“If you do the lightweight rod, now you have a faster travel speed,” Turner continues. “But with the stronger bolt, the risk of tearing that thing apart at extremely-high RPM is greatly reduced.”

Different applications demand their own unique solutions to their challenges. A naturally-aspirated drag car using a delay box has a wide RPM range from launch to finish line. A turbocharged drag car has to contend with high cylinder-pressure from start to finish. A boat may run at 5,000 rpm all day long, but may also occasionally hop out of the water and spike the RPM. All these engines operate under different conditions and have different rod-bolt needs.

There are many bolt options available. In fact, calls to the tech line by professional engine builders are often about which bolt to use for a particular application and bolt torque specifications. “We ask the builder, ‘How much overall power are you making? How long is the rod, and how heavy is that piston? What’s the block deck-height? What is the rod-to-stroke ratio? How many RPM will it run?’” explains Turner. “We go through a whole list of scenarios to come up with what they need for their application.”

Oliver offers several rod-bolt options including the popular upgraded ARP 2000. Or, to meet the discriminating needs of professional engine builders, they can choose the ultimate rod bolt material currently on the market, Custom Age 625 Plus.

Picking the Right Weight

Professional engine builders rarely call the tech line to pick Oliver experts’ brains about rod length and weight selection, as they’ve done their homework for that, Turner revealed. Instead, they generally want to know what the power level recommendation is for a particular rod series.

“Even when we answer that question, we are fairly conservative, because we don’t know who’s going to drive that engine, who’s going to tune that engine, what fuel they are going to use, and how they are going to take care of it,” explains Turner of the complex question.

For less-experienced builders who ask Oliver for recommendations, Oliver’s tech staff will often suggest a rod that is a step above the expected horsepower of the application to give a little added insurance. “We don’t want to give them the bare minimum, because we don’t know how they’re going to tune it, or if they’re going to run into a problem they can’t hear or something like that,” says Turner.

Combining Strength and Light Weight

Turner pointed to Oliver’s design exclusives as enhancing durability for a greater power-to-weight ratio, such as the Parabolic Beam I-beam design that reduces beam stress. By relying on design geometry for strength instead of material volume, a lighter-weight product with the same strength is achieved.

At the parting line between the rod and the cap, Oliver flanges that area to give it a greater mating-surface area. “With a little more thickness under the bolt head on the cap, the connecting rod is more tolerant of assembly errors, such as an incorrect torque process or failing to use the recommended assembly lube under the head of the bolt, which causes the cap to start to gall,” Turner explains.

Quality Control Ensures Consistency

Whether it’s 85 degrees outside or 5-below, Oliver’s northern Michigan facility is temperature-controlled for consistency. “If step one of production started at 85 degrees, and by the time you got to step seven, it was then 75 degrees, the product itself has shrunk,” Turner says. “In order to make our cutting or measuring exact all the way down the line, step-one has to measure the same as step 15. Otherwise, it’s not going to come in true.”

Oliver’s rods are quality-checked throughout each of the 15 machining processes using equipment such as the Zeiss Coordinate Measuring Machine and the Mahr-Federal Dimensionair air gauge to ensure accurate, high-volume manufacturing processes.
“If we get to step seven and something’s not right, it’s ‘Sorry, start over,’” says Turner of the company’s strong commitment to quality parts.

With the bore size of the rod being a critical measurement, Oliver relies on air-gaging for fast, precise measurements. The Federal Dimensionair machine measures the bore diameter down to the hundred-thousandth of an inch.

Making the Decision

While making the decision on which rods to use is a complicated one, Oliver is using technology to assist its customers — whether they are an advanced engine builder or a curious beginner. As of this writing, Oliver’s website is set to be overhauled with some awesome new features.

Rods are now being laser-etched with QR codes, which will eventually be searchable on the new website. Customers and end-users will not only be able to verify the product they are using but it will eliminate cases of “mystery rod” when someone buys second-hand components. Robust technical information on the site should answer many questions currently fielded by tech line staff, who will still be available to help an engine builder’s unique needs, including manufacturing custom rods.

Oliver isn’t just an off-the-shelf application company, and many of its customers specify a custom-length for their builds to accommodate their desired piston compression height or deck clearance, as evidenced by the custom order form on Oliver’s website. And, if a customer has a question about which Standard Light or Ultra Light rod series is the best fit for their application, Oliver experts will be available to assist.

Article Sources

Oliver Racing Parts
(231) 237-4515