Spray-type motors Yamaha Z300 with HPDI system

An interesting 3.3 liter outboard motor of 300 hp came to light relatively recently. To be precise there are two 300-horsepower engine: one is in the “civil” series – «Z300A» («LZ300A»), the other – in the famous series «VMax» – «Z300B».
The design of the fuel system of both models use the same principle, or HPDI, which means “high pressure direct injection of fuel.” And all the major wonders such as efficiency, cleanliness, low vibration (in part) engines – mainly the result of applying it HPDI and other related technologies.

In engines with HPDI some modes that are very tempted to call economical fuel mixture artificially impoverished, and thanks to the original form of the combustion chamber and clear the control computer, which is tied not only to the fuel supply system and ignition system, combustion is obtained to the fullest.

“The maximum complete burning” – this is not absolutely complete combustion, as some might think, but the process by which to date with current technology and manages to burn the maximum amount of air fuel mixture entering the cylinder. But as you know, depleted fuel mixtures have several other combustion modes, rather than conventionally say, classical, and require more durable and, most importantly, more heat-resistant piston elements. And as with HPDI engines can run on blends of homogeneous, they are, in spite of a large swept volume and high power, are today among the most efficient in its class.

The combustion chamber of engines we have developed a structure that allows them at 2500-5500 rev / min continuously work on a homogeneous mixture, which, in turn, leads to fuel savings. To all cylinders fuel mixture is ignited at a certain time and a possible heterogeneity of gasoline (which is observed not only in our country) did not affect the power unit operation (excluding operation of the ignition system and injector), gasoline through the nozzle enters the combustion chamber at a very high pressure – 1000 psi (69 atm), which provides a special high pressure pump. For comparison, the motors «Yamaha» working volume of 2.6 liters in the fuel line pressure up to 700 psi (48 bar). Conducted ten years or so ago, studies have shown that high blood pressure in the injectors not only makes supplied into the cylinder “aerosol” is very fine, but even slightly alters the properties of the fuel due to its compression. It turns out that the higher the pressure at which fuel is injected to the combustion chamber, the higher the energy efficiency. And to bring the pressure in the system to correct and maintain it during operation of the motor, «Yamaha» applies the principle laid down in the same diesel engine with Common Rail technology, which provides the presence of a pressure accumulator.

When considering the moment of ignition, combustion mode and the like must be borne in mind that the 3.3-liter engine runs in a rather harsh conditions, and any, even the minimum deviation from the desired parameters can affect the stability of its work. In this, to eliminate the influence of external conditions on the operation of the motor, it is equipped with a large number of sensors that sensitively catch changes in the environment and promptly report it to the central control processor or ECM. It was he who, relying on the extensive database, forms the fuel mixture and determines the optimum injection timing and ignition timing for each situation. The power control unit is sufficiently large, and the information is processed in a split second. And even with a sharp, sudden change, such as temperature, humidity, the amount of oxygen in the air at the root of the ECM “suppresses” the impact, contributing to the work of their corrections systems.

One of the unique features of the outboard «Z300A» motor is the availability of a forced cooling system inlet path, due to which the air is further cooled, which in turn provides greater stability of the motor operation.

Now let’s say about the overall design of «Z300». «Yamaha», as any manufacturer of motors, based on when they were created some of his inner development, not only in terms of system devices. In this case, it opted for the collapse of the cylinders in 76 °. What exactly caused such a solution is difficult to say, but the engine was very compact, and to deny this fact, hardly anyone will undertake.