With a power to volume ratio of 134 horsepower per liter (more than Ford’s renowned 1.0L EcoBoost) the Volkswagen 2.0L employs Formula 1 grade technology and reportedly achieves record efficiency.
As a rejuvenation of the current VW 2.0L diesel found in the non-U.S. Passat, the new engine adds several salient new features and upgrades. Variable valve timing is a new feature, and so is a special start-stop system, which shuts off the engine in the event the car’s speed falls below 7 mph.
The new 2.0L does add an interesting twist where fuel injection is concerned. Instead of employing the time-tested PD unit injector fuel delivery system, VW went with a common rail injection system, delivering fuel directly to each combustion chamber. The new common rail system delivers fuel at a very high rate, operating at nearly 36,000 psi, or 2,500 bar, which is higher than the current VW TDI engines utilizing unit injection.
A piezoelectric system is used in the fuel injection system. This technology uses quartz crystals situated within the injectors, which expand when electricity is applied. Because the voltage applied to each injector can be manipulated and fine tuned by the ECU, it heightens the precision and efficiency of the injection process.
Perhaps the most technologically advanced aspect of the engine is its turbocharger unit. The turbocharger employed here is Formula 1 grade. Stemming from Audi technology soon to be employed on the next R8, the design essentially uses an electric motor to drive the compressor at lower rpm ranges.
This design will employ an electric motor to drive the turbo at lower rpm, until engine output is sufficient to drive the turbo by exhaust gases. Now, instead of waiting for the exhaust gases to reach a suitable level, power is available almost instantaneously. In Formula 1, the power for this system comes from the KERS system.
Another curious aspect of VW’s improvisation of this turbocharger design is the fact that, in addition to being electrically driven at lower outputs, the engine employs a “twin-turbo” setup. The question of the function of the second turbo is a mystery. Given that the engine is a straight four, that rules out the possibility of a parallel setup, and a sequential setup would seem unlikely due to the presence of the electrical unit. Perhaps, drawing on efficiency concerns, one compressor may be driven electrically, while the second may be much larger and driven by an exhaust turbine; though the first compressor would then technically be reclassified as some sort of supercharger.
The engine will be coupled to Volkswagen’s new 10-speed, dual clutch transmission, pictured below. The 10-speed is of the direct shift gearbox design, which allows either automatic or semi-automatic modes of operation. It replaces the current line of six-speeds and constitutes part of VW’s efforts to drastically improve fuel efficiency across their model range.
Arriving within the next couple of years, this new engine will be one of the more advanced on the market. It represents Volkswagen’s continued commitment to building diesel engines for passenger cars – a trend which seems to have caught on everywhere but in the U.S.