<RPM: Higher RPM move the EFFECTIVE timing closer to TDC.> TRUE < This results in more expansion = lower EGT.> NOT TRUE Imagine the timing advanced to 60 deg before top dead center. This allows more time for fuel and air to burn before tdc resulting in higher cylinder
temperature and pressure and a higher rate of heat transfer into the cylinder and head. If the engine is operating at high MP the fuel air mixture may detonate, spiking temperature, pressure and heat transfer rates even higher. After TDC the combustion products expand over the full CR and cool by Boyle’s law. The fuel releases a fixed amount of energy, and since more of it flows into the
cylinder head there is less energy in the exhaust gas. Under normal operating conditions fuel continues to burn after TDC, so pressure and temp do not drop as fast as Boyle's law predicts. More advance means less fuel available to burn after TDC.
Yahoo! oneSearch: Finally, mobile search
that gives answers, not web links.
|