J.
Once you get into the details of the racing equipment, you can see the difference.
The main reason the RPM's can be increased safely is that the main journals on pro motors are not the 3" stock diameter. I believe they are 2.75" diameter. This does good things for RPM. Such as the block has more meat around the main bearings, the crank has less mass and less friction from reduced bearing area.They also run lightweight aluminum rods and pistons which in turn lets the crank have smaller counterweights.It's not uncommon to turn 10,000 RPM out of a motor like this.
Bob Gliddon proved it. 10 time pro stock champ.
