Autocross: It's a Jeep Thing

Trail-Stomping Grunt

Twist the Jeep’s fasteners and lift off the hoodlike piece, and be careful that your eyes don’t fall out of your head. The 125-horsepower engine from that aforementioned Mazda mini-truck is long gone; Del started out with a rolling chassis, so his engine bay was a blank slate.

A junkyard provided the turbocharged four-cylinder from a 2009 Chevrolet Cobalt SS. These engines are known to be durable and take well to minor modifications. This one was also a bargain: Just $2000 bought 260 late-model horsepower straight away.

That’s a substantial amount of power, but it wasn’t quite enough to make Del competitive in the ultra-bonkers E Mod class. He needed more. So he scrounged up an inexpensive turbo plumbing kit on eBay, fabricated a short side-exit exhaust, then called up Vince J. Geglia II at Trifecta Performance. Vince was able to write fuel and ignition maps optimized to use high-octane, low-cost E85 fuel.

Del hasn’t actually put the chassis on a dynamometer, but his research shows that similarly modified Cobalt SS engines typically make 350 horsepower and an eyebrow-raising 375 lb.-ft. of torque. He says the switch to E85 accounts for about 35 of those ponies. At this point he’s pretty certain the stock fuel pumps—the direct-injected engine has three of them—plus the injectors and turbo are about maxed out.

Of course, if custom intake and exhaust plumbing were required to fit the Ecotec inside the Allison chassis, then a front-wheel-drive transaxle wasn’t going to cut the mustard either. Del mated the Cobalt powerplant to a Doug Nash two-speed, quick-change transmission. The engine’s trail-worthy swath of torque makes even two gears unnecessary, though, as a driver can simply put it into high gear right from the starting line.

That transmission has an interesting story of its own, dating back to the early ’70s. California circle-track racers at the time had a popular Sportsman class that disallowed quick-change differentials. Miffed but determined, Doug Nash decided instead to make a quick-change gearbox that would skirt the rules so he could still swap gears at the track.

Del is happy with his Nash box, but these days they’re becoming very hard to track down. “Find me another and I’ll buy it,” he proclaims.

Since it shares a bolt pattern with early four-speed General Motors transmissions, Del bolted the Doug Nash trans to the Ecotec with an adaptor bell housing sourced from Quad4Rods.com. He then fabricated solid mounts to tie the drivetrain directly to the chassis.

All the Axle Articulation You’ll Need

This isn’t just an engine-swapped baby NASCAR, though—it’s been tweaked all around. The rear axle is a trick piece that started as a full-floating Ford 8-inch unit. A full-floating axle’s hubs are independent of the driveshafts, so its wheels and brakes don’t fall off if a driveshaft snaps.

Del narrowed the Speedway Engineering-sourced rear end to fit it to the chassis, but he left it wider on the driver side so its input yoke would line up with the offset powertrain. Camber and toe were built in when it was narrowed; Del had chosen an axle from Speedway Engineering with crowned splines to accommodate the angle.

The suspension is still more or less original Allison Legacy, but it, too, got a bit of a massage: All of the pickup points were moved. The quarter-inch steel ballast plate mounted at the bottom of the chassis—worthy of use as a skidplate—is now a full 2 inches closer to the asphalt. To avoid introducing bumpsteer with the lowered ride height, Del used washers to shift the steering rack upward.

That last change may have caused a minor issue at the SCCA Solo Nationals this year: Del’s drivers experienced some binding in the steering shaft after the first day, but the team ironed out the problem without much hassle. Bob Tunnell and Jeff Ellerby drove it to second and third place in class, respectively, and Patty Tunnell nabbed second place with the ute in E Modified Ladies.

Those impressive results came despite some decidedly low-budget solutions. Del uses heavy steel-body shocks available at a local parts store for $59 apiece. The front splitter isn’t exotic, either: It’s made of wood, something that more often gets in a Jeep’s way on the trails. But it works. After experiencing some teething pains at its first two events, this machine has proved itself extremely durable.

Muddin’ Buddies

Aside from the attention, a perk of racing a Jeep is the cult support. The brand has a huge, devoted fanbase. Del tells a story about meeting Wiggy Greacen, a Jeep fan, at another autocross event.

At the time, Del was having trouble with the cheap blow-off valve that came with his turbo plumbing kit. “It was not up to the task of holding as much boost as we wanted,” he recalls.

Wiggy had a solution back home: He offered to ship Del a sturdier unit in implicit thanks for repping a Jeep on the tarmac. Some time later, Del received a letter in the mail instead of a box of turbo hardware. Wiggy couldn’t find the blow-off valve in his garage, so he instead enclosed a check for $200 to go toward a new one.

In a nod to the purists—Jeep owners are notoriously critical of any attempts to reduce their ute’s off-road prowess—Del assures us that no Jeeps were harmed in the making of this vehicle. What, then, makes this a Jeep? Nothing beyond the stickers and a vague resemblance, though perhaps it has the soul of one, too.

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