The Radium remote mounted coolant header tank is commonly required for custom Lotus applications such as engine swaps, turbocharger kits, etc. where the OEM expansion tank is no longer in an ideal location.
The main tank is a 2-piece design constructed of CNC 6061 billet aluminum, as shown below. The two halves are bolted together along with a CNC billet aluminum cap receiver which mates to any standard 32mm "Type-A" style pressure cap.
Coolant header tanks are necessary for applications that utilize a low mounted radiator, such as a V-Mount, for proper air bleeding.
The Radium Engineering tank also has an internal swirl feature, as shown below. Hot pressurized coolant from the cylinder head is sent into the vortex chamber's inlet tangentially and accelerated to a high rate of rotation. This is an old hot rod trick to help aid in deaerating the system.
The Radium Coolant Expansion Swirl Tank features three ports that include -6AN male adapter fittings (not tapered pipe threads) for a positive seal. The lower ports are machined with 10AN ORB threads. For a list of other 10AN ORB adapter fittings that can be used, go HERE. The side port is machined with 6AN ORB threads. For a list of other 6AN ORB adapter fittings that can be used.
-Billet Aluminum Coolant Tank Anodized Black
-Aluminum 6AN Male Adapter Fittings Anodized Black
-Nickel Plated Sight Tube Fittings
-Billet Aluminum 32mm Pressure Cap Receiver
-Billet Aluminum Pressure Bleed Nipple
-Laser Cut Aluminum Firewall Mounting Bracket Powder Coated Black
-Aluminum and Stainless Steel Mounting Hardware
The optional Radium pressure caps (sold separately) allow the user to select a range of pressure. The purpose of a high pressure cap is to increase the boiling point in the cooling system providing improved cooling efficiency. Each cap is manufactured from stainless steel with a race proven high pressure valve. This is something to consider when tracking the vehicle in extreme conditions.
The OEM Lotus pressure cap is 1.1 Bar.