bore vs stroke
Generally, tractors and semi's use long stroke engines to maintain the torque as engine speed decreases. In a racing engine the torque drops dramatically as the rev's drop. If a nascar engine is tuned for 10,000 rpm, how much power does it put out at 3,000 rpm? And if you put that 800 hp nascar engine in a loaded semi that originally came with a 220 hp Cummins, you wouldn't be happy with the results.