What is the needed rpm to start diesel engine?

The required RPM to start a diesel engine typically ranges from 150 to 300 RPM, depending on the specific engine design and size. Diesel engines require a higher compression ratio than gasoline engines, so they need sufficient cranking speed to generate the necessary compression for ignition. Additionally, factors such as temperature, fuel quality, and battery condition can influence the starting RPM. Generally, a well-maintained diesel engine should start within this RPM range under normal conditions.