The K&N RU-1037 is a clamp-on universal air filter from K&N Engineering, a reusable high-flow design that the manufacturer designs and manufactures for a wide variety of applications including racing vehicles, radio-controlled cars, generators, snowmobiles, tractors, and other applications. This listing's footprint is a 5-inch flange inside diameter, 6-1/2-inch base, 5-inch top, and 6-1/2-inch height. Because the flange is the fitment point, the key buying step is matching it to your existing intake tube. Compared with a disposable paper element, the washable media lets you clean and reuse the filter instead of replacing it on every service interval, which is where the higher upfront price pays back for track and weekend drivers.
The manufacturer's universal-line literature says the molded rubber flange can also be stretched for up to 1/16 of an inch (1.5mm) to fit in-between sizes. That gives some tolerance for small mismatches, but it is not a substitute for a correct measurement. Search terms buyers commonly use include K&N RU-1037 universal clamp-on air filter, 5 inch flange reusable air filter, 6-1/2 inch base high flow filter, and washable universal intake filter for racing. Installation is generally a simple slip-fit and clamp job, and the manufacturer lists its universal filters under easy installation.
The manufacturer states that the molded rubber flange on its universal filters can stretch up to 1/16 inch (1.5 mm) to fit between standard sizes. Confirm that your intake tube's outside diameter falls within that range of your 5-inch flange before ordering.
Per the manufacturer, K&N universal filters are designed to be cleaned and reused rather than thrown away. Follow the manufacturer's cleaning guidance for your driving conditions.
This is a low-difficulty install. Measure the existing intake tube's inside diameter first, then slide the rubber flange over the tube, seat the filter so the flange sits square, and tighten the hose clamp. The manufacturer's intake instructions describe the same approach, installing the filter onto the adapter and securing it with a hose clamp. Check that the filter does not rub against the hood, fender, or wiring and that the clamp is tight enough to prevent air leaks, since a loose connection can let unfiltered air into the engine.
