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Renault & partners show research prototypes: 2-cyl. 2-stroke diesel, 48V mild-hybrid diesel, delivery EV

POWERFUL two-cylinder, two-stroke diesel. Click to enlarge.

At its recent Innovations@Renault event, the France-based automaker presented three research prototypes developed in tandem with its partners as cooperative projects: a mild-hybrid diesel produced as part of the HYDIVU (Hybrid Diesel for LCVs); a two-cylinder, two-stroke diesel from the POWERFUL (POWERtrain for FUture Light-duty vehicles) project (earlier post); and an electric light commercial van developed as part of the du VELUD (Electric Vehicle for Sustainable Urban Logistics) project.

HYDIVU is a 48V mild-hybrid diesel solution to bring down consumption and emissions in LCVs. The objective of this project is to reduce the consumption of LCVs for business customers who travel long distances. Developed on the base of the Renault Master, this prototype is fitted with a powertrain that integrates an electric motor (mild hybridization), Twin-turbo technology and a downspeeding design. The combination of these three technologies results in a in a fuel consumption saving of up to 10% when used over long distances.

48V mild-hybrid diesel LCV Click to enlarge.

This powertrain is derived from the Energy dCi 165 Twin Turbo engine, to which the engineers have applied the following enhancements:

  • A 48-Volt (10-12kW) starter motor/alternator-type electric motor mounted on the gearbox: this delivers additional torque, thereby reducing the load on the internal combustion engine. With an advantageous position in the powertrain as close as possible to the wheel, it is able to benefit from greater mechanical efficiency, allowing it to recover more energy during periods of deceleration and braking. This recuperated energy is stored inside the 48V battery and can be-used in the form of additional torque, which in turn reduces to a similar degree the load on the internal combustion engine.

  • Downspeeding: this reduces the running speed of the internal combustion engine by lengthening the gear ratios. This reduction in engine revs results in less friction which is directly beneficial to consumption.

  • An improvement in the engine’s thermo-mechanical efficiency has been achieved through the use of a Twin-Turbo concept with variable geometry adapted to downspeeding. The objective is to strike a balance between sufficient torque available from the very lowest revs (from 1,000rpm) and consistent driveability across the entire operating range.

    Further, the engine features a reduction in friction thanks to downspeeding and the use of innovative technologies such as steel pistons.

  • Fuel-injection pressure was increased to 2,500 bar (compared with 2,000 bar) for a reduction in polluting emissions while at the same time ensuring the necessary power output.

Partners on this project are LMS, IFPEN, Valeo, and Continental.

POWERFUL two-stroke diesel. The 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 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 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 CO22 reduction. A new generation of fast solenoid injector was proposed with improved multiple injection control and limited leakage.

The efficiency of two-stroke engines is close to 50%, while four-stroke automotive diesels struggle to achieve 35%, Renault said. 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 40 kg lighter and more compact, thereby making it ideally suited to small vehicle platforms.

Quick Specs
Engine size 730 cc
Maximum power 35-50 kW
Maximum torque 112-145 N·m, available from 1,500rpm
Stroke x Bore 76mm x 80.5mm
Boost Mechanical supercharger and turbocharger

The two-stroke, two-cylinder engine produces the same sound as a four-stroke, four-cylinder unit, Renault said.

Twizy Delivery Concept is a research prototype that forms part of the du VELUD (Electric Vehicle for Sustainable Urban Logistics) project. The VELUD initiative aims to run a pilot delivery scheme in Paris with an electric LCV in order to reduce the impact of urban deliveries on air quality. Based on the Renault Twizy, this prototype explores an alternative for deliveries in built up areas.


The main foci of this project are:

  • Experimenting in the sphere of new uses for ‘final kilometres’ logistics.

  • Testing the adaptive potential of modular cargo zones in accordance with the goods on-board.

  • Defining an intelligent management of the fleet to achieve optimum activity and an efficient delivery service.

This project is intended to help establish the blueprint for a future system of urban logistics, incorporating the criteria of the towns and cities with the changing demands of transport linked to the development of e-commerce.

The prototype consists of a small electric-powered vehicle to which is attached a trailer, which is capable of holding up to 15 adjustable containers depending upon the load in a total space of one cubic meter.

