The evolution of the powertrain

by Derek Clouthier

When it comes to the mechanical components that move a truck, it used to be about one thing – generating power.

For a variety of reasons, the powertrain of today is much different from what you would get 20 years ago. Advanced technologies, environmental concerns, government regulations, and the desire to save on fuel costs are some of the reasons behind the change.

Today’s engines provide comparable performance to older models, and much more efficiently.

There are still questions, however, when it comes to choosing the right powertrain for each application – after all, how much power do you really need? Is there such a thing as having too much power? And what are the dangers of not having enough power?

We talked to a few industry sales experts who have seen firsthand what today’s customers are looking for in a powertrain, and how performance has evolved over the past couple of decades.

“Fleets are starting to understand that it’s more about torque and less about horsepower when they’re buying engines these days,” said Bob McKinley, new truck sales operations for Carrier Centers out of Woodstock, Ont. “The fleets that are really on top of it are ordering things like lower horsepower and more torque because that leads to fuel efficiency, and the power is in the torque.”

McKinley is seeing a shift toward engines with 1,850 lb.-ft. of torque and 450 hp, a transition from the high horsepower buyers were looking for 20 years ago. Many OEMs, he said, had not yet discovered to simply add more torque to the motor.

McKinley said these days, drivers are “shutting the truck off at road speed limits” and using the higher torque to get up hills, eliminating the need for increased horsepower, which essentially just makes the truck move faster.

Blake MacPherson is a truck sales representative at Team Truck Centres in Windsor, Ont., and he, along with his sales colleague Joel Bezaire, said though engines 20 years ago ran “more free with a better seat-of-your-pants feel when driving,” customers need to choose the right powertrain from their particular application.


“With heavy-haul, the more torque and more horsepower, the better,” said MacPherson, adding that an overdrive transmission would also be beneficial.

For over-the-road applications, MacPherson echoed McKinley, saying more torque and less horsepower is the way to go. And for regional hauling, a powertrain with moderate torque and horsepower, as well as a 13-liter engine would work best, according to MacPherson.

The move from 15-liter to 13-liter engines has continued over the past few years.

Mark Dorais, new truck sales representative for Peterbilt dealer Cervus Equipment in Regina, Sask., said emissions targets are driving OEMs to focus on smaller displacement engines.

“A 13-liter engine is commanding the market in North America due to the major fleets in the United States and the lighter weights they haul versus in Canada,” said Dorais, adding that the 13-liter can offer better fuel economy, while the 15-liter provides superior performance. “There are OEM engines, such as the Paccar MX, which is a 13-liter engine and offering up to 510 hp and 1,850 lb.-ft. of torque, that do well pulling heavy weights while getting good fuel economy.”

Dorais said as technology has advanced over the years, and the materials being used in smaller displacement engines have made them lighter and stronger, they are able to increase performance while hauling heavier weights.

MacPherson had a slightly different perspective with regards to the 13-liter versus 15-liter engine debate.

“The 15-liter is commanding the market between Detroit Diesel and the Cummins X15,” said MacPherson.

Longevity, fuel economy, and reduced maintenance were three factors where a 15-liter engine is superior to the 13L, according to MacPherson. It can also command a premium at resale time.

Heavy-haul applications, heavy vocational, and over-the-road are applications where MacPherson would recommend the use of a 15-liter engine, while regional haul, moderate vocational, crane trucks, and dump trucks are suitable for the 13-liter option.

McKinley said 13-liter engines are starting to come into their own.

“With the 13 liters, we’re seeing acceptance in the last six months that we didn’t see the six months before,” he said of the new International A26 engine. “Everybody wanted to wait and see what other people thought of it. The fuel economy that all 13-liters get is there with (the A26) and the reliability has been there, and we’ve sure learned the reliability story. It’s better to be up and running every day than to get the last drop of fuel.”

Tipping his hat to Paccar’s MX-13, McKinley said International is moving away from the maligned MaxxForce engine, which had issues, mainly due to the turbo air control valve.

With International now offering the A26, McKinley said the air system has been changed to mirror other engines, and thus far, feedback has been positive.

“It’s a good motor. Our dealership has sold about 75 to 100 now and it’s been out about a year,” he said. “They’re doing what they promised to do. They’re getting about half a mile a gallon better than a 15-liter. I don’t know if a year is enough time, but they are certainly behaving themselves and they have the power to do the jobs.”

Reiterating McKinley’s opinion, Dorais agreed that today’s engines are more about torque than horsepower.

“There’s a mindset in the industry that you must have the most horsepower to be able to pull, but in fact it’s the torque that gives the power,” he said. “Unless a customer is pulling heavy weights, then a high horsepower engine isn’t really required. With the advances in electronics and software programing, engine manufacturers are able to really focus on specific areas and get the most out of their products.”

But is there a risk of not having enough power?

“The main thing is flexibility,” said McKinley. “Don’t paint yourself into a corner with the truck that just (barely) does it and gets the most fuel economy. You might get a new contract to haul something and wish the truck you bought would be flexible and do the new job.”

MacPherson believes when it comes to heavy-haul, there is no such thing as too much power, but for other applications, there is some wiggle room.

“With over-the-road, you need to balance your power and torque to achieve maximum fuel economy in your application,” he said.

“I don’t think there’s no such thing as too much power compared to how much power is actually required for the application,” added Dorais. “With too much power there’s a tendency to put your foot into it, which will burn more fuel. And being under-powered will burn fuel because the engine has to work that much harder.”

As for resale value, all agreed it should be taken into consideration when purchasing a new truck.

McKinley said going forward he see less of an issue reselling 13-liter trucks because of their fuel efficiency.

MacPherson countered, saying a 15-liter with automated transmission will always bring the best resale value because all over-the-road and heavy-haul applications should use a 15- or 16-liter engine.

Dorais agreed that bigger displacement engines tend to have higher resale value.

“Customers should really focus on what they require for their application,” he said. “It’s either fuel economy or performance.”

If all else fails when trying to decide what kind of powertrain is best for you, McKinley said to heed the advice of others.

“Our story goes, that if you look at all the big fleets, they’re all on B-trains with 450 hp and 1,850 torque, with a 13-speed automated (transmission), so you should too,” he said. “If you’re a small guy, then learn from the big guy, because they’ve had the time to experiment.”

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