Airtight is good, but you do have to move enough air in and out of the box
to keep the engine from slagging down. I don't think the oil and water
cooling are enough especially for accessories like the alternator.

Roger

http://home.earthlink.net/~derbyrm

wrote in message
ups.com...
http://www.auralex.com/sound_isolati...heetblokPL.asp

1#/ft2 as per site. Making it airtight will greatly help reduce noise,
but I am unsure of the fire issues. Sound transmission is affectly
greatly by mass. It may not be the purtiest looking but I bet cement
board would be the most cost effective/fire proof.