I have been fooling around with a few ides in my head and just have a few questions about filters. K&N has a lot of different shapes and size filters, i was curious if there is any real difference between them in how they perform or does it just have to do with how and where they will fit. here are my ideas:

1. get replacement rectangle filter to fit into stock air box, and then cut just around the edge of the fender side casing so that the connection still seals the filter inside, but it is ultimately exposed.

2. attaching a long oval style filter that will take up maximum room after taking filter box right onto the stock rubber 90.

3. putting another 90 onto the stock and adding a cone or cylinder filter on the end.

with all of these setups i will probably also buy the filter wrap to keep dust out because i have heard that these things let in more dust because they are less restrictive to help let in more air. but if someone could tell me what the difference if there is any, between the filters is then that will help me make my decision. Or if you have a reason as to why one of these ideas will not work that would definitely help to. thanks

Why go K&N?....what a waste of money IMO...

Read this...

http://www.duramax-diesel.com/spicer/index.htm

Actually I have read through that whole thing about a month ago, I understand that the reason for more dust getting in, is because the wholes in between that allow more air, also allow more dust. k&n sells some sort of black cover and i can't remember what it is made from that is supposed to block dust molecule down to .5 microns(i can't remember the exact number) without affecting airflow.

also about that test, I know it basically said that a paper filter will last longer and collect more dust particles than any of the after market filters. What I can't remember, is if it says how much air it lets through. If it does and you know which one performs the best then could you please tell me so i can save myself the time of reading through it again.

A/C Delco had the least amount of airflow restriction.

tell me if i'm wrong, the more inch's of water that passed through the filters at a constant 350 cubic feet per minute airflow, meant that it was less restrictive.

also to anyone using an ac delco, do you still hear the turbo scream

I had a dust cover on my dodge and the cummins made the afe filter look like a tin can when it got in a heavy dust area one time. You will have to clean it more often if you are in dusty areas.

also to anyone using an ac delco, do you still hear the turbo scream

I wouldn't call it a scream. I can hear at at certain rpm's coupled with certain boost levels.

Although if I open the back passenger window when driving between the buildings on the streets downtown, you can hear definitely hear it whistle all the time except at idle.

about hearing the turbo, is it basically that the less restrictive the filter, and having it exposed will allow the sound waves to pass up through the intake tubing. also this thread has gotten a little off topic, i appreciate the help but i am still looking for opinions on my 3 custom intake ideas.

i can't seem to find any benefit in even putting a 90* elbow with a cone filter , over the stock because:

the stock intake gets its air from under the fender, which would technically be cold air where as an open cone filter would get it's air from the hot engine. If you were to put a heat shield around the cone to block off that hot air, then you would still only be getting the same amount of air as the stock filter unless you were to cut a larger fender hole. If I am right so far then there would be no difference between an after market rectangle filter that would fit in the stock air box, and a cone filter, unless the cone, or even cylindrical filter is more efficient.

I have heard from a few people that the paper filters work as good or better than any after market one, but i have only seen one test with results. Now i'm not saying it's a fake, but like anything on the internet, you have no idea where that info really came from, anybody with enough time on their hands can post things like that. I can understand that an after market filter can be worse because it lets in more dust, but what i don't understand is how it can be more restrictive as 'thanrabt' said, "A/C Delco had the least amount of airflow restriction." I dont' really understand what the initial restrictive numbers really mean in that 'url'. Also anyone who puts one on says they get a power increase, i can't see this comming from the tubing they used, because the intake on the turbo never changes, which narrows it down to either the filter being less restrictive, or air being forced in through the intake.

I know I seem to be babelling on to some of you, but I am no mechanic and havne't worked with this stuff on a day to day basis. I am basically just a guy who uses common sense in giving my truck more power without wasteing my money on something that doesn't really work. Nobody seems to have touched on some of the key points that I have been trying to figure out and this post kinda sums up what I know and don't. Thanks

tell me if i'm wrong, the more inch's of water that passed through the filters at a constant 350 cubic feet per minute airflow, meant that it was less restrictive.

You are right - you have it backwards. :) More inches of water means it is more restrictive. Inches of water is a measure of how hard it is to pull air through the filter, so more inches of water = more restriction.

