I have had a K&N in just about every vehicle that ive owned for the last 10 years, and have never had an issue. I do in fact have one in my VW diesel and its fine, but I have heard people say that factory paper is the best for a 6.5?

What are some feelings here? Any horror stories?

What about CAI kits VS those through the fender kits?

I am new to the world of diesel trucks and could really use some help.

Thanks,
Rob

I had a K&N on my 89 gasser and after time it started coming apart and turned into just a screen. I dont think I would buy one again, but thats just me. I cleaned it and put that oil stuff on it too, maybe I did something wrong...

I have used K&N for a long time with no issues. You will get a broad range of opinions. I know on the newer trucks over oiling the filter can cause problems with the MAF. I use K&N in my newer truck also and have not had an issue but people have with the Mass Air Flow Sensors

There is a thread here on dieselplace where someone has tested most filters out there and rated them. They have also tested diesel addatives. They were both done by the same guy. I know I posted a question on one of the threads so if you search under my name you should be able to find at least one of them.

My opinion of K&N filters?

a) volumetric testing shows that the AC Delco (round) filters outperformed the K&N in mass airflow ... I like that.
b) lots of reports on here and other forums about higher silicate readings in oil with K&N filters... that's scary to me. 6.5s are dirty enough.
c) Talk with some of the 'experts' and ask what they use, and why. K&N doesn't come up as the #1 choice all that often.

IMHO, anyway, FWIW.

Jim

yeah, I saw that...it said that the stock paper filter flows better than a K&N or amsoil.....I have a hard time believing that....I know in my rabbit diesel ( which couldnt get out of its own way ) I really could feel the difference....

I have always been very sparing with the oil I use when I clean them, that could be why ive never had a problem. I have seen people drench them in that stuff....that I can see causing a problem.

Also my wife has a 06 jeep liberty diesel and we had serious problems with a motor that had 10k miles on it consuming huge amounts of oil. After $250 worth of ( necessary, but not covered under warranty ) testing they told us that when the air filter becomes clogged the engine sucks oil. We switched from the stock paper to a K&N and never had a problem again.

just some food for thought....

interesting...jim im not sure which delco round filters you are talking about.....do you mean a cone shaped filter?

Also my wife has a 06 jeep liberty diesel and we had serious problems with a motor that had 10k miles on it consuming huge amounts of oil. After $250 worth of ( necessary, but not covered under warranty ) testing they told us that when the air filter becomes clogged the engine sucks oil. We switched from the stock paper to a K&N and never had a problem again.

just some food for thought....

Here's some more food for thought... your crankcase ventilation system is supposed to prevent that from happening (on your wife's JEEP). Wonder if underlying issue is still there?

JEEP = Just Empty Every Pocket -- LOL

I have also been told that a 1995 model truck does not have a MAF....is that true?

PS...Deere that is an awesome looking truck....glad to see im not the only one taking a HUGE dually in the mud....

interesting...jim im not sure which delco round filters you are talking about.....do you mean a cone shaped filter?

Nah, the cylindrical ones in the 97+ airbox. The flat-panel ones are crap.

I figure a lot of it depends on which model of airfilter you have... the bigger the stock filter, quite likely the better the airflow and the less difference. In small filters, I bet the rechargeable filters outperform the paper ones.

I do worry about the silicate pass-through, though... you only find that out by oil analysis. Or changing bearings.

Do a search for 'spicer air filter' and you will find what you want....

FWIW - Diesel Power Magazine did a similar test and found the same thing that Spicer did....doesn't take a rocket scientist to figure out what to do....

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

I love google...

I say to the computer "find me this" and POOF, there it is.

I say to my wife "Grab me a beer" and BLAM... I get what I deserve.

I love google...

One of my favorite lines, "Compared to the AC, the K&N “plugged up” nearly 3 times faster, passed 18 times more dirt and captured 37% less dirt. See the data tables for a complete summary of these comparisons" (Spicer, 2004).

Here's a post from the Duramax forum... if you like reading between the lines, this one is interesting.

http://www.dieselplace.com/forum/showpost.php?p=327380&postcount=9

i have been using k&ns for the past 10 yrs and never had a problem.
i have a flat style in my 6.5

i have been using k&ns for the past 10 yrs and never had a problem.
i have a flat style in my 6.5

You have a flat panel filter on a '98? That's definitely a custom thing... why, if I might ask?

(the round ones have much better airflow... the 94/95 guys like me hunt all over the place to get round airboxes so we can switch)

it was in the truck when i got it

maybe i should put a round one in

it was in the truck when i got it

That explains it, but it is still seriously strange... could you post a picture? (I'm curious about this one...)

Looks like I'm getting rid of my K&N and going back to a stock filter.

