Mercedes is clearly dominating the field in terms of performance this year. McLaren, Force India, and Williams, whom all use the Mercedes power plant, have shown greater performance over their counterparts using Renault and even Ferrari power units. Mercedes have taken a unique design over the competitors that they believe is the reason for this advantage.
This year’s engines have moved from a naturally aspirated V8 to a turbocharged V6. Turbochargers vary in design with size, geometry of vanes on compressor wheels, ratios, etc. However, they all have the same basic design. Two “fans” or a turbine and compressor are bolted together inside of separate housings connected by a shared shaft. The exhaust gasses from the engine are directed through the turbine in order to “spool it up”, or make both rotate. The compressor is then able to compress air coming in from the intake to increase the number of molecules that enter the engine in order to create more power per combustion stroke.
The major disadvantage to a turbocharged application is heat. The turbine housing heats up to the same temperature as the exhaust gasses that are passing through it. Since the turbine housing is usually only about a centimeter from the compressor housing. This means that the intake air is heated beyond the point to which the intake air’s temperature already increases from being compressed. When talking a difference of a hundred degrees or more, this is a substantial amount. Have you ever set a sealed bottle from the refrigerator on the counter for a while? Once it has warmed up, the pressure inside increases substantially.
This is with only a few degree change. Since the goal is to get the maximum amount of molecules of air (oxygen) into the combustion chamber, this is counterproductive. The problem of reducing the heat is usually dealt with by the intercooler. The intercooler is just a radiator that the compressed air passes through, so it can be cooled by the ambient air passing over it.
Mercedes’ solution was to go one step farther. Mercedes have split the turbine and compressor housings to opposite ends of the engine.
The main benefit for this is that the turbine housing does not transfer heat to the intake air through the compressor housing. This allows for Mercedes to get a denser intake charge, and thus produce more power.
There are also a few side benefits of this design. Since Mercedes does not need to worry about cooling the intake air as much as Renault or Ferrari, the intercooler can be smaller. This allows for weight savings, but can also be used to allow for cooling of other power unit systems in order to increase efficiency and reliability.
Since the engine designs are essentially locked in at this point of the season, do not expect to see Renault and Ferrari changing their turbo designs for this season. Because of this, Mercedes powered teams will most likely enjoy a substantial performance and reliability margin of the rest of the field.