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NASA Challenge - Iron Horse Play
With NASA's American Iron, There's Finally A Road-Racing Class For Mustangs That Makes Sense
Playing with cars is a one-way street. The machines start out stock but are soon modified to go faster. Then they're modified again to go faster yet, and the process repeats until someone runs out of money, time, or desire. It's a fundamental fact of automotives.
Nowhere is this truer than with race cars. Drivers and cars start out simply-innocently, even. Left unchecked, they end up as sweating adrenal glands, gushing flames from the Bonfire of the Bank Accounts. The challenge for those stewarding the racing is to maintain the flames of passion without incinerating the host. For NASA, the National Auto Sport Association, the strategy is to offer a trilevel playing field to V-8 road-racing enthusiasts, especially Mustang owners. The three steps are Camaro-Mustang Challenge (CMC), American Iron (AI), and American Iron Extreme (AIX).
Step one, the Camaro-Mustang Challenge, we've chronicled before, but to recap, it allows basic chassis modifi-cations such as wheels, tires, springs, bushings, brake pads, and so on, and nearly nothing to the engine other than open exhaust. Thus, CMC Mustangs run totally stock engines, right down to the original, heavily crimped factory headers. With 240 hp or so at the flywheel, CMC cars are still plenty entertaining to drive, and the concept has proven popular on the West Coast for several years.
Inevitably, however, the CMC troops were ready for more power and handling. Enter American Iron, which, as NASA's step two, almost immediately became its most popular V-8 class. The idea was to give CMC racers a class to move up to, but it has also become a strong draw for those looking to move straight into wheel-to-wheel road racing from the street or open tracking. Cleverly thought-out rules make this an easy jump for many enthusiasts.
Conceptually, the American Iron rules start with CMC basics but allow engine modifications, along with more generous chassis improvements. Critical cost-containment provisions are provided, including a stock bodywork stipulation, a 9.5-lb/hp rule, and a spec tire coupled with a maximum 17x9.5-inch wheel. Together with liberal rules on many other aspects of the chassis and engines, these restrictions go far in capping costs, while not crimping the car builder's creativity. They also make American Iron extremely friendly to the aftermarket, as competitors are free to choose from a huge number of parts or systems, rather than being forced to run specific part numbers mandated by the sanctioning body.
Consider the wheel, spec tire, and associated fender-clearancing rule, for example. Fenders must remain stock-no adding or cutting material for flaring, and no tubbing-but they can be rolled or otherwise clearanced. Furthermore, NASA picked the Toyo RA-1 as the spec tire. Practically speaking, that means a 275/40-17 tire is the workable limit.
A relatively durable unit that lasts three race weekends, the RA-1 obviously saves costs by suppressing the need to buy stickier, but shorter-lived, tires every weekend. But by limiting wheel diameter, along with tire width via the fender limitation, these rules also allow NASA to legalize any brake that fits inside the wheel. With a 17-inch maximum, that means the popular and relatively affordable Motorsport 2300-K kit, or the equivalent 13-inch designs from Baer Braking Systems, Brembo, or the like, is where everyone ends up. Thus, by simply stating the wheel and spec-tire dimensions, the tires, wheels, and brakes are taken care of while leaving the owner plenty of room in which to experiment. This is a big help considering most people moving into American Iron already have some modifications done to their cars, and they don't want to obsolete their existing aftermarket parts.
The same is true of the 9.5-lb/hp rule. NASA allows any engine modification in American Iron, so you can make all the power you want and play with titanium connecting rods if that's your thing. However, there's no sense in going too crazy with the power mods. For one thing, you'll only have to add weight. Second, another rule allows only 100 pounds of ballast, so you can't spend a million dollars on a carbon-fiber Mustang, then add lead ballast over the right rear corner.
Practically speaking, by the time a Mustang is lightened by simply jettisoning the usual undesirables (spare, jack, sound deadening, all upholstery, seats, air conditioning, heating, sound system, and so on), then adding the required six-point rollcage, fire extinguisher (on-board fire systems are recommended but not mandatory), and whatever chassis bracing and suspension mods are desired, a dry weight of 2,900-3,000 pounds is about as low as you'll easily get. NASA weighs with the driver, so assuming a 3,000-pound car and nearly 200-pound driver, the resulting 3,200-pound car allows 337 hp at the rear tires. This is more than enough to hold your attention on a road course-even big, open venues such as Willow Springs.
