How to reap the benefits of a lightweight engine

How to reap the benefits of a lightweight engine

Power-to-weight equals more than just productivity

Operating vocational trucks is all about getting the job done as reliably, quickly and productively as possible. Nailing the power-to-weight ratio on the sweet spot can have a major impact on not just your equipment’s productivity but its longevity and your bottom line as well. There are a number of factors that come into play when spec’ing a vocational vehicle that help ensure that performance capability matches the duty cycle and jobsite conditions. It starts with choosing an engine that has the ideal power-to-weight ratio and pairing it with the correct transmission and tires, based on the most demanding aspects of its operating usage. 

Weighing In 

Regardless of whether you are spec’ing a dump, refuse truck, mixer or bulk hauler, there are substantial advantages to using a lighter-weight engine – provided it has sufficient power. In applications which typically gross out, a lighter weight engine gives you the opportunity to carry more payload (equal to the weight savings). Less weight on the front axle also reduces stress and wear over time, reducing maintenance costs. The weight savings/increased payload can be as much as 630 lbs. per trip in a vehicle, when switching from a Cummins ISX12 to a 2021 X12™. 

Productivity Pays 

Having the right spec with a lighter engine pays big dividends, regardless of the business you are in or the type of vocational vehicles in your fleet. For instance: 

Refuse – A lighter engine with the proper spec can accelerate faster between stops and carry more waste, potentially resulting in greater coverage per vehicle on its daily routes. Depending on the size of the municipality being served, it could reduce both the number of vehicles and manpower needed for total coverage. It can also save money at landfills where there is a per-vehicle charge in addition to the cost of the waste being dumped. 

Mixers – The key is to spec the vehicle at maximum load, making sure that it adheres to local load limits for highways, bridges and roadways throughout the area. Some mixers have three drive axles, to help provide the traction needed to negotiate muddy, difficult worksites with steep inclines. 

Dump Trucks – Similar to mixers, construction dumps can have highly variable load weights and taxing work environments. For increased equipment longevity, operators should be trained in proper loading (between the axles with the initial loading, moving over the axles at the end). 

Bulk Haulers – Tractor trailers are a different configuration and have greater flexibility with regards to load distribution. The fifth wheel can be shifted forward to put more weight on the drive axle, or back to put greater load on the rear axles. When spec’ing the tractor, you can often choose a smaller displacement engine (such as a 12-liter rather than a 13-liter), which will allow for a shorter frame rail and wheelbase measured as BBC. The combined weight savings can be as much as 1,000 lbs. in the front end, and an equivalent increase in payload while staying under the 80,000-lb GVW limit. (The typical load pattern for a tractor trailer is 12K steer axle, 34K tandem axle and 34K trailer). 

Additional Considerations

When spec’ing a vocational vehicle, it is critical to take into consideration seasonal additions like a snowplow attachment, pumps, or any feature that requires an extended front bumper or puts extra weight on the drive axle. When spec’ing an engine for weight savings, it is critical to choose a horsepower/torque rating that meets the highest regular power demand in your duty cycle, and to pair it with an appropriate transmission, ensuring that you get the highest productivity, exceptional reliability and longevity plus driver-pleasing performance. All at a reduced powertrain weight. Cummins PowerSpec can guide you through the entire process

Hard Working Engines for The Hardest Working Trucks 

From landscaper’s dump trucks to bulk transport trailers, Cummins engines offer exceptional productivity and the highest power-to-weight ratios in the industry. All three of these engines are offered in natural gas-fueled versions as well as the industry-leading diesels that are listed below. For assistance choosing the right specification for your operation, contact your local dealer or visit our dealer locator page to find one

Cummins B6.7 (200-360 hp) – Covers more Class 6-7 truck power requirements than any other diesel on market. 

Cummins L9 (260-380 hp) – The highest power density in its class plus replaceable wet cylinder liners for ease of overhaul and extended lifespan. 

Cummins X12 (350-500 hp) – The highest power-to-weight ratio of any 10- to 16-liter diesel engine, period.

Leslie Nix

Leslie Nix is a Senior Communications Specialist for Cummins Inc. Leslie joined the Company in 2011 as a college hire after graduating with her Bachelors of Arts in Journalism from Indiana University.

