This article is an extract of "A lot from a little", an article written by Ian Bamsey and published in Race Engine Technology 071. If you wish to read more, you can buy the issue at highpowermedia.com and put 'f1technical' as voucher code to benefit a 10% reduction on your purchase price.
I recall discussing the development of Group C2 engines with John Nicholson, whose company NME prepared naturally aspirated 3.3 litre Cosworth DFL V8s for a number of competing teams, with great success. Instigated in 1984, Group C2 offered only 330 litres of fuel per 1000 km, compared to 600 litres for C1. Engine management was new in those days, and a ‘fully electronic’ version of the DFL was an essential development by NME to maximise the power available within the tight fuel ration. Equally important, Nicholson emphasised, was appropriate aerodynamic development by the teams – “but some of them accept that more readily than others!”
Our sister publication F1 Race Technology reported in its 2013/14 issue that Force India had taken a new approach to aero development for 2012. Technical director Andrew Green remarked to me, “Basically our new concept concerned the flow structures around the car. I would say that with the 2011 car, our approach was more akin to beating the air into submission as it travelled around the car. This year  we are taking the approach of doing the least amount of work to the air as possible. That’s the philosophy we adopted over the winter.”
That was nothing to do with fuel saving; as of 2012 and 2013 the emphasis is on downforce. The point is that all Formula One teams will need to rethink their aero philosophy under the radically new conditions imposed by the revolutionary 2014 formula. However, equally important will be how they integrate that with the work of their engine supplier (or ‘Power Unit supplier’ as we need to call them from now on). As we shall see, there will be a baffling number of options for operating the new-generation Power Units, each with different implications in terms of overall car aero. The 2014 Power Unit won’t be simply a bolt-in item; more than ever it will be part of a complex juggling act determining overall car performance.
At the heart of the 2014 Power Unit will be a combination of internal combustion (IC) engine and electric motor, the latter powered primarily by energy captured from the exhaust stream of the former.
That stream will power a turbine that both supercharges the engine and drives a motor/generator unit (the ‘MGU-H’), which is permitted to supply electrical energy direct (and in quantities unlimited by regulation) to an electric motor/generator unit (the ‘MGU-K’) coupled directly to the crankshaft of the IC engine.
With its maximum crankshaft speed capped at 15,000 rpm but with plenum pressure unlimited, the direct-injected 1.6 litre V6 turbo is expected to produce in the region of 600 bhp, given a mandated fuel flow limit of 100 kg/h. To that is added a stipulation of 100 kg maximum per race. With races typically being 305 km then, going back to our Group C example, that amounts to 328 kg, or about 460 litres per 1000 km. Group C1 engines produced in the region of 750 bhp; pro rata that is 575 bhp given 460 rather than 600 litres per 1000 km. A quarter of a century on, we would indeed expect these new engines to be a little more efficient.
To the IC output the MGU-K will add (by regulation) a maximum of 161 bhp (120 kW). Its ability to create what is in effect (for the sake of argument) a 761 bhp engine will be limited by the amount of energy the MGU-H can harvest, supplemented by the amount of energy the MGU-K can itself harvest by acting as a generator under braking. That recovered kinetic energy, up to a maximum permitted 2 MJ per lap, will primarily be stored in an energy store (ES), which will normally be a lithium ion battery. Alternatively it can be fed to the MGU-H as a means of driving the compressor.
As the diagram below shows, energy harvested by the MGU-H can be fed either directly to the MGU-K or to the ES, which by regulation can release a maximum of 4 MJ per lap to the MGU-K. Clearly there are a number of potential energy flows, and on top of that there are various ways in which the IC engine can be operated, all with different implications in terms of heat rejection and thus impacting heavily on car aero. Ultimately it is all about the car package, and that is where a tight relationship between Power Unit supplier and team will pay dividends.
