Any time you can put an engine together that makes enough torque to strip the concrete off the Hoover Dam, yet still gives away very little hint of what’s really lurking under your hood, you’ve built yourself a winner.
Mike Petralia of Hardcore Horsepower did just that with a 565 cubic inch big block Chevy engine destined for a tricked-out ’70 C10 Chevy truck. The engine cranks out 650 peak horsepower at 5,400 rpm and 700 ft.-lbs. of tire shredding torque at 4,500 rpm, yet idles at 850 rpm and pulls enough vacuum to run power brakes. That’s one awesome street motor.
The peak power numbers don’t tell the whole story. Over the course of a three-day test and tune session Hardcore’s Land & Sea engine dynamometer, the 565 laid down more than 500 ft.-lbs. of torque at 1,800 rpm and 600 ft.-lbs. at 3,000 rpm.
Petralia knew he needed cubic inches to make that kind of torque, so he had Dart punch out the bores of a Big M Sportsman GEN VI block to 4.600 inches. To reach the final displacement of 565 cubic inches, he dropped in a 4.250-inch stroke Scat 4340 forged crank. Petralia and his crew hung Mahle Motorsports dome pistons on Scat’s forged steel H-beam connecting rods and balanced the rotating assembly was balanced using a Trick Flow harmonic damper up front and an SFI-approved external balance flexplate out back. Since the Chevy GEN VI block uses a one piece rear main seal, most aftermarket forged cranks require this kind of offset balancing.
Comp Cams ground the custom hydraulic roller cam with .617 inches of lift on both intake and exhaust sides. Petralia degreed the cam with a Trick Flow double-roller timing set.
The Air Flow Research Magnum rectangular-port cylinder heads came straight out of the box except for the valve springs, which Petralia had AFR swap to 410 lbs.-inch springs suitable for hydraulic roller cams. Other valvetrain components include custom-length Comp Cams 3/8-inch pushrods and a set of Summit Racing 1.7 ratio roller aluminum rockers.
The 565 was topped with a Holley HP EFI system upgraded with 55 lbs.-hr. Trick Flow fuel injectors. This is a multi-port system that can self-tune as you drive, yet allows you to fine-tune the system on the dyno. The results speak for themselves.
If this sounds like an engine combo you’d like under the hood of your street hero, check out the Hardcore Horsepower Big Torque 565 Engine Combos at SummitRacing.com. They list virtually everything you need to build an engine to Hardcore Horsepower’s specifications. And you know what kind of power that makes.