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Researchers in POWERFUL develop new two-stroke diesel featuring low consumption and low criteria emissions

Two-stroke diesel in test car. Click to enlarge.

A European project led by Renault, in collaboration with the Czech Technical University in Prague, IFP Energies Nouvelles, Delphi, Le Moteur Moderne (LMM) and Universitat Politècnica de València have developed an advanced two-cylinder, two-stroke compression ignition (CI) engine integrating LTHC (low temperature homogeneous combustion) as part of the European project POWERFUL (POWERtrain for FUture Light-duty vehicles).

The €25-million (US$31-million) FP7 project, which ended in June, also supported two other engine projects: an advanced four-stroke two-cylinder SI engine concept characterized by low-cost / low emissions; and an advanced four-stroke, three-cylinder CI engine concept able to run also on new tailored fuels and integrating the LTC (low temperature combustion) mode in the CI combustion system.

The objective of POWERFUl was to design engines for light-duty urban and micro-urban vehicles (segment A and B), capable of reducing CO2 and criteria pollutant emissions. The main feature of the Spanish, French and Czech researchers’ work is the reduction in the engine’s weight and size, which results in a high specific power.

The 2-stroke, two-cylinder 730 cm3 engine uses a valve scavenging architecture, with the combustor head defined to optimize the scavenging. Injection pressure is up to 2,000 bar, delivered by the latest common rail generation combined with a high performance HP pump designed to limit the weigh to contribute to the CO2 reduction. A new generation of fast solenoid injector was proposed with improved multiple injection control and limited leakage.

We have been able to reduce the engine weight by between 50 and 60% with regard to the equivalent four-stroke engine. This entails a significant saving in fuel consumption, as well as a reduction in the cost of the engine itself.

—Ricardo Novella, researcher at CMT-Motores Térmicos of the Universitat Politècnica de València

With fewer cylinders, the friction produced in the engine is reduced, increasing its mechanical output and, finally, its overall performance. The engine has been designed for small vehicles such as the Renault Twingo, in which it has been applied.

The validation tests of the engine were performed at CMT-Motores Térmicos at the Universitat Politècnica de València. The researchers of the UPV proved its potential for reducing pollutant emissions and fuel consumption compared to the four-stroke version currently available on the market. Moreover, they studied the possibility of implementing new advanced combustion concepts, as alternatives to the conventional diesel system, with what they said was very promising results.

The research effort is now focused on the development of a boosting system that increases the actual levels of maximum power to the equivalent of a four-stroke engine.

Now the engine needs 20% more power, but it weighs 50% less, so the ratio gives more power per unit of weight (specific power), but not twice as much, which is what it should be. It gives around 1.7 times more. It is necessary to increase the power to a ratio of 2.

—Ricardo Novella

Renault and the IFP Energies Nouvelles are leading this work. In addition, Renault and CMT-Motores Térmicos are continuing their collaboration focusing on the analysis and optimization of new advanced concepts of combustion.

The researchers at Renault and CMT-Motores Térmicos presented the performance, characteristics and output of this new engine at the conference THIESEL 2014 (Thermo- and fluid-dynamic processes in direct injection engines), held at the beginning of September at the Universitat Politècnica de València.


  • J. Benajes, R. Novella, D. de Lima (2014) “Analysis of combustion concepts in a newly designed 2-stroke HSDI compression ignition engine” (THIESEL 2014)

  • Benajes, J., Martin, J., Novella, R., and De Lima, D. (2014) “Analysis of the Load Effect on the Partially Premixed Combustion Concept in a 2-Stroke HSDI Diesel Engine Fueled with Conventional Gasoline,” SAE Technical Paper 2014-01-1291 doi: 10.4271/2014-01-1291

  • Jesus Benajes, Ricardo Novella, Daniela De Lima, Pascal Tribotté, Nicolas Quechon, Philippe Obernesser, Vincent Dugue (2013) “Analysis of the combustion process, pollutant emissions and efficiency of an innovative 2-stroke HSDI engine designed for automotive applications,” Applied Thermal Engineering, Volume 58, Issues 1–2, Pages 181-193 doi: 10.1016/j.applthermaleng.2013.03.050



It always intrigues me, and irritates me, and makes me skeptical when these articles are written without any specifics. I wonder even why greencarcongress congress accepts articles with so little information. For this group to spend $30 million dollars and not have the awareness to tell us some specifics is insulting. I want to know the weight of the engine, how much horsepower it produces, what fuel efficiency it produces, etc, etc. if anyone out there agrees, let's try to make the world a bit better by requiring more specifics, instead of more mores. Thanks.


To citizen, probably a group of incompetent researchers highly paid but having agendas. We will never see this 2 stroke engine in a car because there is nobody interested in commercialisation. They could have tested it at reneauld with the power, the torque curve and consumption but they never finish yje project because they need jpbs instead and their job is to research endlessly only and forever, so goodbye results and welcome endless stream of money.

Nick Lyons

@citizen: Note that the relevant technical papers are referenced in the article. You can purchase them if you want more details.


This is an interesting concept. By reviewing the abstracts, the engine is a 2-stroke two-cylinder Diesel engine with a displacement of 730 cm3 that uses Partially Premixed Combustion (PPC) burning gasoline. Designed for a range of power of about 35-50 kW and a range of torque of 110 – 145 N.m (ref:http://trid.trb.org/view.aspx?id=1255333). Since Renault and Delphi are also involved in the research this could be a good range extender engine for a PHEV.


One more comment. The 2-stroke engine has poppet valves and probably a supercharger, so need to mix oil and gasoline.


Perfect direct drive EV range extender, allowing 4wd.

Connect it to the wheels with a simple clutch single speed gearbox with ratio optimized for highway driving.

The turbo is not needed, but might be better for emissions and extra power.


"Intake begins when the piston is near the bottom dead center. Air is admitted to the cylinder through ports in the cylinder wall (there are no intake valves). All two-stroke Diesel engines require artificial aspiration to operate.."



More abstract mining! From "Air System Conception for a Downsized Two-Stroke Diesel Engine" http://papers.sae.org/2012-01-0831/ - "to allow engine scavenging at any operation, supercharger had to be integrated in the air loop.", also "Among the investigated boosting devices were the positive displacement and centrifugal superchargers driven from the crankshaft and placed upstream or downstream of the turbocharger with either the waste gate or variable turbine. Additionally, the electrically driven compressor as well as the electrically assisted turbocharger was assessed, too."
From SAE Article: http://papers.sae.org/2014-32-0011/ - "Two specific boosting systems were identified as the preferred path forward: (1) Super-turbo with two speed Roots type supercharger, (2) Super-turbo with centrifugal mechanical compressor and CVT transmission both downstream a Fixed Geometry Turbine. " The 2nd option looks similar to the VanDyne Integrated supercharger/turbocharger.

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