Exam Question
(a) With the help of simple diagram, explain Variable Injection Timing (VIT). (8)
(b) Explain with suitable diagram, start and end of VIT points (4)
(c) Explain with a sketch the variation of Pmax with VIT position. (4)
Class 4 (4th Engineer)
MEKM
📅 Nov 2025
Reference Answer
### (a) Variable Injection Timing (VIT)
**1. Definition and Purpose:**
Variable Injection Timing (VIT) is a mechanism in marine diesel engines designed to automatically adjust the start of fuel injection relative to the engine load. The primary objectives of VIT are:
* **To Improve Thermal Efficiency:** By optimizing the combustion process, VIT improves the Specific Fuel Consumption (SFOC), especially at part loads (e.g., 40-85% of MCR).
**1. Definition and Purpose:**
Variable Injection Timing (VIT) is a mechanism in marine diesel engines designed to automatically adjust the start of fuel injection relative to the engine load. The primary objectives of VIT are:
* **To Improve Thermal Efficiency:** By optimizing the combustion process, VIT improves the Specific Fuel Consumption (SFOC), especially at part loads (e.g., 40-85% of MCR).
Full answer on MeoMock — surveyor-grade reference answers for 7,000+ written exam questions.
Prepare on Android — MeoMock on Google Play