Wet air filter

retmil46 · **Posted:** Thu Aug 17, 2006 11:39 am

One thing has occurred to me. I quite agree with oldnavy and others, that if a diesel already has an adequate air intake system to begin with, then a cold air intake or high flow air filter won't make a hill of beans difference and is a waste of money.

However, if doing these mods DOES make a noticeable difference, ie changing to a V6 airbox, that seems to make the opposite point - that the air intake system was undersized/restricted to begin with.

RFCRD · **Posted:** Thu Aug 17, 2006 11:55 am

retmil46 wrote:

One thing has occurred to me. I quite agree with oldnavy and others, that if a diesel already has an adequate air intake system to begin with, then a cold air intake or high flow air filter won't make a hill of beans difference and is a waste of money.

However, if doing these mods DOES make a noticeable difference, ie changing to a V6 airbox, that seems to make the opposite point - that the air intake system was undersized/restricted to begin with.

Isn't is funny how the V6 airbox (that was likely discarded for an aftermarket cold air intake) appears to work just fine on the diesel while drawing twice the airflow???

One thing that occurred to me is the real tight spot appears to be the boot between the MAF/airbox lid and the turbo inlet. This is probably the best argument for an aftermarket intake but don't see any room to increase this with the rest of the plumbing packed around.

oldnavy · **Posted:** Thu Aug 17, 2006 12:23 pm

OK since I have been sick for about 2 weeks now and not been doing anything but laying around and thinking about this, why don't one of you VW TDI owners go look at your TDI filter see what flow rate spec's it has then tell us so we have something here to go on. If the VW filter has a lot higher spec for flow rate then we need to see about we go about changing then rate in our Jeeps, and the only to do that is larger air box. I am not sure how we could do that either, being the lack of room under the hood.

retmil46 · **Posted:** Thu Aug 17, 2006 12:54 pm

Main difference seems to be in the air inlet tube and location.

Same size airbox, same filter, but -

Larger surface area/opening.

Shorter travel, looks to be only 6 to 8 inches till it's dumping into the housing.

No restrictions or doglegs, a large radius open and smooth 90 degree bend.

Some ram air/cold air effect from it suction point up under the hood.

Also, the actual opening into the housing, below where the inlet tube snaps onto the housing, looks to be considerably larger that the inlet tube itself.

retmil46 · **Posted:** Sat Aug 19, 2006 12:11 pm

Went to the Wix Filter website, and compared the specs on different air filters, in particular CFM ratings. This may be a little surprising.

1.9 L VW TDI - 210 cfm
2.0 L VW TDI - 320 cfm
2.8L Jeep CRD - 298 cfm
'83 MB 300 series non-turbo 3.0 L diesel - 450 cfm
'83 MB 300 series 3.0 L turbo diesel - 475 cfm
'87 MB 300D 3.0 L turbo diesel - 650 cfm
'04 Dodge Cummins 5.9L diesel - 675 cfm

The '87 MB is the closest as far as HP and torque to the CRD (145 HP, 200 ft/lbs torque) and has an air filter that has over twice the air flow capacity.

Seems like Dodge/Jeep and MB have different philosophies on sizing air filters. Looks like if MB were producing the Cummins pickup, they'd have an air filter capable of over 1200 cfm in it.

Looks as if either MB/VW is oversizing their filters for long life and ease of air flow, or Dodge/Jeep is undersizing theirs and going with just what is "adequate" for normal driving.

Goglio704 · **Posted:** Sat Aug 19, 2006 12:29 pm

Haven't heard this idea discussed before, so here goes. What if the pleat length on the CRD filter could be increased? Would the box accomodate it? The pleats on my company Dodge Cummins are approx. twice the length of what the CRD has. Just a thought.

oldnavy · **Posted:** Sat Aug 19, 2006 12:29 pm

retmil46 wrote:

Went to the Wix Filter website, and compared the specs on different air filters, in particular CFM ratings. This may be a little surprising.

1.9 L VW TDI - 210 cfm
2.0 L VW TDI - 320 cfm
2.8L Jeep CRD - 298 cfm
'83 MB 300 series non-turbo 3.0 L diesel - 450 cfm
'83 MB 300 series 3.0 L turbo diesel - 475 cfm
'87 MB 300D 3.0 L turbo diesel - 650 cfm
'04 Dodge Cummins 5.9L diesel - 675 cfm

The '87 MB is the closest as far as HP and torque to the CRD (145 HP, 200 ft/lbs torque) and has an air filter that has over twice the air flow capacity.

