Mid-Range Diesels: Going the Distance - Engine Builder Magazine

Mid-Range Diesels: Going the Distance

While it may seem that we’re constantly asking you, the reader, to give us detailed information about your business, the truth is, details are what make this business interesting. In that respect, following the February issue of Engine Builder, a cross-section of readers were asked for their opinions on a number of topics, ranging from your reactions to our editorial content to the types of advertising we ran in the issue to general business topics.

So what, you may be asking, does this have to do with the mid-range diesel market?

Because the results of the survey were wide-ranging and interesting – and the same can be said of mid-range diesel engines.

We asked what different engines you wanted to see covered in this magazine and – along with the exotic one-off performance beasts – many of you asked for an assortment of diesel engines.

Worldwide, the diesel engine market is huge, accepted and understood. But here in the States, it’s a little different. While the market for diesel engines is considerable, the uses are varied and complex.

According to the 2007 Machine Shop Market Profile (the complete results are were published in the June and July 2007 issues of Engine Builder and can also be accessed online), diesel engines, a market segment we’ve been seeing regular growth in over the past few years, fell back a bit last year. The number of diesel engines produced each month fell 25 percent, from 2.2 units per month in 2005 to 1.7 per month in 2006. This is only half-an-engine per month, and the declines in each of the 4-, 6- and 8-cylinder configurations are just in the tenths, but the percentages add up.

However, we’ve also heard success stories of rebuilders who shunned diesel rebuilding only to discover that it can be a positive part of their operations. Getting outside of their comfort zone has allowed many builders to survive and others to thrive. It has brought vitality to some businesses as many of you attested to with your responses to our survey.

But trying to paint a definitive picture of the scope of the market is like trying to catch smoke in your hands. There are some basics:  the majority of new diesel engines produced in North America (71 percent or approximately 1.5 million diesels projected for 2008) are for on-highway use; the diesel engine market can be broken down into three basic categories: light-, medium– and heavy-duty, then further segmented into on- and off-highway and agricultural uses.

Mid-range diesel engines are found in applications classified as light- to medium-duty with horsepower ratings in the 100-300 hp range. Though much of the mid-range diesel market is dominated by larger PERs and OEMs, a CER may find ways to compete in this game as well.

Small engines are putting out some very impressive numbers, blurring the lines between what is mid-range and what is heavy-duty. Further adding to the confusion is the variety of brand names available in the U.S. and the relative scarcity of parts. “Who’s who and where are the replacement parts?” are legitimate questions.

The scope of the mid-range diesel engine applications is stunning when you consider that everything from ambulances and delivery trucks to farm and construction equipment to public transportation and passenger cars utilize these diesel engines, and the future for applications continues to climb. And as the number of applications continues to climb, the number of engines in the mid-range arena may as well. Though a number of economic factors, including worldwide uncertainty, the housing slump and fuel prices will be likely to have a continued impact, it may spell better times for diesel.

Frankly, the benefits of diesel have rarely been questioned. They’ve always been recognized for their advantages over gasoline engines including more torque, increased fuel mileage and better durability. Many businesses purchase fleet vehicles with diesel engines for the long term cost savings. But now, today’s diesel engines are being recognized for their racing prowess as well.

A diesel-powered Audi race car recently won the Le Mans 24-hour endurance race in France. A new land speed record of 328 mph was set by the diesel-powered JCB Dieselmax streamliner at Bonneville a little over a year ago. Back in 2002, Gale Banks set a speed record of 217 mph in a Cummins diesel-powered Dodge Dakota pickup truck at Bonneville.

Bolt-on performance packages for diesel-powered pickup trucks can easily add 75 to 150 horsepower or more for everyday driving and towing. Pulling has been a traditional event for diesel-powered tractors and trucks, but diesel-powered vehicles are now winning races and setting records in venues that have long been the exclusive realm of gasoline-powered engines.

The diesel engine market has been rapidly changing in recent years. Higher fuel prices and changes in emission regulations have brought about a whole new generation of clean diesel engines in both the light and heavy-duty truck markets.

According to the Diesel Technology Forum (www.dieselforum.org), particulate emissions from new on-highway diesel engines have been reduced more than 83 percent since 1988. Nitrogen oxide (NOx) emissions are down 83 percent over the same time period. With the latest low sulfur diesel fuel and exhaust particulate traps, diesel emissions will be reduced up to 90 percent.


Did You Know?

Current diesel engine particulate filter technologies depend on a catalyst to assist in the regeneration of the filter. Catalyst technology, however, requires an exhaust temperature of approximately 650° F to be effective. Small diesel engines rarely achieve this exhaust temperature, except at high loads indicative of high speed vehicle operation, requiring adjustments to engine operating conditions or the use of fuel additives.


The applications you service will depend largely on your location, say experts. If you are close to an airport, for instance, you may find lucrative opportunities because many support vehicles are diesel powered. Of course, businesses don’t exist in a vacuum. Downturns in the housing market affect delivery vehicles of all kinds, and other economic realities may come into play as well.

For the typical automotive machine shop, working on a mid-range diesel engine will not be a big leap from gasoline engines. However, there are some differences that need to be recognized before you dive into this market. For the most part, standard automotive machine tools are appropriate for these engines, but you will need a few specialty tools.

