Volvo's John Moore answers questions about the D13TC engine's design, fuel efficiency and ROI.
What is turbo compounding and how does it help Volvo customers?
“Turbo compounding is a waste heat recovery system, not to be confused with a turbocharger -- in Volvo’s case, a variable geometry turbocharger (VGT). With a typical turbocharger, exhaust gases spin a turbine and that is connected to a compressor wheel which compresses intake air and sends it over to a charge-air cooler and eventually into the combustion chambers. Turbo compounding, on the other hand, uses a separate turbine wheel located downstream of the turbocharger. It too is spun by exhaust gas, but that rotational energy is transferred back to the crankshaft. So, we’re actually recovering energy from the exhaust stream that would normally just vent out the exhaust stack or be exchanged through the cooling system. That free energy translates into lower fuel consumption for vehicle owners.”
How does Volvo’s current use of turbo compounding differ from past applications of the technology?
“There are three areas that make Volvo Trucks’ approach to turbo compounding different. First is the durable design. The turbo compound unit is a long-life design meant for the life of the engine. It’s not something that is meant to be changed out. Second, it was designed for fuel economy when paired with the I-Shift and the proper engine and transmission controls. Specifically because of turbo compounding, the D13TC can now operate at 950 RPM with a peak torque of 900 RPM. And third, it was always considered to part of a system aimed at reducing fuel consumption rather than as an add-on to increase the engine’s horsepower rating.”
How does the fuel efficiency of the D13TC compare with the standard D13 engine?
“If you compare this engine to a standard D13, both 2017 GHG compliant, the TC engine is about 3 percent more fuel efficient than today’s D13. But because we can use a faster rear-axle ratio with the TC, we go from a 2.64 to a 2.47 because it has lower peak torque at 900 RPM, we actually pick up another 1 percent. So, it can be 4 percent better by our books. If you compare it to a 2014 truck equipped with a GHG 2014 engine, the 2017 D13TC is 6.5 percent more efficient.”
What’s the return on investment on a D13TC model engine?
“We expect our customers will see a return on their investment within the first year, depending on the price of fuel. If the technology pays for itself within a year, everything after is savings. As the price of fuel increases, like it’s doing now, turbo compounding technology becomes more and more attractive.”
What are some of the misconceptions about turbo compounding from the past that Volvo hopes to overcome?
“Its complexity. People see it on the side engine and they think that it is super complex. The system and how it operates is actually very simple and it requires no maintenance. A misconception like that might lead customers to think it is not reliable, but it’s included in the D13 B50 rating of 1.2 million miles. There’s very little that can go wrong with it; it’s just a series of gears linked to a simple turbine wheel with a fluid-couple device. Even if there was a major malfunction, you could still drive the vehicle. It is physically separate from the engine.
"We expect our customers will see a return on their investment within the first year."
Product Marketing Manager on the new D13 with Turbo Compounding
Just The Torque You Need
With the D13TC, engine software senses loadweight, throttle inputs and roadway and automatically responds for more performance. It drops back into economy mode when less torque is needed. Unlike competitors, Volvo Trucks engines deliver split torque packages in a number of different combinations, with shift points in more gears.
Catching The Wave
A new, patented piston design uses a wave-shaped tab inside the piston. The injector sprays fuel directly onto the tab, which deflects the fuel back to the center of the cylinder for a cleaner burn. The wave tab eliminates wet spots on the cylinder walls and reduces soot.
A common rail fuel delivery system allows for an assembled camshaft, which saves 21 pounds of weight. Common rail also allows the engine to run more smoothly, cutting noise and vibrations to the cab. The results? A noticeably quieter engine, fuel savings, less wear and tear on the camshaft and longer engine life — plus more relaxed drivers.
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