Seems like Dodge/Jeep and MB have different philosophies on sizing air filters. Looks like if MB were producing the Cummins pickup, they'd have an air filter capable of over 1200 cfm in it.

Looks as if either MB/VW is oversizing their filters for long life and ease of air flow, or Dodge/Jeep is undersizing theirs and going with just what is "adequate" for normal driving.

I was a bit supprised that the VW was only 210 CFM, thought it actually would be more then CRD. As far as the filter lasting on the VW TDI's they were easly lasting 20,000 to 30,000 miles, I bet we are needing them at 7,000 to 10,000 miles.

oldnavy · **Posted:** Sat Aug 19, 2006 12:35 pm

Goglio704 wrote:

Haven't heard this idea discussed before, so here goes. What if the pleat length on the CRD filter could be increased? Would the box accomodate it? The pleats on my company Dodge Cummins are approx. twice the length of what the CRD has. Just a thought.

That should be a big help as the only real restriction in CRD setup is the filter as far as air flow goes, if it will drop in the box.

RFCRD · **Posted:** Sat Aug 19, 2006 12:38 pm

retmil46 wrote:

Looks as if either MB/VW is oversizing their filters for long life and ease of air flow, or Dodge/Jeep is undersizing theirs and going with just what is "adequate" for normal driving.

It's unfortunate but the Liberty is space limited. I think I would have designed an airbox for this space with the filter element either tube shaped or crossing on the diagonal to maximize the surface area.

Have a True-flow foam filter installed now. Hopefully get some spare time this week to play with the old paper filters and some water to see just what it takes to move the Filterminder.

Ranger1 · **Joined:** Mon Oct 17, 2005 7:40 pm **Posts:** 1137

Good information. VW specs on the Passat 2.0 TDI is rated at 134hp and 252 ft-lbs torque. Using engine displacement, it would take 2.8/2.0 x 320 or 448 cfm to equal the VW spec on air flow. We be short, man. This literally sucks. The CRD has 50% more weight over the VW, has 50% more displacement and 50% less filtered airflow. I guess It's a Jeep thing.

I was cleaning my IC hoses again today - on checking the one from the turbo, I found a light black coating on the turbo side - pulled it off and there was some light oil inside the metal turbo output housing. Cleaned it all up again and will check it next week. The end on the IC side had a tiny amount of black oil tiger striping on it. Provent hose to the turbo inlet is clean. My hope is that this is remmants of oil in the compressor chamber. If its not, it'll show up again next week.

Was wondering about the deeper pleats after watching a VW video on cleaning a VW intake screen. If you watch him pull the air filter out on this 1.9L jetta, you can see it looks at least 1.5 times as long as the CRD filter and much deeper in pleat depth as well.
http://cincitdi.com/richc/snowscreen.html

On another thread, I'm also wondering if the CRD has its own constriction sensor. Look at the airbox cover, and on the side is a small tube inserted directly into the top of the airbox, with a plug connector on it with 2 wires. Could be a failsafe to kill the engine if the filter clogs. Could be checked by measuring the output of the connector while restricting the intake tube. This sensor isn't even shown in my FSM. Thge only thing shown on the airbox filter in the FSM is the MAF, which states that it's used for EGR flow rate calculations.

RFCRD · **Posted:** Sun Aug 20, 2006 12:54 am

Ranger1 wrote:

I was cleaning my IC hoses again today - on checking the one from the turbo, I found a light black coating on the turbo side - pulled it off and there was some light oil inside the metal turbo output housing. Cleaned it all up again and will check it next week. The end on the IC side had a tiny amount of black oil tiger striping on it. Provent hose to the turbo inlet is clean. My hope is that this is remmants of oil in the compressor chamber. If its not, it'll show up again next week.

