When is a diesel engine turbocharger capable of highest rotational speeds?

A diesel engine turbocharger is capable of achieving its highest rotational speeds during high engine load and full throttle conditions. This occurs when the engine is producing maximum power, leading to increased exhaust gas flow, which drives the turbocharger more effectively. Additionally, optimal boost pressure and efficiency are achieved at these points, allowing the turbocharger to reach its peak performance. However, it's crucial to manage these speeds to prevent mechanical failure and ensure longevity.