524ci Small-Block Chevy, 1,083 HP At 7,800 RPM
Sonny's Racing Engines, Lynchburg, VA
Not long ago, Bill "Grumpy" Jenkins made history building race engines out of cast-iron production blocks and heads because race-specific parts didn't exist. Today, with five-axis CNC machines spitting out designer cylinder blocks and heads, if you can imagine it there's somebody willing to build it. To that end, Sonny's Racing Engines built this wazoo 524ci small-block Chevy using the latest GM RO7-style NASCAR cylinder heads. Not only do these heads flow hurricane-like numbers, but they are based on a wider bore spacing than the production small-block Chevy's spec of 4.400 inches. The RO7 heads are designed for a 4.500-inch bore spacing, which means they won't fit on a typical Gen I-style cylinder block. This created a demand for a CN Enterprises custom billet block to match the heads, complete with water jackets, so this motor could be used in wild Southern-style match-race drag-racing applications. Just for the record, that four-digit horsepower figure is the normally aspirated power. At 1,083 hp, it computes to just over 2 hp/ci. The SpeedTech nitrous system isn't just for show, but they've not yet tried the squeeze. We are duly impressed.
'At 1,083 hp, this small-block is making 135 hp per cylinder! There are some four-cylinder production engines that don't make that much power from all four holes.
The RO7 heads were originally developed for GM NASCAR applications and began appearing in competition at the end of the '07 season. This new RO7 engine is a complete clean-sheet-of-paper design that has basically nothing in common with any previous production engine. The bore spacing is wider, the distributor is located in the front of the engine like a Ford to eliminate cam-twist effects on ignition, and the cam has been raised in the block to allow shorter pushrods. This should make the GM engines more competitive than ever. Current NASCAR unrestricted power numbers are in the 850hp range . . . and climbing.
It's rare that we put the spotlight on a cylinder block, but a foundation that is fully CNC-machined out of one large chunk of aluminum is newsworthy. CN Enterprises is the company responsible for creating a very large pile of aluminum chips. The block employs a Rat-sized 4.280-inch bore, along with 400 main-bore diameters, a 2.360-inch cam-journal diameter, and a monstrous 4.55-inch long-arm stroke. The stock deck height on a small-block Chevy is 9.025 inches, but this block is built on a 31/44-plus-inch taller 9.855 deck.