jub jub

Since forged pistons weigh a little more than the cast pistons in the LS engines, does anyone know how much HP loss there will be one over the other?

GOaT Cheese

A heavier piston will not affect overall power output, it will "move" it though. For the first milisecond of piston acceleration there may be a tiny bit more energy consumed compared to a lighter rotating assembly, but it is almost imediately regained in the form of kinetic energy due to fact that it is a heavier rotating mass. You can compare it the same way you would with flywheel weight, a hevier flywheel builds more momentum, and the car will launch better, a lighter flywheel will allow the rpm's to ramp up quicker. I know that with comparing flywheel weights, we are talking about a much a larger mass difference than a few grams for the pistons, but the logic is the same. The heavier rotating assembly will help "carry" you on top end, which makes up for the time lost in acceleration. Remember, we are talking miliseconds here, it's not going to be noticed either way.