The Saab Variable Compression engine was a development project of

Saab Automobile Saab Automobile AB () is a defunct automotive industry, car manufacturer that was founded in Sweden in 1945 when its parent company, Saab AB, began a project to design a small automobile. The first production model, the Saab 92, was launched in ...

, for which it won an award both in 2000 and 2001. In a normal internal combustion engine, because cylinder bore diameter, piston stroke length and combustion chamber volume are almost always constant, the

compression ratio The compression ratio is the ratio between the volume of the cylinder and combustion chamber in an internal combustion engine at their maximum and minimum values. A fundamental specification for such engines, it is measured two ways: the stati ...

(CR) for a given engine is almost always constant. One exception is the

experiment An experiment is a procedure carried out to support or refute a hypothesis, or determine the efficacy or likelihood of something previously untried. Experiments provide insight into Causality, cause-and-effect by demonstrating what outcome oc ...

al Saab Variable Compression (SVC) engine, designed for the

Saab 9-5 The Saab 9-5 is an executive car that was produced by the Swedish automobile maker Saab from 1997 to 2012. The first generation 9-5 was introduced in 1997 for the 1998 model year, as the replacement to the Saab 9000. At the time, the car repres ...

. This engine uses a technique that dynamically alters the volume of the combustion chamber, thus changing the compression ratio. To alter the combustion chamber volume, the SVC 'lowers' the

cylinder head In an internal combustion engine, the cylinder head (often abbreviated to simply "head") sits above the cylinders and forms the roof of the combustion chamber. In sidevalve engines, the head is a simple sheet of metal; whereas in more modern ov ...

closer to the

crankshaft A crankshaft is a mechanical component used in a piston engine to convert the reciprocating motion into rotational motion. The crankshaft is a rotating shaft containing one or more crankpins, that are driven by the pistons via the connecting ...

. It does this by replacing the typical one-part engine block with a two-part block, with the crankshaft in the lower block and the cylinders in the upper portion. The two blocks are

hinge A hinge is a mechanical bearing that connects two solid objects, typically allowing only a limited angle of rotation between them. Two objects connected by an ideal hinge rotate relative to each other about a fixed axis of rotation: all other ...

d together at one side. By pivoting the upper block around the hinge point, the volume of the combustion chamber can be modified. In practice, the SVC adjusts the upper block through a small range of motion, using a

hydraulic Hydraulics (from Greek: Υδραυλική) is a technology and applied science using engineering, chemistry, and other sciences involving the mechanical properties and use of liquids. At a very basic level, hydraulics is the liquid counter ...

actuator. This design was originally patented by Gregory J. Larsen of Lakeland, FL USA. SaabVariableCompression-02

The SVC project was shelved by

General Motors The General Motors Company (GM) is an American Multinational corporation, multinational Automotive industry, automotive manufacturing company headquartered in Detroit, Michigan, United States. It is the largest automaker in the United States and ...

, when it took over Saab Automobile, due to cost.

External links

SVC

References

{{Reflist Engine technology Saab engines