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That's what I have been saying for years, but there is a whole group of people who swear by them. They do breathe well, but they let way too much oil in. Sorry to hear that, but glad you got it fixed.
 

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I know that it sounds bad...but, I would rather clean the MAFs than lose the 10 to 15 RWHP :wroom:

Mark
 

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drallen said:
I know that it sounds bad...but, I would rather clean the MAFs than lose the 10 to 15 RWHP :wroom:

Mark
10-15 RWHP ?? On what planet? And is it 10 or 15? You do realize what a gain of 10 or 15 RWHP equates to?

Slowly drop the crack pipe and back away...

-Jeff
 

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Nolift911 said:
You do realize what a gain of 10 or 15 RWHP equates to?
Well it's certainly nothing noticeable on a 400HP car.
 

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Discussion Starter · #7 ·
drallen said:
I know that it sounds bad...but, I would rather clean the MAFs than lose the 10 to 15 RWHP :wroom:

Mark
OK so you gain 10 HP (which is a real stretch, btw) - that will be for about 500 miles before the MAFS get contaminated then you will LOSE horsepower.

So, what is the point?

I've seen 1st hand what they have done and my only reason for this thread is to warn other members.

Not only are they NOT worth it but, you'll lose HP as a result longterm.
 

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I tried the K&N filters and the stock filters with the AA CAI. I could never FEEL a difference in performance when comparing the two, so I left the stock filters in.
 

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tranck said:
OK so you gain 10 HP (which is a real stretch, btw) - that will be for about 500 miles before the MAFS get contaminated then you will LOSE horsepower.

So, what is the point?

I've seen 1st hand what they have done and my only reason for this thread is to warn other members.

Not only are they NOT worth it but, you'll lose HP as a result longterm.
Ive had the K&Ns on my car for over 2 years and have never had a problem. I just serviced/cleaned them last month. With no problems. You must be putting to much oil on them.
Boz
 

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Nolift911 said:
10-15 RWHP ?? On what planet? And is it 10 or 15? You do realize what a gain of 10 or 15 RWHP equates to?

Slowly drop the crack pipe and back away...

-Jeff
IIRC Mark actually did a filter swap on the dyon stand and saw a dramatic increase in whp when he took out fairly new paper filters.

There have been many to use k&n's without problems, many who had problems. I've had my dinan intakes, which use oiled filters (look like k&n's but have a big D on them :2: ) for almost 2 years without issues as well. Must be the special dinan oil filter oil that is mafs friendly. :D
Mike
 

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Nolift911 said:
10-15 RWHP ?? On what planet? And is it 10 or 15? You do realize what a gain of 10 or 15 RWHP equates to?

Slowly drop the crack pipe and back away...

-Jeff
Hi Jeff,

It was not crack...it was just a good quality Vodka and facts...

All readings were taken off a dyno....on the same day....


With STOCK PAPER AIR FILTERS that only had about 500 miles on them...

2500 RPM (Hwy cruise range) 120 RWHP / 255 lbs Torque....

Max Power 343 RWHP / 303 Torque


NO FILTER in the air box...

2500 RPM ... 150 RWHP / 314 lbs Torque

Max Power 358 RWHP / 314 lbs Torque


Just the facts... :cheers:

Mark
 

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drallen said:
Hi Jeff,

It was not crack...it was just a good quality Vodka and facts...

All readings were taken off a dyno....on the same day....


With STOCK PAPER AIR FILTERS that only had about 500 miles on them...

2500 RPM (Hwy cruise range) 120 RWHP / 255 lbs Torque....

Max Power 343 RWHP / 303 Torque


NO FILTER in the air box...

2500 RPM ... 150 RWHP / 314 lbs Torque

Max Power 358 RWHP / 314 lbs Torque


Just the facts... :cheers:

Mark
Ummm...yeah. With NO FILTER - DUH. I find it comical that the hundreds of thousands of hours of R&D that went into these engines via BMW and to think a simple filter swap will net those gains...What was BMW thinking to leave 10-15 RWHP on the table???

Didn't happen to test the K&N filters did ya???????????

You will need filters on the engine for driving btw...and the snake oil that K&N sells is just that - I thin gauze filter that is lubed with oil to attract dirt versus sheer blockage of dirt. MAFS are sensitive. For those folks not having any issues I would wager your oil is alot dirtier as the "scientific" method for lubing these filters is hit or miss at best. Go to a store and open the packages of the K&N filters - in the plastic bags they come in some are drenched in it and some nary a trace.

