New levels of performance, comfort and environment for next generation of diesel engines from Volvo Penta

Volvo Penta is now introducing a totally and newly developed generation of diesel engines, D4 and D6, to the leisure boat industry. The latest technology, including electronically controlled, common rail, direct fuel injection, combines performance with environmental properties that were previously impossible. The results are powerful torque and high power output combined with low exhaust and noise emissions. The D4 and D6 will meet comprehensive environmental requirements planned for introduction in Europe and the US in 2006.
Volvo Penta has a strong position today in the market for high-performance diesel engines ranging from 100 to 300 hp. For all types of planing craft up to about 40 feet, Volvo Penta is the leading engine supplier, thanks in large part to its KAD300. This popular diesel engine has sold more than four times its projected volume and further strengthened Volvo Penta’s position in the leisure boat industry.

Volvo Penta is now taking the next step through its launch of a completely new generation of diesel engines: D4 and D6.

The new engine program was developed completely from scratch and contains a number of new technical solutions that provide a unique combination of high performance, comfort and environmental properties.

One of the objectives when Volvo Penta decided to develop the new diesel engines was to create compact external dimensions combined with large cylinder volume.

The result has exceeded the company’s highest expectations.
“The engines are very compact. Using integrated cylinder liners and a large number of intelligent component solutions, we succeeded in creating large cylinder volume in a compact engine. D6 is the same size as our present 300-engines, but has 30% more cylinder volume, which provides several advantages, particularly the capacity to generate high power output and fine engine performance character,” says Rickard Stefansson, project manager at Volvo Penta.

Low noise and minimal vibrations are high-priority properties of the new D4 and D6. The engine blocks are cast in a single die and are extremely robust. A ladder frame is placed between the engine block and crankcase to reinforce and further stiffen the construction. All of these factors contribute to improved vibration and noise properties.

Low emissions
The capacity to control the flow of fuel to every cylinder at every moment is completely critical for the engine’s performance and environmental properties. The first stage is to replace mechanical control with electronic, a concept that Volvo Penta introduced in 1995 with its EDC-system.

The next major step is being taken now with the introduction of electronically controlled, common rail direct injection.

“In simplified terms, common rail means the fuel is constantly under pressure, which creates a continuous injection pressure in the system. The injectors in every cylinder are controlled by electronics that can release the right amount of fuel at precisely the right time. With electronically controlled common rail, we can now control fuel combustion in a way that was never possible in the past. The result is improved fuel consumption with low exhaust emissions that will meet future comprehensive requirements planned for introduction in Europe and the US in 2006,” says Rickard Stefansson and continues.

“The fuel is fed into the cylinders as many as three times per power stroke. This provides a softer combustion and much lower noise level – the characteristic diesel knock is completely gone. The D4 and D6 engines can also be driven on environmental diesel with full performance standards. And they do not lose power if the fuel is warm, since the fuel system adjusts and compensates for temperature differences.

The D4 and D6 are also equipped with EVC, Volvo Penta’s new electronic CAN-bus based platform, which enables the engine, control and instruments – as well as other functions on the boat – to communicate and exchange information.

Turbo for performance
D4 and D6 will be used on different types of planing boats. Good torque and acceleration, as well as high top speeds, are properties that more customers are demanding today.

“We have selected a traditional turbo that covers a broad rpm range complemented with charge-air cooling and four valves per cylinder. Combined with the large cylinder volume of the engines, this provides powerful torque and high power output. Special priority was assigned to the torque at low rpm, which creates rapid acceleration even if the boat is heavily loaded. High power output provides high top speed and, in turn, effective and economical cruising speeds,” says Rickard Stefansson.
Rational development
Two completely new diesel engines, tested and ready for production in less than four years, is fast work for a company the size of Volvo Penta.

“We used the marine know-how available at Volvo Penta and complemented our skills with contracted expertise in certain areas. Powerful IT-support and very short lead-times in all prototype activities enable us to work fast without sacrificing our high quality standards,” says Rickard Stefansson.

Rapid development does not mean fewer tests. The engines undergo a comprehensive, three-stage test plan during which development personnel have opportunities to make adjustments between each stage. The tests are conducted on testing benches, but also on different types of boats. Volvo Penta has its own test boats for which the engines are intended. And they are driven in comprehensive tests under all imaginable conditions.

Duoprop and inboards
The D4 and D6 engines are available both with Volvo Penta Duoprop drivelines and as inboard engines with hydraulic transmissions. The new DP Duoprop driveline was developed exclusively for D4 and D6, thereby providing extremely fine performance and high reliability. Hydraulic power steering is standard, and a completely new propeller series has been developed. The propellers are produced using an alloy consisting of nickel, aluminum and bronze and are available in nine different sizes for speeds up to 45 knots. For faster boats, the DPR-driveline was developed for speeds in excess of 45 knots.

Existing diesels will be retained
The new D4 and D6 will be top-of-the-line products in Volvo Penta’s already strong range of performance diesel engines, in which previous KAD and KAMD series have achieved substantial success on the market. These products, including the KAD300, will remain available. At the plant in Vara Sweden, Volvo Penta plans to produce its existing turbo diesels in parallel with the new generation of diesel engines to make both models available on the market.

Technical data
Engine model: D4-210
Crankshaft power: 210 hp at 3,500 rpm
Maximum torque: 500 Nm at 2,000 rpm
Configuration: Straight four-cylinder, with turbo and charge-air coolers
Alternator: 115 A
Cylinder volume: 3.7 liters
Weight, excl. trans: 482 kg
Emissions: Will meet future comprehensive requirements to be
introduced in Europe and the US in 2006.

Engine model: D6-310
Crankshaft power: 310 hp at 3,500 rpm
Maximum torque: 730 Nm at 2,000 rpm
Configuration: Straight six-cylinder, with turbo and charge-air coolers
Alternator: 115 A
Cylinder volume: 5.5 liters
Weight, excl. trans: 580 kg
Emissions: Will meet future comprehensive requirements to be
introduced in Europe and the US in 2006.