The 12th G model originally set aside as a P-38J prototype was re-designated P-38K-1-LO and fitted with the aforementioned paddle-blade propellers and new Allison V-1710-75/77 (F15R/L) powerplants rated at at War Emergency Power. These engines were geared 2.36 to 1, unlike the standard P-38 ratio of 2 to 1. The AAF took delivery in September 1943, at Eglin Field. In tests, the P-38K-1 achieved at military power and was predicted to exceed at War Emergency Power with a similar increase in load and range. The initial climb rate was /min and the ceiling was . It reached in five minutes flat; this with a coat of camouflage paint which added weight and drag. Although it was judged superior in climb and speed to the latest and best fighters from all AAF manufacturers, the War Production Board refused to authorize P-38K production due to the two-to-three-week interruption in production necessary to implement cowling modifications for the revised spinners and higher thrust line. Some have also doubted Allison's ability to deliver the F15 engine in quantity. As promising as it had looked, the P-38K project came to a halt.