Natural gas engines: Questions answered

Natural gas engines: Questions answered

When it comes to natural gas engines, there are a range of frequently asked questions about the cost, practicality, and feasibility of integrating natural gas into commercial fleets. There are certainly preparations that need to be considered, but the learning curve to implement natural gas engines is not as steep as people may think, especially in comparison to the benefits of natural gas in transportation applications

In this article we’ll answer some of the most frequently asked questions when it comes to adding natural gas engines to your commercial vehicle fleet. 

Can a diesel engine run on natural gas? 

The short answer is no. If you fueled a diesel engine with natural gas it simply wouldn’t start. Diesel engines can’t run on natural gas because natural gas combustion requires spark plugs. Diesel engines cause fuel to ignite through compression. To self-ignite, natural gas would need to be compressed at a ratio far greater than what internal combustion engines can apply. 

However, there are specially modified engines which can run on either diesel or natural gas. Vehicles with this type of engine, which are known as bi-fuel or dual fuel engines, feature two fuel systems and can switch between one fuel and another as needed. For example, if their compressed natural gas (CNG) cylinder runs out and there is no CNG station nearby, operators can simply flip a switch and keep driving on diesel. There are also engines which use diesel and natural gas at the same time. In these engines, diesel provides ignition and natural gas provides power. Such engines are especially popular in stationary oil and gas drilling applications. If natural gas is being extracted, it can be used to fuel the engines. If no natural gas is available, the engines can revert to using diesel. The Cummins QSK 50 engine, for example, is a popular dual fuel engine commonly used in oil and gas applications.  

Can a natural gas engine run on renewable natural gas?

Absolutely! The option to run on renewable natural gas (RNG) is a big reason fleets switch to natural gas vehicles. While virgin natural gas has many sustainability benefits, including 13% – 17% lower well-to-wheel greenhouse gas (GHG) emissions and 27% lower CO2 emissions than petroleum. But the environmental benefits really shine when using RNG made with biogas. 

For fuels beyond RNG, you can learn more on how natural gas compares to LPG, LNG, and diesel here.  

What are the environmental benefits of RNG? 

Depending on the energy source, the carbon intensity of renewable natural gas can be neutral or even sub-zero. How is that even possible, you might ask?  

It’s because the main elements of RNG come from biogas, which is the fermentation of organic waste in places like landfills, wastewater treatment facilities, or industrial agriculture waste digesters. Biogas like methane is captured during this treatment process, preventing it from ever being emitted into the atmosphere. This carbon intensity score factors into the total well-to-wheel emissions calculation of the vehicle.  

Refined biogas is functionally indistinguishable from fossil natural gas and can be used as a natural gas substitute. If interested, learn more about the production and processing of biogas, natural gas, and other low carbon fuels.  

Is it cheaper to run natural gas engines? 

Most of the time, yes. Natural gas vehicles require less maintenance than diesel vehicles equipped with post combustion exhaust treatment systems. They also result in significantly lower fuel costs. In the United States, the average retail fuel price has been significantly lower than the average retail price of both gasoline and diesel for more than 20 years. Retail natural gas prices are also more stable than the price of other fossil fuels.  

Payback on a natural gas vehicle is dependent on several factors, including the specific application, duty-cycle, number of miles driven per year and the cost of fuel compared to diesel. But by most metrics, natural gas delivers a lower total cost of operation than diesel.  

Do natural gas engines start better than diesel engines in cold weather? 

No engine is completely immune to cold-weather challenges. Some issues are common to most vehicles, including those using an internal combustion engine. One issue natural gas engines sometimes experience in freezing weather is a loss of power by the battery. There are also potential issues specific to the use of natural gas. For example, the O-rings in the fueling receptacle can become frozen, preventing the fuel nozzle from coupling correctly with the receptacle.  

There are two cold weather difficulties that diesel drivers face, which natural gas drivers will never experience. The first is, unlike diesel, natural gas does not turn to gel when it is cold. Regardless of temperature, natural gas is entirely gaseous when it enters the engine. Methane, the main constituent of natural gas, has a boiling point of -258°F, or -161 °C.  

