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Discussion Starter #1
Hey All,

I'm looking at replacing the air filter on my 821 monster and was wondering what the opinions were for the best option out there.

I've looked into K&N, MWR, BMC, etc., but have had trouble deciding.

It seems a common opinion is that K&N is a great all-around upgrade, but MWR will probably yield the best performance increase being a "race" air filter. But the higher flow racing filters could also theoretically allow more dirt/dirty air into the engine. What is the actual trade-off here? Is the engineering on these filters good enough that the dirty air allowed through really isn't any worse than the stock filter?

Would love to hear thoughts!
 

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MWR! 'nuff said. ;)
 

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... but MWR will probably yield the best performance increase being a "race" air filter...
The MWR air filter for the 821 is from their "Performance" product line, not their "Full Race" line, so it's fine for OEM replacement.

Keep in mind that the engineers designed the fueling, emissions, and other performance factors using the stock air filter, and unless you a have goal in mind, such as modyfing the bike's performance in some way, there is no point in replacing the OEM filter (or OEM compatible filter) with a different type of filter.
 

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The MWR air filter for the 821 is from their "Performance" product line, not their "Full Race" line, so it's fine for OEM replacement.

Keep in mind that the engineers designed the fueling, emissions, and other performance factors using the stock air filter, and unless you a have goal in mind, such as modyfing the bike's performance in some way, there is no point in replacing the OEM filter (or OEM compatible) with a different type of fitler.
I agree. Most of the race labeled filters require a tune as stated in fine print. I'm running a KN but this fall thinking of going back to OEM.

tt
 

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Discussion Starter #5
Thanks for the input everyone - I went ahead and ordered the MWR - I AM looking for a little performance boost.

As to needing a tune with the filter: I have the termi slip-ons on my bike, and I got the ECU up-map installed with it. Will this be enough of a tune to where it won't run too lean with the extra air intake?
 

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You should be good with the upmap and Termi. Of course you could benefit more with a dyno but it's not necessary.
 

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You should be good with the upmap and Termi. Of course you could benefit more with a dyno but it's not necessary.
Sweet! I don't see dyno-ing it in the near future, so it's good to know it should be alright with just the termi up-map.

Thanks!
 

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Some related reading. Lengthy, but informative. Also guaranteed to inflame some emotions in those so inclined. ;D

The first is an abbreviated version.

http://forums.nicoclub.com/debunking-the-k-n-myth-why-oem-is-better-t180100.html

This is a longer version with more tables.

http://www.billswebspace.com/AirFilterTest.htm

Myself, I use my MWR clone which only cost me for a sheet of UNI foam. Yes, I know that there are claims that UNI is not effective as paper, but it is certainly more effective than K&N.

Stock, or the DP performance filter, are more than adequate. They just don't sound as cool as the MWR.

As for performance gains/differences, that can usually be more rider related than choice of air filter.
 

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Discussion Starter #9
Thanks for the feedback everyone!

I put the MWR filter in yesterday. Haven't ridden it enough to tell if there's any power difference; and it might be placebo, but I feel like it's running a few degrees cooler.

One of the huge differences I noticed between the MWR and stock filter (aside from the obvious foam/material difference) was the intake size. The stock filter has a rather small intake inner diameter (let's call it an arbitrary 2") and also has 3 plastic brackets occluding the opening - not sure why these brackets were there, only thing I could think of would be to induce turbulent flow. The MWR filter, however, has a larger intake diameter (3 inches?) and no occlusions. So it makes sense to me that the MWR filter will breathe MUCH better than the stock - I just hope it catches an equivalent amount of dirt.
 

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More air means leaner mixture. Don't care what others may opine.

The DP tune leaves a lot to be desired from a performance standpoint. It might enrich the mixture but when I put an AutoTune on mine which had the DP tune, the percentage AFR changes were very high.

Ride the bike and monitor your temps and pipe colors. Any changes from what it was previously would be cause for concern. Might also be informative to pull the plugs and inspect if the pipe colors change.
 

