Driver's Seat: The new wave of turbochargers

The turbo in the 2013 Dodge Dart is especially aimed at fuel efficiency. The turbo used in the 1.4-liter four cylinder is available throughout the entire Dart lineup, except the super-hot-rod RT model.
The turbo in the 2013 Dodge Dart is especially aimed at fuel efficiency. The turbo used in the 1.4-liter four cylinder is available throughout the entire Dart lineup, except the super-hot-rod RT model.
Posted: July 26, 2012

Historically, the word turbocharged has meant more power - at any cost.

It would likely not have conjured up images of the new-for-2013 Dodge Dart or the Chevrolet Cruze Eco.

But those are just two of the latest models using turbochargers to squeeze the most miles out of a drop of fuel, and to do it with little fanfare or stress to the engine.

 Steve McKinley, vice president of Americas engineering for Honeywell Turbo Technologies, also lists the Chevrolet Sonic, Ford Taurus, and Fiat Abarth among the cars that use their powers for green fuel savings rather than neck snapping.

"We're definitely experiencing a very high penetration rate of turbos," McKinley said.

In the Dart: The turbo here is especially aimed at fuel efficiency. Mike Merlo, Chrysler's chief engineer for the just-released 2013 Dodge Dart, said the turbo used in the 1.4-liter four cylinder is available throughout the entire Dart lineup, except the super-hot-rod RT model.

"Turbocharging really allows you to introduce a lot of torque in a relatively small-displacement engine," Merlo said.

How turbos work: To simplify the explanation, a turbocharger captures some of the exhaust gases from the combustion of the fuel and reuses them to power a compressor, which boosts the engine performance.

When I drove the Chevrolet Cruze and Sonic last year, I was amazed at the difference in performance from, say, the 1987 Dodge Shadow I'd driven in my college days.

Especially in the Sonic, where I wrote, "I never really felt the turbo kick in. The Sonic had adequate power at low revs, which is a surprising place for such a tiny engine to spend most of its time."

I experienced no lag under light acceleration followed by a sudden burst of power as the turbocharger kicked in.

"We're making the old response issues go away with smaller turbos and more closely coupling them to the engine," McKinley said.

Merlo actually compared today's Dart turbo to the kind of engine found in the old Shadow. The 1.4-liter in the Dart produces a sprightly 184 foot-pounds of torque. But the real breakthrough is allowing that maximum torque to show up at 2,700 r.p.m., which is extremely early in the power curve. In the old engine, it probably showed up around 4,000 r.p.m.

Other boosts: But small cars do not boost efficiency by turbochargers alone.

Rick Balsley, General Motors engineering group manager for charging, said the company had paired the turbochargers with direct fuel injection and cam phasing, which affect feeding and timing the engine to add power to engine efficiently.

"The turbo starts to make more and more sense when you do those other things," Balsley said.

Signing off: Shutdown was also a problem, once upon a the time, as the engine needed to be idled for a minute before turning it off. But new technologies address that, McKinley said.

"We've gotten to the point where we're water-cooling all the center housing so you don't have to shut it down for a minute," McKinley said. "We want it to be the feel of a larger, naturally aspirating engine."

Balsley explained that for GM, a thermo siphon allows the warm coolant to rise from the turbocharger and flow back to the radiator for cooling, and the cool liquid flows back into the turbocharger. The siphon allows the cooling cycle to continue even after the engine is shut off.

Longevity: Engineers of modern turbochargers have also worked hard to make the engine and turbochargers last longer. One feat has been water-cooling the bearing section of the turbocharger.

And manufacturers are demonstrating that they are confident that the turbos will last.

"Today's turbo has the same warranty as the engine," Balsley said.


Contact Scott Sturgis at 215-854-2558 or ssturgis@phillynews.com.

comments powered by Disqus
|
|
|
|
|