Sand cars are to off-roading what altereds are to drag racing. Lightweight, massive rear tires, purpose-built and often unprecdictable — especially when big horsepower is involved.

Normally, Enginelabs focuses on engine dyno tests, but this chassis dyno run to test a twin-turbo 454 LS7 from Custom Built Motors (CBM Motorsports) is worthy of a closer look.

The engine starts with a World Products Warhawk tall-deck block fitted with a Callies Magnum 4.25-inch-stroke crankshaft and Callies Ultra connecting rods. The 4.125-inch-diameter pistons are from Manley and provide a 9:1 compression ratio. CBM uses a GM oil pan and Melling pump.

“In this type of application, [dry sump] is not a good deal,” explains Chris Bland of CBM, which builds more than 500 LS engines a year ranging from 400 up to 1,800 horsepower and up to 525ci. “Also, we’ve found the tall-deck blocks with high horsepower tend to last longer in off-road. We can keep the piston up in the sleeve.”

The LSX-LS7 GM heads are CNC machined to CBM specs and mated to a custom sheet-metal intake. Providing the boost is a pair of Garrett GT35R turbos with Turbosmart wastegates and dual intercoolers. Engine management is through a Delphi MEFI controller with custom CBM calibrations.

Swapping scooper tires for slicks so it will hook up with the dyno rollers, the Sand Cars Unlimited-built buggy delivered 1,196.5 horsepower to the ground with 16 pounds of boost. Turning up the wick to 20 pounds saw the needle hit 1,315.5 horsepower. Peak torque was well over 1,000 ft-lbs on both runs.

Specializing in off-road applications, CBM typically builds this engine with a Whipple supercharger, but at least 10 customers in the past year wanted turbos.