K&N's don't filter very well. If you are driving in any kind of dusty conditions I'd pass on the K&N. Check out S&B; they are the same style as K&N but with 8 layers of cotton and they tell you exactly how much oil to put on it. They do have stock replacement filters, but I'm not sure if they do for your truck. They are also cost much less than other brands.

Nick

ok....so the AC delco 1618C that spicer references in his report.....is it used in a air box, or a CAI format ?

I do believe that using ouside air has to be better that the hot, underhood air that the 6.5 generates...

so what kind of box or intake do you guys recomend with the AC delco filter?

Stock airbox pulls cold air from behind the front right signal light....what more could you ask for?

The reason some of us 'upgrade' to the 97+ round filter is because of the CFM capability and sealing properties as compared to the junk flat panel filter.

In fact, I have a flat panel K&N filter and airbox downstairs that I pulled out of my 95 when I bought it - I drive dusty roads and I don't trust the K&N as far as I can throw it!

ok....so basically all I have to do is jumo on ebay, and get a stock airbox from a 97 or higher and the ac delco filter...that sounds easy......:rolleyes:

would this one do?

http://cgi.ebay.com/ebaymotors/Duramax-Diesel-Factory-Air-Intake-System_W0QQcmdZViewItemQQcategoryZ38634QQihZ020QQi temZ300187165047QQrdZ1QQsspagenameZWDVW

Not even close....DMAX is different than a 6.5....

K&N's don't filter very well. If you are driving in any kind of dusty conditions I'd pass on the K&N. Check out S&B; they are the same style as K&N but with 8 layers of cotton and they tell you exactly how much oil to put on it. They do have stock replacement filters, but I'm not sure if they do for your truck. They are also cost much less than other brands.

Nick

www.sbfilters.com/truth (http://www.sbfilters.com/truth)

I know this is the filter I prefure. I used to be on the AFE and AEM dry filter bandwagon, then I saw this test. AEM, 6.72 grams of dirt? :eek: AFE 4.70 grams of dirt? OE (AC Delco in our case) 1.31 grams of dirt.

Do you want your engine breathing in Clean air or dirty air?
On top of that, do you want your engine flowing LOTS of dirty air?

If so, get a K&N. Sure you'll have flow, but at the cost of filteration. That's the deal with most "hi-po" air filters, you think it's high performance, it's not, JUST "hi-flow"

I like a company that not only tests products, but publishes it's test results. 0.33 Grams of dirt using the filter oil, and it also increases flow by almost 50%. Since they don't have 6.5 info, no clue the increase in flow, But the worst they have is 23% increase over stock for the new 6.4 powerjoke.

That's my oppinion. They say the best oil filter is your air filter, how's that for food for thought?

dezil,

Why not jump into the deep end and build your own? ChrisK1500 has done a great job, and there are others on the boards too: http://dieselplace.com/forum/showthread.php?t=205996
http://dieselplace.com/forum/showthread.php?t=194100&highlight=airbox

I'm working up the nerve to try it, but I can only imagine the damage my tender hands will take trying to bend the metal ;).

Jon

ok...this has got me interested about reading about the S&B filters. I wonder how hard it would be to buy a S&B filter and fabricate a housing that draws air from the stock location.....

Go on the website, you can custom order one that you give them measurements for (Build your own filter. IIRC) and they will build it to your specifications.

It would be a tad more challenging to build your own, but all you need is some sheet metal, shears, silicone, sheet metal screws and a new elbow. Check out chrisK1500's post about his airbox, has good pics.

4 walls, a bottom, a hole for the ducting and a hole for the cold air to enter...
How "hard" something is, is determined by how hard your willing to work at it. If you can make a box, you should be ok. Just make sure to build your box to fit your filter. ;)

I have been looking for a 97+ airbox on ebay, and havent found anything.....the AC delco filter spicer references in his report is a flat, square filter....not a round filter like I expected....I like the sound of the S&B filter I might go with that....I wonder what the difference between the K&N and the S&B is? I mean they are both layered cotton and oiled....

I guess it all comes down to who do you trust?

S&B's have 8-layers of cotton gauze; more than the K&N. In every test I've seen, the K&N had poor filtration. I have an AFE intake on my '94 with an S&B filter; it pulls air from the stock location. Intakes aren't cheap though, probably close to $300 shipped. Not sure if it would be cheaper to order an intake with a ProGuard7 filter, or just ditch the regular AFE and get an S&B replacement, which was only $36.

Nick

anyone ever try the flat panel fram airhog filter? i found one on clearance real cheap($29). it looks like a K&N, S&B, etc. i believe its a cotton gauze filter. am i risking excess dirt and s$^% in my engine? i know most fram oil filters suck so i'm worried about their air filters.

im my experience with gas hotrods....fram filters are crap...I used the cotton gause K&N's for years with no problems....but thats gas....I have learned here on the board that diesels reqire 7 times more air than gas. I do have a fram filter in my diesel now....and thats only because thats what the previous owner had in it when I bought it a week ago, and I havent decided what to put in it yet.....hell you can have mine if you wanna try it LOL....

