8441 vs 8540

I wonder this: Proxima 8441 is visibly stronger than 8540. At heavy load, the 8441 have a more forceful response by accelerating and it feels a lot stronger. But they have similar size, both have about 85 hp... So what is the reason for this?

Is it because of the turbocharger maybe? On the 8540 I can only hear the turbo spinning at high rpm on engine, while the Proxima have a nice turbosound even when idling...

Well, anyone? Renze?

the 8441 has 5 or 6 speeds and low range, and single gear reduction portal axle.
The 8540 has a planetary 3 stage powershift, 3 gears and low range, and planetary reductions with 3 idler gears, meaning 6 times gear friction. It is also 700kg heavier.
The 8540 is kinda big for its engine power. Thats why Zetor now offers the UR3 (now Forterra) from 100-140hp instead of 75-105hp like 20 years ago, and the new 75-105hp Proximas are based on the old UR1 chassis, with less internal friction. The main final drive components are the same size as the 4011 even in the latest Proximas, because there was so much reserve in them.

I also think there is a gain in turbo technology, i dont know if the 8441 already has a waste gate turbo, but the 8540 most probably not because its only a mild boost it gets.

Furthermore, turbos these days are engineered to take higher rpm spinning, meaning that they can be built smaller, so there is less mass to accelerate to 30.000rpm which gives quite some more responsiveness. The metallurgy for turbochargers has improved quite some over the years.