Despite all of the media attention surrounding electric vehicles and hydrogen fuel cells, don’t expect the internal combustion engine to fade away any time in the foreseeable future. Len DeLuca, director, Ford Commercial Trucks, says it best: “ We will see an increase in alternative fuels with no revolutionary technology in the next five to 10 years . . . Diesel engines will continue to be the predominant engine.”
It takes time to develop alternative power sources and the necessary infrastructure, and currently electric vehicles continue to struggle with range limitations. Hydrogen fuel cells may hold promise, but they are mainly in the development stage and widespread utilization is still in the long-range future.
The perplexing problem is any alternative to the internal combustion engine must meet the objectives of the customer in terms of performance, reliability, and ease of use while still offering the economic viability of an internal combustion engine.
More power in a smaller package
Does that mean life goes on with no big changes? Not exactly! Fuel prices, government regulation and consumer demand have dramatically stepped up the pace of internal combustion engine evolution. With high-pressure fuel injection, new engine block materials, turbocharging and variable valve timing, the power density of the internal combustion engine has risen dramatically.
Greater power density means a customer can accomplish a given task with a smaller displacement engine, thus saving fuel in most cases. This is the basis for the EcoBoost technology Ford is expanding throughout its product line to increase fuel economy. Using smaller displacement engines with turbocharging is a strategy to move the company toward government-mandated fuel economy standards while still providing the performance customers expect.
A shining example is the Ford F-150 EcoBoost that produces 420 ft.-lbs. of torque and 365 hp from a 3.5-liter engine with direct fuel injection, twin turbochargers and variable valve timing. These are big numbers from a small engine, yet highway fuel economy is rated at an impressive 22 mpg. While technology does come with a price tag, orders prove that customers are voting with their wallets. Orders are far exceeding the company’s initial projections vs. the other conventional powerplant choices.
And we have witnessed this trend across a broad range of engine classes. Mack Trucks reports that for the first time, 13-liter engines have become the No. 1 choice of U.S. Class 8 truck customers. “We’re seeing a shift in the market to less than 15-liter engines as customers increasingly focus on operational efficiency,” says Kevin Flaherty, Mack senior vice president – U.S. and Canada. “The powertrain technologies we have in the market today allow us to deliver tremendous horsepower and torque through smaller liter engines while offering significant savings, both in terms of upfront cost and fuel efficiency.”
Bob Mann, Navistar, adds, “We get a lot more horsepower and torque out of a 13-liter than we have been able to get in the past. The 13-liter and 11-liter engines we build today have a compacted graphite iron block, which is a lot stronger. Basically, we are getting 500 hp out of the 13-liter engine.”
Larger displacement engines simply cannot offer the efficiencies of smaller displacement units. “Once you get into a 15-liter engine, the amount of bearing surface that you have, which creates heat and friction, and then just the overall size and weight of the engine – those are things that 20 years ago people viewed as a positive because they thought longevity would come because of all this mass,” Mann comments. “In reality, it takes up weight and burns up a lot of fuel. We still have customers in heavy haul that are going to need a 15-liter engine. They are the ones who need 500 hp and above.”
Other options to improve combustion
Only time will truly tell how far it is possible to go with this trend and how it might affect the longevity of the engines. There is a limit to what can be done.
“There is only so much [fuel economy] we are going to get out of the engine,” notes Mann. “If you want to get a certain amount of horsepower out, you are still going to have to put a certain amount of fuel in. We are already running two turbochargers. We already have high cylinder injection pressure. It is going to have to come in some other ways than just the engine.”
Some other ways to improve internal combustion efficiency include removal of parasitic loads by driving accessories like steering pumps and air conditioners electrically. Then you can gain efficiency through the incorporation of hybrid electrical systems to capture wasted energy and use it to assist the internal combustion engine.
Finally, you can use alternative fuels. Ethanol in blends up to 10% have proven effective, but there are a surprising number of fleets that are converting to Compressed Natural Gas (CNG) and Liquefied Propane Gas (LPG). This trend has been driven by the consumer, so we all need to keep a close eye on this one.
So the next time you go to spec an engine or purchase a new machine, it will not be business as usual. You will have to consider the new options and make decisions that make the most sense for your bottom line. Technology can often increase fuel economy and performance, but you also need to factor in the purchase price and planned utilization to ensure it actually makes financial sense.
