Intake-Valve Temperature Histories During S.I. Engine Warm-Up
The present study is an experimental investigation on the influence of engine operational parameters on the temperature history of intake valves. During the initial stage of the warm-up process, the temperature history of the intake valve followed an exponential behavior with a time constant that ranged from about 23 to 39 s for the test conditions examined. In contrast, the temperature history of the coolant varied linearly with time suggesting that the net heat input to the coolant is roughly constant during the initial stage of the engine warm-up process. After the initial transient phase that lasted about one minute, the temperature rise of the intake valve was quasi-steady. During this latter period, the measured intake valve temperature was predicted by the steady-state temperature correlation developed in an earlier study.