Import, not contesting what you looked up and derived from it. My original source is a well known 30 yr Cummins Engineer who was involved in significant heavy equipment testing using historical oil analysis from scheduled PM on a fleet of equipment having run the oem micron spec filters. K&N asked the customer if they could demonstrate a cost savings on the fleet by use of washable filters. They did save considerable money on the filters. but the oil analysis went to **** with substantially more dirt in it drastically changing the oil change interval and erasing any savings.

This is not urban legend, spoke to the horses mouth. It's become well known in the offroad and diesel truck world.

NOW that was ten yrs ago and if K&N was smart they would have altered their product to perform more admirably. Maybe they have. It's simpler for me just to verify oem micron ratings regardless of brand.

all that said, sleds and boats don't even use air filters. Most of us spoiling our cars don't see a lot of dirt roads, but, it used to be relevant..... and me still be relevant for some.... so i shared, eyes wide open. Forgive the hijack.... motor on:)

I always laugh when people use that chart as an example of "misleading graphs"

The general assumption with most of these data presentations is you have some understanding how to read scale. They aren't going to show it from the perspective of 0-100 because it would be unreadable.

If you want a "fair" way to look at it, take a look at this:

Your 96.8% efficiency on the K&N maps to just shy of a 3.4 sigma process...you are talking 32,000 defects per million opportunities.

Compare to the AC Delco at 99.93%, and you have a ~4.7 sigma process, a mere 700 defects per million opportunities.

In this case, your "defect" is a piece of crap that shouldn't be there (ie, dust, dirt), and you might be surprised at the high number of "opportunities" that appear over the course of a drive.

You can debate all day whether or not an 45 TIMES the crap getting past the filter is a big deal or not all day (and I won't bother because it isn't worth my time), but trying to downplay the number as "just 3%" is misleading. "Just 3%" was the difference between a Motorola that almost went out of business in the 80's, and the Motorola that was a major player in the 90's. Percentages are inherently misleading when viewed by most people, especially regarding high-capability processes (like filtering). We could, of course, illustrate with DPMO, but I imagine those results would appear even more skewed.

Double post...

Hell, no need to imagine. Here you go http://img.tapatalk.com/a6937e8b-553d-72d5.jpg


:tiphat:

:tiphat: nice.
So where does the stock air filter fall in on this chart?

Love it.

I unfortunately do not have access to any data surrounding the stock filter

Would my logic be correct in that an air filter that has the lowest DPMO also is more air restrictive (therefore not providing the typical gains seen from dropin filters (k&N filters since they are most common on this forum)

generally. There could be a filter with a very low DPMO but also has a high flow... but then again things like that would probably cost more than people are willing to pay and so no one bothers to make one. Its all possible..

P.S i would assume the stock filter has a low DPMO and also doesn't flow very well... because as much as we want to believe otherwise, Nissan won't put a filter in there that could cause engine damage and thus have them to pay out on a warranty fix. They will be overly cautious to protect their money.

often but not always

things get even trickier when you start comparing "real world" loaded flow numbers for the filters. That's a topic for someone with more schooling than me.

Well...I ordered the filters, too. I will research it further, but the smooth bellows or whatever are g2g.

This is absolutely incorrect. I just got a FI catback with 18" resonator installed early this week and it drones like CRAZY between 2000-2900 RPM or so under load. Most prominent when you leave the car in auto (D) which seeks the tallest gear always, and then either climb a small incline or generally just speed up slightly (accelerator pedal down about 1/4 to 1/2) without pushing hard enough to force a downshift to a lower gear.

This problem is easily solved by using a Helmholtz resonator attached 90 degrees off of each pipe, but for whatever reason FI didn't take this issue seriously and as a result their exhausts have this problem. I am in fact going to take a loss by having to pay labor twice to have the FI exhaust removed and the original up back on, this drone is so annoying. Telling people they have no drone is causing people to waste money only to find out the truth.

