True overexpansion accounts for 14% efficiency improvement
To optimize each of the 4 strokes of the engine cycle the GoEngine VCR technology uses an eccentric between each conrod bigend and the crankpin of the crankshaft . The eccentric is rotating around the crankshaft at half the crankshaft speed.
The eccentrics with drive gears
To extract more energy from the expansion (work) the expansion stroke has to be increased compared to the compression stroke. To realise this the eccentric is in a downward position at the end of the expansion stroke and thus increasing the expansion stroke. One revolution later the eccentric is in an upward position and thus reducing the intake and compression stroke.
The basic GoEngine cycle - true overexpansion
To get the maximum result from the overexpansion it is important to use high expansion ratios. The GoEngine technology can realise expansion ratios of over 20:1 while in combination with late intake closing a compression ratio of 10 : 1 can be used.
IMPORTANT : When using high expansion ratios it's absolutely necessary to use a long piston stroke (at least 20% longer as the bore) to ensure that the combustion chamber doesn't become to flat, because this will increase heat losses to the wall and thus reduce pressure (and work) to the piston.
