The (off road) air-flow project thread

BiodieselJeep.com · **Posted:** Fri Mar 16, 2007 9:33 am

Now that the benefits of increased FRESH airflow have been realized by the (off road) EGR killing MAF mod (um, you unhook it), its time to get back to really thinking through getting more air in there because you will learn to love the increased power and fuel efficiency (off road).

So far we've heard
1) substituting air filters (and increasing dirt intake)
2) Modifying/substituting air boxes
3)????

1 is a dead end. Seriously, air filters have been beaten to death. If you want to take the risk, go ahead, this isn't the thread unless you have something truly novel. 2 is the route I'm fiddling with.

My project is now delayed as I mourn my totalled Jetta TDI and sell its earthly remains to diesel-heads (check out TDI forum if you want the thing). I was trying to find a second housing from any car that might fit in there to possibly "T" in. But I bet there are some clever ideas just waiting to grow out of the fertile soil in this forum.

Spring is around the corner, time for OFF-ROAD fun.

chrismc · **Posted:** Fri Mar 16, 2007 10:24 am

I have only one response to this: Where's the freakin' KJ snorkel?!! It should be just about over here...

Jeger · **Posted:** Fri Mar 16, 2007 10:51 am

I would like to see if there was a donaldson filter that would fit in the area we have available.

http://www.donaldson.com/en/engine/air/chart.html

What we really need to figure out is how much airflow our engine is capable of moving, then it would be easier to spec a filter.

Saber · **Joined:** Fri Jul 07, 2006 10:48 pm **Posts:** 160

I have made snorkel's out of PVC, but I think that would be a bit tacky on a new KJ :wink:

The snorkel is the the best bet tho. That or a hood scope , but then you'll have water problems

TDI4BY · **Joined:** Sun Apr 02, 2006 11:56 pm **Posts:** 644

I have been thinking about puling air from the cowl area..

retmil46 · **Posted:** Fri Mar 16, 2007 12:24 pm

What kind of air filter setup does the Austrailian snorkel use, ie cfm air flow, manufacturer, filtration efficiency?

Agree with one point - high flow air filter of same size and configuration equals less filtration and more dirt in engine. A no go.

Basically, to get higher air flow with the same filtration efficiency, you need to effectively increase the surface area of the air filter.

MrMopar64 · **Posted:** Fri Mar 16, 2007 12:38 pm

Jeger wrote:

What we really need to figure out is how much airflow our engine is capable of moving, then it would be easier to spec a filter.

Max air flow capability: 670 kg/hr @ 3800rpm

Air induction system should have a max of 50mbar pressure drop with new element and 90mbar pressure drop with dirty element as measured from 50mm upstream of the compressor.

DarbyWalters · **Posted:** Fri Mar 16, 2007 12:42 pm

MrMopar64 wrote:

Jeger wrote:

What we really need to figure out is how much airflow our engine is capable of moving, then it would be easier to spec a filter.

Max air flow capability: 670 kg/hr @ 3800rpm

Air induction system should have a max of 50mbar pressure drop with new element and 90mbar pressure drop with dirty element as measured from 50mm upstream of the compressor.

What would that equate to in CFM (Cubic Feet per Minute)? Seems to be about 309 CFM...

MrMopar64 · **Posted:** Fri Mar 16, 2007 12:50 pm

It's just a hair under 400cfm.

BiodieselJeep.com · **Posted:** Fri Mar 16, 2007 8:04 pm

MrMopar64 wrote:

It's just a hair under 400cfm.

Hmmm, and where are we now with the stock box/filter? Do I remember the figure of 250cfm on a good day through a clean filter and no rain?

I'll take a guess that the beast would do nicely with 2 stock filters feeding her air...plus a wider intake tube past a "T" where they join.

but there isn't much room in there..

retmil46 · **Posted:** Fri Mar 16, 2007 11:44 pm

BiodieselJeep.com wrote:

MrMopar64 wrote:

It's just a hair under 400cfm.

