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Signshop Truck Engine Choices

A diesel or gasoline engine for your next crane truck?

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Signshops that install types of high-rise signs tend to prefer Class 8 trucks, which generally have a gross vehicle weight rating that can exceed 33,000 lbs. The Class 8 category can include tractor trailer rigs as well as single-unit, three or more axle trucks (see www.afdc.energy.gov/data/10380 for class/weight data). 

I’ve often said that signmakers seldom see themselves as truckers, but considering that two crane-truck suppliers say all but 2% of their signmaking truck buyers request diesel engines for their trucks, one must appreciate that a good part of signshop operations is transportation, i.e., the delivery of manufactured goods – signs – by truck. Further, although signmakers tend to stand alone as business enterprises, such shops are indeed manufacturing entities. 

The U.S. Department of Transportation’s Bureau of Transportation says the manufacturing sector – which includes signmakers – consists of establishments engaged in the mechanical, physical or chemical transformation of materials, substance or components into new products. That describes making signs, right? The bureau says the manufacturing sector contributes to the economy by combining raw materials (many of which are produced by other sectors) to make finished products. Its latest data (from 2015) indicates the manufacturing sector was the fourth largest contributor to the national economy in that it contributed $2.17 trillion (12.1%), as measured by Gross Domestic Product (GDP). 

It also says the manufacturing sector uses the third largest amount of US transportation services, slightly more than most other sectors, and relies heavily on truck transportation services. This sector ships the most tons and largest value of product by truck and employs the largest number of transportation workers as heavy and tractor-trailer truck drivers, followed by light truck or delivery services drivers and driver/sales workers.

SIGNSHOP TRUCKS

Mike Bailey and Adam Clayton are truck sales reps for Fyda Freightliner Western Star Company in Walton, KY and are two of the friendliest guys I’ve recently met. I already know a lot about trucks, but these guys got me thinking. For example, when I asked which type of engine – diesel or gasoline – is better for signshop-type crane trucks, Adam began explaining fuel dynamics. “Diesel is the best choice because the fuel has a higher combustion efficiency than gasoline,” he said. He added that diesel fuel produces more power in load/fuel-use situations when compared to gasoline engines. Both men noted that diesel engines, although similar, are notably different than gasoline engines. Mike said they’re both internal combustion engines that convert chemical energy (fuel) into mechanical energy – but you can’t compare them as apples and apples.

For example, unlike gasoline engines, diesel engines don’t have spark plugs. They rely on fuel ignition through heated air. It’s a process of air filling the firing chamber, which is then compressed and heated (air heats when compressed) during the piston upstroke. At top-dead-center, via a separate fuel-injection system, the captured and heated air is misted with diesel fuel that is ignited by the heated air. In some engines, ignition is aided by a constant heat glow plug. The ignition initiates the piston’s power downstroke (which in turn drives the entire power train) and then it returns upward to purge the spent gasses and re-initiate the ignition process. This action, supported by a high compression ratio (15-20:1), is what causes diesel engines’ higher thermal efficiency and lean burn, which reduces fuel usage.

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DIESEL ADVANTAGES

I also discussed sign trucks with Brian Wilkerson at Wilkie Mfg. LLC in Oklahoma City and Paul Cassidy at Elliott Equipment Co. (Omaha, NE). Interestingly, both men said 98% of their sales of crane trucks are those with diesel engines. Wilkerson noted that in addition to the basic fuel design system, modern diesel engines are equipped with extremely precise, computer-equipped fuel management systems that cycle rates for the fuel injectors. He said this type of cycling varies the fuel injection rate in response to engine load circumstances. Noting that such improvements increase road mileage, he also said that other similar, computer-controlled fuel systems produce a fuel-saving multi-pulse fuel feed. Wilkerson said the old-style, non-computer systems were simply on-off fuel systems that arbitrarily and inefficiently fed fuel to the engine.

