Assembly i.e. bolting the engine together, probably takes less than 3 man-hours per engine. A lot of that is probably automated. Then testing and packaging and shipping. Another man-hour. This is a guess as figures are impossible to get. Manufactures don't want you to know. So you have to make educated guesses.
But this is irrelevant as the factory gets billed per engine. A material cost.
Enough going around with you...I obviously know all of that...and you obviously know that virtually everything you state involves labor, much (maybe most) of it union, or union-type labor (such as building plants and robots)...and they ALL factor into the cost of a product (including the labor involved with removing iron ore from the ground)...which is my point - if those labor costs are not controlled, then prices shoot up if we lose access overseas.
So, enjoy your Sunday!