jokes aside, I dont think its wise to pressure wash the engine. It is engineered to be guarded from the elements such as rain, snow, sun, etc. Thats why it is enclosed on 5 of its 6 sides, and the fender wells have splash guards.
Why are you pressure washing the engine in the first place? If it's getting that dirty from just driving the car, then I think you have some major issues.
2012 Mustang Cyclone, 2002 Mustang GT, 2004 F150 FX4, 1999 Ranger O/R 4x4, 2007 Harley FXDB