Has anyone ever polished the beams on the stock connecting rods before? I heard that this can increase their strength. Any ideas?

 

polishing? if you mean shot-peening, then you are correct, it increases the strenght of them a good amount, good for budget built motors..only about $100 from a machine shop

 

No. I meant polishing the casting marks off the side of the rod beam.

 

Beam polishing removes potential stress risers. The casting marks and rough surface give numerous little points, and cracks that can be the starting point for metal fatigue. By polishing the sides of the rods, and removing this cast surface, you are greatly reducing the propensity for stress cracks. Whether or not it is truly necessary is up to you.

I had a set of LS rods in an LS/Vtec motor. The motor saw 9,200 rpm quite often, and saw sustained 8,500 in 5th gear for 4-5 minutes. The rods never failed in 35,000 miles.

These rods were cryo treated, beam polished, ARP bolted, re-sized, balanced and shot peened. Probably cost more than a set of Eagles in the end, but they held up beatifully, and supported a motor producing upwards of 190 whp.



[Modified by Jaker, 10:20 PM 12/25/2002]

 

Thanks for the info

 

I understand that Honda and most rods are shot peened from the factory.

Polishing the rods will remove stress risers, but also the residual compressive stresses from the shot peening. So, if you polish them make sure you shot peen them as well to regain the surface residual compressive stresses (apparently it's easy to get a fake or half-assed shot peening, so watch out).

Shot peening and polishing doesn't really make your rods stronger, it just increases their endurance (fatigue strength).

 

How much can I expect to pay to have the rods shoot peened?