[OpenFlash]

This test is 100% valid. Unfortunately, the test car never moved enough airflow/made enough hp to get to the point where the stock airbox becomes a restriction. It's only above that power level, will the differences in performance become evident.

Shiv

[Orb]

Originally Posted by shiv@vishnu

This test is 100% valid. Unfortunately, the test car never moved enough airflow/made enough hp to get to the point where the stock airbox becomes a restriction. It's only above that power level, will the differences in performance become evident.

Shiv

Look at the first test and the boost delta between them and note the frist test was much cooler but not noted.

Not only the boost will drive the gains but temperatures as well. You know it affect density but viscosity it the driver in pressure drop. Given cooler temperature you will see more losses in the system at lower boost.

It is not all volume flow rate.

Orb

[Former_Boosted_IS]

Part of my problem with tests like this is that the STFT's will not adapt in a run. Therefore your car will dump identical fuel for everyone of these filters regardless of flow. What did you guys expect? The entire gain for an intake on our car is based on the fact that we have an adaptive fuel system. Most cars without adaptive ECUs use an SAFC to add fuel to take advantage of the increase in air flow. Basically all you are doing is leaning out your A/F ratio on these runs my friend. After some driving, the car would detect this leaner A/F ratio, make some changes to the fuel trims (i.e. adding fuel to the mixture), and create more power. I don't understand what people expect?

[David1]

Is helene still around? I have the filter and need a cleaning kit. The website is gone They once said not to use the K&N cleaning kit on it.

Anyone or any vendor input would be helpful.

[Drakos]

Originally Posted by David1

Is helene still around? I have the filter and need a cleaning kit. The website is gone They once said not to use the K&N cleaning kit on it.

Anyone or any vendor input would be helpful.

I don't see why K&N wouldn't be fine. Helene is not around and replaced my the Macht Schnell filters. Tom at EAS said to just use the K&N recharge system.

[645Nm]

Well done...

I have been thinking about stock vs performance vs drop in vs cones vs single vs duals vs K&N vs BMC vs BMS vs gas vs wtf and I am still non the wiser...will stick with my "drop in".

[carve]

Battle Wagon: The aftermarket drop-in filters tend to have much less surface area (far fewer, far shallower pleats). Equal or greater flow through less surface area = much more porous. Due to the reduced surface area, they actually lose performance quicker, AND they let more, bigger grit into the engine. It's not like dirt particles are electrically attracted to the oily fiber- if they're aligned with a hole, they go straight though. Once a big enough particle come to clog the hole, it diminishes a greater % of the air-flow potential than in a paper filter. Some years ago there was an independent test of this, using a box with recirculating air and a standardized dust. Aftermarket filters lost flow quicker than paper filters. You can probably find it floating around on the internet.

About adaptation: are you saying it's running lean? I don't think so. There isn't a whole lot to adapt to- the O2 sensor will keep the mixture stoiciometric.

[carve]

Hey- I found it. Coincidently, the test was regarding old BMW M3's!

http://www.bmwe34.net/E34main/Upgrade/Air_filter.htm

They found the K&N had slightly less pressure drop when new, but the difference was negligible. Here's where the results got interesting...

BMW Stock Filter, Eff. Area of Media: 8.4 sq ft.
K&N Replacement, Eff. Area of Media: 1.6 sq ft.

The filters are the SAME size. They both fit in the STOCK BMW M3 airbox. The difference is that the STOCK filter has 65 pleats 1.5" deep and the K&N only 29 pleats each 0.75" deep.
Now, remember this ratio: " 5.25:1". It's the ratio of the AREA of STOCK to K&N. It's very important and will come into play later.

The STOCK filter efficiency started at 93.4% at 0 loading and increased to 99.2% efficiency as the loading increased to a max tested of 38.8 gm/sq ft of dust.


The K&N filter efficiency started at 85.2% at 0 loading and increased to 98.1% at the max tested loading of 41.38 gm/sq ft.

Now, I hear you. "Jim, that's only a FEW PERCENT". But is it?

