Combined with an integrated turbo manifold and double cam-phasing Variable Valve Timing (VVT), this system ensures that maximum torque is available at low engine speeds and across a broad rev-band. Fuel is injected directly into the combustion chamber to optimize efficiency by carefully adapting the strategy as a function of how the engine is being used. The result is enhanced combustion and, consequently, lower fuel consumption and CO₂ emissions.

Contribution of different technologies and systems toward the 25% reduction in fuel consumption in the Mégane equipped with the TCe 115 turbocharged direct injection engine. Click to enlarge.

This 1,197cc all-aluminium block is poised to replace the 1.6 16V and offers both extra power—up 5 hp to 115 hp (86 kw)—and peak torque up 40 N·m to 190 N·m (140 lb-ft). With 90% of torque available from 1,500 rpm and across a broad rev-band (between 2,000 and 4,000 rpm), the gasoline engine offers the flexibility and acceleration from low revs of a diesel engine.

A Stop&Start system with ultra-fast start-up also contributes to the reduction in fuel consumption. At a standstill, system automatically detects the position of each piston and injects fuel into the most favorably-placed cylinder. Re-starting is instantaneous. Energy recovered by the deceleration/braking energy recovery system is used to recharge the battery and restart the vehicle.

Average fuel consumption (NEDC combined cycle) is down 25% compared with the 1.6 16V engine. Versions of Mégane Collection 2012 powered by this engine consume 5.3 liters/100km (44 mpg US) NEDC combined cycle, a saving of almost 1.5 liters/100km. CO₂ emissions are down to 119 g/km.

Energy dCi 110. The 1.5-liter dCi, the best-selling Renault engine in the world (nearly 1.2 million units sold in 2011), powers one Renault vehicle in three, from Twingo to Laguna. To create the dCi 110, Renault engineers transformed the base with the introduction of technology inaugurated on the Energy dCi 130.

Powered by this transformation of the 1.5 dCi unit, Mégane Collection 2012 offers best-in-class fuel efficiency, with average NEDC combined cycle fuel consumption of just 3.5 liters/100km. CO₂ emissions dropped by 15% to reach the 90g/km mark.

The engine delivers peak torque up 20 N·m to 260 N·m (192 lb-ft) available from as low as 1,750rpm and improved acceleration compared with the dCi 110 unit it replaces. This is the result of advanced work on the air intake system and combustion, as well as the introduction of an innovative turbo architecture which reduces load losses. The path that intake air must travel has been simplified to achieve more efficient, uprated turbo performance with no increase to fuel consumption.

A low-inertia variable-geometry turbocharger ensures shorter response times from low revs due to the optimized size of the blade, for instantaneous re-starting.

Individualized spray cone angle fuel injection nozzles deliver a more precise spray pattern which significantly improves combustion performance (15% less unburned fuel), which in turn has a beneficial effect on fuel consumption and CO₂ emissions. Individualized spray cone angle technology compensates the natural nozzle offset inherent in eight-valve engines due to the asymmetry of the intake and exhaust valves. Injection is ensured by seven-hole piezoelectric injectors.

Cold-loop Exhaust Gas Recirculation (low-pressure EGR) recovers exhaust gases further downstream than a conventional EGR system. They are cooled in a low- pressure intercooler which enables them to be recirculated through the turbo mixed with air and thereby increase turbo pressure. The gases are then cooled by air in the turbo radiator and used for combustion a second time.

This cold loop enables emissions of nitrogen oxides to be cut more efficiently than is the case with a conventional high-pressure EGR, while engine efficiency is improved and combustion is of a higher quality. The Energy dCi 130, the first Energy powerplant, was the first engine in Europe to feature low-pressure EGR technology in 2011.

A thermostat-controlled variable displacement oil pump allows the capacity of the oil pump (and therefore oil pressure) to be adjusted as a function of the engine’s needs at any given moment in order to reduce the pump’s energy consumption. An oil temperature sensor makes real-time adjustments to minimise viscosity-related friction, which has a beneficial knock-on effect on fuel consumption.

