Sprint Filter P08 F1-85 Air Filter for Racing – BMW HP4 Race (2017–2018) PM93S F1-85

Almost every listing for a racing filter has to argue its case, because almost every machine it fits spends its life on public roads, where the specification is wasted. The HP4 Race is the exception here. BMW built it in small numbers, without lights or a number plate, for circuit use only, so the condition under which a high-flow medium earns its place is not something the owner must arrange. It is the only kind of riding this motorcycle was ever able to do.

Key Features

• The racing weave of the P08 family: woven polyester, dry, used without oil
• An 85 µm aperture rated at 15,000 l/m²/sec, the top of Sprint Filter's flow range
• 95.22 per cent retention of 100-micron test particles in the manufacturer's own comparison
• Polyester threads from ø 22 microns, with the aperture between them doing the work
• About double the filtering cloth of a typical performance element, in the standard frame
• Seats in the series airbox, is cleared with air between runs, and carries two years of warranty

The condition met by construction

Flow only becomes relevant where flow is demanded: throttle fully open, high in the rev range, held for seconds and then repeated. On a road that state barely exists. On a circuit it is most of a lap, and a machine that never leaves circuits meets it every time it runs. That is the entire case for the wider 85 µm weave and its rated 15,000 l/m²/sec against the 5,050 of the standard element — a statement about where the motorcycle is used, not a claim about the engine. It adds no power to any of the three machines on this list; nothing fitted inside a series airbox does.

What the garage actually gets from it

Repeatability, mostly. A dry element is cleared with the air line between runs and goes straight back in, so a session starts from a known intake restriction rather than from whatever the last one left behind. There is no oil to reapply and nothing available to travel downstream onto the sensors of a heavily instrumented machine. One caution belongs alongside the retention figure: 95.22 per cent against 93.13 for the standard weave is a measurement made on a coarse test fraction, and it says nothing about the finer material that a wider aperture necessarily passes.

Care and cleaning

Between runs PM93S F1-85 is cleared with compressed air held to the clean face and blown outward, which takes a minute and needs nothing else. After a wet meeting, or before storage, hand-warm water with a little mild detergent removes what air will not, rinsed until clear; then the element must dry completely in moving air before it goes back — never against heat of any kind, which destroys the medium far faster than use does. The maintenance sheet is under the Downloads tab.

Fitment & Compatibility

Made for the BMW HP4 Race of 2017 and 2018, as a direct replacement in the standard airbox of that machine. Three motorcycles share the part number: the HP4 Race, the S 1000 RR of 2010 to 2018 and the Bimota BB3, which was built around the same BMW engine. The Fitment tab lists all three with their years.