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The K&N RX-4140 universal X-Stream clamp-on air filter fits custom intake systems on racing vehicles and performance builds requiring a 3.531 inch flange inside diameter. Its innovative top design increases filter media for greater airflow and dust protection in demanding conditions. This washable reusable filter ensures consistent engine power with easy clamp-on installation.
Key Features
- Round Tapered Shape: 3.531 inch flange ID 4 inch flange OD and 5.969 inch height suits compact custom setups.
- Clamp-On Mounting: Pliable rubber flanges stretch up to 1/16 inch for secure fit on 3.531-3.547 inch openings while absorbing vibration.
- Low Restriction Flow: Pleated cotton gauze media delivers maximum air volume to support high-horsepower engines.
- 0.813 inch flange length ensures stable mounting on throttle bodies or carbs.
- Centered flange with 3.531 inch inside diameter 4 inch outside diameter and 0.813 inch length fits most custom throttle bodies in that range.
- X-Stream Top Design: Built-in pleated filter adds media area inside the top section for higher airflow rates and extended service intervals.
Fitment
| Fitment Status | Universal or dimensional product |
|---|---|
| Required Verification | Exact dimensions, media, connection, mounting interface, and companion part number |
Specifications
| Brand | K&N Engineering |
|---|---|
| Manufacturer Part Number | RX-4140 |
| Product Type | Air Filters - Universal Fit |
| Fitment Type | Universal |
| Condition | New |
What's Included
One new K&N air filters - universal fit identified by manufacturer part number RX-4140. Hardware, adapters, clamps, hoses, filters, and service supplies are included only when stated for this exact product.
About K&N Engineering
K&N develops reusable air filtration, intake, oil filtration, fuel filtration, and related performance products for vehicle-specific and dimensional applications.
Related K&N Engineering Products
- Shop all K&N Engineering products
- K&N Universal X-Stream Clamp-On Air Filter 3.5in Flg ID/4in OD/5.75in H
- K&N Universal Clamp-On Air Filter 3.5in Flg ID x 8.5x5.25in B OD x 6.25x4in T OD x 5.5in H
- K&N Filter Universal X Stream Clamp-On 2.438in Flange ID x 4.5in Base OD x 4in Top OD x 6.563in H
Frequently Asked Questions
How do I confirm K&N RX-4140 fits my setup?
Match every listed dimension, flange or thread size, media type, mounting interface, and companion component. A similar shape or outside dimension alone does not confirm compatibility.
Is K&N RX-4140 washable and reusable?
Serviceability depends on the exact media used for this part number. Follow the K&N cleaning and oiling directions for this filter and never apply oil to media specified as dry.
What should be checked after installing K&N RX-4140?
Verify seals, clamps, fasteners, hoses, sensors, wiring, and surrounding clearance as applicable. Check for leaks or contact, then follow the manufacturer service and reinspection schedule.
Installation Instructions
- Clamp directly to 3.531 inch ID intake tube or carburetor with hose clamp
- Oil filter media after cleaning per K&N instructions for peak performance
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