Lugger 1066 (106 mm bore - 6 cylinder), 6.8 liter diesels have heavy-duty tractor blocks. This high torque design provides a strong foundation; but a marine engine is only as good as its marinization. A Lugger’s expansion tank and liquid-cooled exhaust manifold is cast iron to withstand temperature fluctuations and resist electrolysis. Some engines only use bypass water to cool their exhaust manifolds. Lugger integrates the manifold into the cooling system mainstream. This, and two-pass water flow, assure even temperature control and eliminates hot spots.
Light-duty, small-displacement diesels operate at speeds up to 4200 rpm. This means high piston speed and short life. Lugger power comes from large cubic inch displacement and long stroke design. With less spread between maximum and cruise RPM, a higher percentage of the available horsepower is usable. Lower rpm also means less noise and wear, more complete fuel combustion and longer life.