Lighter is always better! It usually isn't the RPM that is the main stress on the crank and rod, its the pushing and pulling of the piston. As the piston moves up the cylinder at a very fast rate and approaches the top of its travel,the instant it has to reverse direction and begin to move back down, the inertia of all that mass moving is trying to pull the rod in half. That is where all the main stress comes from. That is why many of the 283 Super Stock engines can twist so tight with just a stock small journal rod with relative ease. The piston and wrist pin are so light in comparison to the stock setup, there is hardly any inertia to overstress the rod even at 10,000 RPM. I've seen a piston and pin combo for those engines weight barely over 300 grams together, a stock TRW piston by itself can weigh 680 grams + 150 gram wrist pin with a total of 830 grams vs. 300 grams. That a huge amount of stress gone out of the rotating assembly for all 8 pistons....
Last edited by CNC-Dude; 12/01/08 02:42 PM.
