* Redundancy and Complexity: Both superchargers and turbochargers serve the same purpose – to force more air into the engine for increased power. Having both adds significant complexity to the engine's intake system, requiring intricate plumbing and management of boost pressure. This increases cost, maintenance needs, and the potential for failure.
* Management Challenges: Precisely controlling the boost from two different forced induction systems is extremely difficult. The resulting boost pressure could be unpredictable and potentially damage the engine. Sophisticated engine management systems (ECUs) would be required, and even then, perfect synchronization is challenging.
* Reduced Efficiency: While combining both might seem like a huge power boost, the gains are often far less than expected. The efficiency of both systems can actually be reduced when working in tandem. The supercharger may be working against the turbocharger, or vice versa, depending on engine speed and load.
* Heat Issues: Two forced induction systems generate significant heat, potentially exceeding the engine's cooling capacity. This can lead to overheating, detonation, and ultimately engine damage.
In short, while technically feasible, adding a turbocharger to a supercharged car is usually a highly impractical and inefficient modification. The added complexity, cost, and potential for damage far outweigh any marginal power gains. It's much more effective and efficient to optimize a single forced induction system.
