Stroker Kit Schooling
This is a discussion on Stroker Kit Schooling within the Firebird / WS6 forums, part of the Vehicle Specific category; Stroker Kit Schooling Increasing displacement is an easy way to extract additional power from an engine. While enlarging the cylinder ...
07-02-2008, 02:40 PM #1
- Join Date
- Aug 1999
- San Diego, Ca
- 383 Procharged & N20 Vert
Stroker Kit Schooling
Stroker Kit Schooling
Increasing displacement is an easy way to extract additional power from an engine. While enlarging the cylinder bore diameter certainly increases overall size, its effects are usually limited to about 10 to 12 cubic inches during a typical rebuild. This is because excessive cylinder boring can lead to a number of concerns, ranging from compromised integrity to cooling issues, if the walls get too thin.
Adding length to the crankshaft's stroke is another popular form of increasing displacement. In a Pontiac, that typically involves resizing an original crankshaft's rod journals from the stock diameter of 2.249 inches to 2.2. Offset machining of the journal can add about 0.040-inch of stroke length, thereby providing another 6 to 8 cubic inches of displacement and taking an otherwise typical 0.060-over 455 from 468 to 474ci. The machining process does, however, require precise accuracy to ensure each rod journal's new axis is correctly positioned
Though most components within Pontiac's 326 to 455 freely interchange, the crankshaft is not one of them. Engines originally displacing up to 400ci utilized a crankshaft with 3-inch diameter main journals, while 421 to 455 engines received crankshafts with 3.25-inch journals. Because of these differences, a long-stroke 455 crankshaft will not fit a 400 block without significant modification. But the quest for additional performance associated with long-stroke engines has spawned an entire industry.
A number of crankshaft manufacturing companies and Pontiac engine builders have developed complete rotating assemblies. These affordable kits commonly inc-lude a new nodular cast iron or forged-steel crankshaft boasting longer stroke and are designed to increase overall displacement, subsequently improving performance. We've contacted several companies presently manufacturing or marketing such components, seeking professional opinions about today's "stroker" kits, and here's what they had to say.
Eagle specialty products
Eagle Specialty Products (ESP), in Southaven, Mississippi, has been producing Pontiac engine components for several years. According to General Manager Robert Loftis, the company's first foray into the Pontiac market was forged-steel connecting rods, which were introduced in the mid '90s. "There weren't any affordable rod options for Pontiac engines at the time, so we developed a stock-replacement H-beam, forged from 4340-steel, and it proved popular.
Recognizing the dwindling supply of affordable 455 crankshafts, Loftis states, "We crossed over into the Pontiac crankshaft market around 2000 when we teamed with Butler Performance to develop a cast replacement. At the time, original 400ci crankshafts were plentiful, so there wasn't much need for a 3.75-inch stroke unit. We found that hobbyists wanted maximum displacement, so we introduced a 4.25-inch stroke unit for the 400 block, and other products followed."
Loftis says that his company's crankshafts are cast from material with some properties of steel, making them capable of handling up to 700 horsepower. "Our stroker units are available with 3- and 3.25-inch diameter main journals, and include a 4.25-inch stroke and 2.2-inch rod journals. Our stock-replacement 455ci crankshaft contains standard dimensions-4.21-inch stroke, 3.25-inch main and 2.249-inch rod journals. They all retail for around $280."
ESP's popular forged-steel connecting rods are a two-piece design that are precision-machined on all surfaces, then shot-peened, X-rayed, stress-relieved, and heat-treated for superior strength. "Like our crankshaft, the raw pieces are produced overseas, but some of the finishing is done domestically, using state-of-the-art CNC equipment to ensure proper sizing," Loftis says. All rod sets include ARP bolts, and are weight-matched on both ends for easiest balancing. Stock-replacement Pontiac connecting rods retail for $532 per set.
ESP also offers complete rotating assembly kits for 400 and 455 engines. "Our kits include a cast-steel crank and 6.8-inch long forged connecting rods with 2.2-inch diameter journals, which otherwise retail for $466," adds Loftis. Other pieces include high-quality forged-pistons, Clevite bearings, and a host of other components such as piston pins and rings. "A basic kit starts out around $1,718, but we offer a few options, such as complete balancing using our Hines computer balancing equipment, that can add to the price."
Ohio Crankshaft, in Greenville, Ohio, has been in business since 1969. Originally specializing in heavy-duty applications, the company eventually branched out into the automotive market, and introduced forged-steel and nodular cast iron Pontiac crankshafts within the past few years.
