K&N or aFe

[Kenneth]

I am looking at high performance replacement oem air filters. I have pretty much settled down to k&n or aFe. I just wanted to know what other people are running for the stock air box filters.

With the aFe i can also have the option of the stage II filter or the pro guard 7 filter. Well, these are just ideas, and may not interest any of you, but I just wanted some others' opinions. And if you can convince me I just may go back to a ac delco filter.

[Jochen Woern]

Hi Kenneth, how are you?

I am running a aFe Stage 2 Perfomance Air Intake Kit and am VERY satisfied with it. I have never used a K&N on a Diesel truck, but the aFe is a great upgrade. It certainly does the job, you will immidiately notice improvement in regards to response when you accellerate and you can now hear the turbo whistle. Installation was also very easy.
I got my kit on eBay for 225 bucks and am glad that I installed it.

I personnally would never go back to the stock AC Delco filter. The Upgrade is way better.

Hope this helped.

Good day.

[ccatlett1984]

the AFE filter is a MUCH better filter for your engine, they filter finer particles than the k&n unit. Plus they flow the same if not more.

I have one on my truck and love it.

[Kenneth]

okay, i think I am going to put a aFe filter in my stock box, which filter should I use, the stage 2 filter or the pro guard 7?

BTW, ccatlett1984, how's the rear brakes?

[HH]

Can't speak for the AFE, but I would NOT use the K&N, lets too much dirt past. I switched to the post 97 stock filter.

[Jochen Woern]

As already mentioned below, I got the Stage 2 installed and am very satisfied with it. Can not speak for the Pro Guard since I have never had one.

Why don't you e-mail aFe directly and ask this question, they were very helpful when I contacted them prior to purchasing my stage 2 filter.

[Cowracer]

I would not use a K&N filter. even if it came packed with $100 bills.

Tim

[Kenneth]

I am going to install an aFe, but don't want to buy the intake kit so I am just going to buy the stock replacement filter, which I can in the stage II and pro guard 7 filter. Is the stage II good enough or is $25 more for the pro guard 7 worth it?

[Jochen Woern]

I am not sure, since I bought the kit (which in my opinion is worth every penny). I do not believe that you will get a lot more air through the turbo/motor if you leave the stock box in place. The box is what really restricts the airflow, so in my opinion a new filter alone will most likely not provide the additional performance you are expecting as if you would install the kit, get rid of the airbox and snorkel in order to really let her BREATHE, ........

But, this is only my opinion.

Again, I installed the kit, got rid of the original box and was amazed by the improvement in power.

Good luck.

[DmaxMaverick]

If you are keeping your OEM 1994 airbox, save a load of money and stay with OEM paper filters. The problem with the early airbox is the fit of the filter element to the box, and sealing of the clean side of the filter to the box, not airflow. Spend your time/effort on ensuring the box gets sealed. The filter area is plenty large. You will gain NO additional airflow by changing just the filter. Some elements allow for more turbo noise, but flow no more air. And, you risk using a less efficient filter. If you are serious about trying to gain something via airflow, upgrade the airbox to 1997+ OEM, or install a tried/true aftermarket. AFE makes a good intake system, but I don't support the use of oil/gauze filters, be it K&N or AFE. Oil/foam is better, but just as messy.

[bcbigfoot]

The main thing is make sure the snorckel is out of the fender. The flat filter is at best minimal in size and is rated at only 100cfm (6.5td needs more than that) were the 97+ round filter is rated at 250 cfm, it simply has over 2 times the filter material based on pulling apart two AC Delco filters (a flat and a round one). With even a little dust in the flat filter it starts to hurt your performance. The best all around is find a stock 97+ filter housing and all the parts from a auto wrecker and use a AC Delco filter (K+N is good for keeping out grasshoppers and bird) with the housing attached to the fender like stock, without the snorckel.

[Kenneth]

I have looked around for a 97+ intake setup and can't find one in my area. I found one online but they wante $175. I can get a aFe cold air intake for $225. If you know where I can get a hold of one for less than $100 that would be awesome! Otherwise, I will just wait until I am ready to spend $225 on an aFe cold air. I have heard from others the stock box does okay until you start pumping up your motor, then you need a better intake.

[DmaxMaverick]

The main thing is make sure the snorckel is out of the fender. The flat filter is at best minimal in size and is rated at only 100cfm (6.5td needs more than that) were the 97+ round filter is rated at 250 cfm, it simply has over 2 times the filter material based on pulling apart two AC Delco filters (a flat and a round one). With even a little dust in the flat filter it starts to hurt your performance. The best all around is find a stock 97+ filter housing and all the parts from a auto wrecker and use a AC Delco filter (K+N is good for keeping out grasshoppers and bird) with the housing attached to the fender like stock, without the snorckel.


