I find it strange that there seems to be so much confusion about scale. 
If I make a box that is 180cm tall for example it is always going to be 180 unreal units tall in both UDK and UE4 (unless I change the default settings in UE4).
Make sure you set your units to cm in maya and also make sure the scale factor is 1 when exporting to fbx.
I think it’s as straight forward as it can be o.o