Air & Fuel Delivery

How much air and fuel can your engine get, and can the rest of the system keep up? In this category we bring together parts for intake, boost pressure and fuel supply – from air filters and intake manifolds to turbos, pumps, injectors and tanks. The parts are for you if you want to increase power or ensure a stable supply in your project.

How air and fuel work together

The engine only performs as well as the air and fuel allow. The air filter and intake affect how easily air gets in, while turbos and superchargers increase the amount of air with boost pressure. More air typically requires more fuel, so the pump, regulator, injectors and lines must be able to deliver enough – otherwise the mixture can become too lean. So look at the system as a whole rather than one part at a time. Brands in the category include K&N Engineering, aFe, Wagner Tuning, Wehrli and All Balls Racing.

How to choose intake and cooling

For an air filter or complete intake, the choice depends on filter material, fitment and space in the engine bay. When it comes to air and fuel cooling, size alone does not determine performance: cooling capacity, pressure drop, space and your power target must be weighed together.

Fuel supply: pumps, injectors and tanks

• Pump and regulator: Fuel pumps and pressure regulators are chosen based on the flow and pressure your power target and fuel type require.
• Injectors and fuel rail: Injector size and mounting depend on the engine. Within fuel injection you will find, for example, a fuel rail from Radium Engineering for the Toyota 1JZ-GTE VVT-i and injector bungs for Nissan in 25 and 30 mm.
• Tank and surge tank: In hard cornering, fuel can move away from the pump. A fuel hanger with surge tank, such as the one from Radium Engineering for 350Z/G35/G37/Q50, can keep the supply stable. Check whether pumps are included – they are not always.
• Filters: Fuel filters protect the pump and injectors from contaminants, for example the DeatschWerks filter for the Subaru Impreza 1993-2005.

Installation, compatibility and maintenance

Make sure the part fits the specific engine and model year, and that the connections match, for example 10AN fittings with ORB threads. Changes to the amount of air and fuel often require the engine management to be tuned. Replace or clean filters according to the manufacturer's instructions, and inspect hoses and joints for leaks. Whether a part is road legal depends on the product and the car, so check the approval for the specific part number.

Frequently asked questions

Does the engine management need to be tuned when I change parts in the air or fuel system?

It depends on the part and the car. Larger injectors, a stronger pump or more boost pressure often require the engine management to be adjusted so the mixture stays correct.

When does a surge tank make sense?

During hard cornering, acceleration and braking, fuel can move around in the tank so the pump briefly draws in air. A surge tank keeps a reserve at the pump and can provide more stable fuel pressure.

Can intake and fuel parts be used on the road?

It depends on the product and the car, and some parts are intended for motorsport. Check the approval for the specific part number before fitting the part to a registered car.

How often should the fuel filter be replaced?

It depends on the filter type, fuel quality and the manufacturer's instructions. A clogged filter can cause falling fuel pressure and rough running under load, so replace it at regular intervals.