Renault have achieved an essential renovate of their Formula 1 engine ahead of the 2015 season, as they bid to reduce last year’s performance deficit to Mercedes.
In introducing the new unit, Renault Chief Technical Officer Rob White noted that the second year of a new engine “is always difficult. The 2015 power unit project was started six months before the 2014 units took to the track, ie. before we had any significant experience of the technology. Then we also needed to consider the issues arising during the season. It creates a need to be both forward thinking and reactive. Splitting resources between projects is therefore a delicate balancing act, in the short, mid and long term. While certain decisions can be taken upstream, a number of design decisions were taken quite late in the day, in order to benefit from the experience of the 2014 power unit. The result is a power unit that is very different to its predecessor,” he said.
We have made some fundamental changes to gain performance and reliability. We have upgraded every system and subsystem, with items that will give the most performance prioritized. The principal changes involve the internal combustion engine, turbocharger and battery. The ICE will have a new combustion chamber, exhaust system concept and variable trumpets, as permitted by the 2015 regulations. The compressor is more efficient, while the energy recovery systems are able to deal with more severe usage.
The 2014 unit was already well placed in its center of gravity, however we have tidied up the packaging to give greater ease of integration into the chassis. Additionally many systems and functions have been rationalized and simplified to further ease the task. In short, there are very few carry over pieces between the 2014 and 2015 power units.
Renault Energy F1-2015 Power Unit.
The power units feature a turbocharged internal combustion engine coupled to energy recovery systems. The V6 engine and its electrical motors are capable of producing 850 horsepower (634 kW) using just 100 kg of fuel per race, with fuel flow rate limited to 100 kg/hr max. The engine alone will make around 600 bhp, or more than 3 times the power of a Clio RS.
On conventional turbo engines, a wastegate is used in association with a turbocharger to control the high rotation speeds of the system. The wastegate is a control device that allows excess exhaust gas to by-pass the turbine and match the power produced by the turbine to that needed by the compressor to supply the air required by the engine. On the Renault Energy F1 power unit, the turbo rotation speed is primarily controlled by the MGU-H, although a wastegate is needed to keep full control in any circumstance (quick transient or MGU-H deactivation).
The MGU-K is connected to the crankshaft of the internal combustion engine. Under braking, the MGU-K operates as a generator, recovering some of the kinetic energy dissipated during braking. It converts this into electricity that can be deployed throughout the lap (limited to 120 kW or 160bhp by the rules). Under acceleration, the MGU-K is powered from the Energy Store and/or from the MGU-H and acts as a motor to propel the car.
The MGU-H is connected to the turbocharger. Acting as a generator, it absorbs power from the turbine shaft to convert heat energy from the exhaust gases. The electrical energy can be either directed to the MGU-K or to the battery for storage for later use. The MGU-H is also used to control the speed of the turbocharger to match the air requirement of the engine (eg. to slow it down in place of a wastegate or to accelerate it to compensate for turbo lag.)
The stored energy can be used to propel the car with the MGU-K or to accelerate the turbocharger with the MGU-H. Compared to 2013 KERS, the ERS of the 2015 power unit will have twice the power (120 kW vs 60 kW) and the energy contributing to performance is ten times greater.
Renault Sport F1 has two teams for the 2015 season: Infiniti Red Bull Racing (the Red Bull Racing-Renault collaboration started in 2007); and Scuderia Toro Rosso (the Red Bull junior team, which has been run independently for several years).