1,400-Horsepower AMC-Powered Mud Racer
"If a little is good, a little more must be better," Richard Dunavant said when describing how his '77 CJ-7 ended up a dedicated mud racer. Richard previously owned a whole slew of Jeeps, including a few different CJ-7s, a couple of Grand Cherokees, four XJs, and a J3000. In 1989, though, he sold his '82 CJ-7 because it did not fit the needs of his young family. But Richard was never cured of his Jeep affliction, and three years later his wife Julie helped him drag a CJ frame into their garage so that Richard could start a father-son project with his son Richie. When Richard and Julie lost Richie to cancer 17 years ago, rather than sell the Jeep, Richard decided to make their CJ-7 bigger and better than ever in Richie's memory.
The foundation for Richard's mud machine is the original '77 frame. It has been considerably reinforced with multiple crossmembers and a full eight-point, 1.75-inch diameter, 0.095-wall chromoly rollcage from Mike Graham at Virginia Speed Race Cars. The leaf springs were ditched ten years ago and replaced with coilovers to help the tires hook as the Jeep evolved into a serious mud racer. The fronts are only dinky 14.5x15 Sand Tires Unlimited tires on 15x10 Weld Drag Lites, but the rears are all business. The 15x18 Real Wheels are mounted with a pair of heavily cut 39.5x18.5-15 Super Swamper Boggers for unmatched traction. Virginia Speed Race Cars built the front three-link from 11/4-inch, 0.095-wall chromoly tubing and good 3/4-inch Aurora chromoly rod ends. Strange coilovers keep the whole thing up in the air. Out back, a set of Afco coilovers work in conjunction with a four-link utilizing 0.095-wall chromoly tubing and 3/4-inch Aurora chromoly rod ends. The rear lets the Boggers hook hard enough that even with a 106-inch wheelbase, a 7-foot-long wheelie bar is often put to good use. After all, you don't want the front tires getting too far from terra firma when heading down the track at over 100mph.
A dialed-in suspension is an important component in getting the Jeep to hook up, but it is only part of the equation. It takes some serious horsepower to turn cut Boggers fast enough to make a successful racer. Motorvation comes from an all-aluminum 499ci Indy Racing AMC engine with Indy aluminum cylinder heads, Jessel rockers, and a huge Comp Cams roller camshaft. Barry Allen Racing Engines built the big-displacement AMC engine with a Moldex crankshaft sporting a 4.15-inch stroke, GRP aluminum connection rods, and Diamond Racing pistons for the 4.375-inch bore. The combination squeezes out a 14:1 compression ratio and is fed by a huge 1,200 cfm Holley Dominator. The engine makes 928hp at 7,500 rpm and 694 lb-ft of torque at 6,900 rpm. Oh, and that's before the two-stage nitrous system is activated!
The first NOS Fogger system adds even more power and is activated when the transbrake is released. Yet a second nitrous system on top of that, a NOS Big Shot plate, is activated by a switch on the steering wheel. Both systems are plumbed with enough braided-steel line and anodized aluminum AN fittings to double Aeroquip's quarterly profits. The whole assembly bumps total engine output to nearly 1,400hp and requires 18 volts to properly light off the fire, which Richard accomplishes with an Optima 12-volt battery mounted in series with a smaller Optima 6-volt battery. The high-voltage goes through an MSD 7AL3 ignition box and Mallory distributor that uses a crank trigger to fire. Since the Jeep is only used for short bursts, a dinky, lightweight radiator from a Volkswagen Scirocco is sufficient to cool the engine.