Wet air filter

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

Quote:

Some early CRDs have the identical 3.7 air box inlet (above the light). All newer CRDs have a larger cross-section inlet to account for the larger air demand (guessing).

Reasonable guess, I thought the same until I measured my old 3.7 snorkel input area (1.5x5.5 + another .75 square inch in the half moon corners) = 8.25 + .75 = 9 square inches. I measured the round intake on my CRD and its diameter is 3.25 inches. Using area =( Pi * R^2), I come up with Pi * 1.625^2 or (3.14 * 2.640625) = 8.29 square inches for the CRD intake area from the connector which attaches to the front of the grill area.

So I installed the bottom air box from my 3.7 Liberty on the CRD, using the top cover from the CRD. Fits perfectly. Runs very well. The only difference now is on the V6 libby there is a plastic water dam in front of the air snorkel, which I'll order tomorrow for the CRD. I compared the bottom section of both the V6 and CRD air box and except for one having a snorkel input and the other having a circular hole, they are identical, right down to the mounting studs on the bottom which plug into the rubber grommets in the fender. The air snorkel fits perfectly under the hood and the CRD runs very well. The throttle response is excellent.

The air filter was still in my old V6 liberty airbox and is the identical part number, flow rate and other specifications as the CRD filter. The flow rate and other data stamped right on the CRD/V6 filters are:

Dust capacity - 130 G(rams)
Max air flow - 8.85 cubic meters per minute
Efficiency - 98%
Pressure loss @ Max flow - 0.035 bar

so using 0.035 (14.5) = 0.5075 PSI or less than one half a psi loss by factory oem spec.

Since the snorkel on the V6 airbox was widely touted by DC on launch of the 02 Liberty as being there to prevent water from entering the intake and to enable water fording, I'll check next time I drive through rain on the CRD to see if any water is in the bottom. Should be interesting.

Now for the obvious question - why is the CRD using an airbox with an opening with nearly the same intake capacity as the V6 engine? And turbocharged at that...

oldnavy · **Posted:** Sun Jul 16, 2006 4:00 pm

The intake diameter is only 3 1/4 inches? I would have guessed it at 4 inches and that would have made a big difference. I think I will check the CRD when the wife gets back from grocery store and just measure the opening to be sure. I have had the tube out a couple of time to put the screen over the end a reinstall, and it just seem bigger then 3 1/4 inches.

On my CRD it has a flap like thing in front of the intake so as to maybe deflect incoming water or such, but it looks to be rather poor design compared to V6 gas intake. It looks a lot like the intake on my old MB diesels and to some degree our '02 VW Jetta TDI. Let us known how the V6 replacemt works out.

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

Yea, Oldnavy, I was surprised too. That circular intake tube on the CRD looks bigger than 3.25 inches. I have read that a diesel turbocharged engine will on average take the same air intake as twice the displacement naturally aspirated engine. If that is true, then our little 2.8L engine sucks air like a 5.7 Hemi gasser. What size air filter does the Hemi Ram have? If anyone has one, can you find the air flow data on the filter? On the Jeep, its stamped right on the edge of the filter itself.

RFCRD · **Posted:** Sun Jul 16, 2006 5:37 pm

Ranger1 wrote:

Yea, Oldnavy, I was surprised too. That circular intake tube on the CRD looks bigger than 3.25 inches. I have read that a diesel turbocharged engine will on average take the same air intake as twice the displacement naturally aspirated engine. If that is true, then our little 2.8L engine sucks air like a 5.7 Hemi gasser. What size air filter does the Hemi Ram have? If anyone has one, can you find the air flow data on the filter? On the Jeep, its stamped right on the edge of the filter itself.

