I bought insulating panels from Sailors Solutions. They are supposed to be great at noise-dampening. I noticed some improvement but it was not a radical difference. I will say that they adhesive they used on the panels was incredible - you definitely only want to apply them once.Thanks Cajon. My foam has just disintegrated with time, and is just gunking up the bilge.
If you don't want noise to escape from the engine compartment, you will want to use a sound dampening product. If you don't want heat to escape, use insulation. Both of these products will do both but each is specifically engineered to perform a particular task better than the other. Your selection will depend on what your goal is. Both products can look similar and have silver lined padding. A dampening product will have a dense layer of material in addition to the foam. It is usually a heavier product per square foot. Some dampening products use a lead sheet because it is such a good dampening material.Just to be straight, is the silver lined padding inside an engine compartment's main function insulation or sound dampening?