports, complete fuel-pump-to-injector fuel systemTransmissionTremec case, Pro Motion-installed G-Force internalsRearendMoser 8.8, spool, 4.56 gearing, 31-spline axles
ElectronicsEngine ManagementSCT/MD MotorsportsIgnitionFactory coil on plugGaugesAuto Meter
Suspension And ChassisFront SuspensionK-MemberStockA-ArmsStockSpringsStockStrutsAJE strut/spindle comboWheelsWeld MagnumTiresUnknown BrakesAerospaceRear SuspensionSpringsStockShocksAfco double-adjustableTraction DevicesMegabite Sr. lower control armsWheelsWeld MagnumTiresBFGBrakesAerospaceChassis StiffeningEight-point cage, weld-in subframe connectors