A report in Engine Technology International says Renault is studying ways to put a prototype 2-stroke, 2-cylinder diesel engine into production.

Gale Banks has introduced the concept of supercharging and turbocharging diesels on different platforms.

“We are talking internally as to what to do next,” Pascal Triboté, innovation project manager for Renault’s powertrain research department told ETI. “I personally think it’s worth continuing down this path, making some changes to this engine, like making it slightly bigger, like a 1-liter for example. Because if we’re going to take this into manufacturing we need volumes, and to get volumes we need more power to cover more market segments.”

The small 2-stroke engine was the result of a R&D project titled “Powerful,” and the concept prototype was introduced publicly  in December, 2014. The engine is 50 percent smaller than the best-selling 1.5-liter 4-cylinder engine. Measuring out at 730cc, the prototype weighs less than 220 pounds. Renault noted in its original press release that 2-stroke diesels are common in large container ships and thermal efficiency is around 50 percent. A typical 4-stroke diesel comes in at about 35 percent. The problem with 2-strokes, of course, has always been emissions.

Renault’s 2-stroke diesel is both supercharged and turbocharged and produces between 35kW and 50kW (48 to 68 horsepower) with 112 to 145Nm of peak torque at 1,500 rpm, or about 83 to 107 lb-ft. The concept of combining supercharging and turbocharging on a diesel is hardly new, as EngineLabs has showcased dual-boosted, big-horsepower engines from Gale Banks.  But Renault’s goal is to reach emerging markets as there could be significant cost savings.

Here’s a twin-charged Detroit Diesel from Gale Banks used in Mike Ryan’s Freightliner that ran at Pike’s Peak. It’s capable of producing up to 180 pounds of boost.

“As it is a 2-stroke, we’re firing each cylinder with the same frequency as the 4-cylinder, 4-stroke, so in principle we only need half of the cylinder for the same combustion frequency,” Triboté explained to ETI. “We took exactly half of this engine – same bore, stroke and design for things like the cylinder block – but what really changed was the cylinder head, gaskets and combustion system. Basically the bottom end of the engine is nearly exactly the same, aside from tribology, which we had to change a little bit to make the 2-stroke cycle work.”

According to the article, the supercharger is from Eaton and turbocharger is sourced from Czech-based CV Turbo. Delphi supplied the pressure injection system.

“If we are going to produce a 2-cylinder diesel, it won’t be this specific engine,” summed up Triboté. “It’s an R&D project that’s achieved its goal — to learn enough to go a further step, another closer step to production but nothing yet has been decided.”