Njawb - I have no way to get hard data, I won't lie to you.
The two good V-8's in truck operations failed horriably with a standard trans. The 8.3 DD did well with an automatic trans in a truck, shifting gears killed it - why - I don't know????
The Toroflows I think were just a bad design, again in a truck no-good yet as a higher horse marine engine they were pretty good.
Isotta vs I-6, can't tell you why they failed, just they did, the engines had problems. They may have not been real "engine" porblems as much as accessories like turbos or pumps????
I wish I had real data to give you other than what the end results were, which I know are in-conclusive???
I was wrong and your right stirling the Isottas were V-6, I may have implied V-8. And yes, they were 800 plus Hp, from what I was told basically a stock engine with big fuel & turbos.
I don't know the pump number but you can do alot with the Bosch pumps.
I don't know of a hard way for us to prove this either way.
I will throw in one more big V-8 that you guys should know which again was a disappointment the Perkins or Rolls Royce V-8!!!! Big iron, no power and didn't run long between overhauls, again why???? On paper another great engine that should have set the world on fire, but why not?