Direct and reliable measurements of Top Dead Center dynamic position and of thermodynamic loss angle are necessary for accurately evaluating many engine operating parameters.
For the purpose of taking these measurements, a sensor -whose operating principle is based on the closing of an electrical circuit- was designed and tested by the Author on a research D.I. Diesel engine.
The tests, carried out in motoring conditions, provided at every engine speed a well resolved signal of TDC dynamic position in reference to which thermodynamic loss angle was measured.
A good agreement was found between the angle values so measured and those numerically computed by a thermodynamic mathematical model of compression stroke.