The GTD-1250 engine of the T-80U tank, is smaller and almost 100kg lighter. The better air filtration system of the GTD-1250 provides very clean[OR pure] air (98.5%). It supplies air to the engine and ...

Text is too complex for me.

... in fact the affect of the smaller size of the tank on its survivability is very, very relevant.
NOT IRrelevant!!

The motor transmission unit [??] of the T-80 is 3.15 cubic meters, and that of the Abrans is 6.8 cubic meters.