Partners include Industrial Systems Engineering School (EIGSI, La Rochelle), AIRPARIF, La Petite Reine Groupe Stars Service, and the City of Paris.



Deltahawk has a 2L V4 two cycle aircraft diesel
that creates 200 hp at 2700 rpm at about 300 pounds.

Rotax has as 800cc two cycle gas that creates 160 hp
at 5000 rpm at maybe 150 pounds.

There are plenty of options for range extenders to drive alternators.


Didn't know that four-stroke automotive diesels struggle to achieve 35% efficiency. :)


Interesting unit as an efficient (50%) light weight range extender?

When coupled with a light weight composites body, 400 to 600 Wh/Kg batteries a 100+ mpg light cargo vehicle could become a reality.

Account Deleted

The POWERFUL engine concept is very interesting. If you check out the earlier post and preview SAE Technical Paper 2014-01-1291 doi: 10.4271/2014-01-1291. You will note that the engine uses Partially Premixed Combustion fueled with Gasoline to achieve the high efficiency.
This engine is roughly the size of the BMW i3 Range Extender (a 25 kW 647 cc, two-cylinder) and has almost the power of the 4 cylinder Chevy Volt Range Extender (55 kW), plus it has 50% efficiency.


I would love to see 48V mild hybrids taking off.
because they are not as expensive as full hybrids, they could be used more widely, especially for diesels.
10-12 kw should be enough for most things except hills and motorway driving (on smallish cars).

Roger Pham

Diesel? Just when Paris and London are phasing out diesel vehicles by 2020? Perhaps they will allow exceptions for cars with Diesel Particulate Filter and very low emission based on testing?

A safer bet would be to offer the POWERFUL 2-cylinder engine for PHEV's, so that the car will run on electric-only mode in the cities and only fire up the engine when out of the city limit. Perhaps the PHEV's will be equipped with GPS and computer to shut off the engine when the car is within city limit.

The 2-cylinder engine would be ideal for PHEV use, due to the small size and light weight, allowing for space under the hood for additional battery capacity, thereby sparing room in the trunk for full luggage. Thus, one battery pack can span under the two front seats, while another battery pack under the hood, while leaving a full trunk space for long-distance luggage carrying for a 5-seat car.

Thus, with the POWERFUL engine, we can have a no-compromise PHEV that can fulfill ZEV mission when called for in urban areas, and unlimited range intercity wise when filled up with petrol within 3-4 minutes. Charging locations at work and at businesses can allow a 30-mi PHEV to run on all-electric mode for longer than the 30-mi range while inside the city.

Thomas Pedersen

I think few people would question the thermal efficiency of a 2-stroke diesel. The giant marine engines are a testament to that.

The problem of 2-strokes was always emissions, which incidentally was not mentioned with a single word in the article.

As a range extender, efficiency is less of an issue than in a normal car. And, as a range extender there is much more opportunity to tune the engine for maximum efficiency at a specific rpm.

But who wants to drive down the freeway in their PHEV or EREV with black smoke coming out of the exhaust?

The emissions issue of 2-stroke engines mostly stem from lubrication oil - with poor combustion properties - coming into the induction air via the piston sliding across the induction ports. There is no mention of ways to solve this issue in the article.

How great would it be, if Renault could come up with a low-emission 2-stroke diesel.


A flat opposed two stroke is nice, lower vibrations with reciprocation. It is a small package which can fit with an alternator/transmission which can provide power.

Roger Pham

This POWERFUL engine has overhead valve scavenging instead of piston-ported scavenging so there won't be oil in the exhaust. Though, gasoline direct injection engines do emit quite a bit of particulate matter, though finer than using diesel fuel, still harmful. Fortunately, soon-to-come 4-way catalytic converter with a built-in particulate filter would be able to overcome this issue, so, it's not a game stopper.

A flat oppose engine if running on two stroke cycle would have both cylinders fire simultaneously and would be of no advantage than an oppose 4-stroke cycle twin engine. The beauty of in-line twin lies in the alternate firing of the cylinders, allowing a twin engine the power pulse of a 4-cylinder-4-cycle engine, although engine balancing would require additional pair of balancing shafts running thru the engine.


Horizontally opposed four cylinder cycle the two inside pistons in while the two outside go out, whether they are two for four cycle, reciprocation still reduces vibrations.

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