A while ago there was an interview in Mopar Action with a guy who had been in the engine room at Chryco. I don't remember the name and don't remember what the factory term was for dyno testing, but it wasn't dyno testing.

He had tested many many engines and said the 440s they'd run for hours and hours and they kept gaining power. After X number of hours the power would have maxed out, that was the number. If they kept testing the same engine it'd soon break. If a rod broke it'd pull off something like an inch below the pin. I believe this was why the 908 rods were designed with the thicker beam.

I don't know why Mopar engineers were so in love with heavy pistons, except that they designed engines that usually had pretty short strokes and the heavy piston isn't so much of a detriment, also the heavy pistons probably were much more durable.

R.