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sorry I'm new so may sound stupid but doesn't the termi. exhaust come with a K&N air filter and the buffed ECU
 

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sorry I'm new so may sound stupid but doesn't the termi. exhaust come with a K&N air filter and the buffed ECU
The termi slip-on kit only comes with the cans and the ECU up-map key, there is no new filter included - or at least I didn't get one with my kit.
 

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Mhhmm I was looking them up yesterday for sh!ts and giggles and said it came with k&n filter ecu and cans for 696 and full pipes filter cans and ecu for 796+


Sent from my iPhone using Tapatalk
 

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Mhhmm I was looking them up yesterday for sh!ts and giggles and said it came with k&n filter ecu and cans for 696 and full pipes filter cans and ecu for 796+


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It might be different on the older models, and I know it's different if you get the full-pipe kit (the full kit should come with filter).

But for just the slip-on kit for the 821, you get the cans and ecu map, and that is all.
 

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More air means leaner mixture. Don't care what others may opine.

The DP tune leaves a lot to be desired from a performance standpoint. It might enrich the mixture but when I put an AutoTune on mine which had the DP tune, the percentage AFR changes were very high.

Ride the bike and monitor your temps and pipe colors. Any changes from what it was previously would be cause for concern. Might also be informative to pull the plugs and inspect if the pipe colors change.
Evening !

I'm inclined to chip in here.

The correct answer depends on how the ecu calculates the required fuel.

Modern ecu's rely on 2 sensors to accurately measure the correct amount of fuel to inject.

- Map sensor ( absolute pressure/vacuum )
- Maf ( airflow sensor ).

If our 821's use a MAF, it will then measure the added air, and add fuel accordingly. The result is the exact same, so as long as the intact tube diameter housing the MAF doesn't change. ( you can change the filter or flow BEFORE the maf, but it's calibration is done according to the diameter of the intake tract ).

A MAP relies a volumetric efficiency table as multiplier ( and of course air temp ). ((-0.5bar @ xx*C) x injector pulse width)x compensations = Mapped fueling. If you change the volumetric efficiency of the engine, before or after the cylinder, your are in fact changing the amount of air ingested, and the ecu has no way of seeing this. You could run rich/lean. This is an issue.

MAF's are usually good at measuring airflow in closed loop situations/low flow of air( feedback from the O2 sensors finely correct the fueling, allowing a leaner burn without knock or pre-ignition ). This permits tighter fuel control, and also allows the ecu to target a stoich mix ( 14.7 AFR ).

A combination of both could be used, as a MAP is much more precise, and is not influence by debris, oils, water, etc. It is, much less precise at lower-flow situations.

I've grown to love speed density tuning. A combination of both is doable ( think a transition of MAF correction 0-100 %, where 100% is maf only, and 0% map only. Correlate that to throttle opening and you have yourself a nice smooth transition between riding smoothly and making power )


So, the big question ( I'm new to Ducati's, btw ! ) how are the M821's ( or Duc's in general ) fueled ? Maf ? Map ? Both ? I'm guessing MAP, and simply be deduction, because ducati's require upmaps/remaps when changing the exhausts...

( this is by all means a verrrryyyyyyyyyy short resumé of the fueling systems on modern ecu's, and we could go on for DAYS ).

Source :

Ecu tuned 100'S of cars myself.

Now I want an air filter ! Where did you order it ? I've got the cables to plug it to a laptop, and would love to pull the map and tinker with it. Maybe I could make a few maps and offer them to the community... !
 

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You will be hard pressed to find a MAF sensor on a Duc. Ergo, MAP.
I was kind of expecting that. Being a "shaky v-twin", the airflow must tumble alot. map is def the way to go.

So, yes, changing the velocity of the air ( hence, volumetric efficiency of the engine ) does require a re-tune.

Anyone have their 821 tuned yet ? Or any softwares out there I could use myself ? We could easily build an excel spreadsheet to dump logs in and tune volumetric efficiency if the VE tables are very high res in the map.

Rick
 

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I used the K&N air box elimination kit. I love them and allows me work on carb settings. I hear the air flowing into the beast. John F. 1997 monster 750
 
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