96 plastic fuel rail question

[Crabby]

Some time ago I purchased a set of aluminum fuel rail covers, and although I like them a lot, they get scratched easy and are hard to polish. I have recently returned the plastic stock fuel rails to the engine. I began wondering why they were plastic and why they were vented. Having used the aluminum fuel rail covers for some time, I noticed how long they held heat after the motor was shut off. I began to wonder if the heat might be detrimental to the injector wiring. Anyone know why the stock covers are plastic and vented?

 

[boomdriver]

Weight is the number one reason for plastics. Vented so there will be some air circulation around the fuel system in case of a leak. The under-hood temps are just as hot on one side of the cover as the other, but when the hood is raised, one side cools faster while the cover holds engine heat longer. Its no more heat than anything else gets.
The wiring sufferes from exposure to chemicals and cleaning agents. That causes more damage to wiring and insulation than heat does.