Suck some water one inch up a straw. The amount of effort it takes you is equal to one inch of water. Three inches takes more effort but still not very much. Now try 18 inches - HARD! That is why a restriction of 2 or 3 inches of water for air filters does not really mean much, but a clogged filter with 10-18 inches of restriction takes real power to pull the air through it.

Many filters get low resistance by not filtering as well (bigger holes), or get great filtering but with high resistance (small holes). It is rare to have both, but it can be done by increasing the filter area. This is usually done by adding more folds and pleats. That is what makes the AC Delco the clear winner in that test - it has high airlflow, low restriction AND the best dust filtering. Plus it lasts the longest! That study means I will be using paper Delco filters from now on.

; I dont' really understand what the initial restrictive numbers really mean in that 'url'. Also anyone who puts one on says they get a power increase,
The initial numbers represent the restriction when the filter is new. Clearly some filters are more restrictive than others, even when new. As each gets dirty its resistance to airflow increases (the inches-of-water values increases) until at some point the engine becomes starved for air. The higher the initial restriction the quicker the filter reaches that starvation point. One of the things that SPICER's test showed was how fast the restriction builds up in the various filters as they get dirty. The AC Delco filter had the lowest initial resistance, could hold more dirt before reaching the point where the engine is starved for air, and filtered out more dirt than the other filters. In my book that is the filter trifecta!

Anyone who thinks they feel a power difference from one brand of filter over another is dreaming. All the filters easily allow enough air to get to the engine (even under load) when they are new. Two or three inches of difference in resistance just isn't enough for your engine to notice (remember the straw?). It is when they start to get dirty that the engine can be starved for air. Getting the filter with the lowest resistance when new is important because it takes longer to clog, not because it provides a power boost (it doesn't).

You are right - you can't trust everything you read on the internet, but I think SPICER' filter study is one you can. I sized, tested and evaluated filters and filter efficiency as an environmental engineer for years, and that study seems very well done to me.

I've posted this on DP before and a lot of people don't believe me, but it is much more important to get cool air to your engine than it is to worry about small differences in air-filter efficiency. Unless it is seriously clogged, the effect of filter resistance on power is tiny compared to the effect of air temperature. So never collect air directly from inside the engine compartment. A 15F increase in temperature robs 3% of your power and under-hood temps can be 40F hotter than outside air.

The initial numbers represent the restriction when the filter is new. Clearly some filters are more restrictive than others, even when new. As each gets dirty its resistance to airflow increases (the inches-of-water values increases) until at some point the engine becomes starved for air. The higher the initial restriction the quicker the filter reaches that starvation point. One of the things that SPICER's test showed was how fast the restriction builds up in the various filters as they get dirty. The AC Delco filter had the lowest initial resistance, could hold more dirt before reaching the point where the engine is starved for air, and filtered out more dirt than the other filters. In my book that is the filter trifecta!

Anyone who thinks they feel a power difference from one brand of filter over another is dreaming. All the filters easily allow enough air to get to the engine (even under load) when they are new. It is when they start to get dirty that the engine can be starved for air. Getting the filter with the lowest resistance when new is important because it takes longer to clog, not because it provides a power boost (it doesn't).

You are right - you can't trust everything you read on the internet, but I think SPICER' filter study is one you can. I sized, tested and evaluated filters and filter efficiency as an environmental engineer for years, and that study seems very well done to me.

I've posted this on DP before and a lot of people don't believe me, but it is much more important to get cool air to your engine than it is to worry about small differences in air-filter efficiency. Unless it is seriously clogged, the effect of filter resistance on power is tiny compared to the effect of air temperature. So never collect air directly from inside the engine compartment. A 15F increase in temperature robs 3% of your power and under-hood temps can be 40F hotter than outside air.

Great Post :D . I agree with you totally, everything you say makes sense, and why pay 60-70 dollars for a K&N or AFE filter when you can get a much cheaper AC Declo that does a better job than the expensive filters. Where can you get the AC Delco. I have read that test, and many of your posts about this, but can't seem to find a place to buy the filter.

Thanks, Jacob

Just go to their website and click on a link to find AC retailer on your area. Call them to see if they have it or if they can order it for you to be picked up.

If you can't find a retail locally just go to the dealer....they are actually pretty cheap....

hey chrisk1500, i've pm'd you about your intake.

