In 2014, Formula 1 switched to V8 engines and instead decided to commission all teams with turbocharged V6 engines with 1.6 liter displacement and advanced energy recovery systems. The aim was to bring Formula 1 back to a vague idea of relevance for modern road vehicle technologies, with the focus on efficiency. This has been achieved by mandating maximum fuel economy for racing and placing a heavy emphasis on hybrid technology.
The Mercedes W05 Hybrid was the first of 7 F1 vehicles from the British team with German funding. It quickly demonstrated the value of the team’s split turbo technology.
Since then, Mercedes has dominated the field in today’s turbo-hybrid era. Since then, the German team has taken every driver and constructor championship home with them and often took the crown home long before the end of the season. The team’s engine was seen as an integral part of this dominance, which for the past seven years has been seen as more powerful and efficient than the competition except for a few select races. Much of the credit goes to the innovation of the company’s split turbo system. Today we’re going to explore why Formula 1 innovation was such a game changer.
Lots and varied prizes
This article assumes a basic understanding of turbochargers. If you’re not completely on the cutting edge, check out our introduction to the topic!
The basic blueprint for the teams was to make 1.6 liter forced-induction engines with the option of using a turbocharger or supercharger, with all teams choosing to use turbos in their designs. In addition, the teams were able to use energy recovery systems to further increase performance and efficiency. The MGU-K, which stands for Motor Generator Unit – Kinetic, is connected to the crankshaft of the engine, generates energy when braking and supplies electricity when accelerating. The MGU-H or motor generator unit – heat – is connected to the turbocharger’s shaft and can thus convert energy from the exhaust gas into electricity or, conversely, turn up the turbocharger to reduce turbo lag.
The layout of the Mercedes F1 engine 2014. Note the large distance between the compressor in blue and the turbine in red, which is connected by a long shaft through the middle of the engine V. Photo credit: Giorgio Piola / Motorsport.com
Most manufacturers opted for tightly packed designs with relatively conventional turbos, but with an MGU-H unit for energy recovery. However, Mercedes opted for an unconventional split-turbo design. In a normal turbocharger, the compressor wheel and the turbine wheel are connected by a short shaft with the respective housings mounted directly back to back. However, Mercedes realized there was a multitude of wins by dividing the two halves further apart instead. Instead, the compressor was mounted on the front of the engine and the turbine on the rear. The two were connected with a much longer than usual shaft that went through the V of the engine. This enabled the MGU-H to be mounted in the middle of the V between the compressor and the turbine.
The design promised a multitude of advantages. By separating the turbine from the compressor, the heat from the exhaust gases was not conducted as much into the compressor, which lowered the intake temperatures and allowed the team to install a smaller intercooler. The packaging advantages also enabled the team to make the entire engine or power unit more compact, which gave the chassis designers more freedom to carry out aerodynamic optimizations on the car. It also allowed for cleaner and easier routing of the exhaust pipes, which improves power output, and shorter inlet pipes that reduce lag for better driveability.
Diagram showing other competitors’ engine assemblies in the early turbo hybrid era. Photo credit: Giorgio Piola / Motorsport.com
With all the advantages, the question arises why the solution was so new and the reason is the speed. The turbochargers in an F1 car spin at over 100,000 RPM. At such high angular velocity rates, the slightest imbalance in a shaft can destroy a turbo in seconds. Making this wave an order of magnitude longer will only make matters worse since the arm, with the greater moment created by the length, greatly exacerbates even the smallest vibrations. However, top-class motorsport is the place to be to bring in new feats in terms of material and machining, and Mercedes was able to get the system up and running. The team relied on its institutional experience with turbocharging in the Daimler truck division. Work on the engine began in 2011 to prepare for the first 2014 season. After its dominant performance in the first three years of the turbo hybrid era, Honda decided to copy the idea for their engine in 2017. More recently, Renault has been linked with a switch to layout, with Ferrari reportedly also considering the concept.
Not intended for the open road
The engine in all its glory. Note the compressor on the front of the engine. Photo credit: Mercedes
Despite Formula 1’s renewed focus on technologies transferable to the road, it’s unlikely that you’ll see split turbos in the V of your performance street car anytime soon. Formula 1 is a world where incremental percentage gains can create or interrupt a World Championship effort, and where every last shot of aerodynamic downforce is required to assert yourself as a winner. Street cars simply have no real reason to focus on such dense packaging or small increments at cooler inlet temperatures due to such technology. It’s generally much easier to screw on a larger intercooler and instead make the hood a little longer. In addition, the tight machining tolerances required for such a long high speed shaft would make such turbos prohibitively expensive for any road car. You would also likely have maintenance intervals that are totally inappropriate outside of the racing environment.
While split turbo technology can still be used on the track in Formula 1, it nonetheless shows how thinking outside the box and ignoring conventions can lead to technical advantages in practice. While the competitors are catching up, we are sure that the Mercedes F1 engineers are already around the corner looking for the next nifty idea that will be worth a lap per lap on the track.
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