The Jeep rep told me the 2.8 CRD pulls double the air volume of the 3.7 gasser. Only speculation but maybe when the CRD was enlarged to 2.8L (10% increase) engineers felt it needed a bigger intake??? It's odd because it seems like the hole in the airbox is the tight spot. DC is really anal about reusing common parts, this just doesn't fit their pattern to have 2 different induction tubes. I can see using the same small airbox, where would you put a bigger one? This is even a smaller filter than my 3.4L Impala.

oldnavy · **Posted:** Sun Jul 16, 2006 5:49 pm

RFCRD wrote:

Ranger1 wrote:

Yea, Oldnavy, I was surprised too. That circular intake tube on the CRD looks bigger than 3.25 inches. I have read that a diesel turbocharged engine will on average take the same air intake as twice the displacement naturally aspirated engine. If that is true, then our little 2.8L engine sucks air like a 5.7 Hemi gasser. What size air filter does the Hemi Ram have? If anyone has one, can you find the air flow data on the filter? On the Jeep, its stamped right on the edge of the filter itself.

The Jeep rep told me the 2.8 CRD pulls double the air volume of the 3.7 gasser. Only speculation but maybe when the CRD was enlarged to 2.8L (10% increase) engineers felt it needed a bigger intake??? It's odd because it seems like the hole in the airbox is the tight spot. DC is really anal about reusing common parts, this just doesn't fit their pattern to have 2 different induction tubes. I can see using the same small airbox, where would you put a bigger one? This is even a smaller filter than my 3.4L Impala.

Heck it is smaller then a 1.9L VW diesel by 30% to 50% makes a guy wonder don't it.

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

Quote:

The Jeep rep told me the 2.8 CRD pulls double the air volume of the 3.7 gasser. Only speculation but maybe when the CRD was enlarged to 2.8L (10% increase) engineers felt it needed a bigger intake???

But it appears the CRD intake tube is about the same as the intake snorkel on the 3.7 gasser. If the CRD takes double the air flow of the V6, then you have to wonder what's going on in there with the exact same air filter, rated at the same air flow specs I listed earlier. If the intake area is large enough on either airbox to meet the maximum flow rate on the air filter, is the air filter the limiting factor? I'm guessing if the turbo pulls more air than the the air filter was designed to handle, the pressure drop across the air filter is climbing under high load conditions.

A more practical approach might be to visit a junkyard with a Hemi equipped Ram truck and buy the airbox, duct tape it into the CRD and see if life gets better. Then send a photo of it to Ask Dr. Z so they will actually have some answers to use. :-)

Reminds me of a good chuckle I had when visiting the forum that begins with an E. Someone posted a question to Ask Dr. Z that asked what was going to happen to CRD owners now that the CRD was dropped, as far as announcements from DC is concerned, for parts availability and why DC didn't let buyers know it would be dropped after 06. The response was a commercial for buying a Grand Cherokee CRD! Somebody at DC has a sense of humor :-)

/> Seinfeld translation on - with Poppy answering the Ask Dr. Z hotline:

What, you donna a lika thisa one? We godda another diesel for you!!!

RFCRD · **Posted:** Sun Jul 16, 2006 6:35 pm

oldnavy wrote:

RFCRD wrote:

Ranger1 wrote:

Yea, Oldnavy, I was surprised too. That circular intake tube on the CRD looks bigger than 3.25 inches. I have read that a diesel turbocharged engine will on average take the same air intake as twice the displacement naturally aspirated engine. If that is true, then our little 2.8L engine sucks air like a 5.7 Hemi gasser. What size air filter does the Hemi Ram have? If anyone has one, can you find the air flow data on the filter? On the Jeep, its stamped right on the edge of the filter itself.

The Jeep rep told me the 2.8 CRD pulls double the air volume of the 3.7 gasser. Only speculation but maybe when the CRD was enlarged to 2.8L (10% increase) engineers felt it needed a bigger intake??? It's odd because it seems like the hole in the airbox is the tight spot. DC is really anal about reusing common parts, this just doesn't fit their pattern to have 2 different induction tubes. I can see using the same small airbox, where would you put a bigger one? This is even a smaller filter than my 3.4L Impala.

Heck it is smaller then a 1.9L VW diesel by 30% to 50% makes a guy wonder don't it.

