Ford's redesigned 2016 F-650 and F-750 trucks will offer a lower noise level than outgoing models mostly due to the redesigned turbo diesel engine, Ford announced on the eve of NTEA's Work Truck Show.

The 2016-MY medium-duty trucks are powered by a Ford 6.7L Power Stroke V-8 that's 25% quieter in the cabin, according to Ford. When idling, the engine is as much as 45% quieter in the cabin and 35% quieter in front of the grille.

"While the truck is able to work harder, we also made life inside the cab easier," said John Ruppert, general manager of Ford Commercial Vehicle Sales and Marketing. "Lowering in-cab and exterior noise levels improves driver comfort and minimizes disturbances while idling at work sites."

When traveling at 60 mph, the level of engine noise in the cabin drops to 68 decibels from 74 decibels compared to the prior model, according to Ford. Idling levels have fallen to 48 decibels from 63 decibels.

(Decibels measure the intensity and power of sound. Each 10-unit increase represents a 10-fold increase in sound power perceived by the human ear, so a 10 decibel sound is 10 times more powerful than a zero decibel sound, and 20 decibels is 100 times stronger than zero decibels.)

Ford achieved the quieter cabin through engine engineering.

The PowerStroke V-8 is the only diesel to be used in the new Ford Class 6 and 7 models. The 6.8-liter gasoline V-10, which is convertible to propane and natural gas, will also be available in the F-650. They will be mated to a 6-speed TorqShift automatic that has been beefed up to take the engines’ output in comparatively heavy service.

Enhancements to the Power Stroke combustion system, structural integrity of the compacted graphite iron block and a single turbocharger mounted to the engine block account for many of the noise, vibration and harshness improvements over the previously offered diesel.

Fuel injectors were upgraded to optimize the combustion process, which features a two-stage combustion event instead of a single-injection event, further avoiding harsh, sudden and loud combustion, said John Davis, chief engineer.

A pilot fuel injection into cylinders begins the compression process before the main injection. The result is smoother fuel burning with less diesel clatter and a reduction of intrusive engine sound both inside and outside the truck.

At idle, two pilot injection events are used to make the firing process even smoother and to aid in quietness. The “ticking” of the high-speed injectors is masked by specially designed covers on the engine.

Mounting the engine’s turbocharger inside the engine block valley also brings improvements in overall noise, vibration and harshness.

“We used smart engineering and our unique Power Stroke engine architecture to create a powerful yet quiet diesel for our commercial customers,” Davis said. The powertrains have been tested to more than 50,000 pounds gross combination weight.

The trucks will be available this summer.