Catalina Bird Innovator

The most obvious and controversial modification is the pair of GSO-480 Lycomings outboard of the R-1830-94 P&Ws. The obvious question is, how can an extra 760 horses help an airplane that already has 2,700? Doc Bird has the answer to that. According to him, the outboard section of the Catalina wing never did do the job, especially at slow speeds. It's so big and rough that the airflow tends to break up prematurely.
The contribution of the Lycomings is not to add horsepower, but to act as exotic flow straighteners and aerodynamic boosters for those huge outer wing panels. The slipstream from the Lycomings makes that portion of the wing much more effective and dramatically drops the Vmc with one of the main engines out. They increase cruise speed 20 mph, to a not-too-impressive 150 mph, and drop stall speed at least 5 mph.