MERCEDES AMG HIGH PERFORMANCE ENGINES
will exceed the forced retirement from the race. In 2014 the stored energy can be deployed at a rate of 120kW, twice the current KERS limit of 60kW up to the total of 4MJ. ‘That’s 10 times the [KERS] energy to propel the car today,’ observes Cowell, ‘but through a machine that’s double the power. So, that will be five times the duration, or 30+ seconds of propulsion if you operate at that maximum of 120kW. We’re getting to a level where the additional electrical propulsion is for very nearly the same amount of time as the internal combustion engine on its own.’
Mercedes AMG HPE currently supplies teams such as Force India (above), and will continue to do so in 2014
the cost. It’s a technology constraint we all agreed in a meeting chaired by the FIA and we’re all in the same boat. But we all have the freedom to develop own aerodynamic surfaces within the compressor and the turbine.’ Instead of Kinetic Energy
Recovery Systems (KERS), the new cars will be allowed Energy Recovery Systems (ERS) that embrace energy recovery via all means. That includes a Motor Generator Unit Heat (MGUH) extracting energy from the turbo and a Motor Generator Unit Kinetic (MGUK) recovering energy under braking. ‘It will be up to you to decide
what power level you recover the energy from the turbine,’ explains
ENGINE USAGE W
ith 20 races and eight engines for the season, it
was important to allocate them most effectively, says Cowell. And with Friday practices and the Saturday / Sunday race weekend, the total possible number of permutations is around 36 billion. Mercedes starts by looking at the characteristics of different races. Some put greater inertial loads on engines, while others are more about gas pressure loadings. ‘We try to mix the different types of circuits on each engine,’ says Cowell. ‘An engine degrades differently
depending on whether it has been having a hard time from inertia or a hard time from gas loading. So, if an engine has raced at a high-inertia circuit we will then save it for a high gas pressure event like Spa or Monza. Finally, we’ll give it a less demanding race like Monaco or Singapore. ‘We also try to front load our engine usage to give us extra capacity toward the end of the season. So we put all these parameters into a big computer and press ‘go’. That gives us the plan, but then things happen during a season.’ First,
54
www.racecar-engineering.com • February 2012
there was the cancellation of Bahrain that, while it reduced the mileage requirement of the engines, it upset the running order. ‘It would have been tough on cooling and high on fuel consumption, so we would have had to run the engines lean.’ After that, the company
was continuously responding to events. If an engine was showing well, they could squeeze more mileage out of it. One engine managed more the 3000km this season, while typical was around 2000km. And there was only one engine failure across the six cars in
2011 – Jenson Button at Monaco. Circumstances during a race
can have a big effect on the life of an engine, too. ‘A year or two ago you would often see cars retire two or three laps after re- start from a safety car period.’ The cause is that temperatures would drop below the engine’s ideal operating zone. This can cause all sorts of problems as piston clearances open up and the viscosity of lubricants increase. Drivers are therefore briefed to bring temperatures back up again toward the end of the safety car period by using more throttle.
Cowell. ‘If you recover a lot at a high rate, the back pressure on the exhaust will become high because the turbine creates more of a restriction and the internal
can be returned to the drivetrain on any single lap. That’s quite a lot of energy, but they will need it as, for 2014, the cars are only allowed to be driven through the
“significant controls in the
rules regarding turbo design and position”
combustion engine performance will decay. We have that balance to work out ourselves.’ However, the rates of kinetic
energy generation under braking is limited to no more than 2MJ per lap. More is available from the MGUH but no more than 4MJ
pit lane on electric power. The new regulations also include a rule that cars have to be able to be started by the driver sitting in the driving seat without any external assistance. A tough call and we struggle to think of a penalty from the stewards that
AREAS OF FREEDOM Within these restrictions, what does Cowell see as the most fruitful areas of freedom? ‘Combustion chamber design, port design, fuel injector location, the design of turbine map and round trip efficiencies of the ERS is free. So it is an efficiency formula. The number of power units is five per driver per season, dropping to four for 2015, so it has got to be reliable and got to be highly efficient.’ And what power outputs
should we be expecting? Cowell is cagey on this, but says, ‘I think it will be wonderful if, with this power unit, our lap times are the same as they are today while we are emitting 35 per cent less CO2. If all the manufacturers target that, I think it’ll be wonderful for the sport.’
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