The variable compression engine implies that the compression ratio of the engine is controlled at every engine operation condition.

  • During high load, a lot of power of the engine required and compression ratio is decreased and if the higher efficiency is needed during low load, the compression ratio is increased.
  • The performance and efficiency of an engine vary with load demand and compression adapted to.
  • In addition, the risk of pre-ignition, mega-knock on effects and engine jerking, as the result of retarded combustion phases, can be reduced.

Variable Compression Ratio (VCR) Design Methodology

  1. Moving the Cylinder Head
  2. Variation in Geometry of Connecting Rod
  3. Moving the Crankshaft axis
  4. Changing Piston Deck Height
  5. Dual Piston Mechanism
  6. Gear Based Mechanism

Table 1. Summary of Recent Advanvement Designs by Manufacturers


S.No Automotive Company Design Used
1. Mercedes Benz 2013- Eccentric connected to Journal causing relative motion between crankshaft an cylinder head.
2. Ford 2003- Dual piston method in between which an Elastomeric mass is present
3. Nissan 2014- Two control shaft together to vary the position of control, upper and lower links.
4. Gomecsys 2013- Auxiliary gear method used to change the position of the eccentric at the big end of the connecting rod.
5. MCE-5 MCE-5 VCRi- Used a control jack to change the position of TDS of the main piston. The control jack is moved by inertia and gas force.


The VCR technology  could  provide  the  key  to  enable exceptional efficiency  at light loads without  loss  of  full  load  performance.

Sagar Institute of Science & Technology is working beyond the syllabus. We are preparing students to work on R&D and established an IC engine 2-Stroke and 4-Stroke (Petrol and Diesel Engine) test rig. SISTec organizes module based training to train students on current industry trends and content beyond the syllabus.



Written By: 

Sanjeev Kumar Gupta

Assistant Professor

SISTec– Ratibad Campus

Mechanical Engineering Department


Tripti Kumari

Digital Marketing Associate

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