The other difficulty is caused by the diesel exhaust fluid, or DEF, in diesel vehicles. DEF largely consists of water and can easily freeze. Storing and handling DEF in cold weather can be challenging. Because natural gas burns cleanly and with minimal NOx (nitrogen oxides) formation, natural gas vehicles have no need for heavy-duty DEF-consuming NOx scrubbers. As a result, DEF and DEF-related problems are unknown to natural gas vehicle drivers.  

Who makes natural gas engines? 

Cummins Inc. and several other manufacturers of heavy and medium-duty engines have an extensive portfolio of natural gas engines suitable for a large variety of on-road, off-road and stationary applications. Most truck and bus makers have product lines featuring natural gas engines, so businesses  interested in exploring natural gas options can usually do so with their preferred truck maker. Learn more about Cummins’ full line of natural gas engines. 

Cummins Office Building

Cummins Inc.

Cummins is a global power leader that designs, manufactures, sells and services diesel and alternative fuel engines from 2.8 to 95 liters, diesel and alternative-fueled electrical generator sets from 2.5 to 3,500 kW, as well as related components and technology. Cummins serves its customers through its network of 600 company-owned and independent distributor facilities and more than 7,200 dealer locations in over 190 countries and territories.

Natural gas engines vs. diesel engines

Natural gas engines versus diesel engines - how do they compare?

From tractor trailers and transit buses to delivery trucks and terminal tractors, fleets have traditionally relied on diesel engines to provide the torque, reliability and durability needed by heavy-duty commercial applications. Natural gas engines, however, have emerged as a great alternative to diesel. Drivers, mechanics, and fleet managers appreciate natural gas engines for a variety of reasons.

Drivers find that natural gas engines have similar performance and drivability as diesel engines. The leading difference between natural gas and diesel engines is noise; natural gas engines are quieter.

Natural gas offers convenient refueling options

Natural gas also improves the refueling experience for many fleet drivers. In a world of several alternative fuel options for commercial vehicles ranging from natural gas to liquified petroleum gas (LPG); natural gas can be used in a vehicle in either compressed or liquefied form. For fleets with behind the fence refueling capability, natural gas refueling stations can be set up on site to ensure that each vehicle has a dedicated fuel hose. There are two basic types of fueling equipment: fast-fill and time-fill.

Fast-fill systems combine a compressor and a high-pressure storage system. The storage system, called a cascade, fills the vehicle's fuel tank in about the same time it takes to fuel a diesel vehicle. Compressed natural gas can’t spill during refueling and drivers never go home smelling of diesel.

Time-fill systems don’t have a storage system and typically compress the gas directly into the vehicle storage cylinders to refuel vehicles while they’re parked overnight. With time-fill systems, drivers pull into their designated space at the end of their shift, connect a fuel hose to their vehicle’s natural gas cylinder and go home. Drivers don’t need to wait for their turn at the diesel pump and don’t need to wait again until their tank is full. This saves them time and saves their company money.

Natural gas exhaust systems are cheaper and easier to maintain than diesel aftertreatment systems

There are no complicated exhaust gas aftertreatment systems on natural gas vehicles. Modern diesel trucks require a set of sensors, filters and converters to scrub pollutants such as nitrogen oxides and soot from their exhaust. Some converters consume diesel exhaust fluid, or DEF, a water-based reagent whose handling can be challenging in cold weather. Natural gas burns much cleaner than diesel, so few or none of these systems are required on a natural gas vehicle. All of the exhaust is run through a simple three-way catalyst, resulting in near zero NOx levels (0.02 g/bhp-hr NOx).

It is important to closely follow recommended maintenance intervals with natural gas engines, but with proper maintenance, it’s not uncommon for natural gas trucks to reach a million miles. And mechanics often find that maintaining a natural gas engine can be a more pleasant experience because of how clean they are.

Natural gas promotes cost savings

Besides enjoying savings in terms of lower maintenance costs and reduced maintenance downtime, fleet managers can also save big on fuel costs. In the United States, the retail price of compressed natural gas has been consistently lower than the price of diesel since the start of the shale gas boom in the early 2000s. It is also decoupled from the price of oil, and therefore has been quite stable. As a result, natural gas fleet operators don’t experience wild swings in fuel prices that other fleets must deal with whenever oil prices rise and the cost of diesel jumps. This comes in addition to all the other benefits natural gas engines offer for transportation applications.

