Diesel vs. Gasoline

diesel_insideHistorically, gasoline engines were able to reach high horsepower but low torque, which was due to the fact that high torque output needs to be "protected from itself" so to speak. All engine components must be extra sturdy to withstand such rotational energy, which gasoline engines were not. That is why, for bigger/heavier boats diesel engines were the power of choice. Diesels produce lots of torque at the expense of horsepower. They have extra long strokes, aided by very high compression ratios and the fact that diesel as a fuel releases more energy than gas. And so it was born the myth that diesels are much better for boats, and we say myth because as there is no such thing as a free lunch, diesels have their own set of drawbacks.

They are extremely heavy and large, a result of all the super heavy duty components that can take the punishment Mr. Torque dishes out. And heavy and large means very, very expensive. One cannot truly understand how monstrously massive marine diesels are until one has been inside the engine bay of a very large boat and felt dwarfed by those humongous engines. Diesels may actually produce way more torque than needed for a particular's boat mass, and since that output cannot be detuned or regulated, the only solution is to use super heavy duty transmissions, shafts and propellers, which further aggravate the issue of weight AND cost. Add to that the fact that diesels produce relatively low horsepower given their low RPM curves (gas engines usually go to 5500 RPM, diesels rarely over 3000) which meant diesel-equipped boats would reach anemic top speeds, and to ameliorate that, the engines were fitted with turbochargers and aftercoolers, further adding (you guessed it!), weight and cost to the already heavy and expensive equation. Ironically,  quite a bit of the power a diesel makes just goes to cover the weight of the engine itself and its associated components.

And so, boat manufacturers faced a catch 22 situation. They had to fit their larger models with diesels, even though this added substantially to the cost they had to charge, and then had to resort to gasoline for their smaller vessels. But to reach the needed torque figures, they would use much bigger engines than were needed in terms of horsepower, which resulted in only modest improvements over diesels when it came to size. Those gas engines were also very fuel inefficient and prone to failure, since they still lacked the sturdiness needed to cope with their torque. And that is the conundrum the marine industry has found itself in for the past century.

So, what has changed?

In the last decade, with the advent of many revolutionary metallurgical processes, engine building has experienced nothing short of a miraculous rebirth. Increased structural rigidity can be achieved with much thinner block walls, and rotating assemblies forged out of aerospace grade materials compliment these engines that can produce power levels never dreamed of not so long ago and do it reliably. This new technology is also, for the first time, available to many smaller companies and not just the big engine manufacturers. Diesels have benefited, many of them can be built in much more manageable sizes and with torque figures more representative of their intended uses, though they are still larger, heavier and way more expensive than gas. Gas engines, however, have made the best of this revolution, for they are the best they have ever been, at a cost that puts their manufacture within the hands of many smaller, private companies. Best of all, they have retained all the advantages they are known for: light weight, small size, low cost, ease of maintenance and repairs.

So, are Medusa Engines the result of this revolution in manufacturing?

Absolutely. But, we have taken full advantage of this unmatched opportunity and taken things one step forward. Most other, if not all, marine engine manufacturers still buy their engines from large automotive groups, and though they reap the rewards of excellent pricing on thousands of units and strong warranty backup from a worldwide company, at the core, those engines are very much designed for automotive use. Which means, low end torque. We have our engines hand crafted one by one in a small performance shop, where we can control every step of the process. Further, we can choose exactly the components we want and even mix and match within the same engine model if a particular boat has unique needs. We test EVERY engine after assembly and can fix any issues on the spot. MOST IMPORTANTLY, we build our engines with a much longer stroke than typical gas powerplants, which lets us achieve unsurpassed amounts of low end torque. This "stroker" design has been very popular among racing enthusiasts for decades, but it has finally become completely reliable, and we have added all the needed touches to fully "marinize" these high torque engines.