A relatively narrow lobe separation is key for brutal, hard-hitting mid-range torque, while plenty of overlap and extra exhaust duration is the usual call for making an engine hang on into the higher revs. We found both of these qualities in COMP's new Thumpr line of camshafts. A COMP Big Mutha Thumpr (BMT) PN 11-602-8 stick got the nod, which is an off-the-shelf grind featuring 243/257 degrees of duration at .050 inch, .570/.554-inch lift, and a tight 107-degree lobe separation angle. To make the most of the camshaft, a reliable valvetrain was assembled with components from COMP, including COMP's retrofit hydraulic roller lifters to fit out a Mark IV block, COMP Hi-Tech 3/8-inch pushrods, and aluminum 1.7:1 roller rockers. A final trick to really make the big engine spin to its full potential was to specify COMP's Beehive valvesprings on those RHS cylinder heads. RHS obliged this request and now features this setup with a dedicated part number (11001-05).

With this, we had our basic combination, and the promise of mega torque. We took the load of parts-including oil system components from Melling, all-new tin from AAMidwest, an MSD HEI setup, and ARP bolts to screw it all together-to Andy Mitchell's Outlaw Racing Engines (Upland, CA). Andy oversaw the assembly, and measured everything to blueprint specs, while Hunkins and Outlaw part-timer Tim Martindale, helped work the nuts and bolts between shooting photographs and cooking ribeyes on the grill. What emerged was a hot-looking 496 that will fit under the stock Chevelle hood, chomping at the chance to prove its stuff come dyno day.

It wasn't long before the big-block was hauled to Westech Performance Group and bolted on a SuperFlow 902 dyno to validate the combination. Dyno master Steve Brul performed the preliminary checks of base carb and ignition settings, and the rat fired with authority. With a hydraulic roller combination, the cam break-in drama of a flat tappet is completely sidestepped, but the engine was run through a programmed load cycle to help seat the rings and prepare for the action to come. With a compression ratio of 10.2:1, there was no need to feed the Mighty Demon carb anything but standard-issue pump premium fuel. A few static checks under load helped sort the jetting.

With the formalities out of the way, it was time to let it rip. As the numbers rolled in, the big-block showed its true character. Want to propel a heavy street machine with explosive power? The Howitzer was revealing itself to be the ideal weapon, with a numbing 600 lb-ft churning right from 3,200 rpm, climbing to a peak of 635 lb-ft at 3,800 rpm. Wow, that's a lot of torque, and it comes in right now! We've seen some engines build a lot of low-end torque, only to give up low in the rpm range with no big horsepower bang up top. This isn't the case with The Howitzer. Our big Chevy just kept coming, making power right up to 6,000 rpm, and beyond. Torque recorded over 600 lb-ft right up to 5,300 rpm, and power held strong to the top, recording a peak of 626 hp, coming in at 5,900 rpm. Even past peak, the engine only slowly came off the crest, pulling easily higher. This is an engine that will hit like a cannon out of the hole, and keep pulling like an artillery piece barreling headlong to a shift point just over 6,000 rpm. Our Howitzer is one engine that's earned its name.