"We were getting calls from Pontiac hobbyists all the time," says General Manager Stan Ray. "They simply wanted an affordable, high-quality crankshaft for their engines, and most wanted longer stroke for added performance. We had developed a totally new Pontiac crankshaft for our billet program years before, then used those same CNC codes to produce our forged unit. That's why it looks different than others."
Ray says that his company sources its raw forged 4340-steel units overseas, but all finishing is performed in-house. "We also offer a nodular cast iron crank, and it's the same piece provided by other manufacturers. We pay particular attention to the rear counterweight clearance, however. It runs very close to the oil pump in a Pontiac," he adds.
Ohio's nodular cast iron crankshaft is available in 3- and 3.25-inch main journal diameters, and pricing starts at $295. The 4.21-inch stroke units feature stock 2.249-inch rod journal diameters, while the 4.25-inch units feature 2.2-inch journals. Ohio even offers a 3.25-inch main journal crankshaft with a 4-inch stroke for those rebuilding 428ci engines, or looking to produce a 440ci combo from a 455.
Forged-steel crankshafts are available in a greater variety. Ohio offers direct replacements for 400 and 455ci engines, which retain the stock 3.75- and 4.21-inch stroke lengths, respectively. It also offers 3-inch main journal units with stroke lengths of 4.21, 4.25, 4.5, and 4.75 inches-the latter three include 2.2-inch diameter rod journals. A 3.25-inch main unit with 4.25-inch stroke and 2.2-inch rod journals is presently available, and a 4.5-inch stroke unit is planned. Pricing begins at $575
Ray tells HPP that his company also manufactures connecting rods. A stock-replacement forged 4340-steel H-beam measuring 6.625 inches that contains ARP rod bolts is among them. "Our rods are 100 percent machined on all surfaces, stress-relieved, shot-peened, and honed with the latest diamond and vitreous technology. They start at $429 per set," he adds. Ohio also offers complete rotating assembly kits featuring its crankshafts and connecting rods. "We have Pontiac kits available for virtually any application JE Pistons produces forged pistons for, and our nodular cast iron crankshaft and H-beam rods are standard. Pricing starts around $1,300, and balancing adds $150 to that cost. A forged crank is available for $300 extra."
SCAT Enterprises, in Redondo Beach, California, has been producing forged crankshafts for over 40 years. Owner Tom Lieb says that specialty products are a large part of his company's business. "Pontiacs were, and still are, regarded as performance cars and hobbyists are making big power with them. We saw the need for a high-quality forged crankshaft, and introduced ours about three years ago. It's not big volume, but it's still a good bit of business."
Like other manufacturers, Lieb says that SCAT uses world-market material to produce its crankshafts. "It's not by choice," he adds, "there just aren't any domestic steel sources or forging houses, so we source the raw 4340-steel forgings overseas and finish them in-house." The company's Pontiac crankshafts are presently available with only a 3-inch main-journal diameter. "We've found that 400ci blocks are most popular simply because of availability and a stroker crank is an easy way to increase displacement and performance of it, but we plan to offer a 3.25-inch crank in the near future for those starting with large-journal blocks."
Stroke options are limited to 4, 4.25, and 4.5 inches-all with a 2.2-inch rod journal diameter, and are available in one of three distinct models. "Our Standard Weight unit includes knife-edged counterweights, and weighs around 75 pounds. Our Pro Comp unit is specifically machined to accurately position the counterweights for maximum balance of the entire rotating assembly, and weighs about 10 pounds less. Our Superlight unit is similar to the Pro Comp, but its counterweights are pendulum cut, shedding another five pounds, for a total of 15." Pricing starts at $799, $989, and $1,099, respectively.
Not limited to crankshafts, SCAT also offers its own forged-steel connecting rod. "Like our crankshaft, our H-beam rod is made of 4340-steel, and is forged overseas using a unique manufacturing process aimed at maximizing strength and consistency. All finishing is performed in-house. They also include ARP bolts, and are grouped into sets by weight and retail for $450."
Lieb says that his company's 6.7-inch long connecting rod with a 2.2-inch rod journal diameter is most popular. "It, along with Ross Racing pistons, is included in our complete rotating assembly kits, which start around $2,000. We also offer a stock-replacement H-beam rod in 6.625-inch length with a 2.249-inch rod journal for those using an original Pontiac crankshaft."
Tomahawk performance products
Pacific Performance Racing (PPR), in San Pedro, California, has introduced a number of engine components under its popular Tomahawk Performance Products line. Boasting of such items as intake manifolds, shaft-mounted rocker arms and a windage tray, PPR has recently added proprietary nodular cast iron crankshafts and forged-steel connecting rods. The company also offers complete rotating assemblies for 350 and 400ci engines.
