Besides A-4/5 being a bit overweight, were there really "power complications" with A-4/5 engine? Why? How
The BMW801 series reliabililty problems were solved with two major events early in the development of the motor. First, the exhaust was rerouted during operational testing eliminating the overheating problem in the bottom rear cylinders. Secondly the alkane ratio was adjusted for C3 fuel giving it significantly better antiknock performance and was in place by June 1942.
These are not the only design changed during this time period but they are the most significant as far as reliablity. There were no major changes that effected power production until later in the FW190A5's lifecyle. The exhaust system was changed but this only applied to certain conditions and was not a blanket change to the engine.
The biggest horsepower change appears to have come from 3 major improvements. Two of these come from the BMW801D2V15, developed in 1942, and served as the BMW801TS prototype motor.
In late 1943 the fuel injection system was changed delivering more fuel, more efficiently to the engine.
Later the engine recieved the piston sleeves and redesigned pistons of the BMW801D2V15 as standard on the BMW801D2.
These changed brought the power up to 2050hp at 1.65ata.
The FW-190A4 and even more so, the FW190A5, both gained weight without gaining power.
Now there where propeller changes as well during this time. My research is still ongoing into the details and extent of its use. I will let you know what I find out when I am sure of the results. It appears that a more efficient propeller was adopted during the life cycle of the FW190A4/A5.
All the best,
Crumpp
