i use purple power degreaser diluted 50%...it works great, i do it once a month...when we pulled auxiliary's motor in his 240 we used straight simple green not diluted and a pressure washer to get all the grime out of the engine bay...it worked great.

i have also used that gunk foamy engine bright on a few cars ive cleaned..it works good too i just hate the smell of it..smells like gasoline.

after your engine is dry..spray on some CD2 engine detailer spray...that stuff will make it look brand new