Please provide some documentation of the 100/250 CFM rating. At 100 CFM, the 6.5, even N/A, won't run under load. Also, show where any of the aftermarket filters have more surface area than OEM paper. It's more than just the area of the filter box. The OEM's, both of them, have deep pleats, where most of the aftermarket filters are more shallow. A N/A 6.2/6.5 will flow 400+ CFM at rated power. This is a VERY old argument.

[chickenhunterbob]

There have been more attempts to "improve" on the stock GM air filter system than any other single aspect of these engines, or so it would seem.

Even though it has been proven time and time again that the best filtering and the coldest air charge comes from the stock AC Delco filter in the stock box, which is also capable of passing far more air than your engine can possibly inhale with whatever possible upgrades it may have, the battle to improve rages on.

The 97+ box is bigger, and therefor would take longer to clog, and should be considered then, as better, but either will give you more air than you need.

Do you have excessive black smoke?

[Kenneth]

I do have a fair amount when given heavy throttle. I have a Heath diesel lift pump, new injectors with about 5k miles on them, and the stock exhaust though too.

[rustyk]

From another site I frequent (from another site the poster frequents) come this data:

FILTER EFFICIENCY

AC Delco OE 99.93%
Baldwin 99.72%
No name filter (made for gas engine, 1/3 less pleats) 99.32%
AFE ProGuard 7 (73-10062), panel filter 99.23%
WIX/Napa 99.03%
Purolator 98.73%
Amsoil, new style 98.63%
UNI 97.93%
K&N 96.80%

I use the Wix/NAPA due to easy availability.

[DA BIG ONE]

I've been mulling for awhile now fitting the largest Douglas filter/canister (bigger better) I can within area under hood then use a snorkel w/intake up at edge of roof. Lots of options to separate sand out of intake this way.

Lots of time spent sandy areas from FLA to AZ and use K&N w/prefilter (fine panty hose pulled over filter) would use K&N pre-filter but they don't make one that size. Factory paper w/panty hose pre-filter is good too. Nope some filters just don't last for the amount of miles claimed so $55. is no big deal when replacement is required.

Seen lots of so-called filter tests, however none under strict lab control where all things can be equal. Marketing? Is it test em until you get the results you want, or?

[DmaxMaverick]

......Seen lots of so-called filter tests, however none under strict lab control where all things can be equal. Marketing? Is it test em until you get the results you want, or?

Jim did one here a few years ago. We may have to dig up the article. It's dated, but was a thorough test.

[Kenneth]

Yeah, I would certainly like to see the results of that test! Dig that up if you can.

[RT]

FWIW, I installed a SS Diesel K&N setup with the pre-filter sock. I noticed that grit was getting past the factory filter in my '93 as the airbox was starting to warp over time. When I swapped over to the SS/K&N setup I had oil analysis done three times prior and post swap by Blackstone. I told Blackstone what I was doing and asked their opinion on the analyses. The silica, etc. in the tests decreased after installing the K&N and has remained below normal levels. This should indicate that the K&N is doing what it is supposed to in my application. I should add that my truck is an on-road vehicle and not used in dusty conditions. There is no grit in the intake tract any more either. I understand that the K&N has bee shown to not filter as well as others. It would seem that in my application it filters well enough. I also oil the bejeezus out of the K&N and the pre filter unit. RT

[More Power]

The subject of air filters is one that draws a lot of attention and one that causes frequent controversey. Let me explain.

The best air filter (from both a performance and filter efficiency standpoint) will be different for someone living in rural Phoenix than it would for someone living in suburban Seattle. Some people see low silicon levels in an engine oil analysis when using a K&N and some see high levels.

I've yet to see a perfect air filter test. Laboratory flow benches used by ASTM can provide data that can be verified by other labs. The problem with lab tests is that they don't use the air intake system you use in your truck - under actual driving conditions. How the dirt particles strike the filter element can make a big difference in how efficient it is at capturing dirt. For example, the air intake systems used in these trucks don't allow dirt particles to impact the element until after having traversed a circuitous path and have made several right-angle turns.

As RT indicated, an oil analysis could be the best way to see how well your air filter is filtering...:)

Jim

[bcbigfoot]

Please provide some documentation of the 100/250 CFM rating. At 100 CFM, the 6.5, even N/A, won't run under load. Also, show where any of the aftermarket filters have more surface area than OEM paper. It's more than just the area of the filter box. The OEM's, both of them, have deep pleats, where most of the aftermarket filters are more shallow. A N/A 6.2/6.5 will flow 400+ CFM at rated power. This is a VERY old argument.

