Variable Compression Ratio gives the better fuel economy

VCR (Variable Compression Ratio) is not a very recent technology but many of you may not be well aware of this terminology. It has been existing since decades but only within the boundaries of the laboratories. The reason for not using this technology in the cars is the mechanical complexity of the system but with the advancement in technology, this system is now available in the market. VCR actually increases the fuel efficiency by varying the compression ratios of the engine cylinders depending upon the required pressure and loads. At high loads, a low compression ratio gives the more economical results.

The basic concept is to change the volume above the top dead center of the piston. Turbo chargers enhance the power requirements of the engine but at the same time they tend to increase the pressure inside the cylinder. The increased pressure results in the detonation (which is undesirable) before the burning of the fuel. So by varying the compression ratio, detonation can be avoided. Thanks to VCR which fulfills the basic need of a better fuel economy.

Variable Compression Ratio

Hydraulic system is used to alter the engine head which then responds desirably on power requirements and results in a low fuel consumption. Saab automobiles used this technology for the first time in year 2000. A 1.6 L, 228 hp Variable Compression Ratio super charged engine was used in Saab prototype vehicle to which they named as SVC (Saab Variable Compression). The company claimed 30 % reduction in fuel consumption after using VCR engine.