Paper Filters & Airbox Lid Mod

[Greg Field]

I was going over some old pix, looking for the pix of how to mount the tipover valve when I ran across the photos below, taken the day after we got back from the Deep Forest ride around Mt. St. Helens, taking a few dirt roads.

 

 

 

 

This filter was brand-new the week before we left. It shows how in less than 500 miles there's a pile of dirt in the valley of each pleat that it prevented from entering my engine.

 

 

 

Look at the rocks and clumps it caught. Truly amazing amount of stuff, especially considering that I was in the lead for much of the dirt run and second in line for all the rest, and so wasn't getting the worst of the dirt plume.

 

 

 

 

Here's the results of the white-glove test around the inside of the airbox. Spotless. No grit you could see or feel.

 

My Eldo was on the same run, ridden by someone else, at the back of the pack, eating the worst of the dust. It has individual K&Ns. There are no dirt mounds or chunks in the valleys of the pleats on the K&Ns. In fact, the K&Ns look very clean, totally ready for use. Where did all the dirt go? I bet it's in my engine, or was until I changed the oil and filter.

 

Your K&N-equipped bike may put out more horsepower by a small fraction than my paper-filtered bike now, but 10,000 miles down the road, will it? I bet not.

[Guest ratchethack]

. . . .My Eldo was on the same run, ridden by someone else, at the back of the pack, eating the worst of the dust. It has individual K&Ns. There are no dirt mounds or chunks in the valleys of the pleats on the K&Ns. In fact, the K&Ns look very clean, totally ready for use. Where did all the dirt go? I bet it's in my engine, or was until I changed the oil and filter.

 

Your K&N-equipped bike may put out more horsepower by a small fraction than my paper-filtered bike now, but 10,000 miles down the road, will it? I bet not.

Uh-oh. Careful, Greg.

 

Them's fightin' words to the K&N Faithful. . . . .

 

Some will no doubt recall all the previous Forum Frolic and Frivolity on Air Filters here:

 

http://www.v11lemans.com/forums/index.php?...;hl=K&N

 

NOTE: The Sept. ‘04 ISO 5011 Duramax Air Filter Test has been re-linked:

 

http://www.duramax-diesel.com/spicer/index.htm

 

To many 'round here, it's obvious that y'er a well-paid shill for the paper filter lobby, Greg.

 

You clearly fabricated this evidence!!

[dlaing]

This filter was brand-new the week before we left. It shows how in less than 500 miles there's a pile of dirt in the valley of each pleat that it prevented from entering my engine.

Damn! after 10000 miles each pleat would be more than half full!

So do you replace the filter every 1000 miles, or just dump it out every 1000 so that it lasts 10,000?

Have you considered a pre-filter, like a mesh screen?

Are you still using the lid and snorkles?

I used to go topless with my BMC, but Ratchet convinced me that gauss filters pass too much through.

I definitely lost some HP when I put the lid back on, but too much crap was falling in without the lid and snorkles. Still if I went to paper it would run even more cleanly....maybe after the BMC gets worn out a bit....I think it has been cleaned three times so far.

I wish there were some tests that compared the BMC to the K&N

PS if you go lidless with a paper filter, I imagine rain would be a problem.

[belfastguzzi]

PS if you go lidless with a paper filter, I imagine rain would be a problem.

No, I never had a prob with rain. Half lid & snorkels.

[Greg Field]

I cut a 4-x4-inch hole in just the top of the box lid, leaving snorkels in place. This let's in plenty of air but prevents most of the intake roar you get by removing the lid entirely. I'll do a dyno test shortly of this set-up vs. BMC, just 'cause I'm curious, not because I plan on running a BMC.

[Guest Nogbad]

If you work out the relative area of the paper filter element in the airbox, and that of the conical pleated sections of the K&N pods, I bet the standard paper has a bigger area.

 

Therefore: How do you get more air through a smaller filter area so that you can sell your pods as a performance accessory? Easy, dirty great big holes!

 

Hell who cares anyway if the pods look so cool....

[ArtD]

I cut a 4-x4-inch hole in just the top of the box lid, leaving snorkels in place. This let's in plenty of air but prevents most of the intake roar you get by removing the lid entirely. I'll do a dyno test shortly of this set-up vs. BMC, just 'cause I'm curious, not because I plan on running a BMC.

 

Ok Greg (and everyone else), I'm going to throw out a couple if questions and observations: Is it possible that the bone stock set-up with the snorkels is acually faster in the real world? It seems to me that stock there is a ram air effect that, at speed would tend to force cool air into the box, if I'm wrong here, why? Forget the dyno babble, last time I checked, Dyno's have not been spotted circulating the racetrack Has anyone ever done a TRACK TEST and/or 1/4 mile comparison between the stock airbox, a cut-up box, and individual K&N pods ?back to back, one after the other against the stopwatch? And on that subject for a moment, is there any difference between K&N filters and the BMC's? Back to the Air box issue, what about the crankcase venting sustem? Doesn't the vacum of the stock box help draw out some of the pressure? When you cut up the box, and/or install indivudal pods, don't you loose some of that? As a personal note, I have used K&N filters for many years on various race cars. But that has nothing to do with engines that you want to run for 10's of thousands of miles without having to tear appart! I have never used them on a street engine that I ever lived with long enough to see any effects either positive or negative.

[Guest ratchethack]

Is it possible that the bone stock set-up with the snorkels is acually faster in the real world? It seems to me that stock there is a ram air effect that, at speed would tend to force cool air into the box, if I'm wrong here, why?

Art, your evidently well-qualified comments are appreciated.

 

You ask an interesting question.

 

When I think of "ram air effect" I think of a positive pressurization of the intake over ambient -- or at least less negative intake pressurization than would be the case otherwise, created by airflow over the vehicle at speed, that can be maintained with throttles open, even at WOT.

 

I don't think there's anything about the stock setup that could result in significant enough positive airbox pressurization at speed to keep airbox pressurization more positive (or less negative) than otherwise at any throttle opening up to and including WOT. But o' course that's just reasoned speculation on my part, lacking much of any likely potential for ever finding valid measurements (anywhere).

 

IMHO, unless you've got a wind tunnel - (like the one at Mandello!) , and want to chase boundary velocities and eddy currents using some pretty sophisticated analysis & design tools, trying to come up with air plumbing on a Guzzi to create a ram air effect presents a whole raft o' difficulties best left to the Pro's. . . . IMHO, the most likely outcome of garage plumbing for a ram effect has a greater probability of resulