Volkswagen has cornered 90 percent of the American automotive diesel market, a remarkable achievement, especially considering the diesel engines now in everything from BMW and Audi to even the Jeep Grand Cherokee and the Chevrolet Cruze. To be fair, Volkswagen has had an exclusive on smaller diesel engines in the U.S. No one else has seemed interested. Since 1977, when Volkswagen first offered a diesel engine in the Rabbit, the automaker has sold more than one million cars and SUVs powered by diesel engines.
In time to meet the rising competition in small diesels in the U.S., however, Volkswagen has developed an all-new 2.0-liter diesel engine that shares only its bore centers—how far apart the cylinders are spaced—with its predecessor, the EA189 turbodiesel. The new EA288 engine will see wide application across the VW line—finding its place where the diesel engine had been, plus a few more.
For 2015, the Volkswagen Tiguan will have the diesel option for the first time, at least in the U.S. due emissions rules. While the 2.0-liter diesel could pass DOE emissions regs without diesel exhaust fluid (of D.E.F., also sold under the brand name AdBlue) in the Golf TDi, Beetle TDi and Jetta TDi, the Tiguan is in a heavier weight class, which would have required diesel exhaust fluid injection. The 2014 Volkswagen Passat TDi was also in the heavier weight class, but was in a price point where adding the cost of the injection system wouldn’t impact sales as it would have in the less expensive Tiguan.
The new diesel, however, uses DEF across the board, designed to pass both European regulations and the upcoming U.S. LEV3 standards, which it already meets.
The new EA288 turbodiesel is called the Modular Diesel Matrix, or MDB, which will be the basis of future VW four-cylinder engines. The modular design will allow various components to be changed as needed for different applications without a redesign or new engine, and for different needs in different markets.
The engine block is cast iron with a forged steel crankshaft. To reduce vibrations from the four-cylinder design, the engine in two-liter displacement as used in the U.S. will have twin balance shafts. The engine in 1.6-liter displacement in other markets and as a 2.0-liter in less-expensive VW Group product lines (Skoda, for example), the engine will not have balance shafts.
The new MDB engine used in all four-cylinder VW applications in the U.S. has a water-cooled intercooler incorporated into the intake manifold. This helps reduce emissions as well as reduce turbo lag by decreasing the route of the intake charge between the turbocharger and intake valve.
The head is aluminum alloy with a cross-flow design. Unique to the EA288 cylinder head is integrating camshafts into a separated housing using a thermal joining process. This allows for a very rigid camshaft bearing without adding weight.
Also, instead of having each camshaft with only exhaust or intake cams, each of the dual overhead camshafts operates one intake and one exhaust valve per cylinder (out of four valves per cylinder). Volkswagen says this allows greater air delivery and swirl. Because one of the camshafts can be rotated for variable valve timing, and with intake and exhaust valves on a single camshaft, an Atkinson-cycle effect can be obtained.
The cylinder head also has its own “micro cooling circuit” as part of a sophisticated head management program for the engine.
A new fuel injector is being used in ES288. The high pressure common rail’s injector has a three-piece welded nozzle needle and nano blind hole injector tip.
A complex exhaust gas recirculation helps lower the combustion temperature and reduce NOx production. Higher soot production is cleaned by close-coupled exhaust treatment using a low backpressure, high particulate filtration efficiency with SCR (selective catalytic reduction).
Efficiency of Volkswagen EA288 turbodiesel engine is further improved by a reduction in internal friction, reduced by 15 percent compared to EA189. Roller bearing are used for the drivetrain-side camshaft (camshaft turned by the timing belt), the engine has increased piston-to-wall clearance, and lower piston-ring tension, among other things.
The bottom line is an engine rated at 150 horsepower—up ten horses from EA189—with no change to 236 lb-ft of torque spread over 1750 to 3000 rpm. While torque hasn’t changed, fuel economy is up significantly. For example, in the 2015 Volkswagen Jetta TDi, fuel economy is rated at 31/46 mpg city/highway, an improvement of four miles per gallon over its predecessor.
With the addition of other diesel-powered vehicles, including for example those from Audi and from BMW, the 5-Series, BMW X5 and BMW 7-Series, Volkswagen’s share is likely to decrease, just based on total numbers and percentages. But look for the volume of TDi Volkswagens with the new EA288 2.0-liter turbodiesels to increase with the rollout of 2015 Volkswagen models.