I would suggest to upgrade to the new style filter and housing, were you get the best of both worlds. The old style flat filter is only rated at 100cfm according to NAPA were the new style is rated at 250cfm and has over twice the filter surface. The new stlye filter is used with 454's and 290hp vortec350's and if you check the K&N site there is only 8hp icrease going from new style stock air cleaner and filter to a K&N custom intake and filter combo for a vortec 350. K&N doesn't show a hp increase on a stock filter versus K&N alone so there is probably no increase or they would be promoting it. I havn't seen the numberws but I would suspect the new style filter has a higher flow than the flat K&N filter.

I think if you really want the ultimate intake setup search for what JKAuto has been putting together over the past couple months. It is pictured here: http://www.dieselplace.com/forum/showthread.php?t=128935&page=3 in post 29 In my opinion that is by far the best way to do it, it may be more expensive, and involve more work but I think it is for sure the best I have seen so far by a long shot (nothing against the guys with the 90 degree elbows). If I wouldn't have spent $150 on the 97 airbox I would deffinately do this.

Just my .02

Jacob

I think if you really want the ultimate intake setup search for what JKAuto has been putting together over the past couple months.

You could do that, or perhaps cheaper to just read instarx post again, and save any work or $$$

Wanna do a simple comparo test to see if your air filter is efficient, or dirty?

Engine at idling at operating temp, pull your dipstick out, put a 36" piece of clear 3/8" vinyl tubing over the dipstick tube, other end in a container of water held much lower than the dipstick - prevents water rushing into the crankcase

Increase rpms to ~2000, note the distance the water rises in the tube with the current filter, then again with the new filter.

MrGoodwrench spec is 4-6"H2O at 2000rpm - you'll see less than half of that, with your lazy-man's ometer.

Try it with the oem filter in the airbox vs the paper cone filter(s)

Try it any way you like, just mark each result for comparison, particularly at time to replace the dirty with the fresh.

It's crude, but roughly emulates a manometer test for the lazy man.

Instructions for a manometer project in FAQ's.

Stupid question here......is 4-6" H2O at 2000rpm good or bad? Forgive me.

Not even stupid, dude - good question.

That's the avg vacuum before the CDR starts regulating, is dependent on the air filter - also normal blow-by

If you see that much at idle, the filter is dirty.

i have another recent thread about excesive blow-by where i did this exact same test, but i was told by heath diesel that this test was to check for "excesive blow-by" and that 1/2"-1" is normal vacuum. i had 1 1/2"(i would check the thread i wrote to find out what i am talking about). this is the first i have heard that it had anything to do with the filter cleanliness. I am a little confused now, am i thinking of the same test or something different.

The test verifies the vacuum at the turbo compressor intake is within specs, so as not to draw raw oil thru the valve cover - the screen helps to prevent that, as the vapors condense and precipitate out.

The vacuum at the inlet is result of the resistance to airflow caused by the intake path, including the ducting and the air filter.

The vacuum is referenced to Barometric pressure against the static volume of the crankcase, with normal blow-by - that vacuum will decrease as blow-by increases.

Remembering that vacuum is nothing, is not a force - it is a measurement of any reduction in Barometric pressure, where Baro is ~15psi at sea level.

1psi = 2"hg = 27"H2O, you can see that 4-6"H20 is not much vacuum\pressure reduction in the crankcase, so it is a good indication of dirty air filter and increasing blowby.

Replace the filter when the level increases, check for excess blowby if it decreases.

Leaks in the ducting result in decreased vacuum levels, also - loose clamps, split duct, loose airbox cover, etc

When the water starts bubbling, or is blown completely out of the container, ya gots real problems.

Sowhaddayathimk?

ok i think i get the gist of it. my air filter is a little more dirty then i'd like plus my air box keeps popping off(the rubber washers that hold it down from the inside are gone cuz the previous owner must have broken them or whatever) the cone between it and where the snorkel USED to be leaving like an 1/8 or 3/16" gap around it. I haven't bothered to clean the filter or fix box because i'm planning on ripping it all out anyways to make the intake.

Here are the pics I said I would get....I still have to fab up a shield to go around the filter this spring...

