Air resistence vs miles or time

[widman]

The restriction gauge (added by me) on my Suzuki van just went to orange again so I changed the filter. First filter went 12 months (23,900 km) and I replaced it with an original Suzuki filter ($38) at that time (feb).

So it basically hasn't rained since April. Very dusty and lots of wild fires. After 7 months and 15,500 km, it was time again.

So filter #1 was 23,000 km. #2 was 15,500 km. Weather required a more frequent change.

Note the graph. If I had changed every 10,000 as many suggested, I would have let a lot more dirt into the engine with the 97.5% original efficiency.
Blue line represents the efficiency improvement the way I did it. Dotted lines represent efficiency of changes every 10,000 km.

Not to mention that I would have spent $76 more in filters.

 

[HTSS_TR]

In the dirty area it is best to use/add the restriction gauge to measure the condition of the air filter. Change the air filter too early cost money and it does no good to the engine either.

My area is fairly clean, not much dirt in the air so that my filters do not look dirty at all after 20k miles. My air filter can easily be in service for up to 40-50k miles with little maintenance (tap the filter lightly on hard surface, vacuum ...)

 

[Scotty1981]

Where do you get these guages and how difficult are they to install?

 

[HTSS_TR]

If you Google "WIX Air Filter Monitor" you will see "Shopping results for WIX Air Filter Monitor", then click on "Wix 24804 Air Filter Monitor Kit - $5.78 new - Amazon.com"

You'll get to Amazon.com and there are several choices, Wix 24804 Air Filter Monitor Kit at $5.78, Wix 24801 Air Filter Monitor Kit at $15.85.

Wix 24801 is direct mount, Wix 24804 is remote mount with dash display. Wix 24804 is supposed to cost more but Amazon is having a special on that now. Wix 24801 at $15.85 is very low price too.

Both of them are only 2-3 left at that price, new stock will be much higher. There are 2 other sellers of 24804 and the price are $41 and $51, shipping included.

 

[FZ1]

Now that's dirty! I just trial and error my changes. Different based on location. I go about 30 months which is about 21,000 down here. I never check or clean an AF. I always buy a new Honda AF,open the air box,remove the old af,carefully clean the air box,install the new af,and I'm done for 30 months,or so.

 

[widman]

Originally Posted By: HTSS_TR
If you Google "WIX Air Filter Monitor" you will see "Shopping results for WIX Air Filter Monitor", then click on "Wix 24804 Air Filter Monitor Kit - $5.78 new - Amazon.com"

You'll get to Amazon.com and there are several choices, Wix 24804 Air Filter Monitor Kit at $5.78, Wix 24801 Air Filter Monitor Kit at $15.85.

Wix 24801 is direct mount, Wix 24804 is remote mount with dash display. Wix 24804 is supposed to cost more but Amazon is having a special on that now. Wix 24801 at $15.85 is very low price too.

Both of them are only 2-3 left at that price, new stock will be much higher. There are 2 other sellers of 24804 and the price are $41 and $51, shipping included.


Click on the $5.78 link and it will take you to a $34.51 price.
Standard unit is $15.85 plus shipping.

Mine is a Donaldson unit. I would think FLAPS would stock them.

 

[Jim Allen]

Widman: Could you explain you graph a little more. I'm having trouble catching all the drift.

In any case, good study and a good lesson in cost effective preventative maintenance!!

 

[widman]

The solid line shows the increase in efficiency (or decrease in dirt ingression) the way I did it with the monitor.

The dotted lines show the increase in efficiency if I had changed it every 10,000. You never take advantage of the higher filtration if you change too soon.

The steeper curve of the second filter is from the dry dusty year we are having and many farmers burning off their lands to plant as we go into spring.

 

[SteveSRT8]

nice validation of the factory installed gauges on our GMC products.

 

[mjoekingz28]

So, a dirty filter is better than a fresh one?

 

[Colt45ws]

Up to the point where it causes too much restriction, which may or may not be when you think it is.

 

[Jim Allen]

Originally Posted By: Colt45ws
Up to the point where it causes too much restriction, which may or may not be when you think it is.


Colton, you captured it in a nutshell!

 

[FZ1]

What does the other side of the filter look like?

