Pacific Performance RacingPacific Performance Racing has introduced two distinct stroker assemblies for 350 and 400ci engines that it markets under its Tomahawk Performance Parts line. Both kits include a nodular cast iron crankshaft (top)...
Brewer tells HPP that his Tomahawk crankshafts are cast and finished overseas. "They are our own design, and are definitely stronger than stock units. They feature 3-inch diameter main journals, and a 4-inch stroke. The 383 crank was designed for a rod length of 6.8 inches and contains a rod journal diameter of 2.2, while the 428 crank uses connecting rods with traditional Pontiac dimensions. We also offer a stock-replacement 455 crank with 3.25-inch diameter main journals and a 4.21-inch stroke, as well as one with a 4.25-inch stroke for use with 2.2-inch diameter rods." Pricing starts at $325 for any crank. Tomahawk connecting rods are sourced from the same manufacturer as the crankshaft. "Our entry-level I-beam rod is a forged 5140-steel piece, which is about 30 percent stronger than a stock cast-iron unit, and it's available in 6.625- and 6.8-inch length, for $229. Our Ultralight rods are forged 4340-steel, and are available in either I- or H-beam, with lengths of 6.625, 6.7, and 6.8 inches. Prices start around $375." Brewer adds that all Tomahawk rods include ARP bolts, and that the 6.625-inch units contain 2.249-inch rod journals, while the 6.7- and 6.8-inch units are limited to 2.2-inch journals only.
PPR's rotating assembly kits start at $1,349, and include a Tomahawk crankshaft and 5140-steel connecting rods, Probe SRS-forged pistons, and a host of other necessary components. The entire kit is balanced and ready for installation into a block with minimal machining. Opting for a 4340-steel I-beam rod adds about $200 to the cost, and when asked which combination is most popular, Brewer replies, "We had good success with the 383 combination, especially after the feature build in HPP (Dec. '07), but our 428ci rotating assembly kit is definitely most popular. Hobbyists simply like building the 400 engine."
...and forged-steel connecting rods, with Probe pistons (bottom). The kits are completely balanced and ready to install for $1,379. Photos courtesy of Steve Magnante
Butler Performance
Butler Performance (BP), in Leoma, Tennessee, has been on the forefront of Pontiac performance for decades. David Butler says that a dwindling supply of 455 engines was a concern his company was forced to address. "Pontiac produced its 400ci engine for several years, so blocks were cheap and plentiful. Its displacement could be easily increased to at least 460ci by simply adding a 4.25-inch stroke crankshaft, so we partnered with Eagle Specialty Products to produce a crankshaft that gave hobbyists an affordable alternative to a 455 engine, and expanded our offerings from there."
Hobbyists often discuss the significant advantages that 3-inch main journal diameters like those of a 400 contain, when compared to the 3.25-inch unit found in blocks like the 455. Butler feels those benefits are grossly overrated when dealing with street engines, however. "Bearing speed and main journal strength of most blocks isn't an issue in engines that see less than about 6,500 rpm. During development of our first stroker crank, we chose a 3-inch main journal diameter simply because of the high number of 400 blocks on the market. Everything else at that time was secondary. Of course, the smaller diameter main journal has advantages in higher rpm applications."
Butler tells HPP that there are several distinct benefits to stroking a typical Pontiac block, when compared to other makes. "Installing a stroker crankshaft into a Pontiac is a simple process-it fits with minimal block modifications, and the overall cost of purchasing a long-stroke rotating assembly kit is about the same as a typical rebuild with similar parts. We also incorporate a longer rod, which lets us maintain a very good rod-to-stroke ratio, even with the longer stroke. The main benefits of that are less stress on the block mains, cylinder walls and piston skirts."