During the 1970s, Volvo Penta developed a compact lightweight diesel engine in cooperation with Volvo Trucks. This gave rise to the MD40, a six-cylinder diesel engine with a 3.59 cylinder volume, available with or without turbocharging. The 40 series, as it was called, was an instant success. Its high output and minimum weight were ideal for planing leisure craft. The product range was extended with the introduction of the smaller, four-cylinder 30 series in 1982.
Concept development
The concept of compact, high-performance diesel engines was highly successful for Volvo Penta and became a key feature of its overall product line. Volvo Penta has consistently enhanced its engines in response to the continual demand for higher output and ever-better performance
The TMD40 provided 130 hp when it was introduced. With turbo and charge-air cooling, this could be raised to 165 hp, and even up to 200 hp when fitted with direct injection. A major step was taken in 1991 with the launch of the KAD42 and KAMD42, which provided 230 hp. With this model, Volvo Penta supplemented turbocharging with a mechanical compressor. The result was high power directly from low rpms for rapid acceleration, plus high peak output to ensure top speed. The KAD42 paired with Duoprop proved extremely popular and remains one of the top-selling diesel engines worldwide.
In 1997 the KAD-series was extended with the addition of the four-cylinder KAD32 and six-cylinder KAD43, as well as the electronically controlled KAD44 EDC offering 260 hp. Two years ago, the KAD300 was introduced, which, with its 285 hp, offers more than twice the output as the original TMD40.
Over the years, Volvo Penta has been alone in developing drives specially tailored for diesel engines. Compared with gasoline engines, a diesel works at lower rpms and higher torque – a combination that imposes major demands on drive strength. Moreover, the diesel engine’s character also calls for specially developed propellers to optimize efficiency.
More stringent environmental requirements
In recent years, the focus has switched increasingly to the environmental features of engines, but by no means at the cost of performance. Instead, the requirements are now higher output and simultaneously lower emissions.
“These demands prompted us to launch an entirely new generation of diesel engines. These engines are completely innovative developments based on the very latest technology. Common rail, combined with advanced electronics, gives us precise control of combustion to suit all operating conditions. We can adjust engine character in terms of output and torque to match marine requirements, while also controlling exhaust and sound emissions in a manner previously impossible,” notes Conny Frick, Product Planning Manager Volvo Penta.
Emissions are also well below those of equivalent older engines. Compared with a 10-year old engine, for example, nitrogen-oxide and hydrocarbon emissions have been slashed by some 70%, thereby meeting the general requirements scheduled for introduction in Europe and the US in 2006.
The new generation
The D3, D4 and D6, which have now been launched by Volvo Penta, represent the very latest generation of high-performance diesel engines. These wholly innovative products feature state-of-the art technology. The new engines will be top-of-the-line in the Volvo Penta product range, which will also continue to include the current turbo diesels and, of course, the KAD and KAMD series
“Obviously, we’ve used our own engines as the yardstick in our development program, since these are the market leaders. But the new engines outclass everything! We’re offering 310 hp – compared with the current 285 – along with a newly developed Duoprop drive, which offers boat builders far greater potential to install this type of drive on larger craft than in the past. Lower noise and minimized vibration offer superior comfort. We’ve boosted performance, particularly due to the newly developed drive and new propellers, which provide higher efficiency. Finally, extended electronic control makes it simpler and more fun to drive boats fitted with the new engines,” concludes Conny Frick.
