Connecting Rods

Which connecting rod can handle the boost pressure and revs your project will run? This category brings together single connecting rods, complete sets and kits, as well as piston pin bushings – for you who are rebuilding your engine for more power in a car, motorcycle or UTV.

What the connecting rod does in the engine

The connecting rod links the piston to the crankshaft and converts combustion pressure into rotation. With higher boost pressure and revs, the load typically increases – both the pressure during combustion and the pull at high revs – so stock rods and bolts can become a limitation. The rod should be considered together with pistons and piston rings, the crankshaft and the bearings. If you want the parts matched from the start, a complete rotating assembly can be a solution.

How to choose connecting rods

Start with the engine: the rod must fit the specific engine type, and the center-to-center length must match the crankshaft, piston and block. The length is often stated in the product name, e.g. BoostLine for Honda K24 at 152 mm or for Subaru EJ20/EJ25 Turbo at 130.5 mm. Then consider several factors:

• Power goal and use: the load depends on boost pressure, revs, and whether the engine is used on the road or the track.
• Bolts: kits can be supplied with different bolts, e.g. ARP2000 or ARP 625+, while Carrillo sets are available with CARR bolts in 8 mm or 1/4 inch.
• Piston pin and weight: the pin diameter and the rod weight must suit the pistons and the engine's balancing.

Installation and bushings

Connecting rods are typically installed with the engine disassembled, and bearing clearance as well as tightening – torque or bolt stretch – must follow the manufacturer's instructions for the specific product. Wear in the small end can cause play around the piston pin; for rebuilds we offer piston pin bushings. Brands in the category include Carrillo, Brian Crower, BoostLine, Hot Rods and Clevite.

Frequently asked questions

Should the connecting rod bolts be replaced together with the rods?

New rods are typically supplied with bolts, but it depends on the product. Whether the bolts can be reused, and whether they should be tightened by torque or bolt stretch, you should check in the manufacturer's instructions for the specific part number.

What is the difference between a single connecting rod and a set or kit?

A set contains rods for all cylinders, e.g. four for a four-cylinder engine, so all cylinders get identical rods. A kit can also include bolts. See the product description for exactly what is included.

When should the piston pin bushing be replaced?

Typically when there is play or wear between the piston pin and the small end, which is often discovered during an engine rebuild. Replacement normally requires precise sizing of the bore, so the work should be carried out by a workshop with the right equipment.

Do new connecting rods require the engine to be balanced?

It depends on the engine and on how much the weight of the rods differs from the originals. With a larger weight difference, or if pistons and crankshaft are replaced at the same time, it is typically recommended to have the rotating assembly balanced.