Airflow lovers, here's a thought..

[wolf_walker]

Someone on another board mentioned this, and it was one of those classic "duh" moments for me.

You know how some of you insist the K$N filters and alternate intakes are no good, and some swear by them? Could one not put a vacuum gauge between the turbo inlet and the air filter and see what it says? If there's a vacuum, there is room for improvement, if there is not, then, well, there's not.
I know this should work on a non-turbo motor, but I'm a little fuzzy on what a turbo will do to the deal. I'm guessing it would still be valid.

This is much like large diesels have a little colored vacuum gauge dealy just as I speak of from the factory to tell you when your air filter is dirty.

I can't believe nobody thought of trying this before..

[Wasuchi]

Sounds good to me, but it would be best to be able to read it while you're at road speed (under load)..... that may be your thought.

[wolf_walker]

Yes, a vac gauge and a longish hose was my thought. Though a more permanant setup might be handy for keeping check on the airflow. I bet the one's in commercial engines are set to stay at there highest vac reading somehow..

Get a common Filter Minder and put it on the preturbo side. I don't think there will be enough restriction to make a measurable amount in most vacuum gauges, unless it's really filthy. Any clean filter will flow all the air these engines need. K&N just happens to be a convinent source of filters that suit the many non-stock needs that most Fram, etc. don't make.

[billrok]

Any good HVAC guy who deals with big commercial systems would have a Magnahelic gage/gages in different ranges which could easily be hooked up to check the differential pressure across the filter in question. Very commonly used in commercial buildings on their air handling systems to monitor the condition of the air filters. I still don't see the point. Turbodiesels run with excess air all the time anyway. The real way to test the difference would be on a dynamometer. A couple of runs with the stock air filter and a couple of runs with the overpriced K&N. See who wins.

[wolf_walker]

Seems to me this test should be as valid as a dyno. If a diesel is truly with an excess of air, there will be no difference in any filter.
But if a vacuum is shown with a gauge, there is not an excess of air, yes? I may have to buy a spare elbow and drill it for a hose and just see if nobody beats me to it.

I personaly *hope* the stock setup is not restrictive, but..

[psfred]

The vast majority of the pressure drop and flow restriction is the filter housing, not the filter.

Part of this is for sound reduction -- diesel intakes are pretty noisy with no throttle valve in there to contain the noise of the air getting sucked through the engine.

Peter

[BigMikeT57]

Would a set up like the "economy" gauge on the 126 gasser's do the trick? I've been told it is just a vacuum gauge reading vac from the intake manifold.

[kerry]

My 307d had a little red pop up indicator to show vacuum in the intake when the filter was plugged, so MB beat you to it. Why they don't put it in the automobiles, I don't know.

[wolf_walker]

So, anybody tried this yet?