My engine box is already insulated but it could always use somting better, Im not a expert at sound deading, because most of the things I work on are now fiberglass I.E Boats. But Travis turned me on to these guys they are right up in his neck of the wood's. Travis know a bit about this stuff mabey he will pipe in.
Im going to star a project that will use all sorts of sound deadning material but from what I have learned theres differnt material for diffrent things.
Theres sound blanket's that you see on the undersde of the hoods of lets say a benz this will do way more as far as killing the sound will than Dynamatt, Dynamatt is more used to stop the sound of metal resonating. Go to this link you can learn lots more on what type of material you need for your job, but from what you have said a sound blanket sounds like what you need, Be warned after viewing this link you might get adicted to sound proofing. http://www.cascadeaudio.com/