Cold air intake mods?

greiswig · **Posted:** Fri Apr 21, 2006 8:39 pm

Hi,

I thought I remembered seeing something about someone modifying their air box for improved cold air flow. I couldn't find it using search, though, nor browsing the fabrications section. Anyone?

oldnavy · **Posted:** Fri Apr 21, 2006 9:38 pm

greiswig wrote:

Hi,

I thought I remembered seeing something about someone modifying their air box for improved cold air flow. I couldn't find it using search, though, nor browsing the fabrications section. Anyone?

It's a turbo diesel with intercooler and would be a waste of time and money.

Stan Wright · **Posted:** Fri Apr 21, 2006 10:54 pm

http://liberty.eurekaboy.com/airboxmod.htm

Pablo · **Joined:** Thu Feb 02, 2006 10:06 pm **Posts:** 1201

"It's a turbo diesel with intercooler and would be a waste of time and money."

I would second that. From what little I understand-- the advantage of a CAI is that you get cooler air into the engine, and that cooler air is more dense-- but that is with a real CAI. Any unscrupulous company can call their aftermarket air kit a "cold air" intake-- even if it only lowers the temperature by a degree or so. To make matters worse, if your stock air pathway is already pulling from the coolest possible source-- the cold air intake gains you nothing. In the case of the Liberty-- it can't get much cooler than up in the front of the vehicle where the stock intake already is. (Older carb vehicles had the intake right on top of the engine-- they could benefit from a cooler air intake much more than any new car could.)

But this is moot with a turbo anyway. A turbo sucks air in and compresses it-- making it far more dense than a CAI could ever do. A side effect of this is that the air is heated when it is compressed (put your hand on an air tank when the compressor is running--its warm, when the air is being let out-- the tank is cold.). This means that whatever puny help the CAI did would get undone during compression anyway. To help with the warmer air, turbos usually have intercoolers to cool the air down a bit after compression-- and the CRD has one.

That is not to say that airflow restrictions do not exist on the intake, and perhaps an aftermarket kit could help. I know my CRD goes through air filters fast-- that turbo diesel likes to suck plenty of air. It would be nice to have some firmer data on if the breathing on the CRD is restricted or not-- and by how much. Until then, I am not going to plunk money down on a snake oil air intake-- especially if it lets more air through by performing less filtration. A reputable company will show some airflow numbers, some dyno numbers and compare their filtration effectiveness with the stock system-- I have not seen that yet-- but am hopefull.

Perhaps the best CAI for a Jeep is a snorkel anyway. Pull in cleaner air in from up high and outside the engine bay, and its more durable than crome bling bling.

Stan Wright · **Posted:** Sat Apr 22, 2006 9:25 am

I agree about the cold air. I did my mod to allow MORE air...if it needs it.

retmil46 · **Posted:** Sat Apr 22, 2006 9:32 am

I've been running with a Filterminder air restriction indicator on mine for the past week. Stock dealer air filter with 1000 miles on it, only air mod is I removed the inlet tube to the grille to cut down on the road dirt and bugs it sucks up.

Indicator has graduations at 8, 11, 15, 18, and 25 inches H20. After a week of driving, including a couple WOT tests, it hasn't even moved.

IMHO, for normal driving and with a clean filter, the stock air system is more than adequate, and it'd be a waste of time putting an aftermarket air intake on this beast. Of course, if you plan on adding a performance chip and really hotrodding it, that may be another story.

I wouldn't rule out a reuseable HIGH EFFICIENCY air filter (not a "high flow" piece of tissue paper like K & N), depending on how fast the stock filter clogs up and how often it requires replacement. I won't know that on mine for a few months yet.

oldnavy · **Posted:** Sat Apr 22, 2006 10:20 am

Just cut a 10" circle form window screen wire and fold over the intake tube then sholve intake tube back into the airbox. It works great and you can leave the tube sucking cool air from front of the radiator like it was designed to without all the trash. Took about 10 minutes & $0.50 worth of material and takes about 5 minutes or less to remove, clean, and reinstall.

