The X15N™, an improved design thanks to customer feedback

Summary

The trucking industry is moving towards cleaner, more efficient engines – and the Cummins X15N™ natural gas engine is a big step in that direction. This article explores the X15N’s new features and improvements that were developed based on customer feedback and experiences with the 12-liter ISX12N™, our first natural gas engine designed for use in class 8 trucks. The X15N embodies Cummins’ dedication to innovation and our dedication to customers and their feedback.

Performance improvements from the ISX12N

The ISX12N taught us a lot of lessons about how a natural gas engine needs to perform in the heavy-duty truck market. We carried those lessons and the customer feedback into the design and engineering of the X15N to make it a true heavy-duty option. The X15N was built specifically as a natural gas engine and leverages Cummins’ HELM™ platforms. Here are the highlights on some of the component improvements compared to the ISX12N:

• An X15N natural gas-specific cylinder head allows for improved thermal distribution and improved spark plug life.
• The sculpted block and compact design for the X15N results in reduced weight compared to the ISX12N.
• The X15N turbocharger is now a dual-entry wastegate and has upgraded materials for improved durability and altitude performance.

With up to 500 hp and 1850 lb-ft of torque, the X15N has more low-end torque than the previous model. It has nearly 40% more engine braking power than the ISX12N, and additional braking horsepower is available with the fan on.

In terms of emissions, the X15N meets U.S. Environmental Protection Agency (EPA) and California Air Resources Board (CARB) regulations for 2024. This engine can also significantly reduce greenhouse gas emissions compared to diesel engines. Yet, the environmental benefits really shine when using renewable natural gas made with biogas that offers a carbon intensity that can be neutral or even below zero, depending on the energy source.

Lower total cost of ownership

One of the standout features of the X15N is its improved fuel economy, which is roughly 10% better than the ISX12N with a matching rating and similar duty cycle. This reduces operational costs, and, since less fuel is burned, combustion emissions are also reduced. The X15N has improved fuel control with a fuel injection system that consists of eight separate solenoids instead of the large single fuel control valve on the ISX12N.

The X15N aims to further reduce downtime by increasing the intervals between oil drains and improving spark plug life. This has been made possible by increasing the oil capacity, improving the power cylinder and managing oil oxidation to consequently bring down the rate of oil degradation. The X15N spark plugs have increased ceramic strength and electrode geometry and material, and when coupled with the reduced temperatures, improves its plug life.

All these improvements align with industry ions? to minimize environmental impact through decreased waste and encouraging a longer lifespan for essential engine components.

Improved durability

The X15N engine introduces several features aimed at improving durability and reliability, drawing on the lessons learned from the ISX12N.

One key change is the use of steel pistons, which are more resistant to wear and tear. This adjustment, paired with an integrated ignition and injector control systems, promises to offer more reliable operations and longer engine life.

Furthermore, the ignition system has moved from being a capacitive to an inductive system, which has extended the life of spark plugs. This transition minimizes the need to disconnect the engine harness when replacing spark plugs, reducing wear on terminals and preventing the ignition coil from heat exposure inside the adapter tube, ultimately increasing reliability.

Additional enhancements in the engine include modifications to the crankcase ventilation system motor alignment, the adoption of stainless steel upper and lower bearings with better sealing, and the use of larger bearings. These improvements mark a step forward in achieving a durable and reliable engine.

Fully optimized powertrain

The X15N offers a fully optimized powertrain that integrates the latest advancements in transmission and fuel delivery systems. Specifically, when paired with Eaton Cummins Automated Transmissions' HD™ N 12-speed or XD™ N 18-speed transmission, the engine operates with unmatched efficiency and performance. This synergy allows for smoother gear transitions, improving the overall driving experience, and reducing wear and tear on the vehicle's systems.

Moreover, the incorporation of the Fuel Delivery System from Cummins Clean Fuel Technologies provides industry-changing fuel systems designed with drivers and fleet operators in mind.

The Cummins X15N represents the new era of engine technology and is ready to power fleets to get the job done while reducing emissions. Contact your local Cummins sales office or preferred OEM today to learn more.