MCE-5 VCRi: Pushing back the fuel consumption reduction limits

Carmakers are only
interested in their own technologies

It would seem that carmakers focus on their own technologies, which is normal. However, when no solution has been developed in-house to an identified problem then carmakers generally don’t hesitate to see if one exists outside the company. Hence, OEMs are solution providers in fields of investigation that go beyond a carmaker’s perimeter. Consequently, cars are usually made up of a combination of multiple solutions, mostly developed externally.

Automobile engines are usually made up of a
combination of multiple innovative solutions,
often mostly developed externally

Engines nevertheless remain the exclusive domain of carmakers, and their design and manufacturing is rarely externalized. While many alliances have developed over time, it’s mainly because they enable carmakers to group together to reach the critical production volumes that guarantee an engine’s profitability.

There are few examples of innovative engines developed externally simply because basic engine principles have not changed for 120 years. They still comprise a crankshaft, a connecting rod and a piston. The “Wankel” rotary engine was the only real breakthrough but in the end it provided no real advantages.

The variable compression ratio represents an important stage that requires the redesign of the lower part of the engine. For over a century, the visible progress has mostly been made in the cylinder head and around the combustion chamber. Injection, ignition and valvetrain systems are at the basis of the main evolutions. The power transmission system that defines cylinder volume variation has not changed either in principle or in its general definition. The evolution of the piston-rod-crank system did not concern its function, which remains unchanged, but rather its lightening, the decrease in its noise emissions and friction, the control of oil consumption, blow-by and its fatigue resistance and durability.

VCR is therefore a real turning point in the evolution of engines as it involves a modification to their structural or power transmission parts. This is one of the main obtascles to the development of VCR, even though it is necessary to mark a vital stage towards improved efficiency.

Most carmakers have developed VCR engines. With the same level of performance and relevance, there is no doubt that they will prefer to adopt an in-house solution in which they will have invested time and money. If the in-house solution is less advantageous than an external solution, the external one will come out on top, in view of the importance of the stakes and the unthinkable consequences that could result from a bad choice.