SCAT EnterprisesMost crankshaft manufacturing companies and Pontiac builders offer a number of complete rotating assembly kits that consist of cast-iron or forged-steel crankshaft and forged-steel connecting rods. Ranging from those with stock-replacement dimensions to those with added stroke, complete kits like this from SCAT Enterprises typically start around $1,700 and include everything needed for complete installation.
In his opinion, Butler feels that there are no real negatives associated with increasing stroke. "It simply adds more torque under the curve. One area of concern may be when combining a stock block with a 4.5-inch crankshaft, however. The additional stress of the long stroke when combined with added horsepower and rpm may overstress the block when nearing 750 hp. It's about that point that we start suggesting an aftermarket block, which is better suited for those types of combinations and output levels." While BP offers stroker kits for virtually any stock or aftermarket block, Butler says that combinations using original 350, 400, and 455ci blocks are presently most popular. "We offer kits that produce displacements ranging from 410 to 571ci, and utilize crankshafts from Eagle, SCAT, and Ohio, depending upon the application," he says. "Though they're suitable at a slightly higher level, we limit the cast cranks to about 600 horsepower and suggest forged units much beyond that. The cost difference is less than $400, and we feel that it's simply cheap insurance."
BP's rotating assembly kits are fully balanced in-house and include forged-steel connecting rods from Eagle or SCAT, while billet units from Oliver are an available upgrade-forged Ross Racing pistons and a plethora of high-quality components round out the contents. The average starting price is around $1,699, and many are kept in stock. "Rotating assemblies are among the easiest and most affordable ways to boost the output and durability of any engine at the same time, and we feel they'll remain a popular hobbyist choice for years to come," he says.
SD Performance
Dave Bisschop of SD Performance in Chilliwack, British Columbia, has been building Pontiac engines for several years, and he has noticed a recent increase in the popularity of long-stroke rotating assembly kits.
JE PistonsHigh-quality forged pistons from such companies as JE Pistons (shown) are included in many rotating assembly kits. The pistons are typically custom-made to each builder's specifications to achieve the correct compression and deck-height for a given combination. Photo courtesy of Vicki Cacciotti
"The positive effects are immediately apparent," he says. "Adding stroke is an easy way to add power-especially torque. Torque is very important in heavy street cars, but it's just as important in race applications. It means more power produced at lower rpm, which increases valvetrain longevity and requires less-exotic components, since long-stroke engines typically operate in a lower rpm range when compared to shorter-stroke engines."
When asked about the negative aspects larger displacement engines might possess, specifically after adding a long-stroke crankshaft, Bisschop replies, "In my opinion, the old saying holds true-'there's no replacement for displacement.' The only negative I see with a long-stroke engine is the tire melting torque it produces-and that can require a larger tire budget!"
SD Performance uses a variety of products when assembling its stroker combinations. "Nodular cast iron Eagle crankshafts are included in our base stroker kits," says Bisschop, "but we polish its rear thrust surface to remove the crosshatching. Forged cranks from SCAT or Ohio are utilized in higher horsepower (650+) combinations." A basic rotating assembly kit from SD Performance starts at $1,795 and includes an Eagle crank, 6.7- or 6.8-inch Eagle H-beam rods, lightweight Ross Racing pistons and pins, plasma-moly rings, and high-performance bearings. The entire assembly is balanced using the latest Hines computerized equipment.
Bisschop states that 461 to 468ci engines using a 400ci block are among his favorite combinations to build. "The torque increase from the added stroke is a significant departure from the 400's original 3.75-inch unit, and our customers are thrilled when they get the engine back into their Pontiac. I feel that stroker kits are an excellent foundation to build on, and ours are designed with future power upgrades in mind."