Words: Tommy Parry
It’s an uncommon swap. Not only is this Grand National’s motor both supercharged and turbocharged, the original V6 has been scrapped entirely. Todd ran with the Buick V6 for several years, eventually bumping displacement to a stroked 4.2 liters and enjoying the 600-odd horsepower it provided. However, it lost much of its streetability, and he sought out a factory motor that could provide similar thrust in a civilized fashion.
In its place went an LSA – the engine best suited for boost with the strongest LS factory rods. Additionally, it features piston squirters. This swap was made simple with a complete kit from GM Performance, plus a few items from various vendors to make the install in a G-Body car. Mated to a 4L80-e from Lonnie Dyers at Extreme Automatics, Todd would have a simple, user-friendly package that could take him to the shops and the drag strip.
Inside, Todd added a thick layer of Dynamat keep the car quiet and comforting on longer hauls. However, it was never meant to be a plush cruiser. To keep him stable during quick cornering, he added a set of Scion FR-S seats with the appropriate amount of bolster. Of course, they were reupholstered in the classic gray and black cloth with the turbocharger insignia on the headrest. Those seats, along with the paddle shifters from Twist Machine and the gauges from Dakota Digital, rounded out a purposeful but stylish cabin.
Built to handle the heat of Arizona, Todd had a Vintage Air system added. In fact, with all the ancillaries — more on that in a second — a custom air conditioning system was a must.
Surprisingly, with a frame notch to support the compressor, they easily fit the LSA engine in the bay. However, Todd isn’t a fan of simple builds, and so he decided on adding a set of sizable turbos to add even more power, particularly in the higher revs. Rob Wetzel of Forced Induction Tuning recommended a set of Garrett 57mm turbochargers, mounted high to solve any oil drainage issues, and the two moved forward with tuning the motor for compound boost.
The custom set of manifolds were coated in Cerakote to keep the engine bay from becoming an oven. As for the complex intercooling system, the turbos go to an air-to-water intercooler, then into the supercharger, then through the LSA’s water-to-air intercooler. It’s a complicated process that provides a mile-wide powerband and, depending on boost pressure, 783 hp/778 lb-ft of torque go 965 hp/931 lb-ft. “Holy God, it’s in low boost at all times,” Todd adds.
That would twist most frames, but Todd had the GN’s strengthened and notched. Currently, Todd has a chromoly tube frame being built, but as his plate is already full with a slew of builds, that addition will come later down the road.
Providing style and traction are a set of Simmons barreled wheels, which house massive Baer brakes to bring the ~4,000-pound GN to a halt quickly. In the rear, 305-section Mickey Thompsons help administer most of that power to the ground. Those slick wheels, in conjunction with a new coat of paint from Christian Paul Customs, made this Grand National one of the more eye-catching of its kind.
Efficient propulsion is still an issue, so Todd is dealing with it in a fashion very appropriate for the build: by installing a custom all-wheel drive system to harness that pavement-melting power. Currently, it’s being tested on a 1978 Buick Regal mule. Soon, it’ll be used in Todd’s ultimate daily driver, and though nearly 1,000 horsepower will drive through four sticky tires, the GN shouldn’t have much difficulty leaving long, black stripes on the freeway onramp.
To keep tabs on this unreal build, you can follow Todd’s thread here.