Now, you certainly don't need titanium connecting rods to make 325-350 hp. An Edelbrock intake and Holley carburetor will do the job, as will Twisted Wedge heads and EEC IV. Furthermore, you may prefer a simple 5.0 engine, or perhaps you have a Cobra with a Four-Valve 4.6. Any of these combinations are legal, and mixing and matching chassis and engines is allowed. Thus, you could build a Fox-chassis with Four-Valve modular power or vice versa. All engines can be EFI or carbureted, but do expect to run some sort of muffler, as there are sound limits. Catalytic converters are not required, of course.
The tricky spot in the 9.5-lb/hp rule is determining the horsepower. NASA admits it's something of an honor system, but not that much! Chassis dynos are the main lie detectors, with the car owner submitting a dyno report no more than 90 days old at the beginning of each season for the engine configuration he'll be racing. During the season, random dyno testing by NASA keeps things from getting out of hand. Furthermore, it doesn't take long for competitors to spot suspicious power increases, and the racing we've seen is extremely close. There is no claiming rule.
Suspension-wise, the same laissez-faire doctrine continues to reign. Basically anything goes as long as it fits under the stock bodywork. So not only are enhancements to the stock suspension, such as springs, shocks, urethane bushings, and so on legal, but also are the replacement torque-arm suspensions from Griggs Racing and Maximum Motorsports. These two companies have found American Iron an open battleground, with cars from both camps constantly atop the win column in AI results. In fact, so dominant are these suspensions that simple bolt-on cars are really not competitive, although such racers can still come out and have a blast trying.
A special niche in the suspension rules allows IRS Cobras, but all other vehicles must be live axle. In other words, no Corvettes, and no live-axle Mustang can switch to IRS, although IRS Cobras can swap to a live axle, if desired. So far, all the winning has been done by stick-axle cars, and the only late-model Cobra to run has opted for a live axle. At press time, however, the feeling was there may be an advantage to the IRS after all. The ability to experiment with suspension, brake, and powertrain combinations such as these is a great advantage of American Iron.
Inside, there is no nonsense about retaining headliners or door panels in an attempt to make the cars look or feel like production cars. American Iron cars are gut like mackerel, with not a hint of carpet, insulation, or dashboard left. A full cage with meaningful door bars is mandatory, as are five-point seatbelts, proper racing seats, the electrical master switch, the window net, the fire suit, and the aforementioned fire extinguisher. As removing things costs nothing except your labor, this is a great way of achieving lightness while easing rollcage installation.
Outside, the bodywork must remain stock, save for the front and rear bumper covers, and adding a rear wing and front spoiler is allowed. As mentioned, the stock outer fenders can be rolled, but no metal may be removed or added to the fenders.
Drivers must have the usual helmet, fire suit, shoes, and gloves, and have their doctor fill in a NASA medical form. For drivers 32 years old and younger, the medical is good for five years. From age 32 to 59, the medical must be renewed every three years-from age 59 up, yearly. NASA membership is $30 per year, and a competition license is $50. Entry fees hover around $275 per event. Currently, there are NASA American Iron series on the West Coast (San Diego to north of San Francisco), and in the Southeast. NASA regions are found nationwide, however, and everyone expects American Iron races to spread.
From the Driver's SeatNASA is privately owned by three individuals, one of them being Ryan Flaherty, who-surprise-competes aggressively in American Iron. Wanting to give us as close a look as possible at the class, Ryan turned us loose during a practice session with his own Fox-chassis'd Mustang. A basic hatchback with carbureted 5.0 power, a T5 transmission, an 8.8-inch rear axle, 13-inch Brembo brakes, and full Maximum Motorsports suspension, Ryan's car represents the prototypical American Iron car.
