Which air filter?

[huntindog]

Well after seeing my high temps (1236 stock) a couple of weeks ago. I now have the Banks 4" exhaust installed.
Now I'm thinking of the air filter.
I have not been overly impressed with whats availible.
It would seem to me that in order to get good filtration, AND flow that the surface area of the filter should be larger.
The choices as I see it are,,,
K&N drop in
Pros, easily available, cheap, and seems to work.
Cons, some have reported that it doesn't filter well enough on the DMAXs.
AFE drop in
Pros, claims to have deeper pleats than K&N which may result in more surface area.
About 20 bucks more than the K&N
Cons, Have to order sight unseen.
I have heard no reports on it.
AFE filtercharger
Pros, Looks really cool, may have some benefit of sucking outside air.
Cons, Exspensive, have to order it, some say it requires a sock cover, seems to have a small surface area, and reports of louder turbo whine (stage 2) as well as no performance increases.
Amsoil
Pros, some report good perfomance, I think the cost is reasonable (not sure what they actually go for) Some report good filtration
Cons, have to order, foam contruction has drawbacks, hard to cram in the housing, is an oily mess, hard to clean. In my opinion, I don't see how the performance gain is possible with this material as the surface area should be less than the others.

Well those are the choices I'm aware of.
Did I miss any?
Does Banks have their own filter?

[Kennedy]

I'll know more after the weekend on the AFE Stage II, but my immediate observation is much more turbo noise...


I should add that I have run the Amsoil filter for 38,500 miles now and it has been the only filter in my truck for any dyno session or tow etc.

[ 05-24-2003: Message edited by: kennedy ]</p>

[dmaxalliTech]

I have seen/driven trucks with afe, you better like the turbo noise for that. I too have the amsoil filter that I got from JK, works good for me, I was after cleaner air vs more air though

[GMCTRUCK]

If you're gonna keep the stock air box, cut the front of it out for some extra cool air (behind the headlight) and go with the Amsoil. I was very happy with that setup. The Amsoil is an oily foam mess but, it seals good and catches everything. I've had the AFE stage II for a while now and if nothing else it looks cool and sounds awesome from inside and to bystanders outside. With a big load hooked up it sounds just plain wicked. I had 9,000lbs hooked up yesterday and the turbo whistle was awesome. My buddy in the truck in front of me could hear it and another truck behind me and 30ft of trailer could hear it. I wouldn't run it without an Outerwears type filter wrap though. The gauze type filters seem just to thin on their own.

[tophog]

I'm really glad someone asked the "Which air filter" question as I was about too. Sure, I read the reviews for filtration, air flow, etc. however I think this is the first time someone has specifically identified the "turbo" noise associated with the AFE setup.

I ended up ordering the Amsoil setup last week from JK but may end up going the AFE route as I am one who likes the turbo sound. Guess it will boil down to the try both and sell the other scenario.

[RichBailey]

I have been running the AFE stage 2 filter with AFE filter wrap for over 5k miles. One of my concerns was the amount of dirt that the filter potentially passes. On my previous truck (Dodge), the K&N filter passed a lot of dirt and I stopped using it after the first oil change.

I installed the AFE setup after my last oil change and now have 5k miles on it. I just changed my oil again and got my oil analysis results.

Everything was normal. AFE filter is doing a good job of filtering.

The AFE setup looks good, sound of turbo is very minor, but fitup is a problem. I have discussed this with them, but they are not going to make any changes. Specifically, the intake tube is about 1/2-3/4" too long and this causes the filter to be jammed up against the fender wall. I fixed the problem by cutting the tube in the middle, removing 1" and reconnecting with a 4" hump hose connector. Now the unit fits well and engine torque and vibration is not transmitted to the cold air box.

[GMCTRUCK]

Mine is a tight fit also and a pita to get on but, the filter is about 1/2 from touching the fender.

[afp]

I had the K&N Aircharger system and really liked it. I put the stock airbox back on with an Amsoil filter becasue my dealer said I needed to bring the truck in stock for any warranty work. i didn't hide the fact I had aftermarket parts, he just said remove them before I bring the truck in.

Being the lazy type, I refuse to constatntly swap out the K&N for the stock system if I have to take it to the dealer. Then again, the only warranty work I have had done was the ECM flash for slightly lopey idle and the TCM mod for the OD lockout.

I now have a modified factory airbox and an Amsoil filter. I also have a completely stock airbox with a paper filter that I will swap in for warranty work--takes about 2 minutes.

