Air Separation Tank. It sits inbetween the intercooler and the battery on a stock car.



I have always wondered how important it was. I never removed it due to the cooling nature of the FD. I figured if mazda thought it was needed it must be. Not that I stand by that but we all know how fragile the cooling nature of a FD can be.

I still have the radiator in the stock location and I removed the AST.



no ill effects.



I order a 1986 filler neck cap from Ray at Malloy for $25 and drilled, tapped, and put a bolt where the line on the filler neck attached.



then cut a hose for the radiator nipple and plugged with a bolt. Rock solid temps.



However Rick Engman told me he runs AST's on all his 4 rotors.

actually you can get a filler neck for an NA S4 motor.... it already has the nipple on it so you dont have to tap one.



depending on the age of the stock AST, it could actually do you more harm being there because of the likelyhood of it cracking.... because of course, its made of good ole plastic. but if you have the money and room in your enginebay... by all means, get an aluminum one.

maybe I was unclear...I pulled the nipple off the stock filler neck and drilled and tap and plugged it. I did use an S4 cap. I didn't loop the old nipple to the radiator like most do...I hate the way it looks.

veryy nice, love the red colour https://www.nopistons.com/forums/pub...IR#>/bigok.gif

thanks for all the compliments guys

i love your car.....very, very nice! https://www.nopistons.com/forums/pub...R#>/tongue.png