Diesel engines no longer noisy, smelly monsters

Hey there, time traveller!
This article was published 19/09/2014 (4373 days ago), so information in it may no longer be current.

In Europe, diesel engines dominate the vehicle market and Canadians are much more accepting of diesel-powered passenger vehicles than drivers in the United States. It would be nice to see the small, high-performance diesel powertrains offered in Europe made available in Canada but that is unlikely to happen because our driving requirements are different — long distances here versus short distances in Europe, the expense of certifying the powertrains to meet North American emission standards and the logistics of supporting these powertrains with parts supplies, sales and technician training and repair information just for Canadian customers. If the U.S market were buying more diesels, then the economics of bringing these powertrains to our market would be much better.

Even with these challenges, however, we are seeing more diesel engines in North America, and if you still think of diesels as being slow, smelly and smoky, you will be pleasantly surprised by the performance of the new diesel designs on the market.

Volkswagen has been the most visible manufacturer to offer diesel engines in passenger vehicles, but others such as Mercedes-Benz offer their BlueTEC diesel engines in some sedans and SUVs, Audi in the Q7 SUV and Chevrolet in the Cruze. Over the years, Jeep has also offered diesel-engine options in some of their models, and this year they have a new 3.0-litre V6 diesel option for the Grand Cherokee.

The Grand Cherokee 3.0-litre diesel engine is the same engine offered in the Ram pickups, and it may be small, but is a strong performer. Jeep and Ram call it the EcoDiesel and this single turbocharged V6 puts out 420 ft lbs of torque at just 2,000 rpm and it has been named as one of Wards Auto 10 best engines for 2104.

Already a proven design in Europe, this engine has features exclusive to North America to meet our driving requirements, including a MultiJet2 common-rail fuel-injection system. This direct-injection fuel system operates at pressures up to 29,000 PSI, with fuel to the common rail supplied by a camshaft-driven mechanical pump and fuel pressures controlled by the computer through an electronic pressure regulator and sensors on the fuel rail. The individual fuel injectors for each cylinder are electrically triggered by the engine computer and spray an ultra-fine mist of fuel directly into the cylinder that provides efficient combustion.

The new 3.0L Diesel is very quiet. So quiet, in fact, it would be easy to mistake the vehicle as being powered by a gasoline engine. Filling with the correct fuel is critical and there are bright notices under the fuel door to remind you this is a diesel vehicle. Some of the quietness is made possible by the advanced technology servovalve and injectors that can operate up to eight fuel injection pulses for each cylinder on every power stroke. By spraying the fuel in in steps or pulses, the cylinder pressures can be controlled more accurately, without the high peak pressure loads that produce the rattling sound we used to hear in diesel engines. This multi-injection approach to fuel supply also improves throttle response, fuel economy and reduces emissions.

Other interesting features of the engine include an all-new engine block and bedplate (supports the lower end and bearings in the block) that are made of lightweight compacted graphite iron (CGI). This produces strength and rigidity, which also helps reduce noise from the engine. Variable swirl intake ports and a variable geometry turbocharger move air into the cylinders efficiently so it mixes with the fuel completely.

Compact, quiet, clean-burning and snappy, the engine moves a full-size vehicle like the Grand Cherokee or Ram pickup along very nicely. Fuel economy ratings for this in the Grand Cherokee are listed at 11.2 L/100 km city and 8.4L/100 km highway, which may be higher than you would expect, but these are using the new five-cycle fuel economy test standards that are being implemented for all manufacturers this year. Using the old two-cycle test standard, the highway rating would have been 7.0 L/100 km. That’s impressive for full-size vehicles that still have a towing capacity of 3,265 kg.

Engines such as this new 3.0-L V6 are changing the way drivers view diesel. I doubt if diesel will ever dominate the passenger vehicle market like it does in other parts of the world, but you don’t have to sacrifice performance or feel like you are a long-haul trucker when you are driving the newest diesel-powered vehicles.

Jim Kerr is a mechanic, instructor of automotive technology, freelance journalist and member of the Automobile Journalists’ Association of Canada.

kerr.jim@sasktel.net