Elements contributing to the 20% reduction in fuel consumption from the Energy dCi 130. Click to enlarge.

Energy dCi 130. The Energy dCi 130 features a particularly efficient design based on a square architecture sourced from Renault’s experience in F1. The configuration of an engine is said to be square when the piston stroke is similar to the diameter of the cylinder (bore), an arrangement which allows large-diameter valves to be housed in the cylinder head for more efficient filling of the combustion chambers. This in turn favors performance. The concept is familiar in F1, where the quest for performance is so important, but it is still rarely employed for production diesel engines.

The engine also uses a transverse water flow cooling technique, which is common practice in Formula 1, combined with a double water jacket design for the cylinder head.

Transverse water flow, which is used in F1 to maximize cooling efficiency and minimize downforce losses, enables a smaller and therefore less energy-consuming water pump to be fitted. These two particularities have been exploited in the case of the engine and have been combined with a double water jacket arrangement for the cylinder head. This feature permits the engine to benefit from a controlled rate of water flow to optimize cooling of the hot zones (combustion chamber, injector nozzles).

Each cylinder benefits from identical cooling. Water is taken downstream of the water pump and does not flow round the combustion chambers. The system efficiently cools the cylinder head, enabling the engine’s specific power output to be raised. Meanwhile, the water flows naturally through the system, which means that less energy is required to drive the water pump. This in turn results in lower fuel consumption and CO₂ emissions.

UFLEX oil control ring technology, which has been used in F1 for more than 10 years, was incorporated from the very beginning of this project. The U-shaped geometry is highly flexible and enables the ring to adapt to bore distortion (under the effects of temperature and pressure) in order to achieve the best compromise between efficiency (scraping of oil on the cylinder liner to reduce consumption) and friction. This technology necessitated extensive development work to optimize the ring’s scraping action against the cylinder walls.

The Energy dCi 130 also uses variable swirl technology. The term “swirl” describes the phenomenon of air rotating inside the cylinder, much like a cyclone. Variable swirl technology consists in controlling the amount of swirl by means of a flap situated in the upper duct of the air intake. When the flap is in the closed position, gas flows unhindered through the ports that remain open and increases turbulence.

The air-fuel mix is consequently optimized and this reduces fuel consumption, while also minimizing the emission of CO₂ and other pollutants (nitrogen oxides and particulates) at all engine speeds.

The thermal management system ensures enhanced combustion and reduced friction inside the engine as it warms up, thanks notably to fast warm-up of the oil which is in contact with the cylinders. The system comprises a valve located in the cooling circuit upstream of the cylinder head and cylinder block. When the engine starts from cold, the valve is closed and prevents water from circulating around the combustion chambers. This causes the engine to reach its ideal working temperature and optimal conditions for efficient combustion more quickly.

Other efficiency and performance technologies include:

• Cold-loop exhaust gas recirculation (low-pressure EGR);
• Variable displacement oil pump; and
• A multi-injection system designed to optimise regeneration of the particulate filter.

The engine delivers 130 hp (97 kW) with its capacity of 1,598cc and torque of 320 N·m (236 lb-ft), some 80% of which is available from 1,500 rpm and across a broad rev-band. The Energy dCi 130 revs freely up to 4,500 rpm and offers all the driveability of a bigger-capacity powerplant.

The driver benefits directly from a 20% reduction in fuel consumption (which works out at 1 liter/100km in the European combined cycle) due to its 16% smaller cubic capacity compared with the 1.9 dCi 130 block it replaces, as well as to its other technological innovations. This powerplant returns combined cycle fuel consumption of 4.0 liters/100 km (59 mpg US) and emissions of 104g of CO₂/km, enabling Mégane Collection 2012 to qualify for the eco subsidy available in France.