Date of Award


Degree Name

Master of Science in Engineering


Mechanical and Aeronautical Engineering (to 2013)

First Advisor

Dr. Ho Sung Lee

Second Advisor

Dr. Chris Cho

Third Advisor

Dr. Bade Shrestha

Fourth Advisor

Dr. Claudia Fajardo

Access Setting

Masters Thesis-Campus Only


Previous studies have shown that increasing the coolant temperature in the internal combustion (IC) engine improved engine performance, especially in brake power and fuel consumption. To have more of an understanding about the reasons behind these improvements, a study of the cylinder from the inside was needed. Therefore, a study was conducted to study the effects of increasing the coolant temperature (from 90°C to 120°C) under five different loads (from 20% to 100%) by using a four-cylinder, 1.6L spark ignition (SI) engine in the automotive laboratory at Western Michigan University. In order to measure the indicated work and spark timing, a spark plug with pressure transducer and optical angle encoder were newly installed in the engine. The heat flux, energy balance, and thermal efficiency were calculated under different coolant temperatures and different loads. The study found that the heat flux between the combustion chamber and coolant in the cylinder head increases with an increase of coolant temperatures under different loads.

On the other hand, the indicated work remained steady with the increase of the coolant temperature. Finally, the spark timing retarded when the coolant temperature was increased; an effect that could be seen more clearly with higher loads.