The edge guys have said there was no difference on the dyno between a stock clean paper filter vs no air filter at all. Of course, the dyno isn't the whole story and won't likely show throttle response. The "feel" between my K&N Aircharger system and the modified airbox with the Amsoil is the same. I have not done any side by side testing to verify this, nor will I. One G-tech pass yeilded a 5.9 sec 0-60 time (Juice on level 4) and a 14.49 1/4 mile time with the K&N. One run isn't enough to make an evaluation, and I also didn't keep record of the temp, humidity, and PA for that run.

There has been lots of speculation about the K&N system passing lots of dirt, but so far the several oil analysis results posted have not shown increased amounts of silicone in the oil. Then again, a claim often made with the K&N is that it will pass grit and the grit will not show up in an oil analysis. This would be very bad. I also used the outerwears wrap with my system. My preference would be a K&N or AFE style intake tube with an Amsoil style round filter. However, who knows if that would make any difference.

The biggest problem is I do not know what the airflow requirements of our engine are. It all depends on turbo efficieny, which is something else I don't know. I also do not know what these variuos air intake systems will flow.

Blaine

[LanduytG]

I have said this many times that and air filter alone will not give you hp gains in a turbo charged engine. Throttle respnce will be better as stated above. All that being said I go for the filtration factor myself, in which case I would choose the Amsoil filter. Yes it is a little messy but you won't find a tighter air seal and better filtration in the other brands.

Greg

[mackin]

GMC

When did you switch to an AFE ??

I've reported my findings as you know and I second all of what you reported ....

Luv the turbo whirl and whistle ....

Mac ;)

[mackin]

Greg

Now you know I also run Stage II Amsoil part time,and have a spare ....I also recommend the product .... Matter of fact I just had it in for a week,with stock airbox while working on the AFE inlet tube ...

One thing is for sure YOU WILL get a faster spool up with the AFE ... As I've said any real performance gain in real time numbers is ONLY seat of the pants ...

To stick this out =&gt;"Yes it is a little messy but you won't find a tighter air seal and better filtration in the other brands."

Without solid proof, which I've seen none is like starting another Amsoil Synthetic verses Transynd debate ....

At least say your referring to drop in at best .... Have you tested a AFE drop in ??


Where's the proof cupcake ?? :eek:

Sure isn't in the oil analysis that have been reported here ....

Mac

;)
tongue.gif

[ 05-24-2003: Message edited by: mackin ]</p>

[dmaxalliTech]

The only proof of an air filters effectiveness, other then oil analysis, is MAF reading with the tech-2. The more air your moving, the higher the reading on the MAF. Mine jumped 2-3 gps with the amsoil, not much, but some. One has to remember the stock d-max at idle sucks more air then a Grand Prix and WOT :eek: Of course, the turbo helps alittle ;)

[afp]

How much air does Gran Prix suck?

Blaine

[ 05-24-2003: Message edited by: afp ]</p>

[sdaver]

afe II for a while..........I would never go back :D dave

[dmaxalliTech]

Well, that depends on how the night...........Opps, sorry ;)

The are usually around the 40-45 gps at WOT at idle, most likly more moving at high speeds

Dmax idle is 42-47 stock

[Kennedy]

I'll definitely say that my turbo noise is MUCH louder. Some equate this to power/performance, but the boost levels are similar for load etc. Keep in mind that my turbo front section sounds much different than a stocker at the moment due to the different wheel.

[a64pilot]

If you are wanting to change your air filter to drop your max EGT's, sorry it won't help. If you are stock that is. The reason is that the amount of air that is allowed to flow through the engine at wide open throttle and high load conditions is controlled by the wastegate. At around 22-23 lbs. of boost the wastegate opens. Up until that point less resistance will result in more boost sooner, lower EGT's and an increase in throttle response etc. Once the wastegate opens though you are at the max air flow allowed. If you turn up the boost pressure then you are allowing more air into the engine and should therefore lower EGT's. Be careful that you don't turn it up too much as you will get outside of the turbo's "map". In other words ther is a point where going to a higher boost will result in even higher EGT's and lower power output. I think this is around 30 psi in the Dmax, but I don't have any real proof, just an opinion.

[David Proske]

I am looking at trying a AFE stage 1 with a prefilter. I don't see any benifit in messing with fitting a new intake tube that comes with the stage 2.

Has anyone tried the stage 1 system?

