Fuel Surge Tanks

Does your engine stutter in long corners or under hard braking when the tank is below half? A surge tank is a small collector tank that can keep the high-pressure pump submerged in fuel, even when fuel sloshes around in the main tank. It is for you with a trackday, drift or rally project.

How a surge tank works

The low-pressure pump in the main tank continuously fills the surge tank, and the excess typically returns to the main tank. The high-pressure pump draws from the surge tank, which stays full even when the fuel moves around in corners. This can prevent the pump from sucking air and the pressure from dropping – something that can otherwise cause a lean mixture. The solution is used with both stock fuel tanks and fuel cells.

How to choose a surge tank

• Pumps: Some models come with pumps, e.g. the Radium Engineering FCST-X with three pumps and a lift pump; others without. Check which pumps the housing fits, e.g. Walbro GSS342, AEM 50-1200 or DW440.
• Number of pumps: DeatschWerks' 5.5-litre modular surge tank can be fitted with 1-3 pumps. The requirement depends on power target and fuel type.
• Regulated or not: Regulated models have the pressure regulator integrated, which can simplify the plumbing.
• Vehicle-specific or universal: Kits are available for e.g. Mitsubishi Evo X, Nissan R32 GT-R and BMW E9x with N54/N55. Otherwise you will need to plan brackets and lines yourself.

Installation and maintenance

Placement, mounting, line sizes and fittings depend on the car and the rest of the fuel system. Use fuel-resistant hoses and keep clear of hot parts. If the tank is placed in the cabin or boot, requirements for shielding and approval depend on the car and product – check this for the specific part number. Inspect joints and filters regularly. The category also includes products from Fuelab, Edelbrock and HKS, and more solutions can be found under tanks and fuel cells.

Frequently asked questions

When do I need a surge tank?

Typically when pressure drops in long corners, under hard braking or at low fuel levels, especially with high g-forces on track. Logging fuel pressure can show whether the problem is caused by sloshing or an undersized pump.

Should I choose a surge tank with or without pumps?

A tank without pumps gives you the freedom to choose pumps that suit the housing and your power target. A model with pumps combines the components in one package. Always check which pumps and fittings are included.

Can a surge tank be mounted in the cabin?

It depends on the car, the product and how the tank is shielded and vented. Requirements and approval must be checked for the specific part number and your car before you drive on the road.