The aluminium-block successor to the legendary 4G63, found in the final Lancer Evolution X — genuinely strong in factory form, though independent specialists generally regard it as somewhat less tolerant of aggressive tuning than its cast-iron predecessor.
Mitsubishi moved to an aluminium block for this generation, which reduced weight and improved several aspects of the car's handling balance, but independent specialists generally regard this engine as somewhat less forgiving of extreme tuning than the cast-iron 4G63 it replaced. In factory or mildly modified form, it's a genuinely strong, well-engineered engine; the specific concern is less about factory reliability and more about how aggressively a given example may have been pushed.
Not a guarantee, but a pattern seen consistently across owner forums and independent-garage reporting.
As with the earlier 4G63, risk on this engine correlates more strongly with modification and tuning history than with mileage alone.
Rod bearing wear becomes a more realistic concern specifically on examples pushed significantly past factory output.
This is the single most important check on any 4B11T: ask directly whether the car has been modified or tuned, and get the tuning file and any supporting documentation.
On heavily modified examples specifically, ask about rod bearing inspection or replacement history.
Have a specialist check boost pressure and look for any signs of overboost-related stress before buying a car that's been modified.
Model-specific pages, with notes on how it behaves in that particular car.