As to the overall performance of the Power Unit itself, that will depend a lot on the ability of the system to exploit the potential of the MGU-H, without in turn excessively degrading the output of the IC engine. This hybrid system will be most effective if there is enough energy released through the MGU-K for it not only to top up the IC output to the maximum permitted level but to supplement it to the extent that the IC can be run (as far as possible) within its optimum efficiency band. From what we have gleaned so far, that seems over-optimistic, but at the same time it would appear that there is the potential to run as an effective 761 bhp engine around most of today’s circuits.
But don’t take my word for it. I travelled to Brixworth and Viry Chatillon to talk to engineers developing these new-generation Power Units. On the following pages you will find out what Andy Cowell of Mercedes, and Axel Plasse and Rob White of Renault have to say.
Key points of the 2014 Power Unit and related regulations
three con rod journals
• 80 mm bore
• Four valves (minimum stem size 5 mm) per cylinder
• No variable valve timing
• No variable intake trumpets until 2015
• Many revised restrictions on component materials
• Direct injection with maximum operating pressure of
500 bar. Single injector per cylinder
• Single conventional spark plug and single coil per cylinder
• The exhaust may not exit within the vee
• Maximum of two tailpipes with various restrictions on location of exit(s)
• Maximum 15,000 rpm. No limit on manifold pressure
• Sole single-stage turbine and sole single-stage compressor linked by a shaft parallel to the crankshaft axis and within 25 mm of the car’s centreline. No variable turbo-supercharger geometry
• Exhaust gas recirculation now permitted
• Electric motor/generator MGU-H must be mechanically linked to the exhaust turbine, and must run at a fixed speed ratio relative to it; may be clutched. Maximum 125,000 rpm. No limit on its power
• Electric motor/generator MGU-K linked to crankshaft; must run at fixed speed ratio relative to it. Maximum 50,000 rpm. Maximum torque 200 Nm. Maximum power 120 kW (161 bhp)
• Electrical energy store (ES) must be located within the survival cell and must weigh between 20 and 25 kg
• Fuel regulations unchanged
• Standard ECU as today with some scope for control software development
• Fuel flow meter to ensure conformity to maximum flow rates as per accompanying illustration
• Crankshaft must be on the car centreline, 90 mm above the reference plane
• Minimum weight of power unit, 145 kg
• Centre of gravity of engine must lie at least 200 mm above the reference plane
• Standardised engine mountings
• Maximum of five engines per driver for the 2014 season; four for 2015
Talking to Andy Cowell
Designer of naturally aspirated (Cosworth) V10 and (Mercedes) V8 Formula One engines, Andy Cowell is now managing director of Brixworth, England-based Mercedes AMG High Performance Powertrain (HPP) as it prepares its new-generation V6 turbo with integrated energy recovery system. In May I travelled to Brixworth to discuss the 2014 Power Unit with him.
Cowell starts our conversation by remarking, “The fact that there is a maximum quantity of 100 kg of fuel for the race distance – and that’s specified from red lights out at the start of the race to seeing the chequered flag – means we need a 30% improvement in efficiency to obtain the same power output. That’s fundamentally changing the thinking around the engine.
“What will matter in 2014 is the conversion efficiency in the combustion chamber and the reduction in mechanical friction, and then downstream of the IC engine process, the ability not to have [all the] waste energy going down the exhaust system but to harvest as much of that as possible with the single turbine that’s permitted in the regulations. That’s going to be a key aspect – not only the turbocharging but also the electric machine coupled to the turbine.”
Cowell points out that regulation revisions introduced in December 2012 limit the turbocharger to a maximum speed of 125,000 rpm. He is part of the Working Group advising the FIA on the regulations. “As we’ve gone along, what we’ve tried to do is put regulations in to stop us exploring some quirky opportunities,” he says.
“There are reasonably healthy debates, but the fundamental thing is that we all want rules that make us develop new technology applicable to roadcars. We don’t want to come up with something that is just F1-quirky. Whether we’ll manage that or not, we’ll see. “We’ll have a 160 hp [120 kW] electric motor [the MGU-K], which is challenging, and a motor/generator unit [the MGU-H] connected to the turbocharger, which is challenging as well. But interesting technology.”
Images by Renault Sport F1 / Race Engine Technology