Motors built in the 70s that made 400 plus hp were 855 cubic inch and larger. Ntc 475 cummins,kta models. Cat 1693, 3408 were 400 and up to 600 hp. These all were about twice the cubic inch. The multi fuel motors were like the 1160 cat that was the old verision of the 3208 another low horse power models made for light duty trucks.