[DieselDixon]

Well I need to stir up this question again. I have a stock truck and wanted to add a aftermarket air filter. My buddy just put a K&N filter on and said he likes it, but it that the best one for a stock truck? I'm kind of looking at the AFE, but I do not want to have to make any major modifications, would like to just replace the filter and put the cover back on.

[MAV]

The new "Hot" filter is the new one from UNI. Fits well and is a well built filter. It is a oiled foam type similar to an Amsoil filter. The filter comes with a can of filter cleaner and a can of oil. What a deal. The Amsoil and UNI can both be had for around $50. Kennedy sells them. I am running a UNI myself.

[ratlover]

I have had both the UNI and the amsoil filter for my duramax.

UNI is a slick filter IMO. Looks like a better quality than the amsoil filter. The mesh that is the backing for the UNI is also much larger than the amsoil mesh.

UNI is the way to go, I kinda like the AFE intake just for the reported turbo noise but if I ever get one I will ditch the gauze filter and get a UNI to go in its place. I personally dont like K&N and the like on a non race application. JMO

I got mine from JK

Might swiss-cheese your box while you have it apart.

[max out]

hello all, first post here. just installed AFE stage 2, TIGHT FIT. does make turbo noise more apparent. but that's about it. I will be doing 4 inch pipe next.

[BigO]

huntindog:

There is a company called Air Raid Performance. It is a local company in Scottsdale. They claim to have an extra layer of cotton to filter the finer dirt. I think you can go to airraid.com.

[Cliffee]

Iam running the Amsoil. Excellent filtration and I didn't notice any increase or decrease in response.

[DieselDixon]

I installed the Uni filter on Friday, went on a trip over the weekend with the trailer and did not notice any difference in performance or temperatures. Unloaded don't notice any differences in turbo noise or anything else either. Oh well...

[KenR]

Why even go with an aftermarket air filter at all? From what I've read on this board over the last couple of years, any performance gains are negligible if any, and there is some debate about the effectiveness of cleaning the air in some products.

It seems to me that in a turbo engine, performance gains happen BEHIND the turbocharger. Increased airflow at the air filter may allow the turbo reach max boost a little quicker under full throttle conditions, but we're talking fractions of a second in response time. So unless you're doing 1/4 mile drag races, what's the point?

Perhaps a better question is: Do any of the aftermarket filters do a BETTER job of cleaning the air than a stock paper filter, while at least maintaining or increasing airflow? I haven't seen the results of a test that proves this, but one may exist.

[More Power]

Here are a few ways that nearly anyone can gauge the flow and dirt capturing performance for any air filter.

1- Perform a number of WOT runs, then check the restriction gauge on the air box. Compare clean air filter to clean air filter to get a fair comparison. In my tests, the OEM AC filter would set the gauge about 1/8". The Amsoil & Uni would not budge the gauge.

2- Monitor the maximum boost pressure during a WOT run, using your choice in air filters. The free-er flowing air filter will allow the engine to produce more boost pressure. In my tests, either Amsoil or Uni allow for as much as 3-4 psi more boost pressure, when compared to the OEM AC.

3- Coat the inside of the turbo duct (somewhere below/behind the MAF sensor) with a tacky oil, then check it periodically to see if any grit is being trapped - post air filter.

MP

[ratlover]

Why?

1. I believe the foam will clean as good in not a hair better than a paper AC

2. It has been shown that it will flow a bit better and produce a bit more boost so it will flow a hair more than a paper AC. 3-4 though? Thats a bit higher than i remember hearing.

3. I know what a AC paper filter costs a whack :eek: and the UNI set me back about 50$ ......it will pay for itself very quickly.

Thats why I went foam. Not very scientific I know.

[a bear]

I was a die hard K&N fan untill I noticed a light film of fine dust coating my intake duct. I cleaned the element with the provided cleaner and soft running water per the instructions and noticed many pinholes after oiling and holding it up to the sun. I've been running the UNI since(about a month) but will have to run a few more miles before I check the filter and air duct. All I can say is it's very well made. Will post my findings after the next servicing.