Natural gas cuts greenhouse gas emissions

Natural gas has many sustainability benefits, including 13% – 17% lower well-to-wheel greenhouse gas (GHG) emissions and 27% lower CO2 emissions than petroleum when using virgin natural gas. The benefits really shine when using renewable natural gas (RNG) made with biogas.

RNG can help fleets reach sub-zero GHG emission levels because producing RNG captures biogas like methane that would have otherwise been emitted into the atmosphere through natural decomposition. This biogas comes from the fermentation of organic waste such as animal manure in industrial digesters. Switching to renewable natural gas can be an effective way for these businesses to reach any greenhouse gas reduction objectives they may have. Many transportation businesses operating in agricultural areas have found ways to create win-win partnerships with local farmers willing to invest in a renewable gas production setup. Municipalities and refuse companies that own landfills are able to capture methane generated through waste decomposition and sell that to the RNG fuel producers, essentially offsetting their fuel costs.

If natural gas engines are relevant to your needs, don’t forget to also check our answers to frequently asked questions about natural gas engines. These answers cover topics such as cost, practicality, and feasibility of integrating natural gas into commercial fleets. You can also learn more about Cummins’ natural gas product line and explore the company’s product offerings.

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Cummins Office Building

Cummins Inc.

Cummins is a global power leader that designs, manufactures, sells and services diesel and alternative fuel engines from 2.8 to 95 liters, diesel and alternative-fueled electrical generator sets from 2.5 to 3,500 kW, as well as related components and technology. Cummins serves its customers through its network of 600 company-owned and independent distributor facilities and more than 7,200 dealer locations in over 190 countries and territories.

Natural gas (CNG) vs. LPG, LNG, RNG and Diesel

Gas pump

Commercial vehicle fleet managers face a dizzying array of options when it is time to replace or upgrade vehicles. One question that fleet managers often ask is whether there are any good fuel options available to their business besides diesel or gasoline. Alternative fuels, including natural gas, have grown in popularity in recent years due to their broad appeal. Considering a full or partial switch to an alternative fuel is more often than not a question worth asking. Here is how the main fuel options compare to each other. 

Compressed Natural Gas vs. Diesel 

Natural gas is a great choice for many types of heavy and medium-duty vehicles because it burns cleanly. Anyone who has replaced an oil furnace with a natural gas furnace in their home knows this. Oil furnaces produce soot and must have their flue cleaned regularly. Natural gas furnaces, in contrast, can be vented through the side of the house. You will never see any trace of soot on the wall above the vent because the combustion of natural gas doesn’t produce any. It’s the same thing with natural gas vehicles—they don’t generate particulate matter or volatile organic compounds (VOCs), and they don’t require difficult to maintain exhaust treatment systems. Beyond the environmental aspects, the benefits of natural gas engines are reliability and financial. 

If interested, don’t’ forget to dive deeper in natural gas engines vs. diesel engines

Natural gas vs. LPG 

LPG, or liquefied petroleum gas, is a mixture of light hydrocarbons. In the U.S. and in Canada, LPG consists of at least 90% of propane, with the balance made up of other gases including butane. This is why LPG is sometimes simply known as propane. In other countries, the composition of LPG can vary. In Mexico, for example, LPG’s propane content can be as low as 60%.  

Natural gas, in contrast, is almost entirely made up of methane. If you have a gas grill, then LPG is what you use for your cookouts. If your home has a gas furnace, then natural gas is what keeps it warm (LPG or propane furnaces are also available). 

In vehicle applications, LPG and natural gas present many of the same benefits. Both burn cleanly and silently, can help reduce maintenance vehicle costs, and can eliminate most cold weather start problems. LPG is the third most widely used motor fuel in the world behind gasoline and diesel, and so LPG tends to be easier to find. According to the US Department of Energy, there are almost 2,000 publicly accessible LPG fueling stations in the United States and Canada.  

Compressed Natural Gas, in comparison, is only available at less than half that number of stations. (Both numbers are dwarfed by the number of gas stations dispensing gasoline, which is greater than 100,000). 

