Tom Wilson
November 1, 2003

Horse Sense: Race cars this clean are rare. Dave says that besides it just being the way he does things, he wanted to present an exceptionally-well-turned-out American Iron Extreme car to showcase the wonderful job NASA has done with the class.

It's that custom-blended "Kawasaki Green" you first notice about Dave Martis' American Iron Extreme Mustang. But upon closer inspection at its Fontana, California, track debut this spring, the Kermit color turned out to be just the beginning of a beautifully engineered, new race car.

Inland Empire Driveline Service built Dave a custom aluminum driveshaft, which runs to a "hybrid" 8.8-inch live axle. This is standard practice in road racing, where the well developed live-axle systems have proven more predictable than any Cobra IRS system to date. The hybrid in Dave's axle refers to the larger "Torino" bearings in the outer ends. The axles are Currie Enterprises 31-spline road-racing parts. As is the engine, the rearend is lubed with Red Line products, which, not incidentally, are cooled via Dave-fabbed transmission and rearend coolers.

For Dave, however, it was hardly his first time on track. A longtime SCCA and IMSA racer, he has been following the time-honored tradition of racing when young, followed by business and raising a family, and capped by a behind-the-wheel renaissance when time and finances allow. The manager of Emissions Research and Engine and Vehicle Testing with the University of California in Riverside, Dave has clearly kept his hand in the automotive arts his entire career.

Open-tracking also played an important role in keeping Dave on the fun side of the pit wall. Buying a new '97 Mustang Cobra, he took it on-track immediately but soon yearned for more unrestrained action. As has happened with many others, NASA's American Iron class brought Dave back to wheel-to-wheel road racing. Looking at these photos of a '97 Cobra with plenty of Griggs Racing gear, you might assume that Cobra is the one pictured here-but not so.

"I decided my 'street car' was too nice to get beat up running door-handle-to-door-handle," Dave says, "so I picked up a salvaged '97 Mustang platform and began the transformation. After a year and a half of whittling, bending, grinding, and welding, the AIX 32 car became a reality. In my younger-and maybe more foolish-days, I didn't think twice about taking on such a project. [This time] I asked my now-wiser self if I really wanted to do this [transformation]. I figured I could still do it-no sweat. I'd long forgotten how much time and effort it requires to build a car from the ground up. I did save a ton of money-this car would have cost two, maybe three, times the amount I have in it if I would have paid for someone to do it all. I would not recommend anyone try this unless they have the time, skills, fortitude, tools, and space to put it all together."

But what a beautiful result from all that effort. Dave began with a custom rollcage by Precision Welding in Rialto, California, which also handled the rear bulkhead, the transmission tunnel modifications, and all the tin-work. He then added a complete Griggs GR40R World Challenge suspension as he'd found it to be exactly what he was looking for in his street Cobra. And since Griggs is hugely successful in American Iron and AI Extreme, the GR40R system was a natural choice.

This gives Dave's AIX machine a tubular K-member, a torque arm, through-the-floor subframe connectors, and all new suspension arms from the Griggs catalog. The rear lower control arms are aluminum, working with Koni oval-track coilovers and 350-lb/in springs. The front Konis are double-adjustables with 475-lb/in coilover springs. The bushings are Heim joints, and adjustability has been built in, such as with the 29mm front sway bar with its tunable end links.

The all-important braking was also sourced from Griggs Racing. Given the company's oval-track background, Griggs uses Sierra calipers in its GR40R WC system. The calipers measure 13.5 inches in front and 12.0 inches in the rear and are fitted with Performance Friction pads. At Fontana, Dave had PF 93 pads in the front and 80-compound pads in back. The master-cylinder assembly is a dual unit from Tilton with balance bar.

American Iron Extreme sticks with the reasonable American Iron spec wheel size, which makes the tire and wheel choice fairly straightforward. Thus, Dave's car wears the ubiquitous Ford Racing Performance Parts 17x9-inch '95 Cobra R-style wheels ("What else?" he asks) with 275/40R-17 Hoosier Road Race DOT R3503 tires front and rear.

Dave didn't skimp in the cockpit, as he has a credit-card-maxing set of new everything. Seating is by Kirkey and instrumentation is by Auto Meter. There's a datalogging playback Phantom tachometer in there too. Off-the-shelf Longacre panels and switchgear helped speed the installation. There's also adjustable brake bias (with its own pair of pressure instruments!), on-board fire suppression, a heat mat on the floorboard, and other savvy race-car fitments. The windshield is stock Ford, but the remaining windows are Lexan by Percy's Speed Glass. The paint was sprayed by Joe Valdez.

Covering all this stuff you can't really see is some form-following-function beauty you can. Again, Dave reached for the Griggs catalog to select the hood, rear spoiler, and front bumper cap. The latter is a wonderfully subtle bit of urethane featuring slightly larger foglight and grille openings for better brake and engine cooling-the cooling ducts are built in. The hood is a Heat Extractor GR40 fiberglass unit. The spoiler is a carbon-fiber part with NASCAR style stiffeners. Mimicking the hood louvers are similar units in the stock steel front fenders.

But it's the mod-motor power under the hood louvers that really sets apart Dave's creation. Beginning with an aluminum Cobra engine from a donor car, Dave disassembled the core. The bottom end was machined by Dougan's Rebuilding & Machine Shop in Riverside, California, and the heads received a high-rpm tuning package by Griggs.

