Meet the MCE-5 VCR engine, coming at you from France. VCR stands for Variable Compression Rate, and its creators claim it will replace conventional Fixed Compression Rate engines. According to the press release (found after the jump), what is special about this engine is that it's based on a combination of rod-crank mechanism and long-life gears, integrating both power transmission and compression ratio control for each cylinder.
MCE claims that this allows ratios from 7:1 to 20:1, which adapts the engine for most usage requirements. Oh, and this reduces fuel consumption by 30 percent, as two other prototypes of VCR engines showed by Saab and Audi in 2000. MCE also claims the design is more durable and robust, and will have lower maintenance costs.

This engine has no impact on the rest of the components of a vehicle, so it's potentially installable in every sort of vehicle. MCE's current prototype offers 160 kW (218 HP) with a 1.5-liter engine.

Press Release:

All carmakers share the same opinion: Variable Compression Ratio is the most efficient solution to reduce gasoline engines' Fuel Consumption while opening the way to several strategies for the future.

In March 2000, Saab unveiled its Variable Compression Ratio (VCR) prototype vehicle, powered by a 1.6 L supercharged VCR engine named SVC (Saab Variable Compression). The SVC engine delivers 168 kW of power (228 hp) and 305 Nm of torque, and provides more than 30% Fuel Consumption reduction when compared to a conventional naturally aspirated engine of equivalent power.

Few months later, FEV Motorentechnik also unveiled its own interpretation of Variable Compression Ratio through an impressive A6 Audi, powered by a 1.8 L VCR engine. Thanks to VCR, the FEV engine presents the same performance than that of a 3.0 L engine while reducing Fuel Consumption by 27%.
Saab and FEV demonstrated that Variable Compression Ratio is well the ultimate tool to reduce Fuel Consumption of Spark Ignition engines (gasoline engines).

But Variable Compression Ratio is not a revolution; VCR is only a major technical evolution, which could rapidly be as indispensable for SI engines as multiple Direct Injections for Diesel engines.
In the near-future, VCR will provide to automotive industry a wide range of efficient strategies to produce fuel-efficient, powerful and attractive cars which conform to most stringent emissions standards.
Then the question is: as present, environmental and energy context cannot be more suited to such a strategy, why don't carmakers already produce VCR engines?

In fact, all carmakers don't share the same opinion - for the time being - concerning the point of planning VCR engines production for the near future. Indeed, even if VCR is an old dream which goes back 100 years, producing VCR engines represents a real technological challenge which implies big changes in engine's mechanical definition.

Different VCR prototypes have confirmed the exceptional potential of VCR strategy, but they also revealed that designing VCR engines that respond to mass-production requirements is a tremendous technological challenge.

In this context, next step is to identify and study a design that fulfils all indispensable features for a mass-produced engine in terms of functionalities, robustness, reliability and durability while presenting reasonable production costs.

This is the purpose of the MCE-5 VCR engine block that is intended to replace conventional Fixed Compression Ratio engine blocks. Based on the combination between a rod-crank mechanism and long-life gears, the MCE-5 is an all-in-one VCR technology integrating both power transmission and Compression Ratio control.
Its conservative combustion chamber and its totally conventional and invariable piston kinematics allow making the most of know-how related to combustion and performance control.

The MCE-5 provides an individual, continuous and reactive Compression Ratio control to each cylinder of the engine. Its wide control range comprised between 7:1 and 20:1, permits serving all VCR strategies with no limitation.

Thanks to its long-life gears and to its roller-guided piston which is no longer subjected to radial stress and slap, the MCE-5 guarantees a high robustness and reliability to high-loaded VCR engines, and responds to one of the greatest challenge of high specific power and torque engines: durability.

The high robustness of the MCE-5 VCR engine block also comes from its rigid structure and crankshaft, which ensure a high reliability and a long lifespan to hydrodynamic bearings.
The MCE-5 VCR engine block has no impact on other engine parts or vehicle components. Its connection to gearbox, pipes and peripherals requires no additional device, as well as its integration into vehicles, which remains conventional.

The MCE-5 VCR engine bock has been studied and tested since 1997 and improved by successive steps. Next MCE-5 generation will be representative of a mass-production version and its components will be realized using industrial processes.

Thanks to its reasonable production costs and exclusive features, the MCE-5 could rapidly lead to a new generation of fuel efficient, powerful and attractive vehicles, while opening the way to crucial engine design strategies for the future.

[Source: MCE (thanks to Dominique for the tip)]

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