This document analyzes the performance of a variable compression ratio diesel engine. It discusses how variable compression ratio engines allow the compression ratio to be adjusted while the engine is running based on load demands, improving fuel efficiency. The advantages are listed as increased fuel efficiency up to 30% reduction, reduced emissions, and a compression ratio that can be optimized for power or efficiency. The disadvantages include high initial costs, unproven reliability, and difficult early repairs. In conclusion, variable compression ratio engines show great potential but also face challenges in widespread adoption.

1. CAREER POINT UNIVERSITY
Variable Compression Ratio Diesel Engine
Performance Analysis
Submitted By: Submitted To:
Kartikey Dubey Mr. Amardeep Sir
M.E. 3rd year
Uid: k10963

2. CONTENT
 Introduction
 Compression Ratio
 Variable Compression Ratio
 Vcr – Advantages
 Vcr – Disadvantages
 Conclusions

3. INTRODUCTION
 Variable compression ratio is a technology to
adjust the compression ratio of an internal
combustion engine while the engine is in
operation.
 This is done to increase fuel efficiency while
under varying loads. Higher loads require lower
ratios to be more efficient and vice versa.
 Variable compression engines allow for the
volume above the piston at Top dead centre to be
changed. For automotive use this needs to be
done dynamically in response to the load and
driving demands.

4. COMPRESSION RATIO
 It is ratio by which the fuel/air mixture is
compressed before it is ignited.
 Limited in conventional engines due to auto
ignition.
 Determines how efficiently the engine can utilize
the energy in the fuel.
 Variable Compression Ratio can be obtained by
alternating:
The Clearance Volume
Both the Clearance volume and the Swept
Volume.

5. VARIABLE COMPRESSION RATIO
(VCR)
 The combustion chamber volume, Vc, is
altered to meet the power needs to the vehicle.
 At low power levels, high CR captures fuel
efficiency benefits.
 At high power levels, low CR prevents knock.

6. VCR - ADVANTAGES
 CR modified to meet power demand (CR’s
range from 7:1 to 21:1)
 Increased fuel efficiency
 Claims of up to 30% reduction in fuel
consumption
 Adding variable valve actuation and turbo-
charging further improves fuel efficiency (7-
10% additional reduction in fuel consumption)
 Reduced combustion emissions

7. VCR - DISADVANTAGES
 New technology results in high research and
development and manufacturing costs.
 Reliability is not proven.
 Consumer reactions are unknown and
unpredictable.
 Repairs and maintenance initially may be
difficult and costly.

9. CONCLUSIONS
 Variable Compression Ratio engines have great
potential to increase engine power and fuel economy.
 When coupled with technologies such as turbo
charging, variable valve actuation, and direct fuel
injection, the effectiveness of the system is further
increased.
 Once established, this technology will likely become
commonplace due to increasing energy and
environmental concerns and the ease of integration.
 Due to use of high compression ratio at low loads the
VCR engines has a good starting and idling
performance.

10. Thank you