Also I know for the VW diesels amsoil filters seem to be the standard. The message board I belong to for them seems to feel that K&N's are the devil....but I have had one for 130,000 miles in my jetta, and it runs just as good as the day I bought it and never had a problem.

I also had a K&N in my 98 yukon with the vortech....it did seem to make a difference.....but it was like $75 for that huge roll of papertowel style filter they use....I sold the truck to my grandfather, and its still his daily driver with no issues...

My opinion of K&N filters?

a) volumetric testing shows that the AC Delco (round) filters outperformed the K&N in mass airflow ... I like that.
b) lots of reports on here and other forums about higher silicate readings in oil with K&N filters... that's scary to me. 6.5s are dirty enough.
c) Talk with some of the 'experts' and ask what they use, and why. K&N doesn't come up as the #1 choice all that often.

IMHO, anyway, FWIW.

Jim


I saw a similiar test but it can be skewed. Also, I posted it up on another forum and a Military friend posted up that if its good for Army tanks etc that run in the extremes of the world with no failures, its good enough for your daily driver, ;)

BTW, I have used K@N for 20 plus years with NO engine or turbo failures. My bro's 97 6.5L has used one for 200K and many years, no problems either.

I think the facts are as follows:

1. Any high flow filter such as k&n, afe, etc. allow more air flow which is good.
2. Any high flow filter such as k&n, afe, etc. allow more dirt to pass through than stock.
3. Some high flow filters block more dirt than others.
4. If you use a high flow filter you need to keep up on oil changes because all that excess dirt goes to your oil.

In short, you need to weigh the pros and cons as to how much dirt protection you want vs air flow. If you want maximum air flow and less dirt protection go w/ K&N. BTW I use K&N not because I necesarily like them but because it was on my truck when I bought it. I am planning on replacing it w/ a cleaner high flow filter when I make my air box.

im my experience with gas hotrods....fram filters are crap...I used the cotton gause K&N's for years with no problems....but thats gas....I have learned here on the board that diesels reqire 7 times more air than gas. I do have a fram filter in my diesel now....and thats only because thats what the previous owner had in it when I bought it a week ago, and I havent decided what to put in it yet.....hell you can have mine if you wanna try it LOL....

Also I know for the VW diesels amsoil filters seem to be the standard. The message board I belong to for them seems to feel that K&N's are the devil....but I have had one for 130,000 miles in my jetta, and it runs just as good as the day I bought it and never had a problem.

I also had a K&N in my 98 yukon with the vortech....it did seem to make a difference.....but it was like $75 for that huge roll of papertowel style filter they use....I sold the truck to my grandfather, and its still his daily driver with no issues...

The 97-98GM 5.0-5.7-6.5-7.4 engines use that big papertowel style filter i'm using a holley powershot filter same as k&n #E1796
I think as long as its in the air box it will stay cleaner then just siting on the fender like some i've seen;)

I think the facts are as follows:

1. Any high flow filter such as k&n, afe, etc. allow more air flow which is good.
2. Any high flow filter such as k&n, afe, etc. allow more dirt to pass through than stock.
3. Some high flow filters block more dirt than others.
4. If you use a high flow filter you need to keep up on oil changes because all that excess dirt goes to your oil.

In short, you need to weigh the pros and cons as to how much dirt protection you want vs air flow. If you want maximum air flow and less dirt protection go w/ K&N.

Well said.

NOT

Not?

WHY not?

I believe the tests. I use the 97 & newer style OEM air boxes and filters. The old flat panels were crap & I don't think much more of the K&N's. I did used to use them though. And I still have an AFE on the 96 burb. because I didn't have a 97 air box for it at the time & I haven't had time to swap it since I came up with another 97 air box.
The title was K&N or not. I'm a not.

The title was K&N or not. I'm a not.

Ahh... now I get it. Sheesh.:banghead:

Hmmm. It seems to me that if the paper filters are much more efficient at removing particulate matter, but they have decreased air flow, could you increase the effective surface area to the point where it would have similar air flow, or to where it wouldn't make a difference? For example, in the Spicer test, the initial air restriction on the OEM filter was 6.23, but the K&N was 4.54. What if you put a paper filter on (a BIG paper filter) that has an initial air restriction of 4.54. Wouldn't that be the best of both worlds, best efficiency, and equivalent initial air restriction? The only question would be if the paper filter was small enough to fit under the hood in a proper cool air intake box, yes?

Seems to me that would solve everyone's dilemma.

