Feature: GM’s Diesel Family is Growing

Story and photos by Howard J Elmer, additional photos courtesy of GM

GM’s newest diesel isn’t a heavy truck engine, it’s not a ground pounder, and its target market is very different from what most consumers think of as the diesel-powered niche in this country – pickup trucks. Called the Whisper Diesel, this new four-cylinder turbo-diesel comes from Europe and displaces just 1.6L.

It was introduced by Mike Siegrist, GM regional chief engineer, at a media briefing in Toronto with the overall theme of “GM’s diesel future.”

This new engine is being put to work right away, with it currently being offered in the new 2018 Chevy Equinox. And, while it’s installed here, it’s built as an international collaboration.  It was designed in Torino, Italy, while the hardware and transmission were sourced in Germany. Final assembly of the powertrain is at an engine plant in Hungary.

As might be assumed, the Whisper Diesel is quiet, very quiet. To accomplish this, it uses an acoustic foam top cover, acoustic foam-covered injectors and common rail, as well as a clamshell manifold cover to help in achieving the quiet it’s becoming known for.  However, the other factor in its virtual silence is actually a key design element. It was built utilizing a ten-step solenoid fuel injector. By spraying fuel in small bursts at various stages of compression, the Whisper Diesel stays quiet. Starting with a pre-combustion injection, it follows up with a varying number of rapid pre-ignition shots of fuel. This is what takes the big bang out of the diesel detonation. This system also reduces NOx generation and, of course, lowers the noise level. It also smooths out potential engine vibration. Post-combustion, the injector continues to input pulses to control exhaust gas temperature, burn off particulate matter and thereby further lower emissions.

So, that’s the tech part – but for most consumers, what’s important is that it offers good torque and excellent fuel economy. For example, in the new Equinox, it makes 137 hp and 240 lb-ft of torque – 90% of which is said to be available across a wide rpm range of 1,500 to 3,250.

Fuel consumption in the new Equinox is claimed to be 6.0L/100 km Hwy and 7.4L/100 km City. These numbers are better than most hybrids post, notes GM.

During the presentation, Dan Nicholson, VP of Global Propulsion, sketched out GM’s future with diesel. He says that light-duty diesel has a bright future in North America, with 11 diesel models being offered currently. Meanwhile, on the global scene, GM already offers 34 models.   This global portfolio contains five engines ranging in displacement from 1.0L to 6.6L, though only three of these are currently available here.

To pave the way for greater diesel penetration, GM is working to show North Americans the benefits of buying diesel engines. First off, says GM, a customer can realize a $7,000 savings over the life cycle of a GM vehicle – gas vs. diesel. This more than makes up for the higher up-front cost of a diesel engine, and resale remains higher as well. As for the technology itself, showing off the Whisper Diesel, demonstrates that the commonly held beliefs that diesel engines are slow, loud and dirty are simply no longer true. That’s GM’s message and its battle cry moving forward.

Still, for the moment, pickup trucks currently make up the largest North American vehicle segment that features diesel engines, but SUVs are catching up. GM predicts that by 2020, the SUV market will consume three million units annually – 16% of which will be diesel-powered.  That’s 480,000 diesel engines. It’s this wider use of smaller diesel that will inevitably lead to wider general acceptance of these engines.

On display at the introduction was, of course, the new 1.6L turbo-diesel alongside the existing 2.8L and 6.6L.  These are what are currently available in North America. However, on another note, there is an obvious hole in that lineup. A 4.0L offering aimed at half-ton pickups and larger SUVs (of which GM builds plenty) would certainly fit well into GM’s future diesel strategy. This speculation on my part makes sense by simply looking at the competition. Ram currently has a 3.0L diesel in its Ram 1500, while Nissan offers a 5.0L in its Titan and Ford has announced that the F-150 will get a 4.2L diesel engine option later in 2018.

I asked this question of the VP and assembled engineers. They refused to comment on possible future product additions, but they were all smiling. I say another midsize diesel is coming. It’s not if – it is simply when.