Clearly rpm is the name of the game with a small-displacement, multivalve engine, hence the short-runner Griggs-modified Cobra intake manifold. Filtration is by K&N and the throttle body is FRPP's oval-bore unit. There is no mass air meter, as the engine is sparked and managed by an ACCEL Gen VII DFI system working with NGK plugs and MSD wires. Fuel is supplied from the 25-gallon Fuel Safe cell by a Weldon 2025 pump and custom-bent -8 stainless steel supply and -6 return lines.

Billet fuel rails from Steeda, a Weldon fuel-pressure regulator, and RCI 42-lb/hr Lucas fuel injectors round out the system. The engine is also dry-sumped.

Dave built his own custom headers using computer-designed merge collectors and tubing from Burns Stainless in Costa Mesa, California. The results are stainless step headers starting at 1 7/8 inches at the port exit, moving up to 2 inches, and finally 3 inches at the merge collectors. This is followed by a custom 3 1/2-inch diameter (nominal) oval-shaped exhaust system with X-pipe. The oval stainless tubing is from SpinTech. It allows increased ground clearance required by the track-hugging ride height.

Also a concession to a low ride height is the Quartermaster 7.25-inch-diameter triple-disc clutch and matching Quartermaster bellhousing with rear starter mount. It supports a Jerico five-speed road-race transmission, and if you haven't had the pleasure of sampling one of these strong yet slick-shifting boxes, you're missing a real treat. It's like drawing two magnets together. Dave uses a custom Irv Hoerr Racing Products shifter and is pleased with his transmission choice. He's really excited about the easy, no-clutch, no-lift shifts.

The Jerico and its individually adjustable gear ratios are also important elements of Dave's low-torque, high-rpm Four-Valve strategy. His plan is to use all five speeds, meaning going into First gear on the slowest corners and having fifth just tall enough for the longest straight. This requires plenty of shifting, but it also means the somewhat peaky Four-Valve will buzz along in its powerband at all times. "Like a 125 shifter kart," Dave says.

The slick shifting is not without a price. The Jerico is longer than a Mustang gearbox, with the shifter naturally sprouting through the console where the stock hand-brake lever resides and the box hitting the floor's tunnel. This required cutting the top of the transmission tunnel and fitting a new, fabricated tunnel cover/housing. This modification, and the almost $6,000 cost of a new Jerico (Dave bought his used for considerably less) both just get by the AI Extreme rules.

It would be fun to say Dave laid waste to the American Iron field at his Fontana debut, but not so. Having only 4.10 gears that weekend, he was just going to shake down the car as the gearing was far too short for the long Fontana straight. That lasted about one lap, as Dave savored winging his super-crisp Four-Valve V-8 to 8,000 rpm for the first time. One broken stock valvespring retainer later, the intelligence of having stuck with the original plan was apparent. Dave is taking the enforced rebuilding time to prep a set of the newly released FR500 heads and magnesium-intake manifold. Griggs will once again do the porting, and this time Dave says he'll likely use titanium retainers.

In the meantime, Dave is one of a small club of Four-Valve road racers. Watch out when all this airflow is put to full use.

Dave assembled the engine himself. The displacement is nearly stock, with a 0.020-inch overbore to arrive at 285 ci. A stock steel Cobra crank, Manley Pro Billet rods, and 14:1 Ross Racing pistons with Total Seal rings make up the reciprocating assembly. The heads are Cobra castings, extensively and carefully ported by Griggs to Stage 3 specs and fitted with large 37x32mm valves and 202-degree/0.490-inch-lift Griggs cams. These cam specs seem mild until you recall there are two intake valves per cylinder, and you understand Griggs uses nonstandard measuring techniques. Flow numbers are in the 300-cfm league, and low-lift flow is especially impressive. The lash adjusters, rocker arms, and spring retainers are all stock; the valvesprings are Griggs.

5.0 Tech Specs
ENGINE AND DRIVETRAINGauges
BlockAuto Meter {{{Phantom}}}
Aluminum 4.6 Cobra 
Cylinder HeadsSUSPENSION AND CHASSIS
Aluminum 4.6 CobraFront Suspension
Intake ManifoldSprings
Griggs-modified short-runner475-lb/in Griggs Racing Blue Coil
CobraStruts
CamshaftsKoni double-adjustable
Griggs RacingWheels
Power AdderFRPP 17x9-in Cobra R
NoneTires
Exhaust275/40ZR-17 Hoosier Road Race
Custom stainless steel stepBrakes
headers, X-pipe, no mufflersGriggs/{{{Sierra}}} calipers, 13.1 in
Fuel Pumprotors
WeldonRear Suspension
Fuel InjectorsTraction Devices
42-lb/hr LucasGriggs Racing torque arm,
Horsepoweraluminum lower-control arms,
430 at 7,650 rpm (conservativePanhard bar, adjustable sway bar
tune during abbreviated testing)Springs
Transmission375-lb/in Griggs Racing Blue Coil
Jerico five-speedShocks
RearendKoni double-adjustable
8.8 Hybrid, Griggs Racing designWheels
 FRPP 17x9-in Cobra R
ELECTRONICSTires
Engine Management275/40ZR-17 Hoosier Road Race
Accel Gen VII DFIBrakes
IgnitionGriggs/Sierra calipers, 12.0-in
Accelrotors