Hey Chris....is that just a stock AC-delco air filter? Looks kinda simple. I like it man. :)

That K&n Post, is that a freshly oiled unit? I have put those filters in every vehicle I owned, and never had a problem. On my 6.5TD it does nothing but add power and turbo whine. What exactly can it possibly let into the engine even if it is the worst of the air filters? when you buy oil filters there are so many options, 94% 98%multipass, and so on. Is the engine going to really hate a super small micron of a dust piece enter it? If it is even true? You're talking heavy metal compressing air and fuel, what would a tad of dust per stroke do to an enging? Over 1,000,000 miles maybe something, but over 100,000 miles not much.

How bout this, I put in a 403 olds enging with a buddy, and he accidently forgot to take the rag out of the top of the engine when he put the intake back on. The engine chewed it up and spit it out the tailpipe. If that didn't hurt the engine, how could a few microns of dust hurt a 6.5TD?

It is a Fram filter.....my next one will be an AC Delco filter....just a stock replacement for a 97 6.5 TD though...nothing special....

The argument in the air filter study is that the paper filters flow more than enough air for the Duramax to use....if it is good enough for a DMAX..then there is more than enough air coming through a paper filter for my little 6.5....

hey chrisk1500 what did you use to attach the pipe to the filter, also can you hear the turbo whistle with the exposed paper filter

I've got the same fancy filter kit that chrisk1500 has. The filter presses onto the elbow...for me, it was a very tight fit. I had to trim a little foam off the filter and use some grease to get it to slide in. there's no need for additional fasteners.

Like Joispoi said....the filter is a TIGHT fit onto the elbow.....no need for a clamp....I used a little bit of vaseline on the elbow in order to help the filter slide on....

I can hear my turbo spool up at around 1000 RPM.....

i was thinking of maybe using steel tubing like from a vent in a house washroom or kitchen, their outside diameter is 4" like the abs pipeing, but the inside is almost 4" because the walls are so thin, i haven't seen one of these paper filters yet, would you say this is unnecessary airflow for fighting with it to try to make the filter fit on the bigger end.

What exactly can it possibly let into the engine even if it is the worst of the air filters? when you buy oil filters there are so many options, 94% 98%multipass, and so on. Is the engine going to really hate a super small micron of a dust piece enter it? If it is even true? You're talking heavy metal compressing air and fuel, what would a tad of dust per stroke do to an enging? Over 1,000,000 miles maybe something, but over 100,000 miles not much.
It depends on the severity of your driving conditions. If you drive on paved roads in the Pacific Northwest forests it probably doesn't make any difference, but if you drive in a dusty environment it would matter. For example, much dust in the southwest is very fine talcum-like dust that that is very abrasive and it roils into the air in large quantities when disturbed. Arizona Road Dust is actually a commercial product used to test high-efficiency air filters because it is the most challenging dust for filters. Since much of the dust that gets through your filter ends up in your oil, you decide if adding small abrasive particles to your engine oil is an ok thing or not.:)

So, if you are like me and drive on pavement in a green, humid part of the country then you are right - it probably doesn't matter if your filter doesn't remove fine dust particles. But if you do a lot of off-pavement driving in any dusty part of the country, or any kind of driving in the southwest it can make a big difference in the life of your engine.

One cup of dirt/dust is all it takes to destroy an engine, at least when I went to school, I recall an old Army training film on the dangers of having loose connections on the intake system
and if I recall they discussed the efficency of the old oil bath system and IIRC it was almost 100% effective at filtering all dirt in all conditions

I guess the old oil bath system is for an old dinosaur......
now if someone would take the principal behind it and make it work in todays applications,,,,

The K&N sorta fits into that concept - you're s'posed to keep the screen saturated with that can of 'PAM they sell.

'Course, it don't take much for the turbo to suck that oil right outta the screen.

i was thinking of maybe using steel tubing like from a vent in a house washroom or kitchen, their outside diameter is 4" like the abs pipeing, but the inside is almost 4" because the walls are so thin, i haven't seen one of these paper filters yet, would you say this is unnecessary airflow for fighting with it to try to make the filter fit on the bigger end.

I considered using that but I was told it won't handle the PSI and will collapse. I can't remember what the PSI rating of that stuff is, but it's not very high, less than 10 and possibly less than 5.

Dave

ya i think i'll just go wiht the abs anyways, because it all depends on the flange diameter of the filter and the intake of the turbo, if the sizes of the pipeing or tubing inbetween are bigger then it shouldn't make any difference because only a certain amount of air can flow through the filter and turbo. smaller than these flanges and intakes would obviously be restrictive though.