GTGTGT

Well the time has arrived! I pick up my new GT3 tomorrow. One of the first things that I am going to do is install a BMC air filter. Does anyone have instructions and/or advice on how to change the air filter. I am sure that it is a simple task - but thought I would ask the forum. Thanks!

rockitman

Check out Loren's DYI on renntech...You can view the instructions for a standard 996, the TT/GT3 instructs require a donation to see. Same basic procedure. Disconnect the MAF sensor plug...remove the clamp that holds the airbox hose to the throttle body. There is one bolt to remove infront of the airbox when you are looking in the engine bay. Remove it and the box comes out. Careful not to lose the rubber guides that stick in the holes that secure the airbox to the chassis. You will see them when you pull the box. Use a phillips head screw driver to open up the box and replace the filter...

macfly

Seems a lot of folks use these, what is the benefit of a BMC filter?

rockitman

More air gets to the motor quicker...If you do the filter w/o exhaust, you should notice an improvement in the throttle response time, imo...

With a free flow exhaust, the improvements are more dramatic in terms of hp and most noticeable in the throttle response. When blipping the throttle the revs rise and fall much quicker...like a poor man's version of a single mass flywheel...Obviously not the same, but it was real noticeable for me as compared to when I had it stock...

Steve in FL

Call me a pessimist but I want to see a dyno chart for only the air filter change that shows some noticeable improvement over the stock paper element before I'd bother changing it out.

rockitman

Did I indicate hp increase for the filter alone in my post??? No I didn't, so think before you criticize my opinions. I said throttle repsonse and if you don't believe it wait until you get your car and try it before you pass judgement...

yours truly,

The Guinea Pig

Steve in FL

Rockitman: I'm afraid you'll have to send me your BMC filter to test on my car once it arrives as, due to my currently unemployed state, I'm not likely to be springing for one on my own to try. The extra set of wheels and MPSC tires I'm ordering next are something I know I can use.

I realize you feel the BMC filter an improvement in throttle response but without some sort of quantifiable test to measure exactly what changes between the paper and BMC filters you're making a purely subjective comparison based on your perception of the difference. Not that there's anything wrong with that as perception is very important to how we feel about these cars. I however am a cheap bastard that wants to see some hard evidence that a mod I make will provide a measurable difference.

rockitman

Let me know when you come up with a test that can verify throttle response times...When air gets into the motor faster, which it definately does when compared to paper (The whole idea of a free flow filter), the throttle will respond quicker...simple as that. The throttle lags much less...

GTGTGT

I have used these filers on my M3, M5, and both 911's (C4 and C4s). I agree with the group. Power increase is minimal. I use the filters for a little better air intake sound and better throttle response (it is noticeable). They are not that expensive and it in the long run they are cheaper IMHO. I am waiting for the market to build a tested and tryed exhaust before I buy - and maybe find one on eBay

RayGT3

To give a true indication it would be necessary to measure the pressure (PSIA) on both sides of the filter at several various RPM points. The lower the differential the less the pressure drop and thus the better the flow. Otherwise it's purely subjective. I use one and "think" it sounds great and will last, possibly, the life of the car. Performance, possibly better, but no worse.
You guys are spending $6000 on exhaust systems etc., why sweat $100? I feel very fortunate when I have to pay only $100 for something for my car. Non issue.

bob_dallas

I put one on my previous 996 and the only noticable difference was slightly more induction noise - that was a plus. No noticably faster throttle response and I seriously doubt a HP boost so I never saw a reason to dyno it.

Philip in AL

Could someone post a picture of exactly which filter you are reffering to. I've seen a couple of different ones; one cone that says "GT3 Cup" on it, one that is stock shape.

Has anyone seen this carbon system http://www.gruppemeurope.com/carrometer/carrometer.html

Bob Rouleau

Air Filters are a recurring discussion. Here are a few points to consider:

1) Air filters are not rocket science. If additional power could be developed for the price of an air filter the factory would have done it.

2) If the surface area of the filter does not change, the only way to get more air to the engine is by doing less filtration. What impact does this have on engine longevity?

3) Bruce Anderson tested so called low restriction air filters on a dyno and observed no horsepower gain with a K and N he went even farther and tested the engine with no air filter at all and observed no useful gain IIRC this was on a 3.6 liter 993 engine. They did get about 7 HP more by drilling holes in the 993 airbox cover though.

4) Oil it yourself filters like the BMC and K&N can cause problems if not oiled correctly, the air flow sensor gets contaminated by excess oil and you get a check engine light. This is not to say that everyone has this problem, just the inexperienced.

5) Lastly, I am puzzled how a device which does not increase HP can have a significant effect on throttle response. We are still overcoming the same amount of inertia aren't we? Could it be that the sound gives us the impression? I can't say for sure but I tried a K and N on my 993 with no perceptible differences. I had already drilled out the airbox cover so I had the sound anyway.

Regards,

Steve in FL

The problem with BMC and K&N filters is that the oil can foul the MAF sensor so you have to be very careful when cleaning and re-oiling the filter to not overdo it. Rockitman's plan to buy new a new BMC filter come replacement time hopefully will avoid that problem but strikes me as a wee bit expensive. Of course I have no idea at this point how much Porsche charges for the paper filter so it may not actually be much more expensive than stock.

Steve in FL

Bob: Ah, the sounds and power on the 993 when you got religious on the airbox (or bought the Motor Sound Package option). I wonder how may folks took a hole saw to their 996 airboxes hoping for the same sort of improvment?