Let's look. If we had 100 grams of dust on a new BMW filter we would let through a total of 6.6 grams of dust in. If we used the new K&N filter we get 14.8 grams of dust. That's 224% (TWO HUNDRED TWENTY FOUR PERCENT!!) more dust ingested initially, stock vs. "free flow" and this ratio is pretty much held. Somewhere between 200-300% more dirt gets "ingested" anywhere across loading equivalence. The more INTERESTING thing is when you look at what happens to the DP or Differential Pressure at a constant airflow as you dirty both filters equally with time.

The test used a rate of 75gr of dust per 20 min. Here's where the AREA difference comes MAJORLY into play. See, even though the BMW filter flows a bit less at the SAME loading, it also LOADS UP 5.25 times SLOWER due to it's LARGER effective area. So what happens is that the K&N initially flows better, but as the dirt continues coming in, the K&N eventually flows WORSE while still letting MORE dirt in.

Also notice how both filters gain filtering efficiency the more loaded up they get. The air goes through the low-restriction big pores first, and once those are clogged is forced to go through the finer pores, increasing filtering efficiency at the cost of pressure drop. It's a trade-off, but the paper filter makes the best of it by offering 5x as many of the tiny pores, offering low pressure drop while maintaining efficient filtering.

The allure of a simple mod is testing, but I highly recommend staying stock


Edit: I just found another test, backing this up, on a Miata doing WOT runs up a hill at 6500 rpm.
http://www.bobistheoilguy.com/airfilter/airtest2.htm
The pressure drop for a paper NAPA filter was .249 PSI. For K&N: .231 psi. Less than two hundredths of a psi difference won't make a real difference- espeically if you're running 10-13 psi of boost. And that's BEFORE the K&N clogs up 5x faster, and wears your compression rings out faster. It shouldn't take long until your engine performs WORSE on K&N. To top it off, no filter at all: .184 psi. That's right- filters offer very little resistance- far less than the intake tract alone, at least in this Miata.

[stressdoc]

Bottom line: If you are anywhere near stock power levels (<350 whp), the stock filter works great, and any aftermarket system is not the best way to spend mod $.

[dcstep]

Interesting. Over on M3Post the dynos are all showing 5 to 6 rwhp on E9x M3s going to oil coated filters like Macht Schnell.

Dave

[carve]

Interesting- that's over a 1% increase. Are they comparing to a brand-new paper filter, or one with a few miles on it?

[dcstep]

Originally Posted by carve

Interesting- that's over a 1% increase. Are they comparing to a brand-new paper filter, or one with a few miles on it?

In my case there was 4600 miles on my OEM paper filter; however, it was very clean, with just a touch of black in one small area of the filter.

We had just dynoed the car to get a new baseline with some mods and we did four runs, until the power peaked. Next we dropped in a Macht Schnell and did two or three runs until it peaked again. I gained just under 6 hp.

Dave

[carve]

Originally Posted by dcstep

In my case there was 4600 miles on my OEM paper filter

There's your answer. In spite of looks, that filter was 25% to 40% of the way through a normal change interval, depending on conditions. Put 4600 miles on your after market filter and get back to us.

[dcstep]

Originally Posted by carve

There's your answer. In spite of looks, that filter was 25% to 40% of the way through a normal change interval, depending on conditions. Put 4600 miles on your after market filter and get back to us.

I doubt that explains it. First, the clogging action is likely not linear and accelerates after initial build up starts. There are two or three others reporting similar gains to mine. Those gains are too consistant to all be explained by mileage difference.

I suspect that the lack of difference with the 335 has to do with turbo charging vs. NA, or some other difference. Perhaps the 335's filter is superior to the M3 in terms of being closer to ideal for the application. The OEM M3 filter has a charcoal layer that is not in the aftermarket filters. Maybe the 335s don't have that layer.

Dave

[DMETune]

Great to see this thread resurrected. :-)

I apparently missed the last post from May '08 saying...

