Coolant Expansion Tank for Lotus Elise/Exige 2ZZ-GE, Firewall Mounted, Radium Engineering

The Radium remote mount coolant expansion tank is commonly required for custom Lotus applications, such as engine swaps, turbocharger kits, etc., where the original expansion tank is no longer in an ideal location.

The main tank is a two-piece design manufactured from CNC machined 6061 billet aluminum, as shown below. The two halves bolt together along with a CNC machined billet aluminum cap receiver that mates to any standard 32mm “Type-A” pressure cap.

Coolant expansion tanks are necessary for applications utilizing a low-mount radiator, such as a V-Mount, for proper air bleeding.

The Radium Engineering tank also features an internal swirl system, as shown below. Pressurized hot coolant from the cylinder head is sent tangentially into the vortex chamber inlet and accelerated to a high rotational velocity. This is an old hot rod trick to help de-aerate the system.
The Radium Coolant Expansion Tank features three ports that include male -6AN (non-tapered thread) adapters for a tight seal. The bottom ports are machined with 10AN ORB threads. For a list of other compatible 10AN ORB adapters, click HERE. The side port is machined with 6AN ORB threads. For a list of other compatible 6AN ORB adapters, click HERE.

Includes:

- Black anodized machined aluminum coolant tank

- Black anodized 6AN male aluminum adapters

- Nickel-plated sight tube fittings

- Machined aluminum 32mm pressure cap receiver

- Machined aluminum pressure bleed nipple

- Black powder-coated laser-cut aluminum firewall mounting bracket

- Aluminum and stainless steel mounting hardware

Options:

Pressure Caps

Optional Radium pressure caps (sold separately) allow the user to select a pressure range. The function of a high pressure cap is to increase the boiling point in the cooling system, thereby improving its efficiency. Each cap is manufactured from stainless steel with a race-proven high pressure valve. This is important to consider when using the vehicle in extreme conditions. For more information, click HERE.

The stock Lotus pressure cap is 1.1 bar.

Instructions PDF