Hmmm, and where are we now with the stock box/filter? Do I remember the figure of 250cfm on a good day through a clean filter and no rain?

I'll take a guess that the beast would do nicely with 2 stock filters feeding her air...plus a wider intake tube past a "T" where they join.

but there isn't much room in there..

Specs for the Wix filter list 295 cfm. Stock air filter on my '87 MB 3.0 L with fixed turbo and hp/torque of 140/200 is 630 cfm.

We're only at 75% capacity even with a clean dry filter.

"We need a bigger boat".

retmil46 · **Posted:** Sat Mar 17, 2007 12:02 am

Here's the specs off the last OEM filter I had sitting outside in the original air filter housing.

Dust Capacity 1306. Max Air Flow 8.85 M3/MIN.

Efficiency 98% :shock:

Pressure Loss at Max Flow 0.035 bar

Didn't Walt mention on another thread that 98% was actually a pretty lousy filter by today's standards?

If I remember right, long ago on another thread when we were discussing air filters, I did the conversion from M3/MIN to CFM, and it came out to just a hair over 300 cfm, almost dead on what Wix lists for their replacement.

98% efficient and 300 cfm for the OEM filter. An AEM Dryflow doesn't sound bad by comparison.

Just realized something else. If I'm reading this correctly, a pressure loss of 0.035 bar equals 35 mbar pressure drop.

retmil46 · **Posted:** Sat Mar 17, 2007 9:45 am

retmil46 wrote:

Here's the specs off the last OEM filter I had sitting outside in the original air filter housing.

Dust Capacity 1306. Max Air Flow 8.85 M3/MIN.

Efficiency 98% :shock:

Pressure Loss at Max Flow 0.035 bar

Didn't Walt mention on another thread that 98% was actually a pretty lousy filter by today's standards?

If I remember right, long ago on another thread when we were discussing air filters, I did the conversion from M3/MIN to CFM, and it came out to just a hair over 300 cfm, almost dead on what Wix lists for their replacement.

98% efficient and 300 cfm for the OEM filter. An AEM Dryflow doesn't sound bad by comparison.

Just realized something else. If I'm reading this correctly, a pressure loss of 0.035 bar equals 35 mbar pressure drop.

Oops, misread the printing on the filter, dust capacity is 130 grams.

BiodieselJeep.com · **Posted:** Sat Mar 17, 2007 12:42 pm

Not only do we need a bigger boat

, but I also think we might want a bigger hose (um, I think theres pills for that....). If I were to "T"in a second air filter, I am guessing that we'd need a wider hose after the two join or we run the risk of (slightly) working against ourselves by constricting the flow. Obviously, there has to be some constriction right at the first piece of serious hardware (cooler?), but my recollection of the bernoulli equations is making me guess that a wider diameter air duct might be worth the effort.

But perhaps more experienced heads will have thoughts on this?

oldnavy · **Posted:** Sat Mar 17, 2007 1:21 pm

retmil46 wrote:

Here's the specs off the last OEM filter I had sitting outside in the original air filter housing.

Dust Capacity 1306. Max Air Flow 8.85 M3/MIN.

Efficiency 98% :shock:

Pressure Loss at Max Flow 0.035 bar

Didn't Walt mention on another thread that 98% was actually a pretty lousy filter by today's standards?

If I remember right, long ago on another thread when we were discussing air filters, I did the conversion from M3/MIN to CFM, and it came out to just a hair over 300 cfm, almost dead on what Wix lists for their replacement.

98% efficient and 300 cfm for the OEM filter. An AEM Dryflow doesn't sound bad by comparison.

Just realized something else. If I'm reading this correctly, a pressure loss of 0.035 bar equals 35 mbar pressure drop.

That testing was done about 2 years ago and at that time none of the after market filters beat the OEM filter in overall preformance of airflow. OEM was 99.9% effective and Wix was 99.03% effective for overall filtering of dirt, but unless you looked at time it took to reach those points and how long the 350 CFM (standard flow rate established by OEM engineers) rate was able to be maintained you missed the real test. The OEM ran for 60 minutes to reach the dirt loading that took only 24 minutes for a K&N filter. Compared to the OEM, the K&N “plugged up” nearly 3 times faster, passed 18 times more dirt and captured 37% less dirt.

