In addition the compression ratio was reduced from 16:1 to 14:1.
It is significant that in 1930 the Packard diesel had a compression ratio of 16:1, whereas in 1931 it has been reduced to 14:1.
This seems low, considering the compression ratio and probable leakage past their rather weak piston rings, but it is possible.
The compression ratio of this engine was lowered by almost 20 percent from that of the vertical 4.
You've got thirty tons of fuel—you want to find the compression ratio of the number-one firing-tube chamber—so what do you do?
The original flight engine had a compression ratio of 4.4:1.