K&N air filter for diesel
 

I am contemplating a K&N air filter on my 300d. I am primarily interested in the permanance of it. They also tout increased air flow amd HP. Does this hold true for diesels as well? Would there be any performance change at all?

The reason I bought a Diesel is that it should last a LONG time. I want to do every thing I can to reach that goal. A filter that lets in more air also lets in more dust. Seems counter productive. A Diesel makes enough of it’s own crud. Don’t need to add more.

It is not as if a diesel is a high RPM screamer sucking in vast quantities of air. I would like to see some research on how a “Performance” air filter works on a low RPM engine.

I use K&N
 

Just because a filter lets more air through, doesn't mean more dust gets in...it just means that air flows through with less restriction...could be due to greater surface area, or different configuration.

I cant say that I have noticed any difference in performace.

I like the fact that I don't half to by a $20 filter regularly.

Some individuals have indicated in previous posts that because they can see more daylight through the filter they dont like it, but the K&S does not work by simple physical filtration, as does a simple paper filter. The K&N uses oil...so the filtration process is a combination of both filtration and impinging of dust into oil.

I once ran synth. oil for 10,000 miles before changing, and had it tested. On of the parameters tested for something that was an indicator of road dust (aluminum or silica..i forgot, and I can t find results at the moment)..anyway, that parameter was very low!! Of course, that would also be effected by the type of driving...dirt roads, etc.

I trust the K&N, and have used one for a couple of years.

Follow cleaning directions exactly....dont scrub or use high pressure water...clean on a nice sunny summer day so filter will dry in a few hours.

Air flow on a na diesel is highest at fast idle, drops off at speed due to pumping losses. On a turbo, air flow is related to rpm and boost -- max flow at highest rpm and boost.

If you can see more light through a K&N filter, it is letting more dirt through. Oil on fiber isn't the same as an oilbath air filter, and isn't the same as more fiber, either.

I don't trust "reusable" air filters -- if you can wash the dirt out, you can wash it through, and it will come off the inside when it is dry and go down the motor.

You have enough capacity with the paper filter supplied by MB -- if you are getting full boost on the turbo, you have adequate flow.

The old oilbath filters are probably the most efficient -- air is drawn through a pool of oil, and the oil is strained out of the air by a steel mesh. Works very well until too much oil collects, when the dirty oil starts to travel up to the intake. Also a pain the butt to service -- filthy oil and dirt have to be scrubbed out every oil change. Mine on the 220D usually has an eight inch or so of hard mud on the bottom!

Peter

I've been considering K&N myself, for the increased air flow AND because I don't like the idea of disposable things in general.
MarkM: where did you purchase the filter? Does it fit in the stock housing, or does it require ducting mod.s? How often do you clean yours?

K&N on my e300 because I used them before on other cars. I don't really believe what the ads say, but they do help some

I read on another site where two of the gurus, Marshall and Dennis made about ten 0 to 60 runs to compare without any filter and the oem paper filter. They reported no measurable difference.

One was a 240D but I am not sure of the other car except I am pretty sure it was a turbo.

If any one does that type test, please post the results.

Harry
86 300 SDL

stock K&N for 300D
 

I bought mine at a local performance shop that sells K&N...they ordered it and I recieved in a couple of days...stock filter for the 300D round filter housing.

Now I see that Pep Boys and Auto Zone has them...so I think they could order it too.

I installed a K&N filter in my '82 300 SD. I service it once a year and use them in other vehicles that I own. The car appears to have more power, but I have no testing to prove it.

I belong to another diesel site that tested some air filters a few years back. All filters new out of the box, factory AC paper, K&N and an Amsoil oiled foam type. The paper filtered the best but flowed the lowest CFM's, the K&N flowed really well but passed quite a bit of dirt. The Amsoil flowed almost as well as the K&N and filtered as well as the paper. It's what I use now, and no, I am not an Amsoil dealer or affiliated with them. RT

I put a K&N filter on my car, and now I have the satisfaction of thinking I can put the pedal to the metal and easily pass the Boxster next to me. Of course, only if it is parked.

heres the deal -
 

The Amsoil foam filter(new style) filters by far the most particles and dirt.

Paper comes in second in filtration

K&N third in filtration.

K&N flows the most cfm of air. Paper(new) second, Amsoil foam third,paper (with 5,000mi) 4th.

Both K&N and Amsoil are washable/reuseable and use tack oil of some sort. Take your pick, amsoil - slightly cleaner, normal performance. K&N slight bit better flow(if your engine can actually draw more than your paper flows), slightly dirtier.

My vote goes for the amsoil for overall engine life etc. however when I ordered my amsoil, it didn't fit right(dammnit). So yep, a K&N's in my car. It dropped right in.