On the majority of modern cars, it is totally safe to spray your engine bay with water. Today's vehicles have covered air boxes and weather-proof wiring
How To Clean Engine Bay
Can you wash your engine while it's running? - Quora
Guide to Cleaning Your Engine Bay - Motors Blog
Are There Any Mechanical Benefits to Cleaning an Engine?
How to Clean Your Car's Engine Bay - BreakerLink Blog
How to Use Engine Degreaser - NAPA Auto Parts - NAPA Canada blog
Is it safe to spray water directly to the engine Bay? - Quora
Engine bay clean. 17 years overdue. Toyota 4Runner Forum []
Car engine cleaning and detailing