I cleaned the accumulated tar out of the primary CAC hose again today so I can get a good look if the oiling has finally stopped. I would like to choke the CRD tech that last worked on this. They pointed the hose clamp toward the engine block, had to be a contortionist to get a wrench in there. :evil:

oldnavy · **Posted:** Mon Jul 17, 2006 9:17 am

Well I did some looking and measuring this morning and will try to take pictures tonight or tomorrow if possible. We have company from TX and an estate sale from late sister's home has been underway for the last 4 days and hopfully will be over and done by tomorrow.

Anyway back to the air box my tube is 3 3/4 ID (10.99 sq in) and it goes straight out in front of the radiator brace where it enters a rubber and plastic rain shield box that is hudge compared to one on 3.7L, it is 8" high, 3" front to back of Jeep or as some would say deep, and 4" wide and is curved and and shaped to funnel water away from intake. It looks a lot like the 3.7 intake except it is standing up on its side beside and in front of the radiator. The intake draws it air from right angle or 90* left from the front of the Jeep. All that said I could see where at 70 mph or more you might over come the draining affect of this arrangement, and with my screen over the radiator it may slow down the rain enough to allow for it to drain as intended.

retmil46 · **Posted:** Mon Jul 17, 2006 10:52 am

oldnavy wrote:

Well I did some looking and measuring this morning and will try to take pictures tonight or tomorrow if possible. We have company from TX and an estate sale from late sister's home has been underway for the last 4 days and hopfully will be over and done by tomorrow.

Anyway back to the air box my tube is 3 3/4 ID (10.99 sq in) and it goes straight out in front of the radiator brace where it enters a rubber and plastic rain shield box that is hudge compared to one on 3.7L, it is 8" high, 3" front to back of Jeep or as some would say deep, and 4" wide and is curved and and shaped to funnel water away from intake. It looks a lot like the 3.7 intake except it is standing up on its side beside and in front of the radiator. The intake draws it air from right angle or 90* left from the front of the Jeep. All that said I could see where at 70 mph or more you might over come the draining affect of this arrangement, and with my screen over the radiator it may slow down the rain enough to allow for it to drain as intended.

Hmmm, I'd have to look at mine, but I don't remember any rubber or plastic, just a metal box. Could be they changed things later on, mine was an early (May '05 build).

The real restriction isn't the 3 1/4" hole in the air box. Take a look at where it goes past the headlight. Odd shaped and narrows down to the point I can't even begin to fit my hand thru it. Just a guess, I'd say the headlight opening loses at least 25% of the surface area compared to the air box hole.

RFCRD · **Posted:** Mon Jul 17, 2006 11:57 am

retmil46 wrote:

oldnavy wrote:

Well I did some looking and measuring this morning and will try to take pictures tonight or tomorrow if possible. We have company from TX and an estate sale from late sister's home has been underway for the last 4 days and hopfully will be over and done by tomorrow.

Anyway back to the air box my tube is 3 3/4 ID (10.99 sq in) and it goes straight out in front of the radiator brace where it enters a rubber and plastic rain shield box that is hudge compared to one on 3.7L, it is 8" high, 3" front to back of Jeep or as some would say deep, and 4" wide and is curved and and shaped to funnel water away from intake. It looks a lot like the 3.7 intake except it is standing up on its side beside and in front of the radiator. The intake draws it air from right angle or 90* left from the front of the Jeep. All that said I could see where at 70 mph or more you might over come the draining affect of this arrangement, and with my screen over the radiator it may slow down the rain enough to allow for it to drain as intended.

Hmmm, I'd have to look at mine, but I don't remember any rubber or plastic, just a metal box. Could be they changed things later on, mine was an early (May '05 build).

The real restriction isn't the 3 1/4" hole in the air box. Take a look at where it goes past the headlight. Odd shaped and narrows down to the point I can't even begin to fit my hand thru it. Just a guess, I'd say the headlight opening loses at least 25% of the surface area compared to the air box hole.

Fished what is left of my old tube from the trash, definately 3 1/4" I.D. I tend to agree with retmil46, the tightest spot is the dog-leg in the grill. My theory is it's tight enough at this spot to intensify the vaccume of water in rainy conditions, no different than using a small attachment on the end of a vaccume cleaner hose.

retmil46 · **Posted:** Mon Jul 17, 2006 12:29 pm

Just looked at mine, it is plastic panels, but no rubber flap.

