DETROIT – Turbocharging downsized gasoline engines is a popular solution among auto makers to meet looming government imposed fuel-economy regulations without sacrificing performance, but it’s a strategy that makes little sense forNorth America, a top executive says.
Robert Davis, senior vice president-research, development and quality, doesn’t call out any competitors by name.
However, many auto makers are employing such a strategy, most notablywith its line of direct-injected turbocharged EcoBoost engines.
Whileuses turbochargers in some of its models, including its line of Mazdaspeed performance vehicles and CX-7 and CX-9 cross/utility vehicles, Davis says the technology only makes sense in certain applications.
“When you take a vehicle like the CX-9, it has space for a large displacement 4-cyl. and a turbo,” Davis tells Ward’s during a recent visit here. “But a 1.0L 3-cyl. turbo doesn’t make sense to me.”
Rather than attempt to turbocharge small engines, Davis says it makes more sense to right-size the engine to the vehicle it will power. “A turbo and downsizing is a temporary solution to not having the right engine in the car in the first place.”
Turbochargers also add unnecessary complexity, cost and weight and create a bevy of packaging issues.
“Turbochargers are small, but complex,” he says. “They’re water- (or) oil-cooled, so I have to run lines from the radiator or the oil pump. Then I need an intercooler, and then I have to add the piping to go from the air intake to the turbo and the turbo back to the throttle body.”
Once the intercooler is introduced, the question becomes where to put it, Davis says. Placing it in front of the radiator necessitates the need for a larger radiator, while locating it on top of the engine calls for a heavier hood with a scoop.
“And then you need to get the air out, so you need an evacuator, and then you have to move something on the bottom of the car to evacuate (the air),” he says. “If I have a turbo right next to a catalyst, then I need a different catalyst material because a turbo retains so much more heat and a catalyst won’t live as long.
“Anytime you add a turbo to the system, it’s fundamentally less efficient because of the drag and the motion and the weight and everything that’s associated with it.”
Davis admits Mazda’s powertrain strategy is at odds with long-time partner’s, which still holds a 3.5% stake in the Hiroshima-based auto maker.
The two companies will continue to collaborate on initiatives where it makes sense, he says. But powertrain development, at least for now, is not in the cards.
“I think it’s fair to say we’re on diverging paths and have been for a couple of years,” Davis says. “We do have a relationship, but we’re in different phases and places in our product cycles.”