I regularly clean my engine with Meguiar products. However, I would not recommend using a pressure cleaner simply because of "more damage than good" comes out of it. I do rinse it off with water while the engine is running but at the normal pressure that comes out from the faucet. The best bet is to use a brush and engine cleaner or a degreaser, all of it available from Meguiars. Here is a tip, use mechanics gloves, engine bays are cramped and full of metal edges (even mice no longer find shelter in new engine bays) and you can easily cut and bruise your hands.
Once clean and dry, make sure you spray all rubber parts with silicon spray. This will extend the life of hoses and other rubber parts.