Class Description

The American Iron Spec Iron class was created to provide racers with the best value in amateur level road racing by combining the thunder and excitement of American style pony cars with the best possible reliability and durability of the racing platform, thereby minimizing total cost of ownership for racers.


Eligible Makes and Models

All 2005-2010 Ford Mustang with the 4.6-liter, three-valve V8


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Engine Specs


300 (2005-2009), 315 (2010)


320 pound-feet (2005-2009), 325 (2010)

Compression ratio



6,250 rpm



3,350 pounds, with driver


Fuel Required

93 octane, no need for race gas


Donor Prices and Availability

$6,000 to $15,000 depending on mileage and condition


Average Cost to Build Car

$15,000 to $25,000 for a complete build, donor price included


Average Cost to Buy Built Car

$35,000 to $40,000 from a professional shop


Typical Modifications

Removing door glass, replacing quarter windows with Lexan, air ducting for cooling allowed components, coated manifolds, engine, transmission and rear axle breathers, Ford Racing M-2300 big brake kit, Ford Racing ABS brake module, slotted rotors, air cooling ducts to brakes, removal of unnecessary wiring, battery relocation, PCM relocation, HVAC removal, aftermarket gauges, Ford Racing M-9603-GTB air intake kit, numerous Ford Racing suspension components, Motion Control Suspension shock package SET-1WNR-NS1-01, front strut tower brace.


Average Cost to Race Per Weekend

$500 to $1,000, depending on towing distance, and not including consumables


Consumables Prices

Tires, size, brand and prices

Spec Toyo Proxes RR 275-35ZR-18, $285 each


Brakes, brands and prices

Front, with stock calipers; Hawk DTC $225

Rear, with stock calipers; Hawk DTC 60, $175


Available contingencies

Toyo Tires, Hawk Performance, Redline Oil, Frozen Rotors, Driven Racing Oil, Winding Road Racing, Sampson Racing Communications, AiM Sports.


Factory Participation

Yes. Ford Performance offers contingency prizes for first through third places at the Eastern and Western States Championships, and prize money for regional championships and for regional races.







Spec Iron is a spec’d class with the added benefit of dynamometer testing to ensure all cars create no more than 11.75 horsepower per pound of vehicle weight and 11.25 pound-feet of torque per pound. With larger fields on the East Coast and Great Lakes regions, Spec Iron is a close, competitive class, with bumper-to-bumper racing, according to National Series Director Al Watson. The S197 Mustang comes with reliable engines and transmissions, so consumables are the biggest recurring expense. Tires are good for three race weekends. Front brake pads are good for three or four race weekends and the rears last even longer. Lighter than American Iron cars, Spec Iron cars all have ABS. Oh, and then there is that glorious V8 soundtrack.



The permitted aftermarket Motion Control Suspension shocks are kind of pricey at $2,500 for a set of four, and are a must for a new build.

“It’s one of those things that makes the biggest improvement to your car, so it’s definitely money well spent,” said National Spec Iron Director Al Watson. “It just happens to be a lot of money — but you can’t always get around that in racing.”


Rulebook Highlights

All official SI dynamometer tests will be open. All SI competitors have the option to be present for official chassis dynamometer testing.

  • A restrictor between the throttle body and intake manifold may be used to reduce horsepower and torque. The diameter and thickness of the restrictor plate orifice(s) shall be noted on the dyno sheet and must match at all times. No other means may be used to reduce horsepower and torque.
  • OEM exhaust manifolds may have a coating that is bonded to the parent material. This includes any paint or ceramic type coatings, but does not include header wraps.
  • Exhaust from the end of the exhaust manifolds to the exit is unrestricted other than exhaust must exit behind the driver.
  • The PCM may be relocated to inside the body for protection.
  • The battery may be relocated and may be any size capable of supplying enough current to start the car.
  • Traction control devices are expressly prohibited. Factory installed units must be disabled. See section 8.8 – Burden of proof that unit is disabled lies with the competitor. i.e.- switch disabled, computer indication, etc.
  • Rear wheel negative camber may not be more than 0.50 degrees.
  • Water or other liquid cooling of brakes is not permitted. Air cooling is both allowed and recommended.
  • Hood and trunk may be “gutted” by removing structure from their underside and their struts and associated brackets may be removed.
  • The grill and front bumper cover may have openings enlarged or added for the purposes of routing cooling air to allowed components. However, any such modification that improves or appear to improves aerodynamic performance (increased downforce or decreased drag) are not allowed.
  • All other OEM light assemblies may be replaced with facsimiles, plates, covers, or mesh covered cooling duct openings as long as these maintain the stock external appearance. Replacements for recessed lights must also be recessed.


What Racers Say 

Audrey Zavodsky, NASA Great Lakes


“The cars are constrained, so the difference is in the drivers. It’s a fun series, with a great group of guys to race with. Daytona was a lot of fun, with fantastic racing going on between us. We had a really good size group.”


Robert Miller, NASA Southeast


“I ran American Iron for three years and the costs just kept going higher and higher, with the more expensive cars that are in the class. Spec Iron got my attention because we’re all driving pretty much the same car. It’s a shopping list of the same parts. I think it’s one of the best driver’s series NASA has to offer unless you want to drive Spec Miata. There isn’t but so much money you can spend on a Spec Iron car. It’s the only V8 spec class NASA has to offer. And it’s a Mustang, so you can’t beat that. I’m a little biased.

“2005 through 2010 Mustangs are everywhere and the parts are just getting cheaper, which is good. In spec-class racing, you’re going to need a bumper every now and again.”


Carmine Pace, NASA Florida


“I switched from American Iron to Spec Iron last year. Once you put yourself to it and you get the parts for the car, you just drive the car. I’m only $20,000 into my car so far for a full build. My buddy and I, Dennis, from Ramsey Performance, we built it ourselves, from scratch. That $20,000 includes the price of the car and all the modifications, the cage and parts that I put into the car. The biggest thing is shopping for the car, and recently in the last year, actually, prices for the 2005 to 2009 cars have come down a lot.”


Lapping Videos

Corey Rueth at Texas World Speedway, 2014


Olaaf Rossi at Road Atlanta, 2014


Carmine Pace at Daytona International Speedway, 2015

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