Cowcatcher · **Posted:** Sat Apr 22, 2006 11:29 am

Thanks Oldnavy. The picture makes this easier to understand.

tired_old_dave · **Joined:** Wed Feb 22, 2006 3:45 pm **Posts:** 79

Thanks Stan. I was going to ask you how clean your air cleaner and box are. I've got thousands of miles on my thin o'reillys $8 purolator and it looks as clean as new(so is the air box). Your second picture is what Sean the parts manager at Grubb's showed me with his fingers months ago. Your second picture with the fingers is what we saw but he then thought the hood rubber seal seals that top opening and the air intake is really at the bottom very small slot at the grill. This is the reason the air grabs all the road crap. I have seen web sites for the big rig banks? design showing their new improved cold air pulling from holes in the bumper. The seat of the pants by both my better half and myself was response improvement. I might still take a non cotton aem flat filter-no oil needed. My parts were a 3" PVC male adapter and a 3" to 4" rubber coupling also ~ $8 and no cutting needed. Thanks

oldnavy · **Posted:** Sat Apr 22, 2006 1:44 pm

Cowcatcher wrote:

Thanks Oldnavy. The picture makes this easier to understand.

I guess that is why the old saying of a picture is worth a 1000 words in so true. Nice thing is this will leave the OEM CAI intact and provide some extra filtering. Wife just left for a 60 mile run across bug ally, and I am looking forward to see how these screens work. I also did the whole front grill to protect the I/C, radiator and A/C coils, from bugs and other crap.

tired_old_dave · **Joined:** Wed Feb 22, 2006 3:45 pm **Posts:** 79

Appreciate your screens. One of our ford conversion vans had the a/c fins smashed up in a small hail storm and looked into rv radiator grill covers. Do you prefer plastic or metal screening for the front grill? Do you think silver or dark color matters when driving into the sun for hours in dry hot miles and miles of miles and miles here in Texas? Will the front screen make the cooling fans go to high speed sooner in the summer?

scubanw3 · **Posted:** Sat Apr 22, 2006 2:14 pm

CAI’s do have their place but in many cases the $ vs. performance gain isn’t real good. And, in many cases the systems are noisy. This is why we worked to make the stock replacement ProGuard 7 performance filter available. It does flow more air under ½ to full throttle where you need it. The stock Liberty air filter is disproportionately small for this diesel application and the added flow from the ProGuard 7 media definitely helps. At $56, it is a very affordable way to add performance especially when used with a tuning module.

oldnavy · **Posted:** Sat Apr 22, 2006 2:40 pm

tired_old_dave wrote:

Appreciate your screens. One of our ford conversion vans had the a/c fins smashed up in a small hail storm and looked into rv radiator grill covers. Do you prefer plastic or metal screening for the front grill?I'm not sure, I thought the stuff I used was plastic coated wire, but may just been plastic. Do you think silver or dark color matters when driving into the sun for hours in dry hot miles and miles of miles and miles here in Texas?I haven't a clue, I didn't know there was more then one color. I doubt it, but hey use the lighter color if you think it makes a difference. Will the front screen make the cooling fans go to high speed sooner in the summer? Don't know, it isn't summer here yet.

So many questions, for less then a week of use in town. This is still in a test period if you would like to think of it that way, the wife may come back with that screen all tore up for all I know.

I told her to watch the heat gage to make sure it didn't over heat : edited for comment; I bet she never looks at the stupid gage.

greiswig · **Posted:** Sat Apr 22, 2006 8:21 pm

oldnavy wrote:

It's a turbo diesel with intercooler and would be a waste of time and money.[/quote]

Based on my recent positive experience with a ProGuard air filter, I'm not convinced that is true. Yes, the intercooler cools the heated/compressed air charge. Does that mean it wouldn't benefit from having air come into the turbo a few degrees cooler to begin with? I don't see how it wouldn't. Also, the main modification I was interested in was the one that opened up the smallish opening to the air box. No matter how good your filter flows, if the opening to the box it's in is too small, the turbo is working against vacuum. May not be the case here, though, I'll admit.

oldnavy · **Posted:** Sat Apr 22, 2006 8:49 pm

greiswig wrote:

oldnavy wrote:

It's a turbo diesel with intercooler and would be a waste of time and money.