On another thread, I'm also wondering if the CRD has its own constriction sensor. Look at the airbox cover, and on the side is a small tube inserted directly into the top of the airbox, with a plug connector on it with 2 wires. Could be a failsafe to kill the engine if the filter clogs. Could be checked by measuring the output of the connector while restricting the intake tube. This sensor isn't even shown in my FSM. Thge only thing shown on the airbox filter in the FSM is the MAF, which states that it's used for EGR flow rate calculations.

You noticed that sensor too. Was thinking the same thing, vac switch for a really bad constriction.

My CAC hose showing exactly the same oil situation and inside of the turbo casting was lightly oiled the last time I checked. Doesn't seem to get past the first turn in the hose. Makes more of a mess than anything else, hose is sweating oil near the clamp. Have a strange feeling this is the best we can expect, keep it somewhat under control but can't cure it completely.

retmil46 · **Posted:** Sun Aug 20, 2006 1:08 am

I think you're onto something with the pleat length. On the TDI filters , the one for the 2.0 is actually smaller as far as surface area (length and width) than for the 1.9, but the height (length of pleats) was at least a 1/2" longer if not more.

Perhaps that's what matters. It's not the surface area of the filter itself, but the surface area of the filter MEDIA.

We know the OEM filter is 8.8 cubic meters/minute, Wix is 298 cfm. My engineering reference book says the conversion factor for cubic meters to cubic feet is 35.31. That gives 310 cfm for the OEM filter. Still sucking less air than the 2.0 TDI, with nearly a liter more displacement.

My '87 MB 3.0 L is rated 145 HP, 200 ft/lbs torque, and it's oval filter is rated for a honking 630 cfm. Guess I won't need to change the filter in THAT beast for a while!

While at the Wix site, I also checked the applications list for the CRD filter. Besides being used with the 3.7 L V6 Liberty, it's used in ALL versions of the Commander as well, even the V8's. Looks like the bean counters have struck again.

I've wondered about that extra sensor on the air filter cover as well. Looking at it, including the part inside the cover, it looks just like a MAP sensor. But it wouldn't make any sense to install a MAP sensor ahead of the turbo. Two possibilities - it is a constriction sensor that isn't listed in the FSM, or is somehow a backup for the MAF in case it fails, again not listed in the FSM.

Zonie · **Posted:** Sun Aug 20, 2006 1:49 am

I just replaced the OEM with a Wix. It's my observation that the Wix had 1. noticibly more pleats and 2. obviously longer pleats. In addition, the flat spot right before the turbo kicks in was dramatically smoothed out. It drove like a different car! The air filter made more of a difference than the straight through muffler.

retmil46 · **Posted:** Sun Aug 20, 2006 10:48 am

Well, I have a correction on which vehicles our air filter is used on.

Besides our CRD, it's used on all KJ 3.7 L V6's, ALL Grand Cherokees, and ALL Commanders, up to and including the 5.7 L Hemi versions.

Like I said, the bean counters have struck again. Nothing like one size fits all to save a few bucks. If this filter setup is "marginal" on our 2.8 L engine, then what in the devil are they doing sticking it in front of a Hemi?

I imagine that would really P.O. the horsepower crowd that buys hemis, to find out "their" mighty engine is breathing thru the same puny air filter as our "little" 2.8 L diesel. :lol:

On the bright side, since the GC's and Commanders are using the same filter, that may give us a few more options than a V6 KJ airbox. Guess it's time to drop by a dealership and see how the air intake is set up on the GC's and Commanders.

retmil46 · **Posted:** Sun Aug 20, 2006 11:04 am

Zonie wrote:

I just replaced the OEM with a Wix. It's my observation that the Wix had 1. noticibly more pleats and 2. obviously longer pleats. In addition, the flat spot right before the turbo kicks in was dramatically smoothed out. It drove like a different car! The air filter made more of a difference than the straight through muffler.

Noticed the same on mine. I put in a NAPA Gold (rebadged Wix, even has the same part number). I didn't check pleat height, but did notice that the NG seemed to have more pleats, with a different appearance and texture (made of different material?).

Like you, I've noticed that the beast is noticeably more responsive. I didn't know which was the main contributor in my case, the V6 air inlet or different filter.

retmil46 · **Posted:** Sun Aug 20, 2006 11:09 am

RFCRD wrote:

Have a True-flow foam filter installed now. Hopefully get some spare time this week to play with the old paper filters and some water to see just what it takes to move the Filterminder.