Compressed Natural Gas vs. Liquefied Natural Gas 

Compressed Natural Gas, or CNG, and Liquefied Natural Gas, or LNG, are the same substance. CNG is received and stored a vehicle’s tank is gaseous form. To obtain LNG, natural gas is compressed and cooled to extremely low temperatures, at which point it turns to liquid. LNG can then be shipped, stored, and used to fill the tanks of LNG vehicles. Much of the global natural gas trade occurs in the form of LNG. Some countries, such as South Korea and Japan, receive almost all of the natural gas they use in LNG form.  

In vehicle applications, the main advantage that LNG has over CNG is that it is more dense. For two tanks of the same size, the LNG tank will allow a vehicle to drive further than the CNG tank. This makes LNG an interesting option for heavy trucks traveling long distances.  

LNG, however, is more complicated to use, and is not widely available. LNG fueling stations require complex cryogenic equipment. There are only about 55 public-access LNG stations in the United States, and most are located at industrial facilities where natural gas is processed.  LNG is also more hazardous than CNG. One safety concern results from the need for LNG vehicles to vent off fumes. LNG vehicles do not normally come with LNG cooling systems, so LNG tanks tend to gain heat. The heat gains cause some of the LNG to vaporize. Eventually, the vapors need to be vented to avoid excessive pressure build ups. This is why LNG vehicles should never be parked in interior garages unless special ventilation is installed. LNG, being very cold, can also cause freeze burn. Contact with LNG, LNG vapors and the uninsulated surfaces of LNG fuel system components should also be avoided, and drivers and mechanics need to be trained in LNG safety. 

Natural gas vs. Renewable Natural Gas 

Chemically, natural gas and renewable natural gas are almost identical. Natural gas vehicles can run on renewable natural gas without experiencing any difference. Natural gas and renewable natural gas differ in their origin. Natural gas, like oil, is extracted from fossil resources present in the ground. Renewable natural gas is obtained by fermenting organic waste such as sewage sludge or animal manure in large industrial tanks known as digesters. After some processing, the gases given off by the fermentation process can be used interchangeably with fossil natural gas.

Switching to renewable natural gas is a great way for businesses operating fleets of vehicles to reduce their carbon footprint. It can be produced at almost any dairy farm using relatively low tech equipment. It can be used to fuel nearly any CNG vehicle. If it is not practical to fuel a vehicle entirely on renewable natural gas, then blending with fossil natural gas is possible. Even then, the use of renewable natural gas will result in an instant reduction in CO2 emissions without the need to invest in any upgrades or modifications to the vehicle.  

If natural gas engines are relevant to your needs, don’t forget to also check our answers to frequently asked questions about natural gas engines. These answers cover topics such as cost, practicality, and feasibility of integrating natural gas into commercial fleets.  

Cummins Office Building

Cummins Inc.

Cummins is a global power leader that designs, manufactures, sells and services diesel and alternative fuel engines from 2.8 to 95 liters, diesel and alternative-fueled electrical generator sets from 2.5 to 3,500 kW, as well as related components and technology. Cummins serves its customers through its network of 600 company-owned and independent distributor facilities and more than 7,200 dealer locations in over 190 countries and territories.

Benefits of natural gas engines in transportation

Truck on road

Reducing air pollution generated by commercial vehicles is one of the many benefits of natural gas engines. Nested in a valley in the French Alps, the town of Chamonix is known for breathtaking vistas of Mont Blanc, for being the birthplace of modern mountaineering, and, unfortunately, for its terrible air quality. Emissions from passing vehicles are to blame. The town sits by a major road tunnel used by more than a half million heavy vehicles, every year.  

Wouldn’t it be nice if the exhaust from all these vehicles could be cleaned up? Chamonix’s residents would appreciate it. So would the countless millions who live in polluted cities.  

Natural gas engines use reliable technology 

One sure technology to reduce air pollution already exists—natural gas engines. Hundreds of thousands of vehicles with natural gas engines are operating all over the world. They generate almost no emissions of nitrogen oxides, particulate matter, volatile organic compounds, or carbon monoxide. Transit systems all over the world have deployed natural gas buses to reduce air pollution.  

