Why not just use a powerwasher on it. It is much quicker this way and you can still clean it safely using one. While the engine is off, I'll spray degreaser on everything and let it dwell for a couple of minutes. Then while the car is running, powerwash the underside of the hood and then the engine from front to back, keeping the nozzle about 2 feet or so away from the engine. Apply waterbased engine dressing and continue to let the car run while you're washing the rest of the vehicle. This will help to dry the engine bay quickly and allow the dressing to dry evenly. Engines come out looking great and this method will take you about 5-7 minutes at the most. To date, I've never had a problem with moisture in unwanted places or problems with a car starting afterwards. As a professional, who has time to devote an hour to an engine alone unless the customer requests that and is willing to pay for it?
Matt Williams
Silver Lining Detail