Sincerely,

Rob :)

I JUST went out to my local parts place yesterday evening and picked up a Fram CA8037. This is the severe-duty model that fram shows for the 7.4 for high-dust conditions- do not bother with the lighter 8038 which is except for high dust conditions. Check one out - the outward build quality grounded my decision as my stealer is not very convenient and I need instant satisfaction sometimes (ha!)

http://www.power-21.com/honeywellpower21i/Application.aspx?b=F&vt=1


A word of caution put a little Sil-Glide or some sort of lube on the filter to allow the air box lid to shut easier - it is a tight fit.

Anyways, my truck came with a K&N and I do like it but now at the miles I am wary. The snag is when I clean it sometimes it happens that I need my truck. Funny, but then I am forced to wait for it to dry so I can oil it, etc.

I thought my truck would just bog compared to the K&N, but there is no change and I still hear the turbo. I will keep the K&N ready-to-go in a plastic bag in case I need it, but suspect it will be this Fram or the OE (heavy-duty, apparently 2 OE filters fit the airbox). YMMV, I am pleased thus far and expect this monster to clean the air very nicely

Note I have removed my boost fooler so lame boost, but that is a different on-going (P0237) issue

If the paper filters flow more than enough air for the 6.5 why bother with a cotton filter?

Arlen) SPICER wrote,
“Now that I am not doing the tests and my objectivity is not necessary, let me explain my motivation. The reason I started this crusade was that I was seeing people spend a lot of money on aftermarket filters based on the word of a salesperson or based on the misleading, incomplete or outright deceiving information printed on boxes and in sales literature. Gentlemen and Ladies, Marketing and the lure of profit is VERY POWERFUL!


This is the guy who wrote the unbiased independent study on air filters. If you read the test you can see from the start that he was out to get the aftermarket. He tested the filters in a way that made the ones he liked shine and in the worst posible way for a K&N.
He came up with a new study on additives that basically said aside from biodiesel the ony additive worth a darn was this new to the market crap that nobody heard of. The funny thing was all the dang excuses he gave for not testing other more common addatives. He wanted to stick with the most common ones and then the winner turned out to be one Nobody ever heard of. Con Artist. But back to K&N filters they are use and loved the world over. Ever been to any kind of motor sports event and not seen them???

Arlen) SPICER wrote,
“Now that I am not doing the tests and my objectivity is not necessary, let me explain my motivation. The reason I started this crusade was that I was seeing people spend a lot of money on aftermarket filters based on the word of a salesperson or based on the misleading, incomplete or outright deceiving information printed on boxes and in sales literature. Gentlemen and Ladies, Marketing and the lure of profit is VERY POWERFUL!


This is the guy who wrote the unbiased independent study on air filters. If you read the test you can see from the start that he was out to get the aftermarket. He tested the filters in a way that made the ones he liked shine and in the worst posible way for a K&N.
He came up with a new study on additives that basically said aside from biodiesel the ony additive worth a darn was this new to the market crap that nobody heard of. The funny thing was all the dang excuses he gave for not testing other more common addatives. He wanted to stick with the most common ones and then the winner turned out to be one Nobody ever heard of. Con Artist. But back to K&N filters they are use and loved the world over. Ever been to any kind of motor sports event and not seen them???

Stump you always have to take whatever surveys or tests and look at the logic behind them. The fact is if you have something that breaths better it is going to allow more dirt to pass through. It is as simple as that. Physics. If every filter was tested in the same exact way you have to take the data and decide what you want for your truck. I don't care if spicer was trying to make one filter stand out over the other because the test as I read it was equally applied to each filter. I don't know how many times I have read a review or test about something and said why didn't they test it for that or why didn't they test this product. Not everyone is saticefied.

Stump you always have to take whatever surveys or tests and look at the logic behind them. The fact is if you have something that breaths better it is going to allow more dirt to pass through. It is as simple as that. Physics. If every filter was tested in the same exact way you have to take the data and decide what you want for your truck. I don't care if spicer was trying to make one filter stand out over the other because the test as I read it was equally applied to each filter. I don't know how many times I have read a review or test about something and said why didn't they test it for that or why didn't they test this product. Not everyone is saticefied.

He's right, some of the engineer types on my turbo mopar forum said the same thing, the tests are skewed and don't really prove anything.

Just wondering how K&N is so popular despite high prices. Is it just marketing/advertising or because racing people and several users are happy with it?

Just wondering how K&N is so popular despite high prices. Is it just marketing/advertising or because racing people and several users are happy with it?


How do you figure the prices are high? some stock filters cost the same or more and you throw them away.

Just wondering how K&N is so popular despite high prices. Is it just marketing/advertising or because racing people and several users are happy with it?

Yes.

Face it; if you're running in a fairly clean environment, and taking your engine apart all the time, then airflow is a much bigger draw than cleaning power.

For guys who DON'T operate in a clean environment, or DON'T want to take things apart, the opposite applies.

