Important tips for repowering diesel engines more cost efficiently and in compliance with changing regulations
By Ran Archer
Fuel expense is the single highest operating cost of diesel-powered mining trucks and excavators. Typically, 80%-90% of variable operating costs are allocated to fuel. A fuel savings of just a few percentage points can save thousands of dollars per year, even in the smallest equipment fleets. Achieving improved fuel economy is an extremely important consideration when evaluating a strategic repower. Integral to the success of modern mining operations, successful repowers allow an engine to operate along the optimum power curve, which contributes to highest performance and lowest fuel consumption.
When an engine’s power capability is configured specifically for its applied load, peak performance can be achieved. For example, a haul truck transporting dense copper ore out of a deep pit has a dramatically higher applied load factor than a truck operating in a downhill haul in an Appalachian coal mine, but the same truck model in both applications is often powered by the same engine model with the same maximum power rating.
For the truck operating in a lighter duty load profile, excess available power may not result in faster cycle time or higher payload capacity, but very likely will result in excess fuel burn, and higher haulage costs for the mine. On the other hand, engine life is directly dependent on fuel consumption and the amount of time it operates below rated power. In other words, time between engine overhaul increases in proportion to the time the engine operates below rated power. With this in mind, a truck operating with a low load factor would be a prime repower candidate for replacement with an engine of lower rated power or, in some instances, of smaller displacement.
The differences in the mining industry’s highly variable terrain and production objectives can dramatically impact the ability of OEM factory-configured equipment to operate most efficiently. Straight off the assembly line, standard mining equipment isn’t necessarily customized for a specific haulage or loading profile, or the mine plan evolves over time and the initial engine configuration is no longer optimum. By taking a strategic approach to an engine repower project with the end goal of optimal performance of the complete system, mining equipment operates cleaner and more efficiently with longer engine life between overhauls.
Repowers also give mining operations the opportunity to trial and leverage new technology, such as Tier 4 Final engines at considerably lower cost, and therefore, reduced risk compared to the capital-intense investment of a new vehicle purchase with the T4 engines.
Tip 1: Choose the Right Engine for the Job
To ensure an engine repower project hits the mark, tap into the expertise of a local equipment distributor. With their repower experience and support from the factory, they can renew and upgrade equipment to maximize uptime, minimize fuel consumption and reduce maintenance costs.
A distributor, in partnership with the factory experts, understands the business and can ensure performance and cost expectations are achieved while addressing safety, performance expectations and achieving relevant emissions requirements. With careful analysis, the distributor and factory team members will maintain the delicate balance between power downgrades to achieve cost savings while preserving productivity targets. In some instances, the engine is available with multiple engine power ratings that can be implemented simply by changing the engine calibration. This provides the needed flexibility to scale power to the haulage or loading requirement and avoid an under-powered vehicle with low productivity, reduced component life and higher maintenance cost.
Across the board, the engine manufacturers that have spent the most time engineering their systems, build the most economical and productive engines. Tier 4 engine technology has undergone extensive development to achieve cleaner engines to meet lower exhaust emission regulations, to ensure engines run cleaner, and ultimately require less maintenance.
Repowered equipment will likely feature second-generation common-rail fuel injection, advanced electronic engine controls and more precise fuel metering for improved combustion compared to Tier 1 engines. The cleanliness of an engine’s exhaust is determined by the unit combustion control. The clean combustion of a Tier 4 engine also reduces the amount of soot and combustion byproducts that contaminate or degrade the oil, which helps increase the time before overhaul compared to earlier generation engines.
With extensive engine-application knowledge, a distributor or service provider will carefully consider the equipment’s load profile to avoid sub-optimal system operation, which, beyond compromised durability, can result in inefficiency and higher emissions and operating costs. Together, the coveted balance between reliability and maximum efficiency will be found and the investment will be better protected.
Tip 2: Read the Fine Print
Work with a distributor to make sure the repower strictly adheres to environmental regulations in order to avoid fines.
In an effort to standardize and regulate engine emissions across the board, the U.S. Environmental Protection Agency (EPA) forbids the reselling or reuse of engine cores—even if exported outside the country. Repowered engine cores of prior emissions certification (e.g., Tier 1 or Tier 2) must either be destroyed or sent back to the manufacturer to be remanufactured and stamped with a new serial number. Missing this step will result in large fines accumulated on a per-day, per-engine basis. Financial ramifications this serious could cause significant economic damage to any mining company.
The distributor will also assist in creating a custom maintenance plan for a fleet, which they will recommend a customer follows exactly as prescribed. After consultation with mining customers, engine manufacturers made longer maintenance intervals a key objective in Tier 4 engine development. To avoid catastrophic failure, special precautions are taken to maintain fuel cleanliness and protect the system’s fuel injectors. Distributors can often map out service schedules 12 to 18 months in advance, determining the ideal oil change, fuel injector and turbo change-out intervals for each individual engine. With downtime planned far in advance, mines have the power to plan their business accordingly.
Tip 3: Maximize Downtime for System-wide Harmony
By now, one should have already balanced the cost of a repower with projected fuel savings and determined if a repower is a worthy investment. Engine repowers involve vehicle outage time and present an opportunity to simultaneously upgrade other system components and complete additional maintenance. Consider value-added upgrade options, such as the installation of a larger battery-charging alternator or valve adjustments.
Using this vehicle outage time to implement system changes that will improve fuel cleanliness and protect the system’s fuel injectors is also ideal. Improved fuel filtration reduces injector wear, ensures accurate fuel metering over longer operational time periods, further improves fuel consumption, and extends cylinder component life.
In a business where a single truck can cost millions of dollars to own and operate, every detail counts. Once the repowered equipment is back to work, the decrease in fuel consumption should be evident. However, one might be surprised by additional improvements in noise reduction, responsiveness and maneuverability. When the match between load factor and horsepower is optimized, the entire system will improve and a fleet will be primed for peak performance, which will usher in maximum return on investment.
Ran Archer is the senior sales manager at MTU America in Detroit, Michigan.
Dangers of Water in Fuel
With water in diesel fuel an everyday issue, Clean Solutions, a division of Donaldson, pointed out recently that more and more equipment operators are affected by this often significant problem.
“Free water is probably the single biggest cause of fuel system failure,” said Scott Grossbauer, global director for Donaldson Clean Fuel and Lubricant Solutions. “Engine manufacturers require that zero free water reaches the high-pressure common-rail (HPCR) fuel system, which often means that water in the fuel can lead to denied warranty claims. Additionally, the elimination of water will reduce rust, corrosion, wear, fuel degradation and other damage.”
The company released a short webinar, Water in Diesel Fuel—Best Practices for Getting it Out and Keeping it Out, earlier this year to focus on the variety of problems caused by water in diesel fuel as well as remedies and best practices for keeping fuel clean and dry from the moment it is delivered to a user’s bulk tanks until it is combusted by the engine. It joins other webinars, titled What is Dirty Diesel Costing You? and The Challenges of Diesel in Cold Temperatures, which are already available via Donaldson’s website.
Donaldson officials announced in March that Clean Solutions had developed a strategic alignment with Ryder Fuel Services to provide end-user customers with services that complement their industry-leading bulk filtration products. Ryder offers fuel management, compliance management and project management services.
