Performance Engine Bearings

When building a high horsepower performance engine, every new part has a role. Parts like a high lift, long duration camshaft and high flow, big valve, cylinders heads are the power producers, while the primary job of components like a forged crankshaft and connecting rods are to enable the engine to stay together while making that power. And just like the crank and rods, the engine bearings must also be upgraded to handle the increased load.

While more power and higher operating speeds increase the stress on all engine bearings, the connecting rod bearings are especially affected. Naturally, combustion pressure is intensified on the power stroke, but there is also added load on the compression stroke, particularly on turbocharged and supercharged engines. OE bearings aren’t designed to handle such pressure, and if you don’t upgrade to performance bearings your engine won’t last very long.

If the surface of used bearings display a network of fine cracks, this can be evidence of overloading – the bearings aren’t strong enough for the application. There are different grades of performance bearings to eliminate this problem, from bearings for extended street/strip use to bearings for race engines that are torn down regularly. But any performance bearing should have the strength to withstand the additional load, the durability to endure the additional stress for the engine’s expected lifespan, and a degree of embedability, where dirt particles embed in the bearing instead of damaging the crank journal.

Although there are some performance bi-metal bearings, featuring steel backing topped by high silicon content aluminum, most performance bearings are of tri-metal construction- copper lead alloy applied to a steel backing, with a thin overlay of babbit consisting mostly of lead with small percentages of copper and tin. The tri-metal design provides an optimal combination of extremely high strength with conformability, seizure resistance and embedability. Many performance bearings also come with a proprietary dry film coating to reduce friction, provide startup protection, and increase strength and heat resistance.

In addition to superior materials, performance bearings also have design features better suited to high power output engines. The eccentricity of performance bearings are tailored to the engine block and connecting rod bore characteristics of performance engine components to help maintain proper oil clearance, and they have higher crush for improved bearing retention. Performance bearings may be narrower than stock or chamfered to allow for the larger fillet radiuses of performance crankshafts, and they may have enlarged oil holes and/or grooves to improve lubrication.