You don't see farmers using K&N in their tractors.
You DO see racers and ricers using K&N in their engines.

Look on the sbpower website to see the rationale... at low airflows, the profile is completely different than at the high airflows associated with a turbo diesel.

If longevity and effective filtration is a concern, then K&N fails the test. You can call the test skewed all you want, the ISO 5011 test is a gold standard... and it shows what it shows; don't try to make that data fit some other argument.

Well stated jifaire.

Nick

If longevity and effective filtration is a concern, then K&N fails the test. You can call the test skewed all you want, the ISO 5011 test is a gold standard... and it shows what it shows; don't try to make that data fit some other argument.


Please show me the data to back up what your saying? I am in the industry and have NEVER heard or seen an engine failing or wearing out prematurely due to a K@N air filter installed. Heresay is just that, I want proof.

Again, if its good enough for the US Army, its good enough for me.

Please show me the data to back up what your saying? I am in the industry and have NEVER heard or seen an engine failing or wearing out prematurely due to a K@N air filter installed. Heresay is just that, I want proof.

Again, if its good enough for the US Army, its good enough for me.

Works for me... I'm just looking at the data tables in the spicer study and on the sbpower website. The K&Ns look much better at lower airflows, in terms of filtration efficiency. At higher airflows, they sort of suck in that category.

Have I got proof (hard data) of an engine that wore out prematurely that I could say was caused exclusively by a K&N air filter? Nope. On the other hand, I doubt you have proof that having a K&N airfilter made an engine last longer, either. Nobody I know DID that test.

I also don't have proof that the US Army uses K&N exclusively, either, although it wouldn't surprise me; when you have people shooting ar your butt, airflow might win out over longevity, if you had to pick one.

What amazes me is that the ACDelco appears to out-flow the K&N at Duramax air volumes. And it filters better. That's 2-for-2 in the airfilter argument, which would appear to signify a win. The third factor is price, and as you say, that's a relative thing, depending on lifetime maintenance.

Personally, I could care less. Lots of people have lots of claims on what they like best. Use what makes you happy; I do.

I don't claim the ISO 5011 test is the be-all an end-all of air filters... but it raises questions that I don't think should be simply ignored because they conflict with a particular view of reality.

Are the K&N the same than the S&B, e.g this one : http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&ih=002&sspagename=STRK%3AMEWA%3AIT&viewitem=&item=120204535865&rd=1

That's a decent price, but don't forget that it's the oil that helps the S&B filter so well. So no matter how good the price, if there's no oil, there's no point.

I think jifaire hit the nail pretty close on the head with what he said...

If you want high flow, oil or deal with the fact that dry media doesn't filter as well.
If you want high filteration, oil or deal with the fact that paper doesn't flow as high (to same size cotton).

Engine builders use K&N cause they are always tearin stuff down, and replacing it after a few races... Even the US army can Re&re a tank engine in a few hours, but we don't have jet turbines sucking in air, only turbos.

Or how about running an old CDR that leaks oil like a sive, it's a self oiling post filter dust trap :D I'm not serious btw.

That's a decent price, but don't forget that it's the oil that helps the S&B filter so well. So no matter how good the price, if there's no oil, there's no point.

I think jifaire hit the nail pretty close on the head with what he said...

If you want high flow, oil or deal with the fact that dry media doesn't filter as well.
If you want high filteration, oil or deal with the fact that paper doesn't flow as high (to same size cotton).

Engine builders use K&N cause they are always tearin stuff down, and replacing it after a few races... Even the US army can Re&re a tank engine in a few hours, but we don't have jet turbines sucking in air, only turbos.

Or how about running an old CDR that leaks oil like a sive, it's a self oiling post filter dust trap :D I'm not serious btw.

Jfaire does make sense also but the Army isn't always tearing stuff down, they don't have time. :o:

This whole thread is a good discussion and personally, I'll keep using them. Never lost an engine yet to a K@N but almost lost a turbo to a APC filter years ago when the end cap came off and got sucked into my turbo.

This whole thread is a good discussion and personally, I'll keep using them. Never lost an engine yet to a K@N but almost lost a turbo to a APC filter years ago when the end cap came off and got sucked into my turbo.

Whoa... great point. There was a pile of SSDiesel cone filters that came apart like that. To my knowledge, Walt warrantied them and any damages caused, but still, that kind of thing scares ya.

Why would anybody put a metal end-cap in a cone filter?

I think that, no matter WHO makes the filter, we need to carefully watch the construction and quality control.

Hmmm. It seems to me that if the paper filters are much more efficient at removing particulate matter, but they have decreased air flow, could you increase the effective surface area to the point where it would have similar air flow, or to where it wouldn't make a difference? For example, in the Spicer test, the initial air restriction on the OEM filter was 6.23, but the K&N was 4.54. What if you put a paper filter on (a BIG paper filter) that has an initial air restriction of 4.54. Wouldn't that be the best of both worlds, best efficiency, and equivalent initial air restriction? The only question would be if the paper filter was small enough to fit under the hood in a proper cool air intake box, yes?