OK, $64 dollar question (which is about the price of a True-flow if I remember correctly). Is there any noticeable difference, driveability performance or otherwise, with the True-flow foam filter?

oldnavy · **Posted:** Sun Aug 20, 2006 11:27 am

retmil46 wrote:

Well, I have a correction on which vehicles our air filter is used on.

Besides our CRD, it's used on all KJ 3.7 L V6's, ALL Grand Cherokees, and ALL Commanders, up to and including the 5.7 L Hemi versions.

Like I said, the bean counters have struck again. Nothing like one size fits all to save a few bucks. If this filter setup is "marginal" on our 2.8 L engine, then what in the devil are they doing sticking it in front of a Hemi?

I imagine that would really P.O. the horsepower crowd that buys hemis, to find out "their" mighty engine is breathing thru the same puny air filter as our "little" 2.8 L diesel. :lol:

On the bright side, since the GC's and Commanders are using the same filter, that may give us a few more options than a V6 KJ airbox. Guess it's time to drop by a dealership and see how the air intake is set up on the GC's and Commanders.

Hey I was at the dealer awhile back and actually took the CRD & Hemi air filter and did a side by side comparison and the Hemi filter was noticably bigger. I have a 8 am Tues appointment for the CAC change out and PCM recall, so while there I will recheck the filter sizes to be sure that the parts kid didn't make a mistake.

retmil46 · **Posted:** Sun Aug 20, 2006 12:07 pm

Just checked Wix site again. For the Magnum, it's a different filter than listed for the Jeeps.

But for Jeeps, it lists the KJ, GC, and Commander as all using the same filter, for all engines including the Hemi. Only exception is the little 4 banger gas KJ they discontinued.

At the Wix site, if you click the part number, another window opens with the specs on the filter. In this new window, if you click on "all applications", it'll open a third window listing all vehicles that use the filter.

RFCRD · **Posted:** Sun Aug 20, 2006 10:49 pm

retmil46 wrote:

RFCRD wrote:

Have a True-flow foam filter installed now. Hopefully get some spare time this week to play with the old paper filters and some water to see just what it takes to move the Filterminder.

OK, $64 dollar question (which is about the price of a True-flow if I remember correctly). Is there any noticeable difference, driveability performance or otherwise, with the True-flow foam filter?

Actually a $35 question. I know it's a familiar sales pitch but it's supposed to flow more air but also stop more dirt than paper. I don't notice any difference. I was more interested in it because the foam won't absorb, hold moisture, or wet constrict like paper. Outside of that, I would rather have a disposable premium paper filter.

GilaMonster · **Posted:** Tue Aug 22, 2006 11:09 pm

RFCRD wrote:

retmil46 wrote:

RFCRD wrote:

Have a True-flow foam filter installed now. Hopefully get some spare time this week to play with the old paper filters and some water to see just what it takes to move the Filterminder.

OK, $64 dollar question (which is about the price of a True-flow if I remember correctly). Is there any noticeable difference, driveability performance or otherwise, with the True-flow foam filter?

Actually a $35 question. I know it's a familiar sales pitch but it's supposed to flow more air but also stop more dirt than paper. I don't notice any difference. I was more interested in it because the foam won't absorb, hold moisture, or wet constrict like paper. Outside of that, I would rather have a disposable premium paper filter.

I understand the wet constriction benefits of a foam filter, but what makes you think that a foam filter will not absorb or hold water? Water is used to clean the foam filter and will obviously flow through it. Additionally, the directions for the filter specify to make sure it is dry after cleaning before adding the tacifier. So, it will hold water. I used an ITG on another vehicle, and it could definately get wet and flow water through the foam media.
So, I'm just curious where you aquired this information because it is contrary to my experiance with foam filters. I'm not trying to argue, but am hoping that you can point me to some evidence contrary because I sure would like this filter to give me some insurance against this water build up in the airbox. I don't think DC will ever honor a hydro-lock damaged engine because it is too easy for them to claim you just ran through a huge puddle.

I did suggest adding more drain holes and enlarging them, did you try that? I did, and I definately do not see the water level evidence I did before. Possibly dropped the water line from 2.5 inches to about .5 inches after I drove through heavy monsoon downpours.

Wet air filter

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