Factors of why fuel economy changes

The fuel economy of modern engines may change over the life of the engine. These changes, which can be either increased or decreased fuel economy, are likely to be quite small. The way a machine is operated can have a big impact on fuel economy, as can the design of the engine installation. By involving Perkins engineers early in the design stage you can benefit from their experience of integrating engines into machines for optimum performance.

Many factors can influence the fuel economy of Perkins engines, from the way you design the machine it powers to how the engine is operated over its lifetime.

Many engines will experience a slight improvement in fuel efficiency in the first few hours of their life. This so-called ‘de-greening’ varies from engine to engine. As a result of small reduction in friction over the first 100 hours, an engine can often produce more power on the same fuel, resulting in a small increase in fuel economy.

Normal wear is another factor. Some engine components may change slightly over their life, with a positive or negative effect – usually very small – on fuel economy. On some engines with aftertreatment, there may be a slight deterioration in fuel economy as the aftertreatment ages. These long-term effects will be very gradual and very difficult to measure, as other machine components will also experience wear and change machine efficiency.

Machine design plays a big part

The way the engine is integrated into a machine can have a significant bearing on its fuel economy. Machine designers often use an engine’s maximum power or torque as their point of reference for specification. In reality, that’s not a good indicator of how efficient an engine will be in the machine as few machines spend significant parts of their life at full torque.

Factors of why fuel economy changes
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Factors of why fuel economy changes

At Perkins, our strategy is to optimise our engines for the torque and speed conditions where machines actually spend most of their life, rather than at peak power.

If you’re looking for maximum fuel economy, you might consider reducing the engine speed as part of your machine integration strategy. It also pays to use an engine that’s the right size and is not too big for the machine, however both of these strategies need to be applied with care. Our engineers work with many customers on machine integration projects, and can help to avoid any of the potential pitfalls of reducing engine size or speed.

More significant factors

The biggest contributor to fuel economy is not the engine itself. Numerous studies have concluded that fuel consumption varies widely between operators.

Whilst operator training is one approach to improving this, another is to design software features into your machines that will enable all operators to use the machine at efficient operating points.

By involving Perkins in engineer-to-engineer discussions in the early stage of machine design, the engine and machine can be integrated together for best possible real-world fuel consumption over the whole working life of the machine.