It narrows down in two places - at the 90 degreee dogleg from the grille, and just behind the headlight.

Discovered something else - there's a gap betwen the outside of the headlight and foglight, and the grille. Anything that comes thru those gaps feeds directly into the air intake, straight shot with no dogleg.

DZL_LOU · **Posted:** Mon Jul 17, 2006 1:14 pm

Well, I'm jumping into this topic and violating the rules of reading the last 5 pages on this post! So, excuse me in advance of ignorance. However, would Stan Wrights mod of the air intake box increase make the CRD breath easier less any changes with a magnaflow exhaust?
http://liberty.eurekaboy.com/airboxmod.htm

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

Today was my first daily drive with the older snorkel airbox mod. It definitely breathes easier. Its not a huge difference, but very noticeable. I know it can't be from the opening area into the airbox difference - there wasn't that much. Looks like Retmil's idea of convoluted air path restricting airflow is the best explanation I've seen so far. I'd guess at this point that anything you can do to increase airflow to the airbox would help.

I really wasn't looking to increase airflow - I just wanted to keep the rainwater out. No rain in sight this week. Maybe I'll try the carwash.

oldnavy · **Posted:** Mon Jul 17, 2006 2:50 pm

Just went into the 90* plus garage and remeasured and still got 3 3/4 inch. Unless my tape measure is off big time, why is mine larger???

Ok, I guess I can go measure the thing again to be sure. Back in 30 minutes.

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

What's your build date? Mine is March 1, 05. Definitely 3.25" inside diameter.

oldnavy · **Posted:** Mon Jul 17, 2006 3:28 pm

Ok just back in from removing air box, filter and the short tube and measuring with American made tape measure vs the made in China by political prisoners. It measured 3.25 inches so I tossed the China made piece of crap in the trash. Build date is 7/05

Man the filter has about 6,000 miles on it and may be good for 10,000 miles.

Goglio704 · **Posted:** Mon Jul 17, 2006 10:46 pm

I am having a hard time understanding why they changed the lower half of the air box if the intake has the same cross section. Did they intend a different airbox entirely that would have needed the grill / headlight intake location? Maybe they were going to put in a bigger airbox and backed off the idea? Either that or maybe the CRD intake is cheaper to produce or more applicable to other platforms. The gasser "snorkel" is part of the lower half of the box isn't it? In any case I will be watching for updates.

Goglio704 · **Posted:** Mon Jul 17, 2006 11:00 pm

oldnavy wrote:

Ok just back in from removing air box, filter and the short tube and measuring with American made tape measure vs the made in China by political prisoners. It measured 3.25 inches so I tossed the China made piece of crap in the trash. Build date is 7/05

Man the filter has about 6,000 miles on it and may be good for 10,000 miles.

Don't feel bad about the tape measure, I've actually seen guys cut the end off a damaged tape and then reattach the hook. :shock:

I kid you not. :roll:

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

Quote:

The gasser "snorkel" is part of the lower half of the box isn't it?

Yes.

I don't know the reason for the change. I thought it was to increase airflow for the CRD. Doesn't seem to be the effect, whatever the intention. In some early CRD pictures, you can see different snorkel designs, as is pictured in this link:
http://www.canadiandriver.com/articles/ ... ty_crd.htm

If the change was to shave a few cents, it doesnt seem worth it. For sure it has increased the probability of injesting water and road dirt into the air box. I have cleaned out the CRD airbox and inspected it after a single 20 mile trip, to find some sand and small debris in the bottom. Tonight, I inspected the bottom of the air snorkel airbox and its still clean. It's surprising to me the difference just by raising the intake point a few inches.

Tom_with_a_Dream · **Posted:** Mon Jul 17, 2006 11:34 pm

Ranger -

Canadian Driver gave you a Yellow Card. This link will bring us all to the same place...

Wet air filter

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