K&N vs stock
#1
Rennlist Member
Thread Starter
K&N vs stock
Ive been thinking about this for a long time after hearing that K&N filters don't flow as well as stock. So...I rigged up my mercury gauges to a box and tried it out. For those interested (and not likely to beat me up over it), the K&N does flow better as the vacuum signal was much lower. Yes, these are just showing the setup and I had the filters secured with the bottom of the air-box when testing to ensure a good seal.
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#2
Rennlist Member
K & N filters DO flow better, but in the process of flowing better, they also let a larger amount of dust and dirt though into the engine.
Filters should be installed to keep dust and dirt OUT of your engine, not allow more INTO your engine.
Filters should be installed to keep dust and dirt OUT of your engine, not allow more INTO your engine.
#3
Rennlist Member
I remember an old Rennlist thread and the problem with K&N wasn't lack of flow, it was particles getting through. I think there was discussion about the affect of the filter oil on the MAF too.
#4
Rennlist Member
Bugatti Veyrons use the same exact filter as the 928. The stock filter. If the K & N was a superior filter, wouldn't it make sense that Bugatti would be using them?
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#7
Three Wheelin'
yes, the oil is not good for the MAF , can ruin it. Of course no problem with CIS cars.
I just replaced a K&N with a oem. I had the problem that the border sandwiched between the air boxes is not thick enough , so the straps were "loose" .. oem is thicker and fits better.
I just replaced a K&N with a oem. I had the problem that the border sandwiched between the air boxes is not thick enough , so the straps were "loose" .. oem is thicker and fits better.
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#8
Archive Gatekeeper
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Kudos for doing the bench testing, I do appreciate empiricists.
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hacker-pschorr (03-25-2020)
#9
Cool test. The analysis of your results are most likely correct, but are not definitive. You need to have a complete understanding of the flow characteristics (performance) of your source (shop vac). Take a look at the attached curve (upper one); it is the performance curve of a high performance Aerospace fan. Note at 10 CFM, the static pressure (pressure drop) is lower then when it is flowing 20 CFM. Your shop vac may have a similarly shaped curve, so knowing where on it you are operating is important.
#10
Former Vendor
I love your test and how you did it!
That's one bad *** shop vac that can pull vacuum, on the backside, with either one of those filters!
The question "does this filter allow more air to pass" is completely dependent on how much airflow does any particular engine requires.
In other words, 20% more flow "potential" doesn't affect anything if the stock filter is only using 60% of it's flow capability.
A "real life" test would be to run an engine on a dyno, at full song (with your nanometer) and see what results there are.
That's one bad *** shop vac that can pull vacuum, on the backside, with either one of those filters!
The question "does this filter allow more air to pass" is completely dependent on how much airflow does any particular engine requires.
In other words, 20% more flow "potential" doesn't affect anything if the stock filter is only using 60% of it's flow capability.
A "real life" test would be to run an engine on a dyno, at full song (with your nanometer) and see what results there are.
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hacker-pschorr (03-25-2020)
#11
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I did a dyno test 20 years ago with the K&N and stock filter: no statistically significant difference between the two.
IIRC, Louie Ott did dyno tests and lost power with the K&N.
There is basically no good reason to mount a K&N. And nobody ever f#$%ing cleans them anyway.
This horse is glue.
#12
Pro
Just recently the Project Farm YouTube channel did a comparison test video of a number of air filters, including a K&N filter.
His finding was that the Wix and Purolator filters had the highest filtration, but also the most restriction.
His finding was that the Wix and Purolator filters had the highest filtration, but also the most restriction.
#13
Rennlist Member
A long time ago I had a K&N because I drove off road 4x4s and it was supposed to be the best. Then got a 944 Turbo and continued using K&N from it's off-road recommendations. Then got a 928GT so put a K&N on it. After a month I heard the K&N let lots of dust thru. So, opened the filter box and looked under the filter. The bottom (intake side) was coated with a very fine dust. Immediately cleaned it and replaced K&N with a stock filter. Have never had dust under the filter again.
When using K&N on the 951 cleaned and re-oiled it. Was very difficult oil the filter without getting too much oil and fouling the MAF.
When using K&N on the 951 cleaned and re-oiled it. Was very difficult oil the filter without getting too much oil and fouling the MAF.
#14
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Just recently the Project Farm YouTube channel did a comparison test video of a number of air filters, including a K&N filter.
His finding was that the Wix and Purolator filters had the highest filtration, but also the most restriction.
Video linked here
His finding was that the Wix and Purolator filters had the highest filtration, but also the most restriction.
Video linked here