Seems to me that would solve everyone's dilemma.

Sincerely,

Rob :)

I'm surprised no one has responded to my suggestion here, unless you guys like the controversy. :) In other words, if we used a big enough paper filter, then couldn't it equal the flow of a cotton/foam filter? The only question is how big such a filter would need to be, and if that size was practical to put under the hood. Anyone want to do a size calculation?

"Back of the envelope" calculation would imply that if the K&N flows at 4.54, and the paper filter flows at 6.23, that the K&N only has 72% of the restriction, for a flow improvement of 28%. Suppose we increase the effective surface area by 28% for the paper filter? That wouldn't be too hard. Then no one would have to crab about the tradeoffs.

This suggests that if we made a home made cool air intake, and used a larger filter (perhaps an OEM for a dMax? Just guessing) everyone would be happy!

Sincerely,

Rob :)

I remember seeing in a mag awhile back a guy had a 7.3 PS that he desert raced. He had a huge paper filter from a place called BAF (Big Ass Filters).

Nick

ITA, Rob... that's what many of us are trying to do when we hunt down a round (96+) airbox filter to replace our flat-panel (pre-96) filters.

Great point. There's no reason why we can't have the best of both worlds.

I'm surprised no one has responded to my suggestion here, unless you guys like the controversy. :) In other words, if we used a big enough paper filter, then couldn't it equal the flow of a cotton/foam filter? The only question is how big such a filter would need to be, and if that size was practical to put under the hood. Anyone want to do a size calculation?

"Back of the envelope" calculation would imply that if the K&N flows at 4.54, and the paper filter flows at 6.23, that the K&N only has 72% of the restriction, for a flow improvement of 28%. Suppose we increase the effective surface area by 28% for the paper filter? That wouldn't be too hard. Then no one would have to crab about the tradeoffs.

This suggests that if we made a home made cool air intake, and used a larger filter (perhaps an OEM for a dMax? Just guessing) everyone would be happy!

Sincerely,

Rob :)

Why do you think I went to the round filter instead of the flat panel? ;)

FWIW - when you read the sigs of most of the folks on here you will see that not too many of us have fallen victim to the aftermarket claims ;)

While i believe the tests shown here as the facts seem clear and well supported I almost immediately ran out and purchased a AC delco paper filter and replaced my somewhat dirty K&N, Now I might be crazy bit i notice almost instantly a difference in throttle response off idle and in full throttle acceleration and it is to the negative side

I know that when I went from the flat panel filter to the '97+ setup, my seat-of-pants dyno indicated significantly more airflow, and better throttle response and power. I have now recycled the old panel setup. It does seem a little quieter with the turbo muffler, but no big deal.

I suppose you could put an EVEN BIGGER canister filter and build a honking big box to put around it. At some point, you'd get diminishing returns though.

While i believe the tests shown here as the facts seem clear and well supported I almost immediately ran out and purchased a AC delco paper filter and replaced my somewhat dirty K&N, Now I might be crazy bit i notice almost instantly a difference in throttle response off idle and in full throttle acceleration and it is to the negative side


Because a flowbench can never simulate the air flow your engine has under acceleration. ;)

Because a flowbench can never simulate the air flow your engine has under acceleration. ;)

Okay, I'll bite. Why?

Okay, I'll bite. Why?


Do you think anyone has a flowbench or pressure bench as the case may be, to simulate a 6.5 TD at full throttle at max rpm?

Do you think anyone has a flowbench or pressure bench as the case may be, to simulate a 6.5 TD at full throttle at max rpm?

I always torment the gf that my giga high boost pressures made by the truck creates a small vortex that the little dog minx (one of those fluffy chiwawa lookin things) will get sucked into... Then she laughs at me... Although the truck makes the dog nervous, it's too loud.

And just throwing this one out there, but has anyone thought of some panty hose as a cheap pre filter to help a little with dust and dirt?

I gotta change my filter soon, it's turning grey.

I always torment the gf that my giga high boost pressures made by the truck creates a small vortex that the little dog minx (one of those fluffy chiwawa lookin things) will get sucked into... Then she laughs at me... Although the truck makes the dog nervous, it's too loud.

And just throwing this one out there, but has anyone thought of some panty hose as a cheap pre filter to help a little with dust and dirt?

I gotta change my filter soon, it's turning grey.

The only thing you have to wrorry about w/ the nylon is heat. It will melt. I don't know at what temperature however.

The only thing you have to wrorry about w/ the nylon is heat. It will melt. I don't know at what temperature however.

Even if it's in the airbox (Stock or custom) with cool air passing over/through it?

