MORE GRUNT

Since the advent of small multi-cylinder tractor diesels being marinised as yacht auxiliaries it's never ceased to amaze me the torque and power gains achieved by going from three to four cylinders.

Yanmar's 4JH57 is a prime example. It develops 38 percent more torque and 43 percent more power than its 3JH40 CR counterpart yet is only 15 percent heavier with the down angle KM35A gearbox. And it's only 100mm longer.

Like the 3JH40 CR and 3JH5E the 4JH57 was designed to have the same footprint as its mechanically controlled predecessor, the 4JH5E. Yanmar has been very clever in doing this as altering engine bearers can be an expensive component in re-powering an existing hull. By having the same crankshaft to gearbox output flange dimensions existing stern gear can be used, saving