EngineLabs has uncovered more information about the winning engine in the Extreme Street division at the Amsoil Engine Masters, including a dyno sheet of the winning run.
Built by the students and staff at the School for Automotive Machinists (SAM), the 402ci small-block Chevy pulled 852 horsepower with a peak torque of 655 lb-ft. That wasn’t the highest horsepower of the field, yet it still was the winning number as the competition is based on average horsepower and torque with those numbers factored into the engine displacement.
The engine is based on a Chevy Bowtie iron block and fitted with SB2 cylinder heads. The cylinder port and combustion chamber designs were developed by the students through experimentation and dyno testing, then CNC machined at the SAM school.
“Valve sizes were 2.200 and 1.580,” adds Jud Massingill, the school’s founder and owner. “The block was machined for offset lifter bores to help with the valvetrain geometry.”
The block was bored to 4.128 inches. A Lunati 3.75-inch stroke crank was matched with Lunati rods and Diamond pistons. A Comp Cams solid roller spec’d out at 252/260 @ .050 with total valve lift of .760 and .720, respectively, for the intake and exhaust. Rocker-arm ratios were 2.0:1 for intake and 1.9:1 for exhaust.
Rounding out the engine’s hardware were an Edelbrock NASCAR-style intake manifold, BRE carburetor, Melling oil pump and MSD ignition.