Engine Decisions Require Research

Michael Moore$139 billion. This is the projected health cost our federal government estimates we will spend this year due to diesel exhaust exposure.

21,000. This is the number of people projected to have their lives shortened each year as a result of diesel exhaust exposure-related illnesses, representing the tragic human cost.

Our federal government – specifically the Environmental Protection Agency (EPA) – is determined to improve those costly numbers by mandating new 2010 emission standards for all on-highway diesel engines.

Embracing Change

This time around, we have several reasons to welcome these new emissions standards. The new engine technology is not only cleaning up the air we breathe, but you will also see improvements such as fuel economy, a dramatic reduction of diesel-particulate-filter (DPF) regenerations, and noticeably better throttle response.

While there is no doubt the new standards will add more dollars to the sticker price, it’s a change we all need to embrace.

Two Technologies

Two technologies emerged in the race to meet 2010 emission standards. Soon everyone will be faced with deciding which engine (and technology) to purchase since the inventories of vehicles with older engines, which flooded the market earlier in the year, are in short supply.

The most prevalent technology is referred to as “selective catalytic reduction” (more commonly called SCR); the other is “exhaust gas recirculation” (referred to as EGR). Companies promoting these two technologies have much at stake in the 400,000-unit over-the-road truck market. As such, a battle is taking place, and this fight has included lawsuits and has spawned a significant amount of misleading information that is spilling over into the much smaller fire market.

Now that most original equipment manufacturers (OEMs) have completed design, testing, and packaging of these engines into their products, our market can get a much clearer picture of their true impact.

To better understand the decision at hand and clear up misconceptions, one must first understand the technologies. Let’s start with the most prevalent technology being used.


SCR is based on treating the exhaust downstream of the engine, removing and reducing particulate matter (the black soot you associate with old diesel engines) and nitrous oxides (think smog).

Treating the exhaust includes the use of a particulate filter (introduced to diesel engines since 2007) to trap the particulate matter, a catalytic device, and a new fluid referred to as “diesel exhaust fluid” (DEF) to convert the nitrous oxides, These elements combine to trap soot and turn nitrous oxides into harmless water and nitrogen.

This method allows the engine manufacturers to tune the engines to operate at peak performance, and that is where the following benefits are achieved:

  • Increased fuel efficiency (5 to 7 percent over 2007 engines).
  • Increased horsepower in some engine models.
  • Longer service intervals in some brands.
  • Noticeably improved throttle response.
  • Far less DPF regenerations to remove soot from the filter than the 2007 engines.

SCR is a proven technology that has existed for more than 40 years in industrial applications and for the past six years in Europe to meet EURO4 standards. It is widely used by companies such as Detroit, Cummins, Mack, Volvo, PACCAR (Peterbilt & Kenworth), Ford, Dodge, Mercedes, Toyota, Hino, and Isuzu to meet 2010 standards.

Most of the apprehension regarding SCR technology surrounds system packaging on the vehicle and the use of diesel exhaust fluid. The DEF concerns include whether it’s toxic (it’s not); whether it’s available (it is); whether it has a short shelf life (it does not); and its cost (it is about the same as diesel fuel).

Those DEF concerns are understandable since it is a new fluid to the fire industry. However, we need to consider for a moment that all of these concerns have been addressed for the much larger over-the-road truck industry, which is at least a year ahead of the fire market.

Most OEMs have completed designs and packaging of the SCR system on fire apparatus. Solutions have been developed that have little to no impact on wheelbases, cabs, bodies, or option availability. In fact, other than keeping the DEF tank topped off like one would do for any other fluid on the vehicle, SCR can be virtually transparent to most fire departments.


The other technology, EGR, is based on reducing emissions in the engine’s cylinder by recirculating some of the exhaust back to the engine to burn off the pollutants. EGR also works to reduce in-cylinder temperatures, causing the diesel engine to produce lower nitrous oxide levels. This is the basis for the EGR approach, and it is accomplished through larger cooling systems, as well as new fuel and cylinder technology pioneered by the engine manufacturer.

EGR systems still contain a diesel particulate filter (DPF) that will regenerate to burn off the soot, as well as larger cooling systems that may impact custom cab space and/or size. The system does not, however, require the use of diesel exhaust fluid or a catalytic device.

Do Your Homework

The path taken for buying fire apparatus has always been lined with hundreds of decisions. The good news is there are still engine choices available. The technologies used to meet the new emission requirements offer you a number of options, which means more decisions must be made.

As you begin the task of specifying your next vehicle, you undoubtedly will be faced with making a determination on which technology is best for your department. My recommendation is to follow three time-proven steps:

  1. Research, research, research. The better informed you and your apparatus committees become, the better decisions you will make.
  2. Always verify from multiple sources the accuracy of the information you are being provided.
  3. Engage in discussions with your counterparts at your local municipality. Talk to leaders in other departments – such as parks, refuse and transportation – that use diesel-powered trucks. They will be facing some of the same decisions and may be a great resource.

Editors note: Michael Moore, the vice president of business development for Pierce Manufacturing, is a 26-year veteran of the fire apparatus industry. He is a member of the National Fire Protection Association committee responsible for the NFPA 1901 apparatus standard and has worked in various capacities in engineering, product management, and sales.

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