two-stroke, two-cylinder super-charged and turbo-charged diesel engine
The two-cylinder engine is only half the size of Renault's 1.5-litre dCi diesel, weighs 40 kg less, ideally suited for small vehicle platforms. This 730cc unit is both super-charged and turbo-charged and produces between 35kW and 50kW (48hp-68hp) with 112-145Nm of torque from 1,500rpm.
Initial tests are encouraging, although the performance needs to be improved before Renault could consider introducing it. The engine is being developed with 18 industrial, scientific and academic partners in France, Spain and the Czech Republic, with investment from the European Union.
The pressure to reduce fuel consumption and CO2 emissions demands major breakthroughs in the realm of efficiency. The most efficient engines – which are widespread in large ocean vessels such as container ships – are two-stroke diesels. Their efficiency is close to 50 percent, while four-stroke automotive diesels struggle to achieve 35 percent. Until now, making these two-stroke engines small enough to adapt to the automotive world was impossible, but the POWERFUL (POWERtrain for FUture Light-duty vehicles) project sets itself the goal of investigating solutions for road vehicle applications.
The efficiency gains of the two-stroke cycle offer other benefits: compactness and a reduction in weight, given that it involves halving the engine size and number of cylinders (here a twin-cylinder). The engine is 40kg lighter and more compact, thereby making it ideally suited to small vehicle platforms.
This makes it an additional means of achieving downsizing, the objective being to produce a very small diesel engine for road vehicles that is even more economical, both to purchase and run (improved fuel consumption and lower CO2 emissions). Initial results are promising, even if we are still naturally at the research phase. It must be noted that performance is not yet sufficiently strong, since it is merely an exploratory study at this juncture.
HOW IT WORKS:
-A two-cylinder turbo diesel engine: switch from four to two cylinders while retaining the same bore and stroke.
-A 50 percent reduction in engine size in comparison with a 1.5-litre diesel.
Engine Size: 730cc
Maximum Power: 35-50kW
Maximum Torque: 112-145Nm, available from 1,500rpm
Stroke x Bore: 76mm x 80.5mm
Maximum Engine Speed: 4,000rpm
Boost: Mechanical supercharger and turbocharger
The advantages of two-stroke technology
-Lower fuel consumption / CO2 emissions thanks to improved cycle efficiency and the effects of downsizing
-De-pollution: enhanced efficiency of the de-pollution systems, particulate filters and NOx-Trap to comply with current and forthcoming legislation.
-Cost price: the reduction in the number of components means the cost price is brought closer to that of a petrol engine.
-Sound: a two-stroke, two-cylinder engine produces the same sound as a four-stroke, four-cylinder unit.