K&N Air Filter for UCE

[Arizoni]

My paper air filter had accumulated over 2500 miles of riding.  During this period I occasionally blew some air thru it from the outside towards the inside to remove some of the dust so I decided it might need replacing.

These air filters aren't exactly cheap so I figured that if I bought the K&E filter for the UCE I wouldn't have to ever buy another one.  I also thought I might get a performance improvement in the bargain .

The filter instructions say it should be oiled making sure all of the pleats are covered so that is what I did.

After installing the new filter I didn't notice any gain in power and in fact, my gas mileage dropped from about 73 mph to 61 mpg and between 70 and 75 mph the power seemed to be less than it used to be.

These K&N filters are tapered and larger than the standard paper filter and when I installed it I placed the larger end against the rear wall of the filter plenum.
After noticing the drop in fuel mileage I got to thinking that the larger diameter of the new filter might be blocking off the throttle bodies inlet so today I removed the filter.

While sitting there studying things I thought it would be a good idea to try to measure the airflow thru the filter.
What I needed to do this was some air pump that would suck a LOT of air and I knew just where to get one.
   My wife's vacuum cleaner is just such a device!  
If you do this, and your wife finds out, you married folks  are going to catch hell but it won't harm a thing.  It will only convince her that you are certifiably crazy (which she already knew).
(If you want to avoid your wives glare you could also use your shop vac if you have one.)

To make something that would seal the hose against the filter I used one of those plastic 16 ounce containers that potato salad and margarine comes in by cutting a hole that was the same size as the end of the hose.  This hole should be a fairly close fit but it doesn't have to be perfect.  We will be looking for differences in vaccuum, not absolute values.
 
Resting the filter on top of a 1 gal. paint can and applying the container & hose to the other end a nice flow will be traveling thru the filter.

Now, to measure any changes in the amount of vacuum I had to add something that would measure a change in air pressure.
To this end, I got a long length of clear vinyl tubing and a tall glass filled with water.
Drilling a hole in the plastic container I got the hose to fit very snugly.
With one end of the tubing in the glass of water and the other end in the new vacuum testing container I hung the tubing from the glass over a door knob so it would have to climb vertically that far before it could be eaten by the vacuum cleaner.

With everything in readiness,  I started the vacuum and held the plastic containers mouth against the top of the paint can.  It pulled the water in the tubing about 14 inches above the level of the water in the glass.

Placing the K&N filter on the paint can and applying the vacuum container to the top of the filter the water level in the tube rose about 3/4 inches above the level in the glass.

Doing the same thing to my old paper filter the water level rose about 5/16 inches.

Ah Haw!  This explained the drop in fuel mileage and the lack of power!
It also told me I had applied way too much oil to the K&N.

Using the "Cleaning Kit" for the K&N I washed the oil (and dirt) out of the filter and to speed drying I placed the "shook out" filter on the paint can and applied the vacuum container to the top.  Turning on the vacuum cleaner caused a water rise of about 12 inches and as the water dried the level continued to fall until it was about 1/16" above the level in the glass.  Clearly, when dry these K&N filters are less restrictive than the old paper filter.

What I learned from all of this is if these filters are really "oiled" they are very restrictive.  If lightly oiled they can be less restrictive than the paper filters but they may allow a little more dirt into the engine.

As for the direction of installation, as I mentioned, the K&N is larger and if the large end of the filter is installed to the rear of the inlet plenum it will block off the throttle body's inlet slightly.
When I say, "block off" I don't mean it actually will touch or plug the inlet but with large amounts of air trying to get into the throttle body, any restriction, even if it is some distance away will reduce the amount of air flow.  What is needed is the largest open area that can be obtained at the inlet.

For this reason, I suggest that the K&N should be installed with the smaller end first leaving the large end outward for the steel filter retainer to push against.

Happy Riding!

[barenekd]

Nice test. When I started reading your message, I was going to ask you how much oil you used if your mileage was suffering like it was. I guess you answered my question.. My gas consumption improved when I changed to the K&N. I'm not using the conical one though, mine is a just a round one and I think it has more surface than the conicals, but don't hold me to that.
Bare

[Ratty-matty]

iv got a K&N pan cake filter on mine i found it was better to upgrade the jets in the carbs from 90 to 95/100 runs faster sweeter and i have a small drop in MPG but that hasn't bothered me

[Okie Enfield]

just stuck the K & N on mine too Arizoni...same one you got..found out from the mechanic at the shop that when you get them they come pre oiled...did try to mount it small side in but the plate didnt seem up to holding it that way..put it in the "right" way.. will look for a adaption or different plate to switch it upside down.

[swingarm]

Nice test. When I started reading your message, I was going to ask you how much oil you used if your mileage was suffering like it was. I guess you answered my question.. My gas consumption improved when I changed to the K&N. I'm not using the conical one though, mine is a just a round one and I think it has more surface than the conicals, but don't hold me to that.
Bare

Greetings from Australia.

Can I ask which K&N round filter you're using? I've got a 2009 C5 and it seems I'd need to leave the inner air box cover off to fit the RO-5010 - even then it would be a very tight fit mounted small end down.

Leaving the inner air box cover off doesn't seem a good idea. The stock filter is a Mahle 58100 measuring 119mm OD x 75mm high.

rgds

[barenekd]

I have a K&N filter for a BMW 1200C (97-06) P/N KN-BM-1298. It will fit in a C5, but you might have to squeeze it a bit to get it to clear the intake rubber. Greasing the ends will assure a good seal.

Leaving the inner cover off would totally negate the usefulness of a filter. These filters feed from the inside out. The big hole under the filter is where the air comes in, it goes to the injector through the smaller hole ahead of the filter with the rubber around it.
Bare

[swingarm]

I found the BMW but wondered if it was a bit too high.

Hitchcock's answered a question when I ordered a replacement 581007 to say they're asking K&N to make an equivalent.

On the early EFI's, the inner cover was not fitted. It seems that this was a design error which went undetected for a while, now the later models have this cover fitted and this restricts the size of filter that can be fitted. The RO-5010 will fit at a squeeze, but not ideal. Unfortunately we do not have a suitable filter for the later models but are currently talking to K&N to see if they will produce a batch, but would not expect any results for many months

Worth the wait if they pull it off. Otherwise your suggestion to use the BMW part.

rgds
sw

[barenekd]

My dealer who showed me how to use the K&N had one mounted in a C5 which is why I know you had to squeeze it a bit to clear the intake snorkel. It fit with the cover on.
Bare

[bluesdaddy2]

My dealer who showed me how to use the K&N had one mounted in a C5 which is why I know you had to squeeze it a bit to clear the intake snorkel. It fit with the cover on.
Bare

Just installed one the other day. Things that made it "easier" to squeeze in were:
 - reverse the bolt at the bottom of the box so the remaining threads are on the outside.
 - used a strip of electrical tape to hold the circular backing plate to the lip of the filter.  this held the two together while I finangled the inner cover in place.  Otherwise the filter wanted to drop not allowing proper alignment.

[Arizoni]

As I mentioned before, when I installed my K&N on my G5 I noticed a performance and mileage drop.

I attributed it to the larger tapered body diameter of the new filter blocking off some of the inlet air to the engine.
If someone comes up with a smaller diameter filter that duplicates the OEM filter I will consider buying one.
For now, I'll continue to use the OEM paper filter.

[barenekd]

I use grease to hold the cap while I'm putting mine back in. I did clean mine last week and picked up a couple of MPG for doing it! It had been about 5000 miles since the last cleaning.
Bare