I just bought a K&N a few months ago and am very happy with it. does anybody know the prices on the delcos any better than K&N? will you be able to here turbo better through the delcos like the K&N? or as good as the K&N.

Do you think anyone has a flowbench or pressure bench as the case may be, to simulate a 6.5 TD at full throttle at max rpm?

Uh, are you saying that the flowbench doesn't pull the volumetric airflow that the 6.5 does?

That ain't good... according to the data, as the benches get into higher and higher flow rates, the K&N let more and more crap through.

If the benches can't catch the 6.5 flow rates, that means the K&N would let even MORE crap through on a 6.5! :eek:

Say it ain't so...

Actually, I'm just being a smart-arse. I think the flowbenches probably DO put through the airflow that a 6.5 does. They claim to be able to test at Duramax volumes, and that's a wee bit higher than what we're talking about here.

Mathematically, the approximate airflow for a 6.5 at max HP is about 702 CFM at 3500rpm, just in case we were wondering.

I got a prefilter sock over my K&N.
I've taken it off several times and looked inside.
Clean as a whisle.
When I take the sock off, the outside looks pretty clean too.
I just vacuum off the outside sock once in a while
and I'm good to go.

Mathematically, the approximate airflow for a 6.5 at max HP is about 702 CFM at 3500rpm, just in case we were wondering.

I would say that seems low? math isn't my strong suit, ;)

Ok if that is the case, what about a larger engine at 20 psi etc, there has to be a point where flowbenches can't keep up anymore and become very inaccurate?

I would say that seems low? math isn't my strong suit, ;)

Ok if that is the case, what about a larger engine at 20 psi etc, there has to be a point where flowbenches can't keep up anymore and become very inaccurate?

Probably; I'm not really sure. I just looked at some results from a 7.3 powerstroke and it was theoretically rated to 770 CFM and the bench test was to 940 CFM. They must have bigger flowbenches for bigger applications; I'm sure they don't just start guessing on the big engines.

Imagine an Abrams turbine... those suckers must pull some amazing amounts of air. They can't just put on a small filter, watch it get sucked inside-out, and then say "oops". There must be bigger test equipment than the piddly little stuff you and I have seen at NAPA.

Imagine an Abrams turbine... those suckers must pull some amazing amounts of air. They can't just put on a small filter, watch it get sucked inside-out, and then say "oops". There must be bigger test equipment than the piddly little stuff you and I have seen at NAPA.

Sure they could, then say, my bad, lol! :eek::p:

That one dude with the GM pickup went 1 million miles on his K&N filter and he had the same filter as us so it cant be that bad?

http://www.youtube.com/watch?v=X0_4jByZmSM

I can actually hear my turbo too so maybe it adds a horse or 2? I also pulled of 20+ MPG on a recent road trip so maybe it helps fuel economy?

I got a prefilter sock over my K&N.
I've taken it off several times and looked inside.
Clean as a whisle.
When I take the sock off, the outside looks pretty clean too.
I just vacuum off the outside sock once in a while
and I'm good to go.

What do you use as a prefilter sock?

I use the K&N prefilter sock part # RX-4990DK. It fits my K&N
filter just right.

I like the notion of using a prefilter sock... that just makes sense to me, if there's ANY question about stuff getting through, or about filters clogging up.

Anybody have any idea what that does to airflow? Is there much restriction in a pre-filter sock?

6.5 liters every two revs pushed in at 12 psig and lets say 200F?
PV=nRT, R = 10.7316 ft3 psia °R-1 lb-mol-1
(26.7 psia)(0.11477265 ft3) = n (10.7316 ft3 psia °R-1 lb-mol-1) (660 °R)
n = 0.000432655 lb-mol
at 14.7 psia, 70F V= nRT/P
V = 0.167403398 ft3/rev
@3500 rpm that would be 585.9 cfm

(show off :p:) hope I'm right!

Wow... My head hurts now. And if there isn't a flowbench large enough to flow what a 6.5 flows, how can a company like S&B or AFE or K&N make a claim about how much MORE their product flows then stock?

The new 6.4 powerjoke only needs something like 850 cfm, and that's with it's fancy dual turbo's.

6.5 liters every two revs pushed in at 12 psig and lets say 200F?
PV=nRT, R = 10.7316 ft3 psia °R-1 lb-mol-1
(26.7 psia)(0.11477265 ft3) = n (10.7316 ft3 psia °R-1 lb-mol-1) (660 °R)
n = 0.000432655 lb-mol
at 14.7 psia, 70F V= nRT/P
V = 0.167403398 ft3/rev
@3500 rpm that would be 585.9 cfm

(show off :p:) hope I'm right!


Thats it? wow, I honestly thought it would be over 1000 cfm with boost.

well I installed the K&N today with very little oil at all after I cleaned it. It seems to have made a small improvement in power.

6.5 liters every two revs pushed in at 12 psig and lets say 200F?
PV=nRT, R = 10.7316 ft3 psia °R-1 lb-mol-1
(26.7 psia)(0.11477265 ft3) = n (10.7316 ft3 psia °R-1 lb-mol-1) (660 °R)
n = 0.000432655 lb-mol
at 14.7 psia, 70F V= nRT/P
V = 0.167403398 ft3/rev
@3500 rpm that would be 585.9 cfm

(show off :p:) hope I'm right!



CFM = (CID*RPM*VE)/3456

CID = 396
RPM = 3500 (or 4000 if you have a higher rev limit)
VE = ideally would be 1, but I am going to guess than NA the engine has an 85% VE. This would mean that at 14.7psi it would be 170% or 1.7

CFM = 681.77 CFM @ 3500RPM
CFM = 779.167 CFM @ 4000RPM

Cruising speed ~3lbs boost
CFM = 252.08 @ 2200RPM

Idle
CFM = 68.177

These are just estimates as I am not sure of the exact VE of a 6.5L.



Also, when I removed my head to have it replaced due to a crack the intake valves were all sunken. The truck had a K&N sticker on the airbox and the diesel shop also said that it looked like it had either a dirty or cheap filter on it. My money is on the K&N. It has been proven that they do not filter well. I do not run K&N filters in any of my vehicles. You may gain a couple of HP, but after seeing what it does to the engine is really worth it?

CFM = (CID*RPM*VE)/3456

CID = 396
RPM = 3500 (or 4000 if you have a higher rev limit)
VE = ideally would be 1, but I am going to guess than NA the engine has an 85% VE. This would mean that at 14.7psi it would be 170% or 1.7

CFM = 681.77 CFM @ 3500RPM
CFM = 779.167 CFM @ 4000RPM

Cruising speed ~3lbs boost
CFM = 252.08 @ 2200RPM

Idle
CFM = 68.177

These are just estimates as I am not sure of the exact VE of a 6.5L.



Also, when I removed my head to have it replaced due to a crack the intake valves were all sunken. The truck had a K&N sticker on the airbox and the diesel shop also said that it looked like it had either a dirty or cheap filter on it. My money is on the K&N. It has been proven that they do not filter well. I do not run K&N filters in any of my vehicles. You may gain a couple of HP, but after seeing what it does to the engine is really worth it?


That seems better, :D

I love these stories, please tell me how a bad filter causes valves to sink? I can't wait to hear this one.

I've worked on literally tons of engines and the only ways valves sink is no lead, high egt's, seats not hardened, cheap valves, wrong valve material or just a pure crap design.

My race bike runs a K@N, 2 years at 14,000 rpm and gosh, no valve adjustment, and doesn't burn oil, but how can that be, lol! :eek::cool:

Dirt coming over the valves and eroding them away.

It was the OEM head and it has never been used to tow heavy. I live in middle GA so there also really aren't any hills. How many miles on the race bike? Keep in mind that a diesel has no restriction and a race bike will not always be at WOT so there is a LOT more air being pumped through the diesel.

That seems better, :D

I love these stories, please tell me how a bad filter causes valves to sink? I can't wait to hear this one.

I've worked on literally tons of engines and the only ways valves sink is no lead, high egt's, seats not hardened, cheap valves, wrong valve material or just a pure crap design.

My race bike runs a K@N, 2 years at 14,000 rpm and gosh, no valve adjustment, and doesn't burn oil, but how can that be, lol! :eek::cool:

no K&N for me if they let more air in how is that possable with out leting more dirt in

my 98 I put a napa air filter in 3-weeks it triped the indicater reset it same thing next day to work.S I replaced it with a a/c delco still has not trip the indicater in 4 months. This has happened on other engines to. Most aftermarket air filters dont have as many folds of paper or called pleats, in them as a oem one don't belive me cut some apart see for yourself.

Dirt coming over the valves and eroding them away.

It was the OEM head and it has never been used to tow heavy. I live in middle GA so there also really aren't any hills. How many miles on the race bike? Keep in mind that a diesel has no restriction and a race bike will not always be at WOT so there is a LOT more air being pumped through the diesel.


Dirt coming in doesn't errode them away.

I have 4 valves per cylinder that are smaller and lighter than our hd diesel valves so at 14,000 rpm, compared to 3000 rpm of diesels, and the fact the race bike spends 80% of the time at WOT, for extended periods of time, I guarantee you the forces on the bike are engine far exceed the diesel loads. :cool:

As for miles, not sure, its got 2 full seasons on it at 3 different tracks and it had aprox 20,000 km's on it before it started racing.

20k km is a lot different than 180+k miles. Not to mention that you are not flowing nearly as much air as the 6.5L is.