Pettit Racing Air Separator Tank - Swirl pot FD3SPettit Racing's Air Separator Tank now incorporates swirl pot action, hence AST SP. The redesigned part further improves system efficiency by more effectively removing entrained air circulating with the coolant. A very simple design change, they moved the inlet tube to a position that causes the inflow of coolant to create a swirling action. The AST_SP also benefits from a billet cap neck and hose nipples, all CNC machined from 6061 T6 aluminum then