VCR accounts for 9% efficiency improvement
The efficiency of the combustion proces in a gasoline engine is for an important part determined by the compression ratio. The compression ratio is the ratio between the volume in the cylinder with the piston in bdc and tdc (lowest and highest position). An 1800 cc 4 cilinder engine with a CR of 10 for example has 500 cc cylinder volume in bdc and 50 cc in tdc. Piston stroke volume is 1800/4 = 450cc.
The GoEngine however can vary the compression ratio, in this way the optimum CR for all driving conditions can be choosen and realized. At lower driving speeds (part load) a CR of 15 or higher can be used while at higher speeds lower CR of for example 8 can be used making it possible to run the engine with very high boost pressure.
VCR realized by modification of the eccentric postion in TDC
To realize the variation in compression ratio (and expansion ratio) the basic position of the eccentric is modified so that the desired TDC position of the piston is achieved. The maximum difference in TDC is basicly twice the eccentric dimension. In our current prototype engine this is twice 3 mm, thus a maximum variation in TDC of 6 mm.
