A mí la cosa no me parece tan sencilla. ¿son motores industriales, de carros, de aviones? Hacerle el "overhaul" a un motor de avión no es otra cosa que hacerle una reparacion general y no una puesta a punto que es lo que se denomina un "tunning". Y lo de reconditioning si que es ambiguo, tanto en inglés como en español. Qué es reacondicionar un motor? Que tiene de especial un motor reacondicionado? Muy bueno escuchar las opiniones de especialistas para llegar a una conclusión

--------------------------------------------------
Note added at 44 mins (2008-12-17 20:02:54 GMT)
--------------------------------------------------

ENGINE OVERHAUL

Definition: A general term for major engine work that usually requires removing the engine from the vehicle, and rebuilding or replacing internal components (e.g. pistons, connecting rods, valves).
http://autorepair.about.com/library/glossary/bldef-435.htm

--------------------------------------------------
Note added at 58 mins (2008-12-17 20:16:57 GMT)
--------------------------------------------------

Perdon tuning y no tunnign como erróneamente digité

http://en.wikipedia.org/wiki/Engine_tuning
Engine tuning.
is the adjustment, modification or design of internal combustion engines to yield optimal performance, to increase an engine's power output, economy, or durability. It has a long history, almost as long as the development of the car in general, originating with the development of early racing cars, and later, with the post-war hot-rod movement. Tuning can describe a wide variety of adjustments and modifications, from the routine adjustment of the carburetor and ignition system to significant engine overhauls. At the other end of the scale, performance tuning of an engine can involve revisiting some of the design decisions taken at quite an early stage in the development of the engine.