So if your MAFS are good with the K&N after alot of miles you are not getting the filtering protection you need for your engine - if you are getting the filtering protection your MAFS are going to be screwed because the oil will effect them - just a matter of time.

It's not rocket science - just common sense.

-Jeff
 

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This issue has concerned me since I bought my 03 M5 in March 05. The previous owner installed K&N filters at about 10K miles. I purchased the vehicle with 23665 miles. The K&N filters had not been cleaned since installation. I just had new stock filters installed and replaced the K&N filters. The private tech and dealer's tech recommended that they be replaced. When the K&N filters were removed they didn't appear to be over oiled but they had been in the car for 15K miles. The tech said there was some oil residue on the filters. The K&N's were set down on a shelf and when lifted a lot of sand/dirt was left on the shelf. I'd say about a teaspoon of debris. Apparently they were doing their job. Of course more could have passed through to the engine but who knows.

I haven't noticed any loss in performance with the stock filters. I didn't notice any problems with the MAFs when the K&N's were installed. The car seems to run fine without the K&N's. Maybe I will have to replace the stock filter more frequently.
Also, of interest is that the car was CPO'd 3 months ago and the private tech told me the air filters (for the A/C) should be replaced . It was very dirty. So much for the CPO inspection.

Just my two bits of what I've noticed. I do feel more comfortable with the stock filters.
Andy
 

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Andy Leeper said:
Maybe I will have to replace the stock filter more frequently.
Yes, absolutely. I am thinking every 10k.

Andy Leeper said:
Also, of interest is that the car was CPO'd 3 months ago and the private tech told me the air filters (for the A/C) should be replaced . It was very dirty. So much for the CPO inspection.
They left non-factory air filters in the car and cpo'd it?!?!

makes you warm and fuzzy, huh? What's next, brake pad inspections without taking the wheels off?

A
 

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Chuckc said:
I tried the K&N filters and the stock filters with the AA CAI. I could never FEEL a difference in performance when comparing the two, so I left the stock filters in.
Call me weird...but I could...may be it was the headers or the software...I could not feel very much loss on the top end but the low end loss of torque was noticeable...I changed the filters back and forth several times and ran the same road each time...

I guess that I just need to keep an I on my inlet tracts and keep an eye on my fuel flow rates (thanks DavidS).to make sure that my MAFs stay healthy.... :M5launch:

BTW...If you have not broken into your computer ala DavidS...you should try it...it is kind of fun...

Mark
 

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I just cleaned my mafs (using the process which included the simple green and alchohol) and lemme just say, as i dipped the mafs in the simple green solution, it was like a giant oil slick in the container. However, now the mafs are as good as new :cheers: . Anywho, i slammed the front of the beast last nite (FK coilovers) and now its off to finish the rears. Cheers.
 

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A,

In fairness to the dealer they were going to replace the K&N's but they told me they didn't have the stock filters in stock. I was to return with the car and they wouild replace them. The dealership was 1 1/2 hour drive from my home so I just did it myself. I did obtain the inspection report when the performed the CPO inspection. Nothing done but changed the oil and checked everything else. They did replace the 2 rear tires at my request. Air filters?? Nothing. They just try to save $$ anytime they can. Its enlightening to say the least
 

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If the the oil fouls the MAF's, why cant you just clean them, why are MAF's always on this bosrd being replaced? they are even replaced quite often in cars without the K&N filters, so is it that the K/N filters are the weakest link or the MAF's period? Only wonder as Mottati pointed out, the Dinan folks dont tend to complain to much and they also have a oiled gauze type filters, I am not saying this is all crap, I just saying correlation does not constitute causality, it might not be the K/N's, Josh
 

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I think the K&N MAF incompatibility problem has to do with two things:

1. The amount of oil applied to the filters.
2. The MAF contamination-burn-off process

Now and then the MAF sensor wires are automatically heated to about 1000 deg C to burn off contamination. I think this process evaporates most contaminants, but some fractions present in the K&N oil might evaporate slowly and when heated som much get oxidized and stick to the ultra-thin platinum wire.

David
 

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DavidS said:
I think the K&N MAF incompatibility problem has to do with two things:

1. The amount of oil applied to the filters.
2. The MAF contamination-burn-off process

Now and then the MAF sensor wires are automatically heated to about 1000 deg C to burn off contamination. I think this process evaporates most contaminants, but some fractions present in the K&N oil might evaporate slowly and when heated som much get oxidized and stick to the ultra-thin platinum wire.

David
This sounds like a reasonable possibility:typing: , Josh
 
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