Gomers US Diesel Parts Dyno Day is Saturday, June 1. This is a full day of the most powerful diesel trucks trying to outdo each other. They chain them up to the dyno, sort of like a big treadmill, and then rev them to see what kind of horsepower numbers they can generate to put up on the board. If you want to see some competitive guys, don’t miss this. I drive a diesel and I’ve gone to this event.