Sky F1's Mark Hughes looks at what gives the Brixworth-built unit such an advantage and why 2015 is critical for their rivals
Tuesday 28 April 2015 12:11, UK
Hockenheim emphasised once again that the Mercedes power unit is in a league above those of Renault Sport and Ferrari.
Not only were the works cars of Nico Rosberg and Lewis Hamilton much the fastest, as usual, but in qualifying the Ferraris and the Renault-powered Red Bulls had to give best also to both Williams-Mercedes and the Mercedes-powered McLaren of Kevin Magnussen.
For 2015 the engine departments at both Renault and Ferrari need to make massive gains if we are to have a properly competitive field and already there have been firings within both companies as a result of the poor performance of this year’s motors.
The Mercedes delivers significantly more power from its internal combustion engine/turbo combination than its two rivals as well as from its electrical devices. The key to the internal combustion engine’s superiority is its fuel efficiency: it can provide more power for a given fuel consumption (or less fuel consumption for a given power output – the same thing just used differently). It has a bigger compressor than either the Ferrari or Renault – partly because of the unique split-turbo design that allows the compressor not to have to be situated at the rear of the engine where space is at a particular premium. This contributes significantly to the power unit’s fuel efficiency.
There is an optimum boost pressure for the internal combustion engine and once this boost level has been achieved and fed to the engine, any excess boost of the turbo is used to either charge up the battery or supply more power direct to the engine through the ERS-K. Once it has finished feeding electrical power to the battery through the ERS-H, it feeds the excess through the ERS-K – to the device at the rear that also harvests the braking energy. There is no limit upon this latter function; every bit of excess energy you can produce can be fed to the engine’s crankshaft through the ERS-K. Which is why the Mercedes engine is still delivering this super-boosted power for much further down the straights than the Renault and Ferrari-engined cars. It can create more excess turbo boost and so is still delivering it to the crankshaft long after the other engines have run out of excess.
Renault has admitted it is looking at the split turbo design for its 2015 engine and it would be no surprise if Ferrari is too. (Honda, returning next year as McLaren’s supplier, has seen everyone’s layout and will doubtless have investigated both).
In terms of regulation there is nothing to stop Renault and Ferrari from switching to a new layout. All that has to remain the same from one year to the next are the crankcase and inlet mechanism. After that, there is a system whereby theoretical points are incurred for each change of specification. A change of compressor position, for example, would cost 2 points. For next year a total of 42 points of change are allowed. However, this permitted total decreases sharply each year until in year five no further change is permitted.
What this means is that the big gains to the Mercedes engine have to be made by Ferrari and Renault next year (and that is assuming that Mercedes does not make significant gains of its own). Their ability to close the gap down after that time becomes progressively more strangled by the regulations and the greater restrictions put upon spec changes.
The pressure is therefore on at Ferrari and Renault Sport even more than just the usual resulting from a poor season. They have each produced sub-standards units for 2014 and the opportunity for correcting this gets ever-smaller after 2015. If F1 is not to be locked into a permanent engine performance imbalance, some crucial technical choices need to be being made at Viry and Maranello right now.
MH