Remember in this test OEM was GM turbodiesel of over 6 liters and was equipped witha 350 CFM filter as were the test filters.

retmil46 · **Posted:** Sat Mar 17, 2007 2:58 pm

Over a year ago, a guy at Advance tried to sell me on a K&N air filter. My reply to him was "When I feel like trashing my engine, I'll come back and buy one".

I actually tried a K&N at one time on the old '87 Subaru I had. After a couple thousand miles, one look inside the carb told the story - you wouldn't believe the junk that filter let thru, and on a little 1.8 L 4 banger gas engine no less. K& N filter went into the trash.

Perhaps because of my experience with K&N, I'm prejudiced against any type of filter that says you need to add oil to it for it to work properly. My gut feeling is that oil belongs in the crankcase, not in your air filter (or CAC hoses either).

The goal is to maintain filter efficiency AND increase air flow. Only realisitic way to do that is to effectively increase surface area of the filter.

To me, that basically means we're going to have to ditch the stock air box, whether V6 or CRD.

Then, an air intake tube such as the AEM setup, to which you can adapt the biggest honking diesel air filter you can fit in the space vacated by the air filter housing. IE, a 3" cold air intake tube and the necessary adapter to clamp on a filter for a Cummins 5.9 L.

BiodieselJeep.com · **Posted:** Sat Mar 17, 2007 5:19 pm

hmm, ok. So I'm looking at truck airfilters, and many of them look about the right size. Then I look and their filter box housings...oh dear. They are giant. I doubt that we could fit any of them in even if we move a lot of the small pipes and the radiator hoses (my original thinking). But I'm not a truck guy, perhaps we need a truck guy who sees TONS of different engines to look at it and go "oh sure, I know one that will fit". But my gut says...no.

I think we have three options:
1) miraculously find an existing airbox that will fit (beers to that guy)
2) Put a second airbox below (or where you can make room).
3) Build a very clever airbox with 2 filters in it.

I'm betting on 2 being easier but thinking about 3 today.

Consider this: our airbox is like a letter "N": the diagonal line is the filter and the in and outs are above and below. But we need a "W": the two center diagonals are filters. If you angle them steeply enough, you should be able to make them fit into the same space. Changing them would be interesting, though.

retmil46 · **Posted:** Sat Mar 17, 2007 6:22 pm

Hmmm, I think we're both looking at two different methods.

What I'm picturing is no air filter housing at all. Basically, a standard cold air setup with the pipe and round conical filter on the end, and the two-sided cold air dam if there's room.

But instead of the standard size conical filter that would come with such a kit, use an adapter or spacer to connect the largest, highest flow conical filter to the smaller diameter pipe, that would fit in the space available, if necessary doing away with the cold air dam to make room for it.

Example - one gent just recently purchased an AEM Brute Force intake kit made for the CRD. I'd take the same kit, and see if I could replace the standard Dryflow filter that comes with it with one of AEM's Workhorse HD Dryflow deep pleat conical diesel filters, using an adapter for the difference in size between the filter and cold air pipe. The stock air filter housing would be relegated to the garage, the two sided cold air dam that came with the kit taking it's place. And if necessary, to fit a filter of sufficient size, even the cold air dam would be left out.

For my preference, given that we can maintain adequate filtration, if it's a choice between 15 degrees of intake temp or an extra 100 cfm of air flow, I'd take the 100 cfm.

BiodieselJeep.com · **Posted:** Sat Mar 17, 2007 10:14 pm

Hmmm, I like that idea. sounds relatively simple to do. Could it be a problem in wet weather?

Also, what is the dirt ratio on that kind of filter?

Goglio704 · **Posted:** Sat Mar 17, 2007 11:28 pm

I would like to see a filter with longer pleats myself. It should be possible to do that and still fit the stock airbox.

The (off road) air-flow project thread

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