MODERN DIESEL-ENGINE DESIGN

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Diesel engines can run up to 600,000 miles and sometimes outlast other truck components. And, unlike passenger cars that come with engines installed, diesel motors are often selected as a component, i.e., a buyer’s option for their choice of truck frame/body systems. A practice called “gliding” allows used engine/drive train systems to be installed within a new cab and bed configuration, which provides a serviceable truck at a lower cost, though Cassidy said sign truck buyers generally prefer all new gear.

Most important is that diesel engine manufacturers, in addition to working with fuels and fuel systems that meet government and state requirements, have applied analytical engineering technology to redesign their core products. Cummins Diesel usually leads the top-10 choice list in diesel engine surveys, so it’s no surprise that it has recently introduced its X15 Efficiency Series engines that deliver up to 1,850 pound-feet of torque. 

Cummins says every X15 engine comes with over-the-road calibration capability, a Single Module after-treatment system, a powerful engine brake and extended service intervals. Cummins has also introduced its ISX15 heavy-duty diesel engine –with up to 2,050 pound-feet peak torque – which is offered as an option by every major Class 8 truck manufacturer. The company has also introduced the Cummins X12 in the medium-bore engine category that is smaller in size – up to 600 lbs. lighter than other engines in its class and at least 150 lbs. lighter than the next-closest competitive engine. It delivers 1,250-1,700 pound-feet of torque. Cummins says this engine has the highest power-to-weight ratio of any heavy-duty engine from 10-16 liters.

The International Council on Clean Transportation (ICCT) website quotes Cummins as saying its engines can achieve a 9-15% fuel use reduction from 2017 figures within the 2020-2030 timeframe.

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In a similar redesign movement last year, International Truck launched its 12.4-liter, A26 engine for the Class 8 market. It produces up to 1,750 pound-feet of torque and is 600-700 lbs. lighter than a traditional 15-liter big-bore engine. Engineered to increase uptime and fuel efficiency, the 2,299-lb. International A26 diesel features a titanium compressor wheel, a variable geometry turbocharger, larger piston pins, connecting rods and smaller piston cooling jets that increase oil pressure to improve lubrication and increase oil change service intervals to 70,000 miles.

MANUFACTURER CHOICES

Statista.com reported the 2015 market share of diesel engine manufacturers, based on share of diesel engines installed in US-built trucks, as Cummins (41.7%), Volvo (14.8%), Detroit (14.4%), Paccar (12.2%), Mack (10.3%), Hino (4.1%) and Navistar Intl. (2.5%). Are you keeping score? This indicator does not include same-brand manufacturer truck/engine packages such as Ford. An interesting Ford side note is that its Power Stroke series engines were produced by Navistar from 1994 to 2010, when Ford replaced them with its own 6.7-liter PowerStroke V8 diesel. 

Fiat-owned Dodge diesel engines are manufactured by Cummins and the GM/Chevrolet Duramax, a V8, 6.6-liter diesel is produced by DMAX, which is a joint venture between GM and Isuzu. You might know that Isuzu built the 285-hp Vortec 5300 diesel engine found in 2001–2009 General Motors SUVs and during that period.

EPA EMISSION RULES

Cassidy noted that EPA emission rules worry some diesel buyers, but shouldn’t. Essentially, the post-2006 EPA Diesel Fuel regulations require on-road use of “Ultra Low Sulfur Diesel fuel for new engines and vehicles with advanced emissions control systems that offer significant air quality improvement, such as those described hereon.” The EPA says, to meet its standards, the petroleum industry produces Ultra Low Sulfur Diesel (ULSD) fuel, which is a cleaner-burning diesel fuel and good news for all who breathe air. This change occurred on June 1, 2006, and required 80% of the highway diesel fuel produced or imported to be the low sulfur type. The EPA says this fuel requirement, in combination with cleaner-burning diesel engines and vehicles, has helped improve air quality by significantly reducing emissions.

 

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