[Idle_Chatter]

My personal and "unscientific" take on it is based entirely on perception of the design differences. Filter gauze (K&N, AFE, etc.) and pleated paper (OEM, AC, Fram, etc.) rely on a very short filtration "zone" that is one thickness of the paper or gauze. The filter is designed with "holes" of controlled size to pass air (paper has only holes)and an oily trapping medium on the gauze. Anything that can shoot through a hole without hitting paper fibers or the oily edge of the gauze is through to the intake. It's a one-shot deal on all those filters with a very short "window" to do the job. Foam, on the other hand, relies on a very "deep" and convoluted filtering medium. It has thousands of larger passages with oily obstructions all along the way through nearly ONE INCH of filtering medium. This allows larger passages which can pass more air since there is much more filtration opportunity and oily obstruction to turn and trap the contaminants. Foam also offers much better "loading" capability since it offers so much more air passage capability and the larger oily passages do not get blocked as quickly by doing their job as the calibrated "holes" in the thin filtering medium of paper and gauze. No brainer, foam is the only way to go, and both Amsoil and Uni seem to be offering fine choices for high-flowing, highly efficient and long-lasting filters.

[LanduytG]

I have shown in front of many DP members that paper and K&N do not filter as well as foam. As for performance gain I really feel what you get is a lot faster reaction from the turbo because of less restriction. But as for hp gain it would have to be proven to me. My on the TDI forum have done this and say nothing really gained in hp. I would like to get a UNI 6" by 6" to put in the test set. I am sure it filters just fine.

Greg

[maxinDixon]

Just installed the UNI filter based on Kennedy's impressions of its ability to handle dusty conditions when compared to stock paper type elements. Nice filter and time will tell.

[DieselDixon]

I disagree with the statement about added boost. After installing my UNI, I noticed no additional boost (20 max before, 20 max after). Now other then the filter and gauges my truck is stock, so maybe the people with the programmers might see this added boost?

Now in regards to the turbo spooling, there might be a slight increase, however, as stated in an earlier post it is probably none beneficial.

But I am glad to hear the filter will work better then my stock filter for cleaning the air.

[More Power]

I mentioned in an earlier message: "allow for as much as 3-4 psi"

What that statement means is, you may see an increase in boost pressure anywhere from zero to 3-4...

I saw 19 psi boost pressure with an OEM AC paper air filter during a hard pull with our travel-trailer up a 6% grade, and I saw 22 with an Amsoil air filter. Both filters were compared using the same type of full-pedal run. That was a three psi increase. Your results may vary.

Now, if you have some other performance air filter currently installed, you may not see an increase in boost pressure when switching to an Amsoil or Uni Foam...

MP

[ 10-14-2003, 12:50 PM: Message edited by: More Power ]

[KenR]

Idle_Chatter's comments about the depth of filter media providing better cleaning and increased airflow made a lot of sense to me. I went to UniFilter's website and found some more good information and ordered one of their filters today.

This has been a subject I've gone around and around about for two years. There just seems to be so much contradictory information and evangalists for particular brands of filters, I gave up and stuck with OEM until now. After further study, the Amsoil or Uni seemed like the way to go. I went with Uni mainly because I haven't heard of problems with fit.

Thanks for all the good info.

One question: Any opinions about the effects of sub-zero air temperatures on oiled foam filters and their ability to remove dirt?

[Idle_Chatter]

Good question on the effects of temperature, Ken. The oiled foam filters use a heavy and very tacky oil, feels like it may be 90 weight. Although it would undoubtably thicken with low temps, I don't think it will get any less sticky - and that's what counts in a filter. Since the oil is essentially stationary in the foam, clinging to the webs in the matrix, there shouldn't be any real effect on performance.

[DieselDixon]

Well there is one thing that no one really considered about the foam filter. Although it does work well for fine dirt and such matter. It is a proven fact it does not work well for sand. I have ran UNI filters on my ATV for years, however I always run them covered with a super fine cover made by Outerwears. I mention this because one weekend one of my friend forgot to but the Outerwear over the UNI filter and when he took it off there was a pile of sand in the carburetor.

Now in defense of the GM application the air has to go up into the filter, so it is less likely the sand will make it through.

[Kent Tuttle]

DieselDixson...interesting observation on the sand with the Uni filter. I have two Uni filters that I swap with each other after each weekend of use on my ATV and I have never found any sand past the filter. Do you still use the stock air box?

[DieselDixon]

Originally posted by Kent Tuttle:
DieselDixson...interesting observation on the sand with the Uni filter. I have two Uni filters that I swap with each other after each weekend of use on my ATV and I have never found any sand past the filter. Do you still use the stock air box? Well this might be the difference, on one of my ATV's I use the stock air box with the lid removed. On the other one the UNI's are hanging off the back of the carb in the open air. The other thing you need to consider is if you are a leader or a follower.