The limit of the amount of supercharging that an engine can tolerate is reached when:

The limit of the amount of supercharging that an engine can tolerate is primarily reached when maximum boost pressure is obtained. Supercharging increases the amount of air entering the engine, which enhances the fuel combustion process and can significantly improve engine power output. However, each engine design has a specific threshold for how much boost pressure it can handle safely.

When the boost pressure exceeds the engine's designed limit, several negative effects can arise, including the risk of engine knock or detonation. This is a critical failure condition where fuel ignites prematurely in the combustion chamber, potentially leading to serious engine damage. Therefore, understanding the relationship between boost pressure and engine performance is crucial, as reaching the maximum boost pressure is often when the engine begins to operate outside of safe limits.

While reaching maximum RPM or being at rated altitude are relevant factors in engine operation and performance, they do not specifically indicate the supercharging limits as directly as the boost pressure does. Similarly, although detonation is a sign that the engine is experiencing adverse conditions due to excessive boost, the point of supercharging tolerance is more accurately defined by achieving maximum boost pressure.