Civilization – Which wonders can I not speed up with a Great Engineer in Civ 5 BNW

If you kill quite a number of units of a city state and/or keep trespassing on their territory enough to get your score very very low over an extended period of time, they eventually will be convinced that you are so evil it's not worth considering peaceful coexistence, so they will be in perpetual war with you. You will not be able to buy their friendship and relations will not heal by themselves over time.

Actually that doesn't mean too much, though. If you go near them, they'll attack you, and if you leave cities undefended near them, they'll capture those. Apart from that, they won't hunt you across the map and they won't make others hate you as well. If you just leave them alone now and make their area taboo to your units you can still get along with the other city states just fine.

You might choose to have one perpetual warring city-state next to your army outfitter because city-state units train your troops longer than barbarians do.

The amount of production of a great engineer on normal speed is calculated using the formula

300 + 30 * city population

So in a city with a population of 1 the engineer only results in 330 production, in a size 15 it results in 750 production.

For quick speed the formula is:

200 + 20 * city population

For epic speed it is:

450 + 45 * city population

and for marathon it is:

900 + 90 * city population

The amount of hammers does not seem to be influenced by era, map size or difficulty level.

Conclusion: If you want to hurry late game wonders, build it in a city with a large population.