Project 718 Cayman T: Part 8 – BMC Air Filter

Is the BMC air filter worth it? Well, on the 2.0L engine with a tune, the BMC filter gains about 2% in power which is roughly 6 whp. On the bigger 2.5L engine in the S and GTS Caymans, I’d expect the gain to be a little more. On cars with turbo upgrades, the gain will be even more. From a durability point of view, the BMC giveth and taketh away. Eliminating the compressor surge should improve turbocharger life. But more tiny particles can make it past the filter and into the engine. If you live in a particularly dusty and dirty area, maybe staying with the stock filter is the right call and just drive around the compressor surge by not getting into boost until you’re at higher engine revs. From a cost point of view, a factory air filter is about $45 and the BMC is about $90. So the BMC pays for itself after two filter changes. I’ll probably do a filter cleaning every 5k-7.5k miles and I plan on keeping the car for 150k miles, so that’s about a thousand dollars in savings in air filter costs over the life of the car.

One, er, two small updates on the COBB Accessport. Up to this point, I just stuffed the Accessport in the driver’s side door pocket, but I wanted a way to look at it while driving. I used my new cordless Dremel and cut slots into the magnetic holder that came with the Accessport. I found this old Velcro strap in my box of old bicycle parts; I think its original purpose was to hold a pump. Anyway, I worked the strap through the holder.

I can now strap the Accessport holder quickly to the door handle and remove it just as quickly.

Now, I can give the Accessport a quick glance whenever I need to. I can also easily start and stop datalogging.

I had Alex at Stratified Auto do another tune update to the Accessport to address a thermal issue. After driving and then parking the car, the coolant for the air-to-water intercooler gets heat-soaked. The whole system is located in the engine bay, so all the heat coming off the engine (oil, engine coolant, engine block, turbo, headers, cat, etc) soaks into the coolant for the air-to-water intercooler system. When you go to drive the car after it’s been sitting for a bit, the intake air temperatures are much hotter than ambient. With the stock tune, the fans wouldn’t kick on to bring the coolant, and therefore intake air temperatures, down. At least, I hadn’t seen it happen yet when ambient was 77F and the IAT was 122F during one occasion. On the APR tune for the 718 turbo cars, they crank up the fan to max speed in Sport Plus mode all the time I believe. That wasn’t what I was looking for as the fans are quite loud when they are cranked up and I drive in Sport Plus 100% of the time. In the picture above, you can see the ambient was 61F and the IAT had heat soaked up to 118F. Alex adjusted the fan and coolant pump settings to have them come on at moderate speeds to bring the IATs down. Here, the temperatures had come down to 108F from 118F after a couple minutes. I took the picture after the car been started and sat stationary, so no airflow from driving to bring down the IAT. Stock tune, there would not have been a reduction in temperature and it would only come down once driving. If driving on surface streets in stop and go traffic, the temperature won’t come down very far. I haven’t looked at the stock tables, but I’m guessing the fans would kick on at IAT of 135F or so.

The BMC air filter is a minor power gain at stock turbo power levels; the power gains will be greater as the airflow going into the engine increases (hint hint…). In addition to the little power gain with the air filter, the tweak to the tune to kick on the fans for the air-to-water intercooler system sooner will make the car quicker in everyday use too. These little details add up.


    1. I’ve heard with practice, it can be done in 45 minutes. If done by the dealership, the question is how careful are they and how many little black cones will they lose. Also, getting the lid back on properly seated and sealed takes a bit of work. I didn’t have it seated correctly the first time.

  1. There is a big intake restriction after the intake filter, just before the turbo. There’s a company “Ragdoll Motorsports” that has replacement turbo inlet that showed great results on the 2.5.

    1. Already have that on the way with a bigger spinny thingy that does the ‘hint hint….’ more airflow part.

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