Even with multiple door bars, climbing in Ryan's machine is easy enough, especially with a removable steering wheel and simple dashboard. Once in, the race-car ambiance is complete. The lack of upholstery and aftermarket instrumentation gives the visual clues, while the undampened road and drivetrain noises provide the hot-rod soundtrack. As always, the wide, five-point harness and supportive racing seat felt secure and inviting.
It didn't take but one lap to understand Ryan's Mustang is a real race car and a total gas to drive. Our previous experience with Camaro-Mustang Challenge cars proved they were definitely entertaining to drive, but with their basic engines and chassis mods, they lacked sharpness at the limit. They were also torquey off the turns, but ran out of breath at midstraight. Not so with the American Iron machines. Ryan's example pulled with authority right up the tach, giving the car both snap off the corner and continued speed down the straights. On Buttonwillow's curved back straight, we guesstimated via rpm, gearing, and tire diameter approximately 130 mph before braking for the next turn. That'll hold your attention when approaching a 90-degree left-hander with a slight rise and fall immediately in front of it.
As for the handling, with a full torque-arm suspension, reduced overall weight, and improved front-to-rear balance, these feel like baby Trans Am cars. Understeer or oversteer can be tuned using the usual spring, bar, and shock tools during practice, and power oversteer is available in the slower corners any time you want to get into the throttle, of course. Turn-in is sharp, especially on high-speed corners, yet we found Ryan's car neutral, with maybe a hint of understeer at midcorner. Coming off the slower turns, you can steer as much with the throttle as you think the rear tires can take. Overall, the balance is neutral enough that these cars can be drifted out of the turns when you get it right.
There's always something to discuss around Mustang brakes, and with Ryan's car, the stopping was fine, with minimal brake dive (greatly reduced brake dive is a torque-arm character-istic) and no fade. The pedal was soft for a race car, however, and maybe a bit different to modulate depending on what sort of vacuum the booster was seeing at the moment. Maximum Motorsports, which has been working with Ryan, says several combinations of master cylinder and rear brakes have been tried, but in the end, they probably prefer the more consistent, firmer pedal offered by Hydraboost systems. We've found Hydraboost brakes OK on the racetrack, but don't think we'd go to the trouble of retrofitting them to a Fox Mustang. If anything, we'd likely go with no booster at all. That gives a hard, heavy pedal.
Well, no matter. The brakes in Ryan's car stopped with authority. Anyone stepping into one of these cars from a street Mustang would be amazed at how deeply into the corners they can go.
Ryan cautioned against hammering the shifts, as his T5 transmission is at the ragged edge with this sort of power. Hard shifts aren't desirable in road racing, anyway, so this didn't seem much of a limitation, other than the knowledge that the T5 is going to be something of a consumable item that needs freshening occasionally. The shifting was expectedly light and smooth, while the clutch effort seemed a bit higher than stock, but hardly out of line.
We didn't get to ask Ryan about his instrument placement, but we'd be tempted to reorient the instruments higher in the dash, or at least redirect them due to line-of-sight troubles with the steering wheel. In the cut and thrust of tight American Iron racing, there isn't time to peruse the dash like the Sunday paper anyway, but it would be nice to consult the tachometer out of the corner of the eye rather than having to look down at the transmission tunnel.
Pulling into the pits, we had found Ryan's Mustang leaner, more responsive, faster, and far more fun than imagined. It drove with light arm movements-fingertips, really-giving the feel of a smaller car with great power. We rate its combination of power and poise as perfectly suited to both challenge the beginner without overwhelming him and to keep the old hand well entertained. You could race this car for years and never get tired of it. That there are many other pony cars to mix it up with is only icing on the cake.
Going ExtremeIf CMC has proven popular, and American Iron is rocketing into the lead, American Iron Extreme is, well, there and waiting for the all-out sort of racers. Extreme, as AIX is normally referred to by NASA people, is similar to American Iron, but the power-to-weight limit is not in effect.
