Im thinking about purchasing one of these. Since it was said that due to the freeflowing design of this filter it would not be a good idea to have it on a DD. So I was thinking of buying one and jsut swaping it out with my stock filter everytime I track the car and putting the stockone back on when im done tracking the car. Is this a good idea or will it be too much of a hassle to do this( about once a month) How do you install one; easy?

 

As you said, it's OK to use occasionally.
And the BMC 's are the best .
I bought one which I used only a few times on the track ( 997 S )
As far as installation goes, just pull up the air box, remove 6 or 7 torx screws and drop it in ( takes about 15 min.)

I paid $110 for it and I'll ship it to you for $50 ( in the US )
Drop me a line if you are interested .

 

I had one on my car and it was fine. Enlighten me as to why it is not good on a DD, what does the free flowing design have to do with it?

Dave

 

JCS, is the BMC filter a cotton weave like the K&N or is it foam?
thanks

 

from previous posts i had read that it lets too much dirt into your engine.

 

I'm not sure it's cotton, but it is some type of proprietary micro fiber cloth and much better constructed than the K&N .
It's made in Italy to stringent quality controls and is supposed to be one of the best filters of it's kind available. Not surprisingly , it also costs a lot more than the K&N.

But, if you only plan to use it occasionally , the quality difference may not be of that much importance to you .
I do know, that the K&N is reputed to let a lot more dirt thru it, due to its design/construction.

 

The main difference between normal and "oiled" filters is that the regular filters have dense , randomly arranged fibers which are designed to catch and retain the dirt particles.
In fact, a regular filter gets more "efficient" the dirtier it gets. The spaces for the dirt to get thru get smaller and it filters out ever smaller dirt particles.
Of course, eventually the engine has to suck harder to get the air thru and you lose performance and the filter needs to get replaced.

An oiled filter on the other hand works differently .
The fibers are arranged further apart.That's why there is less resistance for the air to get thru.

They work on the principle that dirt particles, being heavier than air , tend to keep going in a straight line . They then eventually "hit" one of the filter sides , and cling to the oil while the air passes by .

The drawbacks are that once the oil is coated with dirt particles, it can no longer hold any more and they wind up in the engine oil.
Also, if it's very humid outside ( raining etc. ) water molecules containing dirt particles will "roll off " the oil , and again the dirt winds up in the engine.
( oil and water does not mix very well )

Last, once the outside temperaturte drops below freezing, the oil viscosity changes and is less capable to retain the dirt .So they are definitely not for Alaska or Canada in the winter.

For these reasons ,even K&N has a big WARNING on their fiters not to use them in wet weather and colder temperatures. I just can't understand why otherwise reasonably intelligent people keep disregarding it for the sake of a few extra HP.

Keep in mind, we are talking about dirt particles measured in microns.
Eventually a lot of it builds up in the engine oil. Since it's so fine,
the oil filter does not retain it and it winds up being a great polishing compound. /Lol
If you change your engine oil very frequently , like every few thousand miles,
clean and re-oil it frequently and live in a warm climate where the viscosity is not affected , you should be OK .

I would not have a problem with occasional use on the track, but I for one will not use them on a daily basis.I like my engine.It's pretty tight and I want to keep it that way for as long as possible.

Hope this answers your question and if someone has further info ,any additional comments would be welcome.

 

Thanks for the info. I hadn't read anything negative on the BMC filter

 

Hey have you ran any stock 997S's with your car after your mods.?

 

i've got one and its great. just make sure to clean it once in a while.

 

You're welcome .
There is nothing "negative" about BMC or any other oil type filter.
As long as one understands what their uses and limitations are .

 

I'd like to use one all the time and just clean it out every month or 2. I've always run K&N in my motorcycles and Vette with out any problems. I'd like to be able to do this with my new 997S.

JCS, why are you selling your BMC filter?

 

When a brand new filter is ordered does it already come oiled and ready to pop in or are there some other preperations people do before... I heard that most of the time they come way soaked in oil and people have to dry it out somhow before putting it in their car; such as placing it out in the sun for about an hour.

 

they come pre-oiled in a plastic bag. Some folks towel off any additional oil and install. I've followed threads on these kinds of filters and it seems to me the problems arise when folks clean them and re-oil them with too much oil. I've used k&n's abd bmc's in my 996 and boxsters. never had a problem. i throw them away rather than re-use them. Less worry than re-oiling

 

I have always used K&N's and let them dry in the sun for a couple hours before install. I currently have the K&N FIPK with the dust cover on it.

I think when I clean it next I will use just water to hose it off and not re-oil it