5.0 Mustang & Super FordsFeatured Vehicles
1999 Ford Mustang Cobra - Party Crasher - NMRA Factory Stock Champ
Thanks To Shawn Johnson, NMRA Factory Stock Is No Longer Dominated By The 5.0 Mustang
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."