This is especially true for the newer engines. Many of them are quite complicated compared to the older mechanical engines. They often require dyno time to properly tune the engine and time the injector pumps, and a rebuilder may need to tune the engine with the engine control unit (ECU) in many cases.

Rebuilding diesel engines requires precision machining – this is absolutely critical. For instance, if you mill too much off a cylinder head and raise the compression ratio, you will also affect the injection timing. You will have to be concerned with injector protrusion, valve recession and protrusion and injector sleeves, so everything on a diesel engine has to be set exactly right or you will have a comeback.

Another difference you will find when working with diesels is that, despite their high mileage characteristics, when they do finally wear out, they are completely worn out. So you will have to rebuild every component in the engine as well as many of its accessories such as the turbo (if applicable) and fuel injection pump.

There are many similarities between rebuilding gasoline engines and midrange diesel engines. Many custom engine rebuilders (CER) have most of the equipment needed to do the machine work on one of these engines. There’s not much difference in rebuilding a mid-range diesel engine from any other diesel engine, say the experts, but idiosyncrasies within some of them mean you’ll need skill patience and parts to do the job correctly – and that means you’re likely to face off against the OEM.

Reliving History

In 2001, the Environmental Protection Agency (EPA) adopted the 2007 Heavy Duty Highway Final Rule for 2007 diesel engines and ultra-low sulfur diesel fuel. The new engines were required to reduce NOx emissions by 95 percent and particulate matter emissions by 80 percent, and the sulfur in diesel fuel has now been reduced 97 percent from its earlier level of  500 parts per million (ppm) to 15 ppm. This ultra-low sulfur diesel was phased in over a period of about six years.

To meet the 2007 emissions standards, engine manufacturers turned to particulate traps to reduce particulate matter and exhaust after-treatment catalyst technology for the NOx. When combined with exhaust gas recirculation, truck manufacturers can meet the EPA’s standards. Engines made before 2007 without emissions reduction equipment can be retrofitted with these devices and use the ultra-low sulfur diesel fuel, resulting in a reduction of particulate matter by 90 percent and undetectable levels of hydrocarbons. Ultra-low diesel fuel alone can result in a 10 percent reduction in emissions in those older trucks.

The cost of clean can be considerable, say experts, with these new particulate traps and emissions devices adding upwards of thousands of dollars to the price of a new truck. The cost of not cleaning up the pollutants from diesel can be just as remarkable. The EPA says nearly 3 million tons of NOx and another 110,000 tons of particulate matter will be reduced with complete implementation of the program. That, says the EPA, will prevent 8,300 premature deaths, 5,500 cases of chronic bronchitis and 17,600 cases of acute bronchitis in children.

The EPA requires that engines meet the new standards over the course of their useful life. For any diesel engine over 50 hp, the useful life is determined to be 8,000 hours or 10 years. That means as these long-lasting engines continue to age, service opportunities should be plentiful.

The problem, however, is that as the OEMs moved to meet the rapidly changing Tier 1, Tier 2 and Tier 3 emissions standards, they weren’t keeping engines in the pipeline very long. According to one industry insider, the EPA forced such rapid change in engine design that aftermarket companies couldn’t keep up.

Consider the original 855 Cummins truck engine – a standard inline-six that went into production in the 1950s and continued to be produced in very nearly the same configuration for nearly the next 40 years. Even when changes were made, they were usually relatively minor machining changes. “Stock a set of rods and main bearings and you could support some of these engines for 30 years,” we’ve been told.

Today, things aren’t so simple. Meeting EPA standards seemed to be an industry cat and mouse game for awhile, but things seem to be settling down. Everyone has, for the most part, met the next tier of standards, say experts, and the major manufacturers have engines that that are good for the next 3 or 4 years.

“The window of opportunity from the late ’90s until a year or so ago was very short,” said a representative from a leading aftermarket parts manufacturer. “Several different engines were only produced for a short time. Consequently, the aftermarket didn’t even look at making parts for them.”

For the aftermarket, the initial investment to produce parts for an engine is high and the payback is slow with a short window opening. Unlike the problems caused by parts proliferation in the automotive industry – seemingly every part available from every supplier for every engine ever made – diesel parts tend to be harder to come by. Nonetheless, some manufacturers continue to work on developing parts to fit popular diesel applications.

Engine platform development should be better for the aftermarket moving forward and experts say the technology in some cases is so new that there are still problems with some designs, but a stabilization of parts, such as crankshafts, bearings, pistons, liners and gaskets can be expected.

In some cases, because of the scarcity of parts, a small shop may find it hard to make money. On the other hand, because the scarcity of parts may actually scare off the competition, if you can develop a niche, you may have the market pretty much to yourself and the OEM.

One of the key opportunities within mid-range diesels happens because a number of them are parent bore engines without cylinder sleeves. Engine builders’ machining equipment may have an advantage with these engines because while sleeves are often available to fit the parent bore engines, oversize pistons are also available from some aftermarket manufacturers to fit the original or slightly increased bore sizes.

There continues to be a great deal of confusion in the market over what constitutes a mid-range diesel, because it can fall into both the light- and heavy-duty service sector and engine size range, may be found in any manner of applications and may be badged as anything from Ford and General Motors to Caterpillar and Cummins to Detroit Diesel to Volvo to Mercedes to Hino.

Experts say with the right research, patience and skill you might easily find a niche in this market that can help your bottom line.

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