I think you need to re read my post, I didn't say after market filters have more or deeper pleats don't know how you got that from what I wrote. Here is Napa's info and cfm rating on the filter, I have seen similar ratings in other filter manufactures sites as well. http://www.napafilters.com/filterlookup/PartDetail.asp?Part=6441 http://www.napafilters.com/filterlookup/PartDetail.asp?Part=6316

I have done searchs on this site about cfm ratings, filter suface area of the flat and round filters and the filter material of each but never found any good info on the subject, so it maybe a very old argument but it has been one with very little real info by the sounds of it. As I have said the OEM/AC Delco round filter has over twice the filter suface area as the OEM/AC Delco flat filter, I came to this conclusion by cutting them both apart. This is why I changed to a round filter from a local auto wrecker for 30$.

[DA BIG ONE]

The larger the round cylinder filter is the better as it flows/filters more air & would allow much longer periods before cleanup is needed, overkill perhaps but your engine will be happy.

When I figure which douglas canister & filter will fit my burb best I will share that info.

[bcbigfoot]

Industrial and Heavy Duty filters are intended to act as a surface for the dust to sit on, THE DUST ITSELF IS INTENDED TO BE THE FILTER, finner the dust the better it will filter out contaminantes but you need more suface area to avoid pressure drop across the filter. This is one of the reasons why the round filter is much better than the flat filter.

The K+N accomplishes it's initial hi flow rating by having large inconsistant holes in its filter media and not trapping dust laden air thats going through it's filter media(not really doing its job) when it finally does get a proper layer/conditioning of dust, it turns the dust to a matted oily wet goey mess that won't allow any air through. It's ability to carry much dust is very limited and it goes from flowing lots of unfiltered air to plugged very quickly.

[RT]

The K+N accomplishes it's initial hi flow rating by having large inconsistant holes in its filter media and not trapping dust laden air thats going through it's filter media(not really doing its job) when it finally does get a proper layer/conditioning of dust, it turns the dust to a matted oily wet goey mess that won't allow any air through. It's ability to carry much dust is very limited and it goes from flowing lots of unfiltered air to plugged very quickly.

Let me reiterate: When I installed a K&N the silica levels DECREASED. Granted the silica levels were higher than they should be due to the faulty seal on the factory airbox. The silica levels have REMAINED LOW, low enough that they are well within the acceptable range, as indicated with repeated oil analysis. If your statements were true, the oil analysis would show otherwise. In addition I have had no issues whatsoever in the care, cleaning and maintenance of the filter. There is never a "matted oily wet goey mess". If it didn't allow air through then there would be plenty of black smoke from the exhaust and the soot levels on oil analysis would be unacceptable. IIRC, they are also in the low side of the acceptable range. I am curious as to where you got your information from? Reading anti-K&N posts or actual experience? I have tried all types of filters on my diesel vehicles and used to be a K&N hater too. The results of my own testing has proven me wrong. Granted, I live and operate the vehicles in a fairly non-dusty climate/environment. That said, I would take a carefully maintained K&N over a neglected stock setup any day. RT

[bcbigfoot]

RT I used to be pro K+N and as we speak still have 3 of them in use on my vehicles that don't see any off ashpalt driving. The problem started when I started using K+N on my work vehicles that see alot of dust on gravel roads, I began seeing signs of dirt/contamination in the intake so on. Also the filters would plug in no time. I switched back to OEM filters and the contamination in the inlet tube disappeared. Then a few years later I came across this article that did a test on the differnant air filters syles and manufacturers. http://www.duramax-diesel.com/spicer/index.htm


Read it I suspect your opinion of K+N will drop. Also check the fine print at K+N's website, nowhere does it say they filters better than OEM filters just that it flows more, and by more usally only 20% more. What I don't understand is why anyone would put a K+N filter in a flat filter housing like on our trucks that only flows 20% more air when you can put on the round filter with the OEM filter that flows 100+% more air and its clean air.

By the way RT I have owned and operated litterally dozens of pieces of equip that operated in extreme dusty conditions, Dump trucks, wheel loaders and rock crushers, ashphalt dryers with baghouse dust colection equipment. I'm very familiar with the principals of operation and use of filtration equipment.

