Wow, beautiful engine and engine compartment, Barry ! It looks like it is better than brand new !
I am so proud of you !!!
I use P/power too and cut it with water; it will still work but could take a little while longer to clean.
On really dirty, greasy, oily engines, I also turn the P/power up a notch, and brush some of the harder, dirtier areas.
Since I use my pressure washer to wash it down first, spray the chemical, and then pressure wash to rinse, I dont have any issues getting it clean.
The only thing I might suggest is that your engine was so clean to begin with, it might not have needed full strength cleaner, which is dangerous at that mix to the rest of the paint - it will want to remove your wax..
I usually wash the front end of the car with alot of soapy stuff and leave it on to help "protect" the finish while I spray the thing with the chemical.
Wait till your try a can of Chemical Guys Fade to Black on that bad boy - wow, that stuff is also really good, and doesnt leave a greasy, residue like some treatments do.
Again, that engine now looks like the rest of the car - Perfect - ! ! !
Dan F