Comparison Mercury F15M vs Honda BF15D3SHU

The working volume of a gasoline outboard engine (see "Engine type"). This term usually means the total working volume of the cylinders.

The larger this value, the higher the motor power, usually (see the relevant paragraph). At the same time, with an increase in the working volume, fuel consumption, weight and dimensions of the unit also increase; and power depends not only on this indicator, but also on a number of other factors — ranging from the number of strokes (see "Engine duty cycle") or the presence of turbocharging (see below) and ending with specific design features. Therefore, situations are not excluded when a smaller engine will have more power, and vice versa.

The working stroke is the distance between the two extreme positions of the piston in a gasoline (see "Engine type") outboard motor. In most cases, this parameter is purely reference; situations where such data is really needed are extremely rare — usually during the repair or maintenance of the engine.

Possibility to use a petrol engine generator(see "Engine type") to power an external load.

The generator is an indispensable element in the design of any petrol engine — it is responsible for creating the spark necessary for ignition. However, not every outboard motor has the ability to power an external load from this generator — therefore, if such an opportunity is important to you, you should choose a model where it is directly stated. And the generator system can come in handy, first of all, if you plan to use additional equipment on the boat — power from the generator is in a number of ways more convenient than from autonomous batteries, and it is for it that many navigation systems, echolocation, radio communications and other instruments and equipment are made . In addition, if necessary, devices outside the boat can also be powered from the generator — for example, a starting charger for a car.

The supply voltage supplied by the generator system installed in the outboard motor.

Almost all such systems work with a voltage of 12 V — this is a standard widely used in modern automotive and water technology, it is under it that the electrical systems of the engines themselves, and electronic devices for cars and boats are made. There are practically no exceptions to this rule.

The highest current that the generator system installed in the outboard engine is capable of delivering (see above). The characteristics of the load that can be connected to the generator depend on this indicator: its total current consumption should not be higher than the maximum current of the generator, otherwise the latter will work with overload, which is fraught with malfunctions and even accidents. Also, this information is useful if you plan to use the generator to charge batteries (car or boat): each battery has its own charging current, and the power source must match them.

The type of gasoline recommended for use in an internal combustion engine outboard (see "Engine Type"). In fact, this paragraph indicates gasoline with the lowest octane rating that is allowed to be used in the engine; higher rates are allowed, lower ones are highly undesirable, if not outright prohibited.

The octane number is an indicator that determines the resistance of a particular brand of gasoline to detonation (self-ignition during compression in the cylinder). Detonation is a very undesirable phenomenon, because. it leads to an increase in engine loads simultaneously with a decrease in its power and an increase in the amount of harmful substances in the exhaust gases. And this phenomenon occurs in cases where the engine uses gasoline with lower octane numbers than those for which the unit is designed.

Automobile gasoline, which is also used for refueling boat engines, is marked with the AI or RON index; the first option is used in the characteristics of east european motors, the second — in foreign ones. However, in both indexes, the number after the letters means the octane number. The higher this number, the more demanding the engine is on fuel quality. Thus, for example, a unit under AI-92 will be able to work normally with AI-95, but AI-90 or AI-87 cannot be filled into it. "Record holders" for unpretentiousness today are engines that can work even on the AI-76; but they are a rare exception to the general rule.

The gear ratio describes how fast the propeller of the outboard motor rotates relative to the speed of rotation of its shaft. For example, a gear ratio of 2 means that for each revolution of the shaft, the screw, in turn, makes two revolutions (that is, it rotates twice as fast). In modern outboard motors, this parameter, in fact, is purely reference, because. the practical characteristics of the unit (power, traction, etc.) depend on many design features and are practically not related to the gear ratio.

The design of the propeller supplied with the appropriate type of outboard motor (see above). In this case, the simplest division is used — by the number of blades.

This indicator actually refers to reference, and not practically significant, because. the practical characteristics of the propeller depend not only on the number of blades, but also on their shape and length, and a number of other indicators (power, thrust, etc.) affect the general characteristics of the motor. In addition, manufacturers tend to select propellers based on the best match with the desired capabilities of the motor.

The presence of the motor rev limiter.

This function is most often implemented in the form of an automatic system that prevents overloads and overheating of the engine: when the temperature rises critically, fraught with overheating, the automation reduces the engine speed, allowing it to cool down (or at least not heat up further). Of course, when the system is triggered, the speed of movement decreases, but this can hardly be considered a serious nuisance compared to a motor breakdown.