Basically all you are doing is leaning out your A/F ratio on these runs my friend. After some driving, the car would detect this leaner A/F ratio, make some changes to the fuel trims (i.e. adding fuel to the mixture), and create more power. I don't understand what people expect?

The AFR measurements are on the graphs, and you can see that there's virtually no difference between filters compared to stock. Moreover, the widebands keep the AFR where it's programmed to be, regardless of air filter contraption. More-moreover, I did several runs (4) on each filter to allow for any adaptation to take place and the AFR did not substantially vary from run to run.

Bottom line: If you are anywhere near stock power levels (<350 whp), the stock filter works great, and any aftermarket system is not the best way to spend mod $.

^Exactly. I've not even seen real quantitative proof that the intake is a restriction at levels above 350whp, but cannot conclusively say that it isn't. Perhaps a "Round 3" test is in order...hmm.

Scott

[carve]

That's weird. I wonder what the charcoal layer is for, driving through clouds of corrosive gas after WWIII?

[dcstep]

Originally Posted by carve

That's weird. I wonder what the charcoal layer is for, driving through clouds of corrosive gas after WWIII?

It's an emissions solution. Apparently there can be unburned fuel in the throttle bodies in certain conditions, which would evaporate into the atmosphere. The charcoal attempts to absorb those emissions rather than release them.

Dave

[TwnTrboCAT1212]

Ok, so I just bought a Macht Schnell drop-in for my 335 and was going to install it today...Now, are you all seriously telling me I'm going to be doing more HARM than Good by replacing my stock paper filter with this thing? That just seems outrageous to me. I find it hard to believe that while the dyno numbers don't lie, that a credible company would produce (and other credible company's would sell) an $80+ drop-in that will allow for dangerous dust and dirt particles to make their way into my engine over time and cause a decrease in performance / damage. Somebody please give me some positive feedback here.

~ Chris ~

[Drakos]

I just wish there was a dyno comparing stock, stock with drop in like Macht Schnell and dci's with a tuned car. I have been holding back on the dci's because I am not truely convinced on it's benefits besides a bit better airflow. I think the AIT's would be higher on the dci's vs stock airbox. I just got a MS drop in and noticed a little difference on throttle response, but is still hard to tell. The HP increase (if any) is barely noticable unlike the DP's I put in. Dinan's CAI will be out any moment now and I am very eager to see if It will out perform current intake systems.

[GreenPlease]

Very informative. Thanks.

[DMETune]

Originally Posted by TwnTrboCAT1212

Ok, so I just bought a Macht Schnell drop-in for my 335 and was going to install it today...Now, are you all seriously telling me I'm going to be doing more HARM than Good by replacing my stock paper filter with this thing? That just seems outrageous to me. I find it hard to believe that while the dyno numbers don't lie, that a credible company would produce (and other credible company's would sell) an $80+ drop-in that will allow for dangerous dust and dirt particles to make their way into my engine over time and cause a decrease in performance / damage. Somebody please give me some positive feedback here.

~ Chris ~

In all likelihood you're not going to hurt anything by using an aftermarket drop-in filter. However it IS unlikely that you'll yeild a performance improvement from this modification at power levels anywhere near stock. Granted, I did not test the Macht Schnell filter specifically -- it could very well be magical.

Scott

[carve]

Oh- well due to the charcoal filter, you may well see a noticable improvement. I'd probably go with an aftermarket paper filter with no charcoal layer instead though (e.g. NAPA gold). That engine is too damn expensive to let extra dust in for little to no gain.

CAT1212: without some sort of SAE industry-standard testing, claims are just claims. There probably was a time these things did make a big difference, but the engineering going into a performance-oriented OEM car is pretty good these days. If they were losing power from the filter, they'd make it bigger, which they have.

It'll take a long time for any noticable wear to accumulate, but if there is no real benefit, what's the point?

I was at a drag strip in CA a while back and saw two 335s set up identically, except one was a coupe with an injen intake, and one a sedan with an OEM intake. The one with the OEM intake was faster every time, although it's possible there were other factors.