Torque Show

Manufacturing engines and transmissions that are original equipment in the Freightliner and Western Star brands, Detroit also takes a prominent place in the latest fuel cell and electric drivetrain developments for parent company Daimler.
Engine assembly line at a Detroit production facility in the US.

Owned by Daimler since 2000, the organisation once known as Detroit Diesel was rebranded simply as Detroit in 2011.

As the organisation progressed to become more than an engine manufacturer, componentry including transmissions, drive axles, telematics and safety systems have become important features of the Detroit portfolio which today also extends to include electric drivetrains.

The current annual production of the plant in Detroit, Michigan totals 110,000 heavy duty engines, 10,000 medium duty engines and 45,000 transmissions. Since its purchase by Daimler, Detroit has since been a key factor in the global developments and manufacture of Daimler’s major truck driveline components.

Detroit continues to develop and refine its range of diese- powered engines in parallel with rapid developments in battery electric and fuel cell electric technologies and is the supplier of the electric drivetrains in the successful Freightliner eCascadia trucks.

“The long-term future is all about zero emissions,” says Bob Gowans, Business Manager–Detroit at Penske Australia.

“As a business we are part of the Daimler family globally and Detroit is absolutely up there in terms of fuel cell and electric drivetrain developments. For the moment, our strategy for Australia is to make the best of the fuel we have available and keep improving the fuel consumption within the legal requirements as far as emissions go, and to make the most of renewable options within a combustion engine.

“We want to minimise the fuel we use, which is a noble thing to do from a CO² point of view, but it’s also a fairly important thing to do from an operational question of how much it costs to run a truck.”

Every Detroit engine in the truck range is now Hydrotreated Vegetable Oil (HVO) fuel compatible. HVO is chemically identical to diesel and the engine operates exactly the same when running on the renewable fuel.

A key environmental factor is for the HVO to be sourced from agricultural crops rather than fossil bases such as natural gas as it looks to provide a medium-term solution for applications in remote locations where electricity or hydrogen facilities are unlikely to be readily available.

Down-speeding has also contributed to the current Detroit engines’ fuel efficiency and lower exhaust emissions.

“Down-speeding suits the light- to medium-duty cycles that we see in hundreds of thousands of trucks in the United States,” says Bob. “You can argue that a single trailer or even B-double application here is not that difficult a duty cycle for the engine because we’re not actually running it at full power for significant portions of the time. With down-speeding we’re getting the same power and torque outputs at a lower engine speed which results in a more efficient engine.”

The DD13 and the DD15 used in the United States are providing maximum power at 1500rpm, requiring a drop off in the engine speed.

The DD16, according to Bob, is purposely an 1800rpm maximum power engine which utilises the turbo compounding technology to recover energy from exhaust heat and significantly improves the thermal efficiency of the engine.

Bob Gowans.

The inherent design of Detroit engines such as the DD13 has focused on delivering a long flat torque curve to provide the driveability and fuel efficiency associated with engine down-speeding.

This has resulted in the DD13’s ability to deliver 90 per cent of its peak torque in just 1.5 seconds, whereas a competitor’s engine in the same time frame will only be at 50 per cent.

Factors contributing to this improved performance include the use of non-waste gated turbochargers and low inertia camshafts. The use of the proprietary asymmetric turbocharger reduces weight and complexity plus delivers improved performance with sustainable reliability.

The turbochargers are manufactured in-house by Detroit and the turbo shafts have a tolerance of just six microns. The manufacturing process involves bar codes and data matrix stamps to ensure the aerospace-like quality of the components which is intended to eliminate any turbo problems to be associated with Detroit engines.

Turbocharger testing involves shaft speeds of up to 405,000rpm.

“Turbo compounding works when you have nice high gas flows in a fast-spinning engine,” explains Bob. “That works well in the DD16 which is our highest performance engine and for the power and torque that it produces it’s great on fuel.”

All displacements of the Detroit engines benefit from having similar modular designs incorporating wet cylinder liners, cast engine blocks and one piece cylinder heads.

Extensive webbing in the Detroit block castings is used for strength as well as reduction in noise and vibration.

Detroit engines are renowned for the retardation braking capabilities delivered by the improved ‘Jake’ engine brake which is integrated into the overhead camshafts rather than located on top of the rocker arms.

This design provides three stages of engine braking and is relatively quiet in its operation, allowing for the safe application of the engine brake in built up areas.

Most key maintenance components are located above chassis rail height to provide direct access for servicing technicians and results in reduced service time being required, as well as good heat dissipation. Large capacity engine sumps help extend oil drain intervals as does the maintenance free crankcase breather which is a closed system and returns any blow by oil to the sump.

After assembly, every engine is hot run tested on one of the 42 dynamometers located in the Detroit plant prior to being shipped.

At the Daimler truck plant in Charlotte, North Carolina, the engines are retested after installation into Freightliner and Western Star trucks to ensure there are no issues and to confirm the power and torque ratings.

Intended to provide first rate performance for a long operating life, Detroit engines have been designed and manufactured with best-in-class fuel economy and low-cost maintenance and service in mind.

This, combined with environmentally responsible emission levels, make it a formidable product platform.

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