 

[finalyzd]

So when one of my customers comes in with a filthy air filter its still good? I'm actually doing more harm then good by replacing it? Also in a uoa sometimes blackstone recommends changing the air filter if its dirty? Why? Its filtering better? Also after about 15k miles of driving both the knNs on my car have a layer of black dirt. Are they more efficient when dirty? So many questions wow

 

[Jim Allen]

"Dirty" is usually just a visual interpretation. WHen checked objectively, the filter can be caked with dirt and have little restriction.

Since you use K&Ns, you may remember how they advertised letting the filter get really dirty because it filtered better. The same thing applies to any filter. When filter restriction exceeds a certain amount, assuming you have the device to tell you when that point comes, then you KNOW you have obtained the full life from the filter

Until restriction becomes a problem, what harm does a visually dirty filter do? Absolutely none. It may help a salesman sell a replacement filter sooner than the customer actually needs but there's no real benefit to replacing a filter early. No extra dirt is getting through. Just the opposite, in fact. The engine won't get air any dirtier until restriction reaches the point where it sucks dirt through the filter. If you have a monitoring device, hopefully you will have changed the filter before that point.

Some trot out the fuel economy thing, but that's been disproven and you can see it here;

Air Filters

This 2009 report tests the effect of dirty air filter on fuel economy using standard EPA dyno routines. They used later model EFI cars (2003-2007)and one 1975 carbureted car. The conclusion what that the fuel injection could compensate for the restriction up to the point where the car's performance had deteriorated to barely running and fuel economy decreased only by a percent or so. Performance degraded, of course. The carbureted car was more effected but fuel economy wasn't lowered by nearly as much as "common knowledge" dictates... only 2.5 percent.

In every case lower end performance was unaffected until the restriction reached the level at which insufficient air was being inhaled. Performance dropped mightily but the EFI could trim fuel to keep the mixture about right. They found that in "normal" driving situation, the car was almost unaffected by a clogged filter because the airflow needs were so low. In a few cases, the filters were so clogged that the engine sucked them into the intake tube.

In the absence of a restriction monitor, you have to use the manufacturer's recommendations. Unless a person lives in a really dirty environment, based on the research some of us here have done (you can see some of Widman's here), those recommendations may be overly conservative.Ditto for a visual evaluation.

One of the dangers of changing air filters too often involve getting dirt into the clean side of the intake system in the process, obtaining proper fitment of the new filter into the air box. You'll see some of these things illustrated here and elsewhere if you research.

 

[Kestas]

Nice data. It tells me that I certainly change my air filter too often. Not a big deal way back, when I could buy Caseite filters for a buck. But now that air filters cost $14 and up, I'll need to pay attention to this data.

 

[widman]

Here is the other side

When an analysis result says change air filter, they assume you must be cleaning it or have done something to ruin the gasket, letting extra dirt in. I usually add that you should check out the entire intake system for leaks. A dirty filter does not let more through. It shows itself in reduced power at high rpm's

The K&N filter starts at about 85% efficiency and clogs around 98% according to several studies. Some of that, including the 85% is no their site.

A good paper filter is 98-99%, the best paper filters (usually not available for cars) are 99.99%

restriction can't be determined by where you drive either. My Grand cherokee now has 20 months and 29,000 km or so. It has spent quite a bit of time off road, where the Suzuki has been all city driving. Everyone here wanted me to change that filter in March or so when I posted the first pics. I'm still waiting for the restriction to register.

 

[finalyzd]

Thanks for that. Wonder if I could use one of those kits in my car. Never new a dirty air filter is better then a new one up to a point. Or a oil filter filters better into the oci. And oil gets better with age also up to a point.

 

[finalyzd]

What about the amsoil conical air filters?

 

[bigmike]

Originally Posted By: widman


The K&N filter starts at about 85% efficiency and clogs around 98% according to several studies. Some of that, including the 85% is no their site.

A good paper filter is 98-99%, the best paper filters (usually not available for cars) are 99.99%



Our actual air filters when tested generally demonstrate a cumulative filtration efficiency of between 96% and 99%.

So you are stating the above is actually false? Do you believe other manufacturer claims are also false, or just K&N?