Based on my recent positive experience with a ProGuard air filter, I'm not convinced that is true. Yes, the intercooler cools the heated/compressed air charge. Does that mean it wouldn't benefit from having air come into the turbo a few degrees cooler to begin with? I don't see how it wouldn't. Also, the main modification I was interested in was the one that opened up the smallish opening to the air box. No matter how good your filter flows, if the opening to the box it's in is too small, the turbo is working against vacuum. May not be the case here, though, I'll admit.[/quote]From everything I have seen the OEM airbox is a excellent design, and draws the coolest air you can get by having it's intake in front of the radiator. The down side is lots of trash injested and after talking with local tech who says the 3.7L V6 gets a filter dirty pretty fast also according to him. My guess is Jeep kept cost down by using all the common parts they could between the gasser and diesel. In the picture below is about the cheapest way to probably add 50% to the life of the air filter.

I did decide to do the whole grill and here is that from behind.

Here is the outside from the front.

Wife is currently on the way back home from about 70 miles of one way travel across bug flats.

torqueofthetown · **Posted:** Sun Apr 23, 2006 1:53 am

oldnavy wrote:

It's a turbo diesel with intercooler and would be a waste of time and money.

I would respectfully disagree, the cooler the air is when it hits the turbo, the cooler it is when it hits the cylinder....with all other things being equal. Plenty of the boyz with diesel pick-ups pay big money for quality intake systems that pulls air from outside the engine compartment vs the noisy air filters on a stick.
The only real question is whether the cost is worth the gain for the smaller engines. I suspect some will call it a waste and some won't.

longarm · **Posted:** Sun Apr 23, 2006 2:55 am

oldnavy, thats just regular screen door material right? No problems as of yet?

oldnavy · **Posted:** Sun Apr 23, 2006 9:45 am

torqueofthetown wrote:

oldnavy wrote:

It's a turbo diesel with intercooler and would be a waste of time and money.

I would respectfully disagree, the cooler the air is when it hits the turbo, the cooler it is when it hits the cylinder....with all other things being equal. Plenty of the boyz with diesel pick-ups pay big money for quality intake systems that pulls air from outside the engine compartment vs the noisy air filters on a stick.
The only real question is whether the cost is worth the gain for the smaller engines. I suspect some will call it a waste and some won't.

Well I may be mistaken but I think you need to read what has been said by myself and others an little better, the intake system on a stick is what we were talking about in general and also making a bigger front feed like OEM . The CRD has a system that routes cool air from in front of the vehicle into the air cleaner, and yes it does help some to start with cooler air before it is heated by compression of turbo, cooled some by IC, and then heated again by compression of cylinders before firing.

The gain for making some kind of special bigger cool air intake out in front is not worth the time and trouble for average street/trail use, just the dragstrip or race track. But hey lots of people do all these mods just for show and don't race the vehicle as a rule. Seldom is the thought of the dollar investment vs mpg gain given any serious math to figure out how many thousands of mile before the cost is regained. What could have been better for CRD is a bigger air filter, but they really didn't have room to do so under the hood. Some here might have liked a big box like thing on top of the hood with big air cleaner in it, but most buyers of CRD would not have bought the truck if it had such a thing on the hood.

Longarm, yes it's just window/door screen wire from local farm/harware supply store. I did this same mod on the wife's Jetta and after 3 years it was still working great. I had to buy a whole roll and I have done several VW's at my GTG's and now having done it to the CRD I am about to get the roll used up.

brew1 · **Posted:** Sun Aug 24, 2008 7:30 pm

oldnavy wrote:

Just cut a 10" circle form window screen wire and fold over the intake tube then sholve intake tube back into the airbox. It works great and you can leave the tube sucking cool air from front of the radiator like it was designed to without all the trash. Took about 10 minutes & $0.50 worth of material and takes about 5 minutes or less to remove, clean, and reinstall.

How has that window screen pre-filter been working out for you? I kinda like that idea.

Pablo · **Joined:** Thu Feb 02, 2006 10:06 pm **Posts:** 1201

Old Navy sold his CRD, and this thread is old, so I don't know if he will respond. Last I heard it worked ok for him. Several others have done similar and others still have adopted the 3.7 intake to the CRD to keep excessive water from getting in the intake during rainstorms.

Cold air intake mods?

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