Cummins set to launch its entirely new 15-litre engine platform, Down Under at the Brisbane Truck Show. Called the X15D. The new engines will deliver the highest-ever outputs for a Cummins truck engine while setting new standards for fuel efficiency at ultra-low emissions levels.

Cummins X15D 660 Horsepower
“With the all-new X-series platform, Cummins is taking the internal combustion engine to a next generation level, capable of meeting future ultra-low emission standards with a low-to-zero carbon fuel capability,” said Mike Fowler, director of on-highway business for Cummins Asia Pacific.
In early 2021 Cummins commenced an extensive field test program in Australia.
“The X15D will only be released when we are completely satisfied with its reliability and durability in meeting the harsh demands of the Australian B-Double duty cycle,” Mike explained to KWDU.
A key feature of the X15D is its dry weight reduction of 225 kg compared with the current X15. A sculpted iron block and composite oil pan are among the weight saving features that result in the X15D having the highest power-to-weight density in the industry.
“The unique power cylinder design enables much higher peak cylinder pressures – 20 percent higher than the current engine – and that enhances power density and overall efficiency,” Mike pointed out.
Extreme Pressure Injection
Featuring the latest evolution of Cummins’ XPI (Extreme Pressure Injection) fuel system, the X15D will be offered with ratings up to 660 hp (492 kW) backed up by massive peak torque of 2360 lb ft (3199 Nm).
The highest rating eclipses the current X15 peaks of 615 hp (458 kW) 2050 lb ft (2779 Nm)and will enhance Cummins’ engine down-speeding strategy for improved fuel economy.
“This strategy is about reducing cruise rpm for fuel economy gains while at the same time providing the grunt to meet both driver and trip time expectations,” said Mike, noting that peak torque extends over a wide band, from 1500 rpm all the way back to 1000 rpm.
He pointed out that field trials of the X15D rated at 660 hp in Australia have shown fuel economy improvements up to eight percent. By the end of 2023, more than 10 trucks will be involved in the field trial and the aim is to accumulate more than five million test kilometres.
Furthermore, as part of its ‘Destination Zero’ decarbonisation strategy, Cummins is taking practical steps now to reach net-zero carbon emissions by 2050 rather than waiting for more advanced technologies to be ready to deploy.
This is clearly evident in the all-new X15 platform.
Cummins is continuing to advance the internal combustion engine technology it is renowned for with further improvements in efficiency, as well as compatibility with cleaner fuels like hydrogen, biodiesel and hydrotreated vegetable oil (HVO), also known as ‘renewable’ diesel.
X15D
The X15D is a key part of Cummins’ industry-first fuel agnostic platform, which comprises diesel, natural gas and hydrogen internal combustion engines derived from a common base which facilitates high parts commonality.
The all-new 15-litre platform basically comprises one block and three-cylinder head options – a compression ignition head for diesel, and spark ignition heads for natural gas and hydrogen.
Internal combustion engines have a significantly lower upfront cost than fuel cell or battery electric installations, require little modification to today’s trucks, and provide familiarity for truck operators.
“The X15D will have the flexibility to operate on B100 biodiesel or renewable diesel to significantly reduce CO2 emissions further,” said Mike
B100 biodiesel enables up to a 70 percent reduction in carbon while using HVO renewable diesel achieves up to 90 percent. HVO (hydrotreated vegetable oil) has chemical and physical properties like those of diesel fuel, but its fossil-free composition and low carbon content provides a simple and efficient alternative to diesel. Importantly, HVO can be blended and used in any proportion with diesel which allows for ease of transition.
The natural gas and hydrogen versions of the internal combustion X15 – the X15N and X15H – are expected to become available in Australia in the next two to four years depending on successful field testing. “There’s a lot of interest in both engines,” Mike confirmed.
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