I've said it before, and i'll say it again. Putting a drop in K&N filter is a waste of money, not because of the filter, but because of the design of the stock air assembly you're putting it into. No filter is going to make the stock air assembly any better, it is just far to restrictive. Air has to come in the fender, take a 90 degree turn into the tube, then travel down the tube (which is not smooth inside, so air speed is compromised), turn 90 up through the filter, then 180 degrees back down into the TB. By this time, there has to be virtually no air velocity, and the volumn of air is limited.

 

for $8 I think it was a great deal. yea, it was new.

 

listen to silver the first day i got my truck i popped the hood and looked at the intake, i couldnt believe what they had the air doin, the opening to the stock filter was 1" x 3". stock filter k&n filter or no filter cant get enough air with the stock system on !!!!!!!!!

 

I put a K&N drop in on my '98 318, and I can definatley say I could feel a difference in power over a 1 month old Napa filter. There is alot more pep in this thing now. I agree with Silver_Dodge that the stock air setup is pretty anti-efficient though.

 

yes yes...thats the first thing i noticed too. all i was thinking was "LS1 lid mod"

 

I don't consider the factory 1994-2001 air inlet especially 'terrible' but I did measure as much as 4.25 inches of water vacuum before the filter element. Total air pressure is about 401 inches of water = 14.7 psi = 29.9 inches of mercury....so this loss is about 1% of potential maximum horsepower, and about 1.5% loss if you figure in 'Ram Air' effect.

It is actually pretty easy to measure with just a few feet of clear plastic hose, but you can also use your factory IAT and MAP sensors to judge intakes....and the Ram aftermarket talk on all forums would be greatly improved if owners would do either of these.

Here's the old post from Nov of 2000:
-----
Two winters ago I tried removing the air tube (from airbox to fender) on my
1995 Club Cab 1500 Laramie SLT 4x2 5.9 auto. I was experimenting to find out
if I would get better MPG in the cold weather with the engine sucking hot air
from the engine compartment all the time.

I left it off for about 2 months but could detect no improvement - but no
degradation of MPG either.

In theory the hot air is less dense with oxygen and takes away some of your
maximum horsepower. You can hardly detect that loss in most daily driving.

I have measured the restriction that the intake tube and lower airbox entry
causes to the airflow by the various bends, turns, corregations in the tube,
etc.

On the lower driver's side of the factory airbox there is already a plastic
1/2 inch nipple that the rubber tube leading to the valve cover breather
pushes onto. This nipple is on the 'outside' of the filter so it is a place
you can measure the 'vacuum' caused by restriction BEFORE the restriction
caused by the filter itself. It is a place where you can measure how bad/good
the Dodge engineers did at making a free flowing inlet.

If you go to a hardware store and buy 12 feet of 1/2 internal diameter clear
plastic tube (about $3.50 cost ) you can make a 'manometer' pressure measurer
that will connect to the 1/2 nipple on the airbox.

Press the 1/2 clear plastic tube onto the airbox nipple, run the tubing into
the cab by pushing over a little of the weatherstripping at the rear of the
hood to make a hole where it won't get crimped when you shut the hood. Then
leave the window partly open and run the rest of the tubing inside.

Make a U loop at the cab's open end of the tube. The sides of the U have to
be at least 10 inches high or so. Tape the U loop in place to some part of
the dash to keep it still. I taped it to the infamous over-radio-cupholder.
Now use a waterbottle to put some water in the tube - enough to fill the
bottom of the U with water going up 6 inches.

Now go for a test drive. Accelerate to full throttle. The 'vacuum' caused by
the inlet tube and airbox restriction pulls the water in the bottom of the U
tube up on the engine side and down on the open end side. The new difference
in height between the two water levels is the pressure difference.

I measured 4.25 inches of water level difference. That is also about 0.3
inches of mercury if you use a conversion factor for the math.

Each 27.7 inches of water equals 1 psi of pressure.

Typical atmospheric pressure is about 14.5 psi (14.7 at exact sea level).
So in terms of inches of water, the atmospheric pressure all around us is:
14.5 times 27.7 equals = 400 inches

So the restriction in the Ram's air inlet tube and lower airbox is about
(4.25 inches /400 inches) times 100% equal = 1% pressure loss.

That is actually pretty BAD design.
One inch of restriction, or less, would be a good design.
It would be interesting to measure the same thing on a KN Generation II
aftermarket intake system, but I don't have one.

Heard of the 'Ram Air' effect where the speed of the air hitting the vehicle
builds up pressure in a forward facing air duct and helps 'supercharge' your
engine a bit ? Well the formula for that is:

Inches of water pressure from Ram Air = (mph) times (mph) divided by 2025.

So at 70 mph the ram air effect is:
(70 mph) times (70 mph) divided by 2025 = 2.4 inches of water.

So the very best possible air inlet tube designed for Ram Air would actually
have a positive pressure of 2.4 inches of water, compared to the negative 4.25
inches I measured on my Ram truck.

-HankL

PS: an airplane travelling at 200 mph would have a ram air effect of:
200 x 200 /2025 = 19.7 inches of water.

You can also use this same home-made Manometer to detect whether your bellypan
gasket is blown. You connect it to the hole for PCV valve opening in the
passenger's side valve cover after removing the PCV valve itself, and also
blocking the breather inlet with tape on the driver's side valve cover
(opposite for post 1999 Rams). If you detect a vacuum in the PCV inlet - your
bellypan gasket is leaking - allowing vacuum from the intake manifold into the
'V' of the V8 engine.