Mr. Turbo and the return of turbocharging: fuel economy and performance

September 2, 1:19 PMAuto Review ExaminerJohn Matras

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 My colleague Jim Henry wrote in bnet.com about the resurgence of turbocharging and Saab’s Mr. Turbo, Per Gillbrand, who was an early and constant supporter of turbocharging as a method of getting power and fuel economy from a small four cylinder engine.

As Henry notes, Gillbrand’s work at Saab began in the late ‘70’s, but as General Motors took over the Swedish carmaker, naturally-aspirated V-6s were imposed on Saab…although we’ll note that Gillbrand fought back in a way by turbocharging the V-6.

In particular, Saab used “asymmetrical turbocharging,” taking boost from only one side of the engine.

Turbocharging—forced induction—was indeed all the rage in the eighties, however, and that largely as a result of the gas crisis of the late seventies and as a way of compensating for the automotive anemia in the late carbureted era. The small turbocharged engine with newly-practical electronic fuel injection was the way to go.

Chrysler in particular put turbo fours in everything from the (downsized) New Yorker to the Dodge Omni…and even the Dodge Caravan. Audi used them in its awesome rally cars and Subaru used turbos to go from dreadfully slow to merely pokey.

But there was a problem with turbocharged engine: the dreaded turbo lag. Turbochargers use exhaust gases to spin a turbine that spins an impeller that pushes more intake charge into the cylinders than would otherwise be admitted via atmospheric pressure alone. With more air-fuel mixture in the cylinder, the more horsepower could be produced (via a process that would require a treatise much longer than this will be). However, it takes time for the exhaust pressure to “spool up” the turbocharger so it can produce boost. That time was the lag in turbo lag.

For some enthusiasts, turbo lag was exhilarating. That sudden whoosh out of nowhere was a hoot, and if one kept the turbo spinning by driving hard, the lag disappeared. Of course, in day to day driving that wasn’t possible, and anyway, not everyone has racing stripes on their soul.

So when OPEC was tamed for a time and fuel prices stopped what seemed to be an inexorable rise, combined with technological advances made possible by the microchip, people abandoned the turbo rush for the comfort and ease of torque on demand. Turbos became rare birds.

But they didn’t go away entirely in the Nineties. Witness the Toyota Supra Turbo and the twin-turbo rotary-powered Mazda RX-7, both of which expired in the U.S. market because they were great performance cars but simply too expensive.

However, even Saab didn’t give up turbocharging entirely, but even Saab, with perhaps more turbo experience than anyone in the business, wasn’t able to tame turbo lag entirely. A review in Edmunds.com on the 1997 Saab 9000 Aero powered by a 2.3-liter turbocharged four bemoaned its bipolar performance:

“This big Saab, which purports to have 0-to-60 times in the low 6-second area, is positively anemic at low revs. Twice in 2 miles other cars nearly creamed me when I was making left hand turns in heavy traffic. Expecting this big, allegedly fast car to launch through a turn, I instead found myself sitting for what seemed like an eternity waiting for the turbo to spool up. When the turbo finally did come alive, the cacophony created by the piercing whine of the powerplant and the smoking and chirping of the front tires was enough to startle fellow motorists, passing pedestrians, nearby children, and distant dogs.”

The Saab, Edmunds.com noted, required a special driving technique:

“The trick to driving a car with a turbocharger is to keep the revs in a tightly defined range at all times. As mentioned before, our Aero didn’t move terribly quickly when the clutch was released under 2500 rpm. At engine speeds over 4,000 rpm the Aero’s tremendous torque caused the wheels to spin ineffectually, overwhelming the Z-rated tires in a smoky, stinky, and largely frivolous display of power.”

For most drivers, that explosive performance wasn’t worth giving up the linear response of a bigger, naturally-aspirated engine for a few mpg of relatively inexpensive fuel.

Only the recent spike in fuel prices has returned turbocharging to automotive engineering and the public’s interest. As Henry notes, Ford’s ECO-boost direct-injection turbocharged engines are a serendipitous arrival for the Dearborn-based automaker. We’ll withhold comment until we’ve actually driven an example.

We’ve also recently driven a Saab 9-3 2.3T and found its turbocharged 2.3-liter engine to be almost lag free.

But with fuel prices headed back down, at least fot the time being, turbo lust could cool again, unless then new generation of turbo engines have overcome the driving disadvantages of the earlier turbo motors and don’t add too much to the initial purchase price.

Per Gillbrand’s turbocharging may not be the solution but it may be a solution. As physicist Niels Bohr noted, “Prediction is very difficult, especially about the future.”

Illustrations, top to bottom: 1997 Saab 9000 CSE, Saab photo/author archives; 1984 Audi Sport Quattro, author photo; 2007 Saab 9-3 2.0T, author photo.