>1890
If the Russian Empire successfully wiped out Turks, basically all of the balkans and east Europe would be firm allies if not completely incorporated. This means more Russian access to Mediterranean, and more experienced shipbuilders and Western educated technicians coming into Russia.
>1900
By 1900 Russia would be apporoximately 10-15 years ahead technologically compared to the medieval shithole it was at the time, so that when the Japanese invaded in 1904, Russia would be able to fight them off. This prevents the publics ability to question the tsar, and prevents the 1905 Revolution, a Marxist attempt at organizing.
>1920
Lenin himself said that Bolshevism could not have risen if they didn't have the oppurtunity to drive a wedge between the Tsar and the people in 1905 Revolution, it is what made the Revolution of 1917 possible. Ergo, this actually prevents bolshevism from starting out, and Russia would remain an ever more constitutional monarchy (like the UK) well into the 20th century.
When WWI results would have been much the same, except Germany would be knocked out quicker, but German economy wouldn't be quite as bad because Russian Empire wouldn't have requested the same ruinous shit as the Bolsheviks did, and the Russian empire would not spam socialist degeneracy into the region as the Bolsheviks did.
>1940
The result of this is that with no Weimar republic and no excesses, Hitler may never rise to power, and could spend the rest of his day being a prolific artist and author. Goebbels might just go into television and build the European version of hollywood, minus the degeneracy.
I don't think it would prevent WWII though. It would happen much later, but the British were pretty keen on wrecking any kind of continental European power, only this time it might be Germany and Russia vs Britain and France, and that might not go the same way. Small island would get wrecked and have their economy get rebuilt by USA, like Japan did after the war. This means instead of Japanese robotics and cyberpunk, there would be British robotics and cyberpunk in 2000.
>1950
America wouldn't have the impetus to create federal reserve, or to shit on its constitution with DA NU DEEL, so the America of 1960s might have a 5% federal taxation rate and basically no army except defensive. Any offensive moves would happen in its own backyard, maybe conquering and wiping out Mexico, or conquering nearby islands much like china today to increase ocean zones.
>1960+
Russian Empire might last until today without fracturing, although considering that Russian Empire and America have always been on friendly terms, it stands to reason the two biggest countries in the 20th century actually cooperating might produce much different results.