Boeing revived the design for the tender , with the Model 40A replacing the Liberty engine with a 425 hp ( 317 kW ) air-cooled Pratt & Whitney Wasp radial engine , which was 200 lb ( 91 kg ) lighter than the Liberty , ignoring the weight of the Liberty 's radiator and cooling water .
The Model 40A had a new engine , which was 200 lb ( 91 kg ) lighter than the old one .