The Merriam-Webster Dictionary defines a muscle car as “any of a group of American-made, two-door sports coupes with powerful engines designed for high-performance driving.” Wikipedia also defines it as, “A large V8 engine is fitted in a two-door, rear-wheel-drive, family-style, mid-size or full-size car designed for four or more passengers.” Notice that there is no reference to the fuel type?
Rick Fletes, of Galt, California, is a true muscle car enthusiast. Better still, he’s a diesel lover, too. At 32, Rick was born 10 years after his Chevelle came off the production line. But that doesn’t mean he doesn’t appreciate Detroit iron and the power potential of a diesel engine.
When looking at the most efficient way to make his Chevelle a real power producer, Rick found that the best of the stock factory OE 454s had factory ratings of 450 hp and 500 lb/ft of torque. While he could have spent more than 13 grand for a stroker, race 454 block with 540 inches of displacement, 800 hp and 725 lb/ft of torque, he knew that a diesel engine was a better option. After all, a stock LB7 has 300 hp and 520 lb/ft out of the box; and with much less money, you can reach 1,000 lb/ft. And torque is the key to a quick launch and tire-roasting power when you want it.
Rick found a wrecked truck on the Internet and drove to Arizona to bring home the donor 2004 GM truck that had an LB7 motor. He extracted the motor, wire harness and most of the stock exhaust system and made it fit into the Chevelle as if it were stock. He also massaged the engine a little to gain an output of 500 hp and 1000 lb/ft to the ground for his oil-burning Chevelle.
The LB7 Duramax is mated to the stock Chevelle TH400 trans and a Gear Vendors overdrive. Rick also did some mods to the trans. This package provides a 2.5:1 first gear, and the 0.78 OD improves economy. The stock 12-bolt rear end has been upgraded and now includes a Detroit locker, 3.08:1 gears and 33-spline Yukon axle shafts. Strengthening the drivelines are 1350 yokes and U-joints.
Motor modifications include a custom 4-inch intake tube and a wastegate mod to gain 30 to 32psi of boost. The exhaust manifolds are BD Full Bore units, providing a significant exhaust flow increase. The exhaust system has 3½ downpipes and a Y-pipe. Then, it all runs down the driver’s side of the frame to the muffler, keeping the stock Chevelle rear-exit, stock-look, 3-inch tailpipes where required. An EFI Live tune helps boost power, and the programming has been tweaked by Rick and a few others to improve power.
The Chevelle body is basically stock, with the exception of the 3½-inch-rise fiberglass cowl induction hood from Unlimited Products. AAA auto body, in Los Banos, did a great job of painting this Chevelle a titanium-silver metallic that looks stock from afar but is much nicer that the factory paint ever was. The stripe graphics are painted on with charcoal-gray metallic.
Inside, Rick has installed black factory-reproduction carpet, and the stock seats were reupholstered for a stock look by Lindsay Upholstery, out of Salinas, California. The steering wheel is stock, too. You see, Rick wants this Chevelle to look as if the Duramax were a factory option, so this means not only doing a clean engine conversion but also keeping the stock look around the entire car. The only real exception to this is the eight-point race cage and eight-point racing belts.
Suspension modifications include a stock frame notched for rear drag slick clearance, new Moroso springs front and rear, as well as a set of C&E shocks. Up front, the drums have been swapped for a set of manual discs, and at the rear, the stock drum brakes were retained. For tires and wheels, Rick used American Racing Torque Trust II wheels. However, for racing, Rick runs Mickey Thompson 29.5 x 11.5 x 15 ET Drag tires on the rear. Up front are Goodyear 215/17 street tires, as well as at the rear for street driving. Yes, this is also a daily driver, and Rick points out that it get better mileage than the truck he uses to tow it to the track.
Rick’s 1970 Chevelle is a true muscle car. It proves that while the oil crises of 1973-1974 and current emission regulations may have stuck a fork in the factory-built American muscle car, you can build one yourself and make more power by going diesel with your build.
www.zeroto60times.com shows the following: The 1970 Chevrolet Chevelle SS turned in a quarter-mile time of 13.6 seconds. We’ve also seen claims of a 1970s 454 SS Chevelle with 8:1 comp, TH400, 3.07:1 gears running in the 13:30s.
Rick’s Duramax Chevelle had faithfully run the quarter-mile with a time of 11.27 seconds at 118 mph, with an estimated top end of 150 mph. The 60-foot time is 1.61 seconds. All this—and the Chevelle still gets 30/35 mpg (city/highway) with the Gear Vendors O/D.
As we write this story, Rick is swapping in an LBZ from RPM Motorsports that should produce more than 1,000 hp and about 2,000 lb/ft of torque. He looks for it to run in the 8s at the track.
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By Trent Riddle
Photography: Trent Riddle and courtesy of the owner