I posted earlier about a double filter on my US M coupe. There is an Orange filter and a grey filter. I have come to the conclusion that the grey filter is a charcoal filter and is only on US models. I decided to do a test. I got my friends G-tech and we did several runs and consistantly got 188 hp going one direction (210hp the other way, but not consistant) where we were doing the test. Then we pulled off the road, took out the charcoal filter, and did more runs in the same direction and peaked @ 189hp. TO THE COMPUTER BATMAN. so we downloaded the info and found that the peak gain was only 1hp, but over the mid range the gain was max 5 hp. So, if you want the extra 5 hp mid range, remove the grey filter from the airbox.

Good info. This filter is also found on the US E60 M5. Many E60 M5 owners have removed this filter and have gone to the dyno to show how much additional HP they gain with this mod.

Does that sound different 2?

Does that sound different 2?

I couldn't hear any difference, but for removing the grey filter, and gaining 5hp mid range, its a easy gain.

Expensive to mod, but many e36ers are swapping the underpowered M for an LS1 or an EVO engine since it's cheaper

Expensive to mod, but many e36ers are swapping the underpowered M for an LS1 or an EVO engine since it's cheaper
what does this have to do with anything?

Expensive to mod, but many e36ers are swapping the underpowered M for an LS1 or an EVO engine since it's cheaper

Yes you are right, in addition orange peels are more slippery then apple peels at higher altitudes...:lol

the 3.0si has the same dual filter design....it looks to me as though the grey filter catches alot of dirt that the orange filter lets through

I posted earlier about a double filter on my US M coupe. There is an Orange filter and a grey filter. I have come to the conclusion that the grey filter is a charcoal filter and is only on US models. I decided to do a test. I got my friends G-tech and we did several runs and consistantly got 188 hp going one direction (210hp the other way, but not consistant) where we were doing the test. Then we pulled off the road, took out the charcoal filter, and did more runs in the same direction and peaked @ 189hp. TO THE COMPUTER BATMAN. so we downloaded the info and found that the peak gain was only 1hp, but over the mid range the gain was max 5 hp. So, if you want the extra 5 hp mid range, remove the grey filter from the airbox.


I have a 2007 M6 convertible. Is it really worth all that to just get ONE hp? Am I missing something here? I would like to do some mods to my car, but was hoping that there was something I could do that would add more than just one hp.

FatLip removed mine and I noticed a little better mid range immediately. It isn't much but we are talking FREE and EASY. (my 2 favorite words)

(It was either this of put a Viper engine in my M Coupe!) What the hell was that about?
:lol

Free and easy but at WHAT expense? Chances are good that many of us wont keep the cars long enough to cause issues. But when you consider the education of the engineers who designed these motors, the extensive testing they did, and yet they added this filter.

Then a few of us "shadetree mechancics" determined in just a G-Tech test that the car made 5hp midrange and 1hp peak overall more power? Lets be a bit more realistic here... your gains come at what cost? I'll keep my filter, thanks.

PS: Sure short-term the effects are probably minimal ... but I'd hate to even thing that I'll have some internal motor issues while still owning my car, just because I removed some stupid filter for 1hp.

Free and easy but at WHAT expense? Chances are good that many of us wont keep the cars long enough to cause issues. But when you consider the education of the engineers who designed these motors, the extensive testing they did, and yet they added this filter.

Yup... I'm curious as to why this filter is there as well.

Yup... I'm curious as to why this filter is there as well.

US Emissions.

Something about catching excess hydrocarbon from the fuel system. It's not present on European models.

Another cheap and easy mod is a Twin Screw Super Charger.

US Emissions.

Something about catching excess hydrocarbon from the fuel system. It's not present on European models.

Ok... that's good enough for me. It'll be added to the spare parts pile next weekend.

Do you think removing this filter will affect warranty service or do you just drop it back in before taking to BMW?

Do you think removing this filter will affect warranty service or do you just drop it back in before taking to BMW?

[service rep]
"Sir, it appears that your car has been modified. It is missing the charcoal filter. This may affect your warranty situation."

[owner]
"What?!?!? This an outrage!!! BMW must have failed to install the filter at the factory!!! I demand a free replacement filter be installed and a written statement that if the car suffered any damage due to this factory oversight, the damage will be covered by BMW!" :D

[service rep]
"Sir, it appears that your car has been modified. It is missing the charcoal filter. This may affect your warranty situation."

[owner]
"What?!?!? This an outrage!!! BMW must have failed to install the filter at the factory!!! I demand a free replacement filter be installed and a written statement that if the car suffered any damage due to this factory oversight, the damage will be covered by BMW!" :D


Touche`

Do you think removing this filter will affect warranty service or do you just drop it back in before taking to BMW?

I asked the dealership if this would affect the warranty. They told me it does not affect the warranty. I was told this by Crown BMW's service department.

I took the filter out, but put it back in because I don't need the extra power at this exact moment in time. When it warms back up and I feel like I want to have more fun than usual (whatever that means), it will be coming back out.

I will still put it back in prior to any servicing done by BMW.

I asked the dealership if this would affect the warranty. They told me it does not affect the warranty. I was told this by Crown BMW's service department.

I took the filter out, but put it back in because I don't need the extra power at this exact moment in time. When it warms back up and I feel like I want to have more fun than usual (whatever that means), it will be coming back out.

I will still put it back in prior to any servicing done by BMW.


So, where exactly IS this filter? Is it easy to remove?

So, where exactly IS this filter? Is it easy to remove?
In the airfilter box. Evidently. More info is here:
http://www.z4coupeaddicts.com/viewtopic.php?t=118