USE THE kitty hair or tiger hair (usually blue or green with strands of fiberglass in it) as opposed to actual resin or Matt. It comes in long strand and short strand depending on the size of area your working on. It's stronger than regular body filler but doesn't finish as well so you skim filler over it once you have built up the area and snapped it roughly. Actually fiberglass will eventually seperate as it expands and contracts at different rates than metal does. This will deffinitly be an issue in an engine bay. You can also chose weather u want to put filler directly I've metal or prime and then apply over primer. Epoxy primer seems to be best at rust protection but just a pain to sand. And yes you will prime over the filler as well. Check out wild card customs and diyautoschool on youtube for tips. If your a pro at this then forgive me. Let me know the size of those intercoolers though.
"torque gets you off the line...& hp gets you over the line." - TTKeeper
