Fuel saving technology tested for diesels

Cylinder deactivation has long been offered in vehicles with gasoline engines. With this technology, the engine deactivates some of its cylinders when full power is not needed. Thus a V8 engine could be turned into a four-cylinder motor when cruising on a level surface, a circumstance under which full power is not needed. Even when more power is needed, when encountering an uphill stretch, for example, the V8 might only activate six cylinders.

Now, Automotive News is reporting that Cummins, a maker of diesel engines, and

Tula Technology, Inc., a Silicon Valley software control company with ties to Delphi Technologies and General Motors, is working on similar technology for diesel engines. This Dynamic Skip Fire technology will be tested on a 15-liter Cummins in-line six-cylinder diesel that is used in long-haul trucks.

The key to applying this technology to diesels mimics the approach used in gasoline engines: adopting a valve train that keeps the valves closed all the time on deactivated cylinders. The energy exerted on the compression stroke is regained on what would have been the power stroke, had the cylinder been active. Early testing suggests that the fuel efficiency gains would be modest, up to 3 percent, but in a long-haul truck, that could equate to savings of up to $1,800 a year. Of greater significance could be a reduction in carbon dioxide and oxides of nitrogen emissions, which was described as being “huge” in a quote from Tula CEO Scott Bailey, obtained by Automotive News.