R&R 144mm 20mm Pin Solid Beam Aluminum Connecting Rods 3/8 ARP L19 VW Jetta GTI Audi TT A4 1.8T 20V

Max Effort steel connecting rods that can survive racing at 250+hp per cylinder typically have to be made bulky enough that their weight can cause bearing longevity issues in an engine that has to last through a season of racing. 

 

The faster you spin a heavy duty piston and rod, the more force it pinches the bearings with. If a bearing gets pinched too hard it will fail and take the engine out with it. You always want to use the lightest weight engine parts that will survive at your intended power and abuse level. The lighter the weight, the easier it is on the bearings, and the longer they will live. 

 

Aluminum rods are often lighter than max effort steel rods, but can survive at the same power levels. Also, aluminum being softer than steel makes it a better "shock absorber" between the opposing forces of the piston and the crankshaft changing direction, which allows the bearing to live longer without giving out and taking the engine with it.  

 

Aluminum rod are a safer choice for maximum effort race engines than steel. The downside to aluminum rods are that they expand with heat (like a piston) so the heat growth must be accounted for in the rod length and bearing clearance. Aluminum rods will also change shape sooner than a steel rod will, so figure that a set of aluminum rods will probably last about as long as the aluminum piston they are attached to and should be replaced when the pistons are replaced.

 

If you have questions regarding if aluminum rods are appropriate for your build, please reach out to us and let us help you make the best decision for your engine.