I have ARK DT-S exhaust, there is practically NO DRONE on highway. It sounds great on WOT, however its pretty quiet, its distinctively louder than stock exhaust, but not a dramatic change. The tone/note has a really nice low grumble/growl.

Are you going to be doing this every chance you get? Give it up already. Buyers remorse sucks but man..........

If you believe there's drone and chris says there's not then i believe he was actually correct in saying drone is subjective. I certainly believe drone is a subjective topic and i wanted little to none in my exhaust. I had the FI CF exhaust with 12" resonators paired with motordyne art pipes and noticed VERY little drone and was extremely pleased with the exhaust entirely. That was my 4th exhaust set up on a VQ engine. Your tangent is noted by the entire community. Go fix your problem please instead of complaining in every thread on the forum.

I second rich on this one, I also have the ARK DTS w/o HFC and it is 100% flawless. makes arguably the best deep growl of any exhaust available, zero drone. you can hardly hear it if your cruising at 65 on zero incline unless you get on it a little. and it doesnt make that wheezing rasp noise when you let off the peddle. also it makes a nice gurgle/pop sounds on decel kinda like a Mercedes AMG. Makes it sound very aggressive and mean.

but, its a different animal under load. if you accelerate hard it goes from quiet....... to OMFG loud. echoing off buildings and nearby cars. its about 104 db roughly under load. and they claim 89 at 3k, which is probably about right.

And Romulus, honestly? Drone is a thing. Its not subjective. If you can hear the car go RRRRRRRRRRRRRRRR with a constant tone while at cruising speed, and its a buzz/moan noise and not a nice growl like at idle.....thats drone. I would be pissed too if people who didnt know wtf it was, or just wanted to fanboy support a product they own, flaws and all....told me there was no drone and there was. Some of these exhausts are HEADACHE INDUCING. The ark dts is inaudible at speed unless you are giving it gas, in which case u can here a faint whir noise, then it screams like hell when u gas it. Drone is the constant annoying monotone sound of the exhaust resonating in the cabin, some people actually LIKE that sound as they think it sounds bad ***. And it DOES, but not when ur driving on the highway for 2-3 hours, it makes u wanna drive the car off a cliff. My 401 74 hornet does the same thing but thats just because its 500 hp NA and loud. I HATE driving it on the highway.

But to be fair, if you want to hear absolutely zero cabin noise at cruise....then dont go aftermarket. There isnt a single one that doesnt drone a LITTLE.

Yes honestly, are you trying to tell me what I can and cant hear and how to perceive things? I didn't notice much in mine. It IS a subjective issue. I'm not fan boying my set up, i had several and i liked them all but for the price i recommend FI if youre spending 1200 on and exhaust as its a quality product with quality customer service.

People can hear different frequencies of noise that others cant so it would affect some more than others. Which goes with if you cant hear something how do you say it is or isnt there? So I stand by it. You may hear it and it bother you, I do not and it doesnt. Subjective

I guess if your hearings been damaged that much then yeah, your right. Generally speaking 99% of humans hear in or around the exact same freq range. Otherwise there wouldnt be a thing called a hearing test, it would give completely inaccurate unacceptable results every single time for each different person. Its subjective to a point of TOLLERANCE is more to the point. How high is your "annoying" level. But common sense comes into play too. We are talking about if you can hear it or not, not if it bothers u. Drone is a physical provable occurance that could be monitored if one so chose. Aka how much NOISE its making in cabin at speed in a constant tone. If you cant hear that...i dont know what to say.

So basically yes, you are telling me what I perceive. I will continue to stick with, with my set up, casual conversation was 100% easy to carry on with who ever was in the car with no yelling over cabin noise or complaints about the "drone" even on 4-6 hour trips. I guess the 1% of the 100's of owners that comprise this exhaust all have severely damaged hearing. Good talk brah


Also note, I never attested to that exhaust by itself. I always point out that mine is paired with art pipes so mine made almost no noticible drone.

What is the db lvl of the fi exhaust anyway? Its louder than my ark right? 89 at 3k and about 106-108 under load.