In the development of Internal Combustion Engine higher thermal efficiency is something the modern car manufacturers are trying to achieve from a very long time.
But the fundamental laws of Thermodynamics and the conventional working process have long prevented this dream of achieving a higher level of thermal efficiencies. Textbook generally tops out the efficiency at 30-35% only. Some marine engine diesel engines and hybrid vehicles like Toyota Prius and Hyundai Ioniq have shown efficiencies of about 40-42% but never in street petrol driven cars and yes Mercedes did it!.
Mercedes AMG F1 Racing division has recently hit a benchmark, developing a Formula One engine which achieved brake thermal efficiency in excess of 50% at Dyno testing. The engine GH-50 of M08 EQ Power+ hybrid unit breaks the barrier of 50% thermal efficiency at Company’s Brixworth Factory while hooked up on temperature controlled Dyno.
Thermal efficiency is the amount of useful work output that the engine can produce at a given amount of heat input. So, Mercedes 50% figure means that the power to waste ratio of conventional petrol engine is improved, yes, “waste”. Heat engines produce work from the chemical energy entrapped in fuel but according to the Second Law of Thermodynamics “All of this energy can’t be converted to useful work” some of it is lost in form of heat which is a waste. Here’s where Mercedes Engineers step in and extract every tat bit of energy from fuel to improve our power to waste ratio.
M08 EQ Power+ is a 1.6L V6 turbocharged engine along with the hybrid battery unit. Mercedes main ingredient of Power+ is the rigorous development in the gas exchange processes occurring during the combustion cycle, engine redlines at 18000 RPM and idle RPM is of about 4000 RPM with relatively short stroke length making an almost square head engine. Both of these factors contribute to low heat losses from the combustion chamber. For valve actuation engine uses pneumatic spring having compressed nitrogen gas that makes working a higher RPM’s smooth and fuel and exhaust openings precise and timed. This engine also make use of “Hot Inside V” engine layout, this layout is a very clever setup separating the hot and cold sections of engine which makes the inlet air-fuel mixture to be relatively cooler than any other engine layout making combustion more powerful.
The next big setup for such high efficiency is the MGU-H unit or Motor Generator Unit via exhaust Heat. A large amount of energy from combustion is dumped into the exhaust in form of heat; the engine uses a turbocharger so it is already composed of a compact but highly efficient turbine. But this turbine along with compressor of turbocharger also runs a generator charging a battery. The battery then runs a set of motors connected to engine’s crankshaft providing extra power. This system along with MGU-K unit which is the generation of energy using regenerative braking composes additional 160Hp of engine power per lap.
Once the energy is developed it’s all about minimizing
the losses, So, Mercedes along with the PETRONAS have developed a series of engine oils which can be used in various prevailing conditions to reduce the losses in friction. Again for fuel engine uses PETRONAS developed special petrol type fuel called PETRONAS PRIMAX that also contribute to engine efficiency.
The big thing about this achievement of Mercedes is that for the first time any giant car manufacturer has worked from the basic principles of thermodynamics to propel its engine development program. It’s for the first time in SI engine history that we are producing more power than wasting it. Plus unlike any other high-performance engine like W-16 of Bugatti Veyron and Chiron this Mercedes engine doesn’t use any exotic materials like Titanium and other precious metal it is simply made up of steel
The Mercedes M08 EQ Power+ unit use is not only limited to its ferocious Formula One cars but the Mercedes in Frankfurt Motor show 2017 has also unveiled its Mercedes AMG Project One; a street legal hypercar which uses broadly same 1.6L M08 engine unit as engine and it has reported an efficiency in excess of 43% in simple Hypercar fuel too. The engine makes over 1000Hp propelling the car from 0 to 200kmph in under six seconds and reportedly max out at 350kmph.