Natural gas engines are also a great fit for a wide variety of medium and heavy-duty applications, such as garbage collection trucks, delivery trucks and tractor trailers. Natural gas engines have been around for a long time. They are durable, reliable and they have enough power to get the job done.  

Natural gas engines are kind to the environment 

Natural gas vehicles can help fleets reduce greenhouse gas emissions. According to a well-to-wheels model developed by Argonne National Laboratory, compressed natural gas (CNG) vehicles were shown to reduce greenhouse gas emissions by up to 16% compared to an equivalent vehicle running on gasoline. These well-to wheel models incorporate emissions occurring as a result of the extraction, processing and transportation of fuels. 

Natural gas vehicles can also run on renewable natural gas. Renewable natural gas is manufactured using organic waste such as animal manure, sewage sludge or agricultural by-products. Once it is suitably refined, renewable natural gas can be used interchangeably with regular natural gas. Depending on the energy source, the carbon intensity of renewable natural gas can be neutral, or even sub-zero. Switching to renewable natural gas is a great way for businesses to reduce their carbon footprint and lower transportation emissions. It can often be done without any capital investment. It’s also a way to act now without waiting for technology that may not be available for several years. 

Natural gas presents additional environmental benefits. For example, natural gas can’t spill since it’s lighter than air. It can’t puddle or lead to ground contamination like an oil spill would. You can read more about these often-overlooked benefits of natural gas engines in environmental sustainability. 

Natural gas engines are good for the business financials 

Natural gas vehicles can also lead to big savings for businesses. Unlike some vehicles with diesel engines, natural gas vehicles do not require extensive exhaust aftertreatment systems. Many operators spend a lot of time and money maintaining these systems. Secondly, natural gas fuel costs less than gasoline and diesel. In some areas, the retail price of natural gas is less than half of the price of diesel. Natural gas prices are also stable—in North America, average retail prices have remained relatively stable for the past 20 years. This makes it easy for fleets to forecast their monthly and yearly fuel costs. 

Switching to natural gas vehicles can also help businesses grow their revenues. Natural gas vehicles reduce transportation emissions, which is an attractive benefit for companies looking for lower carbon options that can help them meet corporate sustainability or ESG (environmental, social, and governance) goals.  

Natural gas engines are noticeably quieter than diesel engines, making them an attractive option for service companies, delivery fleets, transit companies and school corporations operating in urban environments. For example, garbage collection companies or private school bus operators bidding for city contracts.  

Natural gas engines are the mature, proven, and least disruptive alternative power technology available today 

Natural gas vehicles fit current transportation, people and goods movement models. Integrating natural gas trucks into your fleet doesn’t require radical changes in vehicle technology, transportation infrastructure or support networks. Natural gas engines share approximately 80% of the same components as their diesel counterparts, making it easier for mixed fleets to keep parts in stock and easier to train service technicians.  

If interested in different fuels, don’t forget to explore natural gas (CNG), LPG, LNG, RNG, and diesel. 

The natural gas learning curve isn’t as steep as many people think 

When it comes to integrating natural gas vehicles into a commercial or municipal fleet, Cummins Inc. is a trusted partner with more than 30 years of experience making natural gas engines. We maintain deep relationships with channel partners to help customers understand whether natural gas is the right choice for their fleet. We also work directly with the truck OEM, fuel suppliers, fleet maintenance teams, etc. to ensure a smooth integration. 

If these benefits sound interesting to you, don’t forget to also check our answers to frequently asked questions about natural gas engines. These answers cover topics such as cost, practicality, and feasibility of integrating natural gas into commercial fleets.  

Drivers like driving natural gas trucks 

Did you know that drivers prefer the experience of operating natural gas vehicles? You can learn why by reading about how natural gas and diesel engines compare

Cummins Office Building

Cummins Inc.

Cummins is a global power leader that designs, manufactures, sells and services diesel and alternative fuel engines from 2.8 to 95 liters, diesel and alternative-fueled electrical generator sets from 2.5 to 3,500 kW, as well as related components and technology. Cummins serves its customers through its network of 600 company-owned and independent distributor facilities and more than 7,200 dealer locations in over 190 countries and territories.

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