It was not that long ago that U.S. motorists were paying $1 for a gallon of regular gasoline. Today, the auto industry and outside researchers have a big incentive to explore energy-saving ideas that they would have considered zany just a few years ago.
Automotive history is ripe with tales of inventors with promising new engine technologies who were never able to bring their "ideas" to market. This time, maybe one or two of the ideas that follow will actively deliver a breakthrough.
One of the most promising new ideas in energy efficiency comes from researchers at the Massachusetts Institute of Technology. The proposition: get more power and efficiency out of turbocharged motors by injecting ethanol, methanol or E85 (85 percent methanol, 15 percent gasoline) into the engine at times of higher demands for power.
The MIT crowd claims this technology can boost gas mileage by as much as 30 percent, and that it allows a high-compression engine and high-boost turbocharger to operate on regular gasoline. Daniel Cohn, senior research scientist at the MIT Laboratory for Energy and the Environment, and other MIT professors, have formed a company, Ethanol Boosting Systems, and are testing their concept with Ford Motor.
Casey Selicman of CSM Worldwide, an automotive research and consulting firm, explains, "With aggressive turbocharging, you get a heavy case of knocking if you try to use regular fuel." The direct injection of ethanol into the combustion chamber has an evaporative cooling effect and eliminates the knocking.
Ethanol Boosting Systems thinks it is possible to get as much as 330 horsepower and 360 foot-pounds of torque from a 1.9-liter engine using regular-grade gasoline as the primary fuel. For comparison, Volkswagen's state-of-the-art two-liter, turbocharged direct-injection four-cylinder delivers 200 hp and 207 foot-pounds of maximum torque — and requires premium fuel.
Whereas the average turbo installation costs manufacturers an additional $1,000, Ethanol Boosting Systems estimates that their system would run a total of $1,400 to beef up the engine and add a second fuel-injection system, plus a small (4- to 6-gallon) secondary fuel tank for the "boost fluid."
Cohn says that the additional manufacturing cost for a turbo diesel is $5,000, and a diesel motor — unlike ethanol boost — requires advanced exhaust treatment. This technology is mostly theoretical, but not that different from the common practice of injecting extra gasoline into a conventional turbo engine to cool the combustion chamber, rather than power the motor.
Gasoline tech, meet diesel
On another front, Daimler and General Motors are experimenting with motors that run on gasoline but combine features of traditional gasoline engines (fuel ignited by a spark) and diesel technology (fuel ignited by compression of fuel and air).
Daimler calls its version the DiesOtto. During startup and under full load, the engine uses a spark plug to ignite the gasoline/air mixture, as in a conventional gasoline engine. At low and medium engine speeds, within one engine stroke, the motor automatically switches to a mode similar to that of a diesel, in which it ignites the gasoline-air mixture by compressing it.
Mercedes claims that its DiesOtto motor minimizes nitrogen oxide emissions because the compression ignition takes place at relatively low temperatures (unlike a conventional diesel) and thus generates only small amounts of nitrogen oxides. As a result, the exhaust gas treatment requires nothing more than a standard three-way catalytic converter, rather than the sophisticated controls needed for a pure diesel.
Daimler has a 1.8-liter V-4 DiesOtto in its F 700 show car, a full-sized luxury sedan. This little motor — which bristles with other advanced technology, such as two sequential turbochargers, variable valve timing and variable compression ratio — bangs out 238 hp. A hybrid electric motor adds another 20 hp.
Probably the toughest part of the DiesOtto development is managing the transition between spark- and compression-ignition and making it smooth and transparent to the driver. In all likelihood, this idea is still several years away (at best) from being in a production vehicle.
An even more radical long shot is an internal combustion engine that switches between two- and four-stroke operations. Most consumers associate two-stroke with chain saws, grass trimmers and smelly exhaust, but this technology also found its way into a few automobiles, such as Saabs in the 1950s and the unloved East German Trabant. Now, a consortium led by Ricardo of the U.K. — and including Ford Motor, Denso, Ma2T4, Brunel University in the U.K. and the University of London — is investigating such an engine.
The camless engine
Over the past two decades, automakers have adopted variable-valve technology, in which various mechanical systems vary the lift and duration of valves opening and closing for intake and exhaust in order to maximize power and efficiency and minimize exhaust emissions. This technology in one form or another is widespread in modern automobiles.
The next big breakthrough could be the camless engine, a motor that does away with the conventional camshaft to operate the engine valves and replace them with electromechanical or hydraulic-powered values.
The lure of the camless motor? A significant reduction in internal friction from powering a crankshaft and associated belts, gears, etc., as well as precise control of valve timing. French auto parts supplier Valeo claims this technology could deliver 20 percent gains in fuel efficiency, emissions reduction and low-end torque. According to Valeo, this technology could appear in a production motor in the near future.
The challenge is designing a camless system so that a possible failure of the valves is not catastrophic to the engine; other issues are reliability, noise and vibration.