RPM’s desire to get the motor as close to the ground as possible necessitated building a c
With 14 months to go before deadline, RPM procured a ’71 Challenger that Curt describes as “fairly decent” but would give most hot rodders a heart attack. Soda blasting the body revealed a big mess of holes, and the quarter-panels, doorskins, fenders, and floors were replaced accordingly. In fact, every panel except for the roof is brand new. Since Goodguys events have become synonymous with legit max-effort g-Machines that go like stink around the autocross, RPM knew the chassis couldn’t disappoint. The factory torsion bars and leaf springs just wouldn’t cut it. As such, the crew welded in a Roadster Shop front clip complete with tubular twin A-arms and RideTech coilovers. The E-Body’s posterior is even more trick, boasting a Roadster Shop independent rear suspension. Super heavy-duty splined sway bars virtually eliminate body roll, and the wheels are anchored by C6 Corvette spindles and hubs at every corner. Massive 14-inch Baer discs brakes with six-piston calipers bring the Missile to a halt in a hurry.
Just as impressive as the chassis and suspension hardware is how RPM merged it with the body. By welding the Roadster Shop front clip and IRS cradle assembly together, the Challenger was transformed from a unibody into a full-frame chassis. To achieve a downright sinister stance while retaining full suspension travel, RPM performed some serious surgery with the plasma cutter and welder. Just like a ’70s-era NASCAR stock car, the chassis was tucked way up into the body. “We cut out the entire floor, dropped the body over the chassis, built custom channels over the framerails, then welded everything back up,” Curt says. “Now the body attaches to the rocker panels, and the bottom of the rockers are even with the bottom of the chassis. For additional ground clearance, we ran the exhaust through the driveshaft tunnel.”
To emulate the look of the tunnel ram of the original Motown/Mopar Missile’s Hemi, the sma
Since the original Motown and Mopar Missiles relied on Hemi power under their hoods, Curt wanted to retain elements of that hallowed heritage but with a modern flair. Consequently, he ordered up a crate 426ci Gen III Hemi small-block from Indy Cylinder Head. The combo is based on a production block that’s been bored to 4.090 inches, then stroked the rest of the way with a forged Compstar rotating assembly. CNC-ported factory aluminum cylinder heads provide 370 cfm of flow to the short-block, and a custom COMP Cams 230/234-at-.050 hydraulic roller camshaft kicks open the valves. For the full late-model effect, a FAST XFI engine management system controls the fuel and spark delivery. The net result is 505 hp in a package that weighs hundreds of pounds less than the original Gen II Hemi big-block. “So many cars these days are getting built with GM LS-series motors, but the new Hemis are great engines as well,” Curt opines. “They make a ton of power, and get great fuel mileage. In a few years I think they’ll really start catching on.”
As RPM’s May 2012 deadline loomed, and the Challenger was scheduled to be on display at the Goodguys Nashville Nationals, Curt and company worked 24 hours a day for a week to get the project wrapped up. A testament to the meticulous engineering and fabrication that went into the Goodguys Missile, the car exceeded all performance expectations right out of the box. “To be honest, the first miles we put on it were on the autocross at Nashville,” Curt says. “The car sticks, handles, and performs just like a modern sports car should. The fastest lap of the weekend in our class was 35 seconds, and we posted 38- second laps without any tuning or practice.”