As Ryan puts it, "AIX takes the few [American Iron engine] limitations and puts them away. Anyone who loves to modify Foxes or F-bodies can go crazy." As any racer will quickly explain, going crazy costs considerably more than simply dissipating a fortune via racing, and so the Extreme ranks have been thin. In fact, at press time there were but a handful of cars running, though we can say those driving them were grinning ear to ear. Furthermore, with just one year behind the class, not many people were either ready to move into Extreme or had time to build a car.
The big attraction, of course, is more power. Ryan Flaherty's racing and business partner in NASA is John Lindsey. John has chosen to run his Fox chassis in Extreme, and as with Ryan's, John's car uses a Maximum torque-arm suspension, but it is powered by 425 hp worth of small-block rather than Ryan's 303hp 5.0 engine. Just after we visited with John, he fitted a dry sump to his engine, which conventional wisdom says adds another 25-30 hp, so you can see how an Extreme car is ready to rumble when the loud pedal hits the stop.
Expect to see even more power in Extreme, as the engine rules are rather liberal. Forced induction is legal, for example, but Ryan says, "I haven't seen an aftermarket power adder that can stand the rigors of a 40-minute race at 110 degrees in the desert." As the class stabilizes, we expect to see maybe 500hp naturally aspirated small-blocks combined with well-sorted chassis carrying the day.
To support the power increase, Extreme cars can run any size Toyo RA-1 they can fit on a 17x9.5-inch wheel, and somewhat more liberal fender-flare rules are given. Frankly, unless you are a seasoned racer and have a penchant for taking overall wins, we'd definitely stick with American Iron as you'll spend less money, more time racing, and less time monkeying with engines.
But in any case, we certainly urge you to get on track and go for it.
Not Just Late-ModelsAmerican Iron is open to any American-made, rear-wheel-drive sedan certified by the Department of Transportation, with a 100-inch-or-greater wheelbase and using a live rear axle. That means all sorts of cars are legal, such as a Dodge Charger. More to the point, early Mustangs (and Camaros) are welcome. At press time, no '60s-era Mustangs had made it to the track, but some were reportedly under construction for the series.
Too Much Power?With a power-to-weight limit, it's possible to have too much horsepower. Just ask Ryan Flaherty. When preparing his American Iron car, he came in with 331 hp and just 2,970 pounds of car weight. That's 8.9 lb/hp-so even after ballasting up, he had to reduce horsepower to meet the 9.5-lb/hp class limit.
Ryan obviously wanted to choke the air at the top end so he wouldn't kill any torque, only the peak horsepower. He tried pinching off the ends of the tailpipes, but this didn't do anything. Then the ignition timing was retarded 6 degrees in 2-degree increments. Unfortunately, removing the first 2 degrees of timing added 10 hp. Ryan took out another 4 degrees, which took out another 10 hp, for a 20hp total reduction. Then the air filter was changed from a 3-inch K&N round to the low-profile 111/42-inch paper element "street rod" filter. This killed another 15 hp, which got him under the limit.
The full Dynojet rear-wheel power figures for the mild carbureted 5.0 are as follows.
Baseline331.1 hp at 5,700 rpm331.7 lb-ft of torque at 4,400 rpm
SupPressed (Timing retarded 6 degrees, low-profile air filter)303.8 hp at 5,800 rpm304.7 lb-ft of torque at 4,400 rpm
Modular engines should not have these issues. Ryan says the 9.5:1 power-to-weight rule was carefully selected to allow the Four-Valve engine all the power it could get with simple bolt-ons (long-tube headers, pulleys, throttle body, and so on) without going into the basic engine. In practice, this means the 5.0 guys have an easy time of making power, while the 4.6 racers have to work harder at it.
Have An American Sedan?What about American Sedan Mustangs currently running in the much larger Sports Car Club of America? Interestingly, even with their much more specific SCCA rule book, American Sedan cars are legal for NASA's American Iron, with two provisions. One, they must run the spec RA-1 Toyo tire, and two, the best SCCA American Sedan cars are probably a tad overpowered to meet the 9.5:1 rule. Simple adjustments ought to take care of both issues.
Alternately, American Sedan cars could enter AIX with no changes, but they would likely suffer a 100hp deficit. Still, for the AS owner looking for another race weekend, AI or AIX offer reasonable alternatives.