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“Two stroke or four stroke, what should I buy?”
There is hardly a day goes by that we don’t have a discussion about the differences and benefits of 2 stroke vs. 4 stroke outboards. This is one of the most often debated topics when shopping for a new outboard powered boat package.
The first thing that we like to point out is consumers can choose between three very different technologies, not just two:
Conventional (carbureted) two stroke
Two stroke with direct fuel injection, and
Four stroke outboards.

At Proctor Marine, we sell all three technologies from the 3 leading domestic brands: Mercury, Evinrude and Johnson. We feel this qualifies us to speak openly and without bias or prejudice about all three technologies offered by our brands, as well as our competitor’s makes.
Lets take a look at the characteristics and merits of all three:

Carbureted Two Stroke Outboards.

The simplest, lightest engine in any horsepower category, the basic two stroke is the design the outboard motor as we know it was pioneered on. If you own an outboard motor built prior to 1995, it’s a common 2 stroke design, with very few exceptions.
Since they are simpler by design, two strokes are affordable to buy. They offer brisk acceleration to help boats reach plane quicker and easier. Two stroke engines have the fewest moving parts making them simpler to repair and maintain.
Two strokes get a bad rap for fuel economy and their “dirty” image. It is generally conceded that a common two stroke wastes about 1/3 of the fuel that passes through the engine at low speed. The carbureted two stroke design can not be improved to meet the looming emission standards and are being phased out of production for the North American market.

Four Stroke Outboards

Clearly the sales leader for the past 5 years, 4 strokes have been embraced by the boat buying public. Four strokes are built using technology that has also been around for a very long time. Every one of us drives a four cycle automobile. In smaller engine applications, 4 stroke engines are also commonly found on generators, garden tractors, motorcycles and ATVs.
When emission standards began to phase in, 4 cycle technology was readily available and most manufacturers quickly jumped on the 4 stroke “band wagon”. Boaters were comfortable purchasing four stroke outboards – they are quiet, fuel efficient, and easy to start.
All leading outboard manufacturers produce a line of four stroke outboards. For Honda and Suzuki, 4 stroke is all they make for the North American market place.
Four stroke outboards are not the perfect match for every hull. Their heavier weight shifts the “point of balance” on many boats. Since they make power on every other revolution of the crankshaft, 4 strokes are slower to accelerate and the boat may work harder to come to plane. This is especially true of older hull designs with more deadrise and beams that narrow astern. It is possible for a boat to be “brand new”, but built from an older hull design.
Four strokes make an excellent source of power for high thrust applications, for example, pontoon boats. Their power characteristics serve this market well. While slower to accelerate, they have lots of grunt for low speed maneuverability. Many of today’s modern hull designs carry much more beam astern to create lift with less forward speed. These hulls also make a great platform to showcase what 4 strokes do best. If a 4 cycle outboard is best for you, make sure that you match it with a hull to highlight the engine’s strengths and help to overcome it’s weakness’.

Direct Injected Two Stroke Outboards

Direct injected two strokes are among the cleanest and most fuel efficient outboards produced. As the words, “two stroke”, appear in their name, they are often categorized with the conventional two strokes and black-listed by prospective buyers. Direct injected engines use the proven internal components of a simple two stroke but improve the breed by injecting fuel and oil, only as needed, where needed, and when needed. This provides the best of both worlds, an engine with the acceleration and “fun factor” of a 2 stroke, and the economy and environmental responsibility of a 4 stroke.
Evinrude markets direct injected engines under the “E-Tec” banner. Mercury labels their DI two strokes “OptiMax”. Two other brands also compete in this market Yamaha with their “HPDI” family of outboards, while Nissan offers “TLDI”.
Direct injected 2 strokes are light, peppy and they have fewer moving parts than 4 strokes. Two stroke engines love to rev! Sustained high speed running won’t lead to premature wear or component failure, as it can with the more complex 4 stroke design.
Only one outboard motor has ever won the prestigious Clean Air Excellence Award from the U.S. Environmental Protection Agency. It was a Direct Injected Two Stroke.

Each technology has its own strengths and its own place in the marine propulsion marketplace. We look forward to the opportunity to help you decide which brand and type of outboard motor bests fits your boating needs.


 
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