I use Megs APC (diluted 4:1) and a range of detail brushes.
If there is anything i think / consider to be at risk i'll cover it with cling film to protect it from moisture but generally with modern engines this isnt a
problem.
Cover everything with the APC and work in with the brushes - i dont have the engine running at this point as i dont want a brush or cloth getting snagged by a moving belt etc. Its common sense to avoid these areas but i'd rather be safe than sorry.
Once everything has been soaked in APC and cleaned i start the engine and rinse with the jet wash - not directing the jet of water directly at the engine though.
Once rinsed i'll remove any cling film and shut the bonnet and leave the engine running for 10-15 minutes. Then open the bonnet, shut off the engine and dry up any remaining water.
Once its all clean and dry i apply Chemical Guys bare bones to everything then shut the bonnet and let it soak in with the heat of the engine.
After a few hours (generally at the later stages of a detail) i'll pop the bonnet and wipe everthing over with a MF cloth.
Heres my old vRS
and my FR
hth, Nige