[HH]

Let me reiterate: When I installed a K&N the silica levels DECREASED. Granted the silica levels were higher than they should be due to the faulty seal on the factory airbox. The silica levels have REMAINED LOW, low enough that they are well within the acceptable range, as indicated with repeated oil analysis. If your statements were true, the oil analysis would show otherwise. In addition I have had no issues whatsoever in the care, cleaning and maintenance of the filter. There is never a "matted oily wet goey mess". If it didn't allow air through then there would be plenty of black smoke from the exhaust and the soot levels on oil analysis would be unacceptable. IIRC, they are also in the low side of the acceptable range. I am curious as to where you got your information from? Reading anti-K&N posts or actual experience? I have tried all types of filters on my diesel vehicles and used to be a K&N hater too. The results of my own testing has proven me wrong. Granted, I live and operate the vehicles in a fairly non-dusty climate/environment. That said, I would take a carefully maintained K&N over a neglected stock setup any day. RT


I had the opposite. My silica level was low initially, but after about 1 year of time on the K&N, which was oiled regularly, the silica level was high soon after installing my new engine. When I replaced it with a stock paper filter, the levels came back to normal. I then switched to the 97+ filter style I am currently running, it will have 2 years on it in January, about 20k miles. I run in a variety of conditions. I would not go back to a K&N, except maybe a race vehicle.

[enforcer233]

DMax;

If I read you last post correctly you are saying that you do not have to replace the OEM box, just the filter to get more air in?

I have a 97 and was thinking about replacing the entire intake including the OEM box.

It seems that those who have replied like the aFe filter best.

Thanks

[DmaxMaverick]

I was referring to replacement filters that fit in the pre-97 OEM box, at first. Other strategies got mixed in later.

I have an AFE Stage II in my '01 and like the intake very well. I'm not sure which filter came with it, but it was oil/gauze so it stayed in the box. I have an Amsoil dry/cleanable cone (EaA) in now. I had to order it from Greg (www.lubricationspecialist.com) to get the size I wanted, and cut out the sheet metal baffles in the fender to fit it into the AFE box location. It's quite a bit longer than the AFE that came in the kit. (PM/email me if you want more info. I'm done with this argument)

The '95 has the OEM box and filter. I take the time to fit the filter to the box for a good seal, and have not had issues with dirt passing. It gets plenty of air, but the engine, etc. is stock. It's a welding/utility truck, so optimum filtration is most important.

[RT]

RT I used to be pro K+N and as we speak still have 3 of them in use on my vehicles that don't see any off ashpalt driving. The problem started when I started using K+N on my work vehicles that see alot of dust on gravel roads, I began seeing signs of dirt/contamination in the intake so on. Also the filters would plug in no time. I switched back to OEM filters and the contamination in the inlet tube disappeared. Then a few years later I came across this article that did a test on the differnant air filters syles and manufacturers. http://www.duramax-diesel.com/spicer/index.htm


Read it I suspect your opinion of K+N will drop. Also check the fine print at K+N's website, nowhere does it say they filters better than OEM filters just that it flows more, and by more usally only 20% more. What I don't understand is why anyone would put a K+N filter in a flat filter housing like on our trucks that only flows 20% more air when you can put on the round filter with the OEM filter that flows 100+% more air and its clean air.

By the way RT I have owned and operated litterally dozens of pieces of equip that operated in extreme dusty conditions, Dump trucks, wheel loaders and rock crushers, ashphalt dryers with baghouse dust colection equipment. I'm very familiar with the principals of operation and use of filtration equipment.

I'm in construction as well and quite familiar with the conditions that you are alluding too. That said, in MY particular application the K&N appears just fine. None of the problems as stated. There are applications where a K&N is perfectly acceptable and there are plenty where they have no place. It isn't a black and white arguement and anyone considering a K&N, or any other filter, should know the issues. RT

[RT]

I had the opposite. My silica level was low initially, but after about 1 year of time on the K&N, which was oiled regularly, the silica level was high soon after installing my new engine. When I replaced it with a stock paper filter, the levels came back to normal. I then switched to the 97+ filter style I am currently running, it will have 2 years on it in January, about 20k miles. I run in a variety of conditions. I would not go back to a K&N, except maybe a race vehicle.

My truck is due for an analysis at the next change so I would like to see what happens. I have no problem "eating crow" and will post the results when I get them. RT

[rustyk]

Here's some DuraMax filter test results posted on another forum:

FILTER EFFICIENCY

AC Delco OE 99.93%
Baldwin 99.72%
No name filter (made for gas engine, 1/3 less pleats) 99.32%
AFE ProGuard 7 (73-10062), panel filter 99.23%
WIX/Napa 99.03%
Purolator 98.73%
Amsoil, new style 98.63%
UNI 97.93%
K&N 96.80%


For the price, I stick with the Wix/NAPA (for oil filters, too), as I used to be a lube engineer, and was party to tests of filter paper produced by various manufacturers. Not all of those listed above even existed back then, but Wix always topped the list.