Marine Engine Architecture

How an engine balances its displacement versus its torque and horsepower output, and where on the power curve each of those values are strongest or weakest, determines the engine's suitability for its intended application. Boats and cars have very different needs, so it stands to reason that marine and automotive engines should be designed with architectures tailored to their specific requirements. Only they are not. All gasoline marine engines nowadays are automotive engines that remain practically unchanged save for the addition of a few marine components that bear no impact on the engine's performance (in fact, they decrease it). And so, this mismatched architecture has been responsible for the poor reputation marine gasoline engines have 'enjoyed' for the last 50 years. Until Medusa came along.

In stark contrast to a car, boats have a very heavy mass that must move through a very dense medium, so the key is to generate enough low end power to get the boat moving from a dead stop and to go from low speed to high speed relatively quickly. In other words, TORQUE. Automotive engines have very little low end torque, since cars are relatively light and rolling on the pavement is easy, which is why diesel engines, which posses lots of low end torque, have been favored for boats. So at Medusa, rather than buying and refitting an automotive engine that is lacking in torque, we started from scratch, designing our engines and their components all around one goal: to have plenty of low end torque like a diesel. But while diesels can actually have too much torque, which necessitates extremely sturdy drive trains (aka. heavy and expensive), Medusas have just the right amount for the intended target vessels, and we can reach 80% of our peak torque as low as 1800 RPM, and then stay above 90% all the way until around 4000 RPM, where torque peaks, and then slowly tapers off but still stays above 80%. This is a much broader curve than any diesel, and exactly what a boat needs, for it allows it to precisely navigate at slow speeds and still climb out of the hole immediately and get on plane easily.

The best part is that we keep all the attributes of gasoline engines, such as the extended horsepower curve, which increases the range for high speed maneuvers and allows the use of smaller propellers and drive trains, as well as light weight, smaller footprint, and affordability. The best of both worlds: The power of diesel with none of its drawbacks.