What is the hose that runs in to the intake on our cars? And what's it for?

 

Sorry.. just noticed I posted this in teh Ls1 theard and not teh LT1. Sorry.

 

Well ill make it into an LS1 question...

If i would rather spend 3 bucks buyingthe smooth bellows at Homedepot rather than spending 15 bucks....what do i get at homedepot? what is the diameter of the hose?

 

I would rather spend the $15 on the bellow with one rib. Some people don't understand that the engine shifts side to side as you drive. The one rib smoothe bellow allows for this movement.
The $3 Home Depot model does not allow for this movement and tends to crack the lids.
Size of it I believe is in between 3-4 inches. Its one or the other I can not remember.