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Old 07-29-2018, 07:28 PM   #1
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K and N filter

This might be a post for another, more general forum but I'm looking for info from Sprinter owners.

An aquaintance suggested I replace the OEM engine (not cabin) air filter with a K and M filter. It's about $80 on Amazon but he swears it will give me another 5-15 horse power (HP) and better mileage than OEM and the filter has a "good forever" warranty - never has to be replaced. He's also suggested modifying the exhaust for a further HP gain.

Anyone had any experience with this filter? Has anyone modified their exhaust system and seen an HP or mileage gain?

My relatively new rig (7500 miles) - Forest River Forester 2401WS MBS - is barely making 13 MPG and that is unusually low in my 13 years of owning Sprinter based RVs.

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Old 07-29-2018, 07:32 PM   #2
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It's K&N and I doubt you would notice a difference in anything. As for modifying the exhaust system, it would probably void any warranty you have.

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Old 07-29-2018, 07:49 PM   #3
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A K&N air filter will give you more air flow, and probably a little increase in HP, but not enough to make a difference. They do last much longer than other filters, but they need to be cleaned and re-oiled on a regular basis so you have the cost of cleaner and oil. K&N products are good products, but do not work miracles.

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Old 07-29-2018, 07:53 PM   #4
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K&N filters allow much more dirt into the engine for little to no upside. Waste of money, IMO.
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Old 07-29-2018, 08:09 PM   #5
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This is my opinion based on experience.
Your acquaintance is suggesting you improve the air flow into and out off the engine, this was an easy mod years ago when engines didn't have computers and a gazillion sensors. A K&N filter (probably in conjunction with a new air box) can help you with that as long as the filter is new and has big enough holes ...., you see where I'm going with this? If you don't have a shop with a sink or a parts washer and have to clean and dry the filter in the master bath you may be doomed for the dog house. Bigger pipes on the exhaust side would help on that end but would very likely cause a bunch of sensors through all kinds of codes. Let's say you could get it to work somehow, the best you would see is an improvement in HP, not in fuel economy - most likely the opposite. Worse, if you ever need anything done on the powertrain under warranty - good luck.
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Old 07-30-2018, 10:02 AM   #6
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K&N filters flow better because they filter less. You get more airborne particles into your engine (and into the oil) running one. For the exceedingly minimal gains you get, and the potential for harm, I personally stay far away from them. Maybe 3% better flow, up to 3 times more dirt passed through without being filtered out.

A good quality (OEM) pleated paper filter is the best.


P.S. Link to a very dense and technical article where they did a subjective test to a variety of filters. The first 3 graphs is all you really need to know.

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Old 07-30-2018, 06:48 PM   #7
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Never ever try to outsmart the huge team of engineers that not only designed your vehicle, but spent millions of dollars and countless man-hours doing research and development.
Or, you could just blow off what they developed and do your own thing. Your choice.
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Old 07-30-2018, 07:31 PM   #8
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I have used a K&N filter replacement on my Duramax for 150k miles. I like them as I can just clean every so often and reuse it. Much cheaper than continually buying new filters.

As far as increasing your mpg, not likely enough to notice.

You can find all kinds of studies of air filter effectiveness. Most of them are BS, and if you don't like one graph, just look for another one. I always think the graphs that show one filter is bad or good can be explained by who sponsored the study.
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Old 07-30-2018, 07:44 PM   #9
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Originally Posted by Cowracer View Post
K&N filters flow better because they filter less.
Yep...seen quite a few studies where they do flow measurements and put an additional screen behind the filter that shows what can get by. I would never put a K&N filter on any vehicle I own. Plus, if it's a gas engine, very easy to destroy the MAF.
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Old 07-31-2018, 07:06 AM   #10
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Originally Posted by barnbnb View Post
Never ever try to outsmart the huge team of engineers that not only designed your vehicle, but spent millions of dollars and countless man-hours doing research and development.

Or, you could just blow off what they developed and do your own thing. Your choice.

Do keep in mind those engineers are designing our vehicles being strapped by government regulations!


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