There are certain automotive products that demand greater attention than others. The majority of parts that fit that description reside inside performance engines where there is little, if any, room for components that just “get by.”
And that scenario is intensified when racing comes into the equation. Among those internal parts, connecting rods are at the top of any list and are yet another part that is subject to technological advancements in both materials and methods as well.
Any good engine builder worth his or her torque wrench needs to stay on top of those advances for a better out-the-door product. So do the people that sell connecting rods. We polled a few connecting rod companies on just what’s happening in the market these days, and the latest information builders need to know.
Everyone knows exactly what purpose a connecting rod serves-or do they? Let’s start with their importance to an overall successful build.
“(Connecting rods) transmit the power from the piston/combustion to the crank and keep these two components connected,” explains CP/Carrillo’s Richard Batchelor. “It’s important to have a strong enough rod to help keep these components together. (The goal is) maximum strength and durability without weight gain.”
And their role is expanding in today’s high-powered engines.
“Connecting rods are simple in their intent, but due to stroker combinations, ever-increasing rpm and power levels, they have become a critical component in building a reliable racing engine,” says Eagle Specialty Products’ Alan Davis.
And they are more than just a connection between points A and B.
“Connecting rods must provide enough strength and rigidity to withstand the abuse they are subjected to, yet when other parts fail, they need to be flexible enough to ‘wad up’ instead of fracture to help preserve other vital (not to mention expensive) engine parts like cylinder heads,” he adds. “All of this while being as light as possible and fitting nicely in stroker applications.”
They are an important piece to the performance puzzle.
“To build a quality engine, you need a good block, crank and a set of rods and pistons,” says Dyer’s Top Rods’ Roger Friedman. “You need the best parts in engines from 327 to 480 cubic inches that will rev anywhere from 7,000 to 9,500 rpm. I’d say 90 percent of rod failures are due to detonation or lack of oil. Next in line are fasteners (rod bolts) not torqued or stretched properly. Failure to replace them on a timely basis leads to rod failures.”
Where to Look
Of course, connecting rod sales are a strong indicator of which engines are popular. So, if you’re looking to expand your offerings, here are some possible areas to focus on.
“In spite of more engines being introduced into various racing series, and more parts being available for a wider variety of engines, the good ol’ Chevy small block 5.700- and 6.000-inch H-Beam rods still dominate the landscape,” says Davis.
Friedman adds, “Most of our stuff is for off-road trucks, dirt late models and dirt Sprint cars. They are mostly small-block Chevys and small-block Fords.”
And for Batchelor, sales can be found in “GM Duramax diesels, the Suzuki Hayabusa and Toyota 2JZ.”
Whether for applications old or new, however, the performance of the connecting rod is critical. Fortunately, advancements in materials and machining continue to improve the function and durability of these important components.
“We have seen better material consistency and machining repeatability,” notes Davis. “These things contribute to more predictable performance and contribute to longer fatigue life.”
Like everywhere in the racing and performance world, the goal is to have it all.
“From a manufacturing standpoint, new technology has provided us the ability to manufacture lighter and stronger parts,” says Batchelor.
And the goal is to work together seamlessly with the rest of the internal engine components.
“Newer-style fuel injection, blocks, bore and stroke-all this new technology affects horsepower and torque,” says Friedman. “You need stronger rods and fasteners. We did an upgrade on rods, trying to address high horsepower and torque. There are some very good connecting rod makers in this country.”
What to Watch For
Even with a fairly straightforward product, there are common misconceptions and misinformation builders should watch for when it comes to choosing connecting rods for their engines.
CP/Carrillo’s Batchelor gives us two.
“One is that lighter is always better. While this is true in some applications, there are times when a heavier rod will help the motor and car perform better,” he says. “For example, in a manual transmission drag car, we have seen heavier rods used and the cars are running quicker. This is due to the inertia of the extra weight allowing the engine to maintain rpm during a shift. We have also seen that a heavier steel rod in place of a lighter aluminum rod has resulted in more horsepower, due to the fact that a steel rod will not stretch as much as an aluminum rod and the engine builders can tighten up the deck clearance.
“Second is that horsepower and rpm are the only things that affect a connecting rod,” he continues. “In actuality, the rpm, horsepower, stroke rod length, piston assembly weight, type and amount of power adders and type of racing should all be taken into consideration when selecting or designing a connecting rod. A rod designed for a 900-hp NASCAR engine may not be suitable for a 900-hp drag motor. The same could be said about a rod designed for a drag motor turning 10,000 rpm. It may not be suitable for an endurance engine turning the same rpm. One is running for six seconds, the other would run for 12 hours.”
It’s also important to remember, however, that a good rod does offer some versatility.
“When choosing rods, a lot of builders ask for recommendations. They ask for the weight of the rod. The misconception is that some manufacturers rate a rod at a certain horsepower, and that the heavier the rod, the more horsepower it will take,” says Friedman of Dyer’s.
As is often the case, the more experience builders have with the products, the better they understand the various strengths and abilities of individual applications.
“The single biggest debate the average racer has concerning connecting rods is I-beam vs. H-beam design-which is better?” says Eagle’s Davis. “The answer is determined by what you need. The H-beam design is, without question, the stronger design (all other factors being equal such as material, bolts, etc.). The I-beam design is easier to manufacture. The racer needing every bit of strength they can find will need an H-beam rod. The more budget-minded racer can opt for the easier-to-manufacture I-beam and save some money.”
He admits it’s an opinion, but one he’s prepared to defend.
“Some people by now are shaking their heads in disagreement. But without writing an entire article to prove the point, I will simply insert the fact that the original concept of an H-beam rod was invented to replace failing I-beam rods in Allied World War II fighter planes when nitrous oxide was added.”
Making that Connection
Lastly, we asked our sources what their best shops are doing to make more money when it comes to connecting rods.
“We all know the engine builder is a poor man. He makes money but he doesn’t make tons of it,” says Friedman. “We know we are at a price threshold and we try to hold the line. We’re always trying to put better pieces in our work.”
Promoting your products’ use in top-tier racing series can help build trust with customers, he adds.
“We do a lot of racer sponsorships. We’ve won the Daytona 24 hours, prototypes, World of Outlaws, UMP late models. We use magazines. We use websites such as Dirt on Dirt. And trade shows.”
And presenting package propositions is always enticing to customers.
“We sell through distribution, but in general, we hear that shops try to sell additional items and complete rebuilds,” says Batchelor.
As an expert, your knowledge is your most powerful product.
“Educating the customer is the biggest thing a shop can do,” says Davis. “Help the customers figure out what they need and why. Helping them figure out the best place to spend their money instead of wasting it will sometimes give customers the confidence to spend more money.”
In the end, it’s all about connections. And connecting rods are a great example.