Owner Ken Brewer says he prefers smaller displacement engines to larger units because he feels that the horsepower they produce is more usable. "I developed stroker kits for hobbyists with 350 and 400ci engines to arrive 383 and 428 cubic inches, respectively. Either increases displacement providing superior torque over a stock combination, but it's not so much that it grossly overpowers available traction, ultimately losing the race."
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."
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."
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.
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.
"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."
Frank Gostyla of AllPontiac.com, in Richmond, Virginia, says that he takes Pontiac performance very seriously, and is sincerely enthused with the number of maximum-performance Pontiac parts from all manufacturers presently on the market. "It's a good sign for the hobby, and we're hearing that our large-bore IA II block and high-flowing Tiger heads are helping Pontiac hobbyists compete with similar-sized engines of other makes on the track. We're hoping that our new rotating assemblies will provide racers with a performance edge."Gostyla says that generally speaking, adding stroke is an easy way to increase available torque in any application. "It seems our customers are interested in producing as much power as possible. The only negative effects we've seen from additional torque is in applications where tire size is limited or the chassis cannot simply handle the power. In these instances, additional torque can induce tire spin, ultimately slowing the car down.
"Testing of our 505 and 535ci engines, which contain the same bore diameter but different stroke length, indicates that with the same heads and camshaft the two engines produce nearly identical horsepower numbers, but the 535ci clearly produces more torque-about 40 lb-ft. If the added torque can be applied, the owner can usually install a lower (numerically) gear set and run quicker, even though trap speed stays about the same."
Gostyla tells HPP that he partnered with SCAT and combines its forged-steel crankshaft with his company's large-bore IA II block. "SCAT's crank contains a 3-inch main journal diameter and is available with a stroke length of 4, 4.25, and 4.5 inches. That allows us to produce engines that range between 477 and 541ci using our IA II block, which seems necessary to seriously compete with the large-displacement Chevy engines commonly seen on the track today."
In addition to a SCAT crankshaft, AllPontiac.com's complete balanced rotating assembly kits include SCAT 6.8-inch forged-steel connecting rods, forged pistons from JE Pistons, and a host of other high-quality components with pricing that starts at $2,695. "We also offer a complete short-block, which includes a rotating assembly installed into our IA II block. It's completely machined and assembled, and is available in a number of displacements, ranging from 477 to 541, for just $6,595."
When asked which combinations sell best, Gostyla replies, "The trend we're seeing right now is towards the 535ci combination. It seems most popular because it includes an IA II block with a 4.35-inch bore and a 4.5-inch crankshaft. That bore diameter gives owners at least one future rebuild, which might then include taking the block to our maximum-recommended bore diameter of 4.375 inches, subsequently producing a 541ci mill."
You may have noticed that Kauffman Racing Equipment (KRE) wasn't included in this story. The reason is we have a full buildup of a KRE 505 stroker engine following this story, so Jeff and Mark Kauffman's comments regarding stroker combos will be published in that article.
Though there may be other companies presently producing Pontiac crankshafts, and a number of skilled builders using various rotating assembly kits, it wasn't practical to contact them all. So we limited our story to those products that seemed most popular, and sought the opinions of a few Pontiac-specific builders who were quite familiar with each. That doesn't mean, however, that the components from other companies-or abilities of other builders-are inferior to those we've featured.
After hearing the comments from our panel of experts, we learned that the quickest and most affordable way of increasing the output of virtually any combination is with a stroker crankshaft, and that the resultant torque increase can be beneficial in dedicated street and race applications alike.
Such kits might make hobbyists look at that once-mundane 350 or 400ci block in a different light, or provide an edge against that large-cube big-block Chevy in the opposing lane. No matter the case, with so few negatives associated with them, stroker kits seem like a positive step towards maximizing your Pontiac in a number of ways.
Photo Gallery: Stroker Kit Schooling - High Performance Pontiac
Read More | Digg It | Add to del.icio.us
Users Browsing this Thread
There are currently 1 users browsing this thread. (0 members and 1 guests)
By JwMonE99 in forum Almost Anything GoesReplies: 6Last Post: 05-27-2008, 02:36 PM
By lt5performance in forum Firebird / WS6Replies: 0Last Post: 05-03-2007, 06:08 PM
By v6batmobile in forum V6Replies: 2Last Post: 12-04-2006, 04:15 PM
By 1986camarojoe in forum Internal EngineReplies: 1Last Post: 10-03-2006, 06:31 AM
By tazinhawaii in forum Internal EngineReplies: 1Last Post: 09-26-2005, 03:23 AM