Back in the mid-'80s, Buick produced the Grand National, one of the quickest production cars of its time. Powered by a turbocharged 3.8L V-6, the car was capable of 14-second quarter-mile times stock and able to dip into the 13s with minor tweaking and a set of slicks. When we first noticed this black diesel hot rod on the Internet, we thought, "Oh, neat, a Duramax Grand National clone-he kept the turbo theme, but added a diesel." When we actually saw it and sat down and talked with owner David Morad, we realized this Buick just may be one of the most incredible diesel-powered vehicles we've ever seen. Don't believe us? Read on, and you'll see what we mean.
It all started about two years ago when David decided that although he loved his LB7 Duramax truck, he felt the diesel engine would be even more awesome in something a lot lighter. But what? He liked cars with newer interiors but didn't want to be hassled by the smog police, so the idea of a Grand National with a Duramax was born.
After his decision, David spent another year collecting anything he could that was Grand National-a hood, fenders, taillights, and bumpers were all acquired from parts traders, eBay, or wrecked GNs. Then he found the perfect car: an '82 Buick Regal diesel. The car had been converted to gas but was originally a diesel vehicle, so a Duramax would be a perfectly legal swap as far as the DMV was concerned. Then disaster struck. On the way home, the Regal's gas engine sprang a fuel leak, and the entire car burned to the ground.
The engine's computers are...
The engine's computers are cleanly tucked away on one of the custom fenders. With separate wiring systems for the engine, transmission, and vehicle itself, the electrical work on this car must have been a nightmare.
Determined to stick with his plan even if he had to do it the hard way, David found an '81 Oldsmobile diesel and started again. The body modification list to turn the Olds into a Buick clone was immense. The car was cut in half, and the back clip was welded on from a Buick Regal to make it look like a Grand National. Then the parts were added: a hood, bumpers, a trunk lid, taillights, emblems, and David even went to such lengths as finding an original GNX dash plaque (a GNX was a special version of the Grand National) and aluminum bumper supports from an original GN. The deception is enough that he has actually been yelled at for doing that to an original Grand National. If that's not enough, the car's entire floorpan was cut out and raised up a couple of inches to make room for the big diesel's exhaust.
After a bit of calculating, David soon realized the stock chassis wasn't going to cut it, so an Art Morrison front-strut subframe was added along with a set of cross-drilled Wilwood disc brakes and a rack-and-pinion steering setup. For the rear, Art Morrison was used once again, this time supplying a four-link setup designed for a fully tubbed vehicle. Out back, a Ford 9-inch rearend with 35-spline axles, a nodular centersection, and a Detroit Locker provide all the strength and traction necessary to propel the Buick to warp speeds. Because of the diesel's low-rpm powerband, the rearend was fitted with a 3.23 axle ratio.
With the body and chassis sorted out, it was time to fit the engine and transmission. Just like with the previous steps, David took no shortcuts. The firewall (which originally had A/C) was smoothed and notched for exhaust clearance. Once custom mounts were built for the engine, inner fenders were formed out of aluminum to give the entire engine bay a smoothed look. David wanted to keep the stock hood line, so a custom oil pan had to be made for the engine, the oil pick up had to be modified, and the filter had to be relocated underneath the driver seat. David also didn't want a huge bulge in the interior of his ride, so a 4L85E transmission (the one that comes in Duramax-equipped vans) was used instead of an Allison, and it was installed on a custom transmission mount.
 With 6.6 liters of Duramax...  With 6.6 liters of Duramax diesel power residing where a turbo'd six-banger should be, David Morad's diesel GN makes more power and gets better fuel economy than the original ever did. The smoothed firewall and custom inner fenders also create the illusion that the engine is floating in a sea of black. Neat. |  The bad-in-black paint and...  The bad-in-black paint and GNX emblems have many wondering whether it's a clone or a real Buick Grand National. A real GNX dashplate and serial number make the matter even more confusing. |  There was no clear way through...  There was no clear way through the engine to connect the rack-and-pinion steering to the column inside the vehicle, so a solution had to be found. The solution turned out to be this Steer Clear (arrow) unit, made by Wizard Fabrication, which dropped the steering shaft underneath the engine, where it was a straight shot to the frontend. |