4ocious

Normally I'm a skeptic when it comes to the claims K&N and BMC make about their after market performance filters. I think the OEM's typically flow air just fine but I was wondering if anyone here has installed the BMC F1 filter in their GT4 and did you notice any difference?

MidEngineRules

^^ A good aftermarket filter should provide better air filtration and more air flow. Interested as well from any who have made the change. Keeping them clean requires more effort. K&Ns on older air cooled motorcycles was ideal as they could be removed and installed in seconds. How much actual effort is there in getting to the BMC filter to remove and replace? Cleaning it is easy.

PS-GT4

No clue on actual performance change, but there is more noise (in a good way) from the drivers side intake (assuming passenger side too) and it does pull a little harder to redline. Not too worried about cleaning - I plan to do annually. At the current rate, my driving isn’t more than 2-3k annually.

jmartpr

I really don't think there's any significant HP increase with them. Sound wise you do hear more engine noise.
Changing/cleaning them is not so simple (but doable once you learn) as in other cars and I do recommend doing it every 3-4 k miles.......those side scoops pick up all kind of stuff from the road and track.
I always keep a second set of BMC ready so there's no down time and I can clean them when I have the time.

4ocious

Thank you. My TTS (with K&Ns) is quiet compared to my GT4. I'm glad to hear that installing BMC's will get me a little more exhaust note which I've come to like. I'm not sure there is any performance difference between K&N and BMC other than cost (BMC's are over 50% more) and the BMC's are shaped differently. I've also read that small performance gains only occur when the engine is modified and at high speed. Most modern era DFI engines utilize demand-air systems that use computer-controlled sensors to regulate fuel/air intake based upon current driving conditions. So, the engine is always getting the right amount of regulated fuel/air it requires for peak performance regardless of the OEM or after market type air filters. So, my pending decision to purchase BMC's is strictly one of sound but not one of performance.

okie981

You don't get a louder exhaust note, you hear more intake sound, and since the intakes are just behind the doors, it's pretty noticeable when intake sound changes.

colnagoG60

FWIW, I just changed my air filters (w/stock filters)...first timer, just bought car in August, and I'm getting more exhaust, and intake sound, by leaving off the small interior side panels in the trunk. The filter replacement process was only taking a few minutes using the Sharkwerks YouTube instructions, but I hit a snag trying to screw the new filters into the mounts. I couldn't get the screws started as the screw points weren't threaded like the old ones...only has what looks like a ring, and had to use a lot of force to get it started after trip back to dealer to confirm "that's how they are now".

I left the panels and trim pieces off only because it got dark and it was taking way longer than anticipated...wanted to get a test ride in to see if the intermittent knock issue I've had since purchase was resolved. But I'm liking the new sounds in its current setup. Louder intake noise could very well be attributed to the filters not having half a cup of dirt trapped in them. 🙄 I originally planned on getting the BMC, but figured I'd wait until I can start tuning it, which couldn't happen until I at least resolve the knock/ping. If nothing else, car is running so much better now!

4ocious

Yesterday my BMC filters were installed and yes I did notice an improvement. But, I think the improvement is due to 1) my filters were almost black with dust and dirt, 2) they were probably 75% clogged and not flowing air, and 3) the intake canals were full of leaves and other crap. Based upon their condition I suspect there were the OEM filters that came with the car when it was manufactured. I also noticed some sound improvement and perhaps a bit more performance but that is still to be determined. But, my biggest concern is why didn't the CPO catch this earlier, why wasn't this caught during prior routine Porsche maintenance, and why didn't Carmax catch it when they serviced and certified the car for sale? Bottom line, if you haven't changed your filters in a while, or you don't know their history I suggest you consider changing them soon with OEMs. BMC's or K&N's.

James88

Thanks for sharing, how many miles on the car?

4ocious

Just turned 24K.

sgreer78

Because Carmax is just a used car lot. A very big one, but still a used car lot. Judging by the way they handled stuff on the e92 M3 I bought from the local one to me, I'd say they just couldn't find the filters or care to find out. FYI, my car had 12,500 miles when I swapped out my OE filters and they were almost black too. I bought my car with 9400 miles CPO.

Richard.

AFE power items far better quality than all, the hard plastic screw mountings on the BMC are a design failure, its metal on both K&N/AFE and soft plastic on OEM

Richard.

but noting the K&N items are MUCH shorter unfortunately than OEM/BMC/AFE, so less surface intake area

sgreer78

Don’t overtighten the screws and you’ll have no problem. It’s not like they’re under a load while in their enclosures.

jmartpr

I have two sets of BMCs and swap them every 3K miles......those side scopes really pick up a lot of debris and dirt.