cone air filter???

[uncleben]

i need room under the hood to fit a small tank for SVO.
The air box is to large and i would like to gain some room by switching with a cone air K&N filter. Is there any possible problem with this modification. Do you guys got K&N air filter on your car?
thanks

[mk1vdub]

I think as long as you take precautons to sheild the filter so you don't draw in hot air from the engine you should be fine, will give a louder intake noise too

[vwmike]

I don't even think hot air is so much of a concern. In datalogging we found a cone filter under the hood to be just fine. Temps heated up a bit while sitting but cooled right down when you started moving. I don't think you're going to miss the 1/2 hp in the first 20 feet. After the initial cool down under the hood we actually saw intake temps below ambient. I would be more scared of water.

[Dr. Diesel]

i found no considerable difference in power between an open filter, and the factory airbox with a fresh paper filter. The paper filter, however, is far superior in filtering than a k&n or foam.

[fspGTD]

I don't even think hot air is so much of a concern. In datalogging we found a cone filter under the hood to be just fine. Temps heated up a bit while sitting but cooled right down when you started moving. I don't think you're going to miss the 1/2 hp in the first 20 feet.

I disagree with your conclusion, as I have have found hot air to make a big difference performance-wise in my case, even with the vehicle in motion.  Refer to this post for a test of a *big* cone filter in engine compartment vs a free-flow filter that took air from a cool air source.  The cool-air source resulted in a power gain over the big cone, as measured on the G-tech of about 3-7%: http://www.hostboard.com/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=4037&t=291

After the initial cool down under the hood we actually saw intake temps below ambient.

That just doesn't make sense that the air temps could be cooler than ambient anywhere inside the engine compartment (except maybe right next to some A/C lines or something...)  Out of curiosity, do you have all the baffling around your radiator, and how were you acquiring these temperature readings?

I have also done in the past air temperature measurements at various points in the intake tract using a Fluke 80TK thermocouple module, and I have used these to measure the temperature inside the air intake tract at various points.  It was years ago, but I could probably dig those measurements if needbe.

[fspGTD]

i found no considerable difference in power between an open filter, and the factory airbox with a fresh paper filter. The paper filter, however, is far superior in filtering than a k&n or foam.

A while back, with the G-tech, I did a test of factory airbox with element vs without element.  I don't have the results handy, but I do remember finding that at least for my Rabbit 1.6lTD, the element was restrictive (IIRC, removing the element increased power somewhere in the 3-5% area.)  Although I'm surprised that your test results differ, I suppose it depends how much air the test motor is flowing... I was running intercooled, and probably 14psi boost pressure at the time of this test.

Edit: maybe the A1 filter box with element is more restrictive than the A2 filter box?

[web]

Theoretically, the wastegate should make up for any intake restriction. In practice, turbo cars do tend to "wake up" a bit from removing intake restrictions. Easier on the turbo, and that's where the extra power comes from. Especially if you keep the air cold.

I suggest keeping the stock airbox and getting a K&N drop-in filter for it. On most turbo gassers that proves to be the best intake, short of a full custom cold air intake. I see no reason why diesels would be any different. Just a cone in the engine bay looks pretty but performs worse, proven time and time again. Gassers do benefit slightly in throttle response from extremely short intakes, but obviously diesels don't have this intake inertia "problem" so that advantage hardly exists at all.

This "wisdom" applies to turbo cars only. For non turbo the stock airbox will probably suffice even with the paper filterm as long as it's changed on time.

K&N style filters don't filter as good as a paper filter, but not as bad as foam. No problems doing a LOT of miles on them, so I consider it an acceptable tradeoff. Note that some French cars come with foam filters from the factory...yuck! (enclosed in airboxes of course but still...)

Marcel

[andy2]

I cobbled up a fitler box for my overkill 4 inch cone thats used for a duramax setup. And just reciently AFE came out with pre filter , its a neopreme sock that sildes over the filter and its main purpose is to repel water/mud and it keeps alot of large debres from getting to the filter that makes it easier to clean. Yes there is a restriction but its very minimal says the company, anyways its a nice add on for us cone lovers and one other reason to go this route, also even if the cone only improves hp a bit It sure lets anyone in and out of the car know that the diesel's hard at work.Another note to mention is that before I fabed up a filter box and just had the filter sitting there,It was too loud and anoying hearing the engine through the filter espiacally at highway speeds ,so when I made up a half deciently sealed air box it cut the noise in half and now the turbo is the only sound that is heard , So I would also suggest if you have a cone that you make up a box for that reason alone it sure a difference.Just my 2 cents

[fspGTD]

I suggest keeping the stock airbox and getting a K&N drop-in filter for it. On most turbo gassers that proves to be the best intake, short of a full custom cold air intake. I see no reason why diesels would be any different. Just a cone in the engine bay looks pretty but performs worse, proven time and time again. Gassers do benefit slightly in throttle response from extremely short intakes, but obviously diesels don't have this intake inertia "problem" so that advantage hardly exists at all.

This "wisdom" applies to turbo cars only. For non turbo the stock airbox will probably suffice even with the paper filterm as long as it's changed on time.

K&N style filters don't filter as good as a paper filter, but not as bad as foam. No problems doing a LOT of miles on them, so I consider it an acceptable tradeoff. Note that some French cars come with foam filters from the factory...yuck! (enclosed in airboxes of course but still...)

Marcel

I agree with you in general, however for the 1.6lTD application in particular, I wouldn't recommend the K&N panel replacement filter, because that particular panel filter is much thinner than the factory TD paper element.  While VW specs 2 parts numbers for 1.6lD and 1.6lTD respectively with the TD filter being thicker, the K&N replacement filter is only available in a "one size fits all" size, and it's the same thickness as the naturally aspirated diesel filter.  So, comparing factory paper 1.6lTD filter to K&N panel replacement, I found no measurable performance advantage with the K&N.

Also, do you have any evidence that K&N doesn't filter as well as factory paper, or is that just conjecture?  I've heard a lot of conjecture from various folks along those lines, but never any test results or evidence.

[Dr. Diesel]

I found consistantly, that with a k&n (especially cone, and over a longer stretch, the panel) the pipe between filter and turbo was quite gritty, and a paper towel rubbed inside came out really nasty looking. It literally felt sandy! A paper filter prevented this in my car. Between the panel k&n and new paper, there wasn't any difference in power. Between the cone k&n and the panel k&n (cold air) there wasn't any difference in power. So i'm just interpolating that there's no difference between open cone (hot air) and paper factory box (cold air). Maybe it's different A1 to A2.
In any case, I'd pay for the superior filtering with 5 hp if I had to.

[web]

I agree with you in general, however for the 1.6lTD application in particular, I wouldn't recommend the K&N panel replacement filter, because that particular panel filter is much thinner than the factory TD paper element.  While VW specs 2 parts numbers for 1.6lD and 1.6lTD respectively with the TD filter being thicker, the K&N replacement filter is only available in a "one size fits all" size, and it's the same thickness as the naturally aspirated diesel filter.

It is fairly normal for K&N drop-in replacements to be a bit thinner than the paper filter they're replacing, but it could very well be that in this case the K&N is dimensioned for a naturally aspirated diesel and therefore does not help a TD. Which would be a shame as it's generally the best solution...

Also, do you have any evidence that K&N doesn't filter as well as factory paper, or is that just conjecture?  I've heard a lot of conjecture from various folks along those lines, but never any test results or evidence.

Yes, lots of conjecture going around. I also tend to look for scientific evidence, and I found it. I have read an actual test of both flow and particle filtering performance of various filter types. It has been a while though, so unfortunately I cannot tell you where I saw this test or produce a link. I did take mental note of the results and formed my opinion. Unfortunately all I can give you now is just that - my opinion, based on some test results and hands-on experience.

Dr.D : A sandy/gritty feeling intake sounds real bad. You sure the filter you used didn't have a leak or something? Or was cheap imitation? Real K&Ns do filter slightly worse than paper but not nearly THAT bad. I have run one for close to 100 k miles on a gasser and never noticed anything like that. My intake was as clean then, as it was back when I used paper filters. No nasty surprises inside the engine either. (i've had it apart about halfway through this period). Similar results on many other engines. Only ever found slight grittiness where people continued using damaged filters. Might as well have used no filter at all...

Marcel