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Power and efficiency are two of the most important factors for semi-trucks. These big rigs can typically travel up to 2100 miles when equipped with two diesel tanks, but that doesn’t make them efficient. The new Volvo VNL line provides new technology, with these trucks being 90% new while providing an efficiency increase of 10% compared to the Volvo trucks from 2015.

Volvo D13 Wavy Piston Cap Design increases power and efficinecy with a cleaner burn in the semi-truck engine chamber.
Volvo D13 Wavy Piston Cap Design | Volvo

What makes these new Volvo semi-trucks more efficient?

Although the total fuel efficiency improvement results from all systems working together, something new happens in the engine. Most engines use pistons with a smooth top, but Volvo learned this creates an inefficient process and doesn’t effectively burn the oxygen in the chamber.

Volvo engineers discovered the flaw with traditional piston crowns using computational fluid dynamics. This led the team to a wavy design, which forces the flame toward the center of the chamber instead of allowing it to move to the walls.

According to The Drive, the new D13 engine piston crowns have ridges arranged radially to control the burn and focus the flame on the center. Fuel injector nozzles are pointed to spray fuel between these ridges, creating flame fronts that move toward the cylinder wall and reverse back to the middle. Early versions of this piston crown had six segments, but the most recent design has seven.

Reduced soot emissions and small gains

Adding of a seventh segment and using smaller, lighter components means more control in the chamber. These upgrades provide a 2% fuel economy increase and cut soot emissions in half.

In addition to the improved efficiency, Volvo uses a lower-profile crown for the D13 engine in the VNL trucks. This reduces friction and side loading on the cylinder walls, making these trucks more efficient. This change provides a small change, but these small gains can add up.

Even the turbo in these Volvo semi-trucks is more efficient

The new D13 engine includes a smaller turbo than most semi-truck engines. Typically, maximum torque occurs between 1300 and 1500 rpm. Still, with this engine and turbo, the max torque begins at 1050 rpm and is maintained until 1500 rpm. This allows for another 1.5% increase in fuel economy.

How efficient is the new VNL semi-truck line?

Using the D13 inline-six engine, the new VNL truck line can reach maximum torque figures of 1,850 lb-ft and returns 8.5 mpg while driving at 85 mph. This is an incredible figure for big rigs that pull up to 80,000 pounds across the country.

The new VNL semi-truck line comes in six cab configurations, four trim levels, and three versions of the D13 engine.