Advantages and drawbacks

Main VCR technologies principles are represented on the following scheme:

A	Articulated cylinder head	D	Multilink rod-crank mechanisms
B	Hydraulic pistons	E	Additional piston in cylinder head
C	Eccentrics on bearings	F	Gear-based mechanisms

Main advantages, defects and particularities for these principles are shown below:

		A	B	C			D			E	F
				1	2	3	1	2	3
Combustion chamber integrity		0	0	0	0	0	0	0	0	--	0
Piston kinematics		≠	0	≠	≠	≠	≠≠	≠≠	≠≠	0	0
Rotational speed		0	0	0	0	0	0	0	0	0	0
Compression Ratio control		++	--	-	-	++	+	+	+	+	++
Friction losses		0	-	0	0	0	-	-	-	-	++
Reliability, durability		--	-	-	-	-	0	0	0	0	++
Inertia forces and balancing		0	-	-	-	0	-	-	-	0	-
Noise emissions		--	0	0/-	0/-	0/-	0	0	0	0	0/+
Overallsize & vehicle integration		--	-	-	-	-	-	-	-	-	-

Advantages / disadvantages compared to conventional engine

Identical 0 Different / Very different ≠ ≠≠ Advantage / Big Advantage + ++ Defect / Big defect - --

Impacts of main VCR design features are discussed in the section named «VCR engines: mass production challenges».