Air Cleaners, Stacks & Scoops

Does your engine need a complete air cleaner assembly, or does the carburettor or throttle body need a velocity stack that can provide smoother air entry? In this category we bring together air cleaner assemblies, velocity stacks, scoops as well as bases and lids for the air cleaner. It is for you if you want to replace a worn part or adapt the intake on your project.

What do air cleaner assemblies, stacks and scoops do?

An air cleaner assembly holds the filter in place over the carburettor or throttle body so the intake is protected against dirt. Under complete air cleaner assemblies you will find complete kits, e.g. the S&S Cycle Stealth Air Cleaner Kit. Air cleaner bases and lids are relevant when only a single part needs replacing. Velocity stacks and scoops shape the path of the air. A stack with a rounded mouth can reduce turbulence at the inlet, and a scoop can direct air towards the intake. Brands in the category include K&N Engineering, aFe, Kuryakyn and Performance Machine.

How to choose a stack, assembly or scoop

• Diameter: The neck must fit the throttle body, carburettor or intake tube. Vibrant stacks are available e.g. with a 3-5 inch neck and BLOX Racing with 2.5-4 inch.
• Material: Vibrant is available e.g. in aluminium and BLOX Racing in composite. The choice depends on heat conditions, weight and appearance.
• Space: Measure the clearance to the bonnet, frame and other parts before choosing a tall assembly or a scoop.
• Filter: Check whether the assembly comes with a filter or whether you need to choose one from air filter elements and wraps.
• Tuning: A modified intake may require adjustment of the carburettor or fuel injection. It depends on the engine.

Fitting and maintenance

Check gaskets and clamps so that no unfiltered air gets in at the joints. A stack without a filter should only be used where the intake is protected against dirt and foreign objects. Clean or replace the filter according to the manufacturer's instructions, and inspect the assembly for cracks. If your project also includes the fuel system, you will find more parts under air and fuel.

Frequently asked questions

What is the difference between a velocity stack and an air cleaner assembly?

A velocity stack is a funnel that shapes the air entry to the throttle body or carburettor. It typically does not filter the air. An air cleaner assembly holds a filter and protects the intake against dirt. Some setups combine a stack and a filter.

Does the engine need tuning after fitting a new air cleaner assembly?

It depends on the engine, the fuel system and how much the airflow changes. An assembly with a different air volume can affect the air-fuel ratio, so the carburettor or fuel injection may need adjustment. Follow the manufacturer's instructions for the specific part number.

How do I find the right size velocity stack?

Measure the outside diameter where the stack will sit: on the throttle body, carburettor neck or intake tube. Compare the measurement with the neck size in the product name. Also check whether the diameter of the funnel mouth fits in the space around the intake.

Can I use a new air cleaner assembly or a scoop on the road?

It depends on the product and the vehicle. Changes to the intake and bodywork may matter at a roadworthiness inspection. Check approval and documentation for the specific part number before fitting the part to a registered vehicle.