I have gone through 2 con rods myself. Both of these were on a Norvel Big Mig 0.61. I thought I might try swapping this out for vmax6 since it is the same weight and rpm range, but supposedly 0.31hp instead of the vmax6 0.13hp.

I ended up breaking the first rod during the first 10 seconds of break-in running. What luck that Sig, the US Norvel service center, is only about 1 hour away from me. I called them up then drove out. They replaced the engine on the spot and even broke in the new one with an electric starter for me. My buddy and I got a tour of the facilities to boot.

That engine gave me so-so performance in the LMH. At first I was getting more power and 10% higher max head speed (~2200 vs ~2000). But after some inconsistent running, I opened the engine and found the con rod had hogged out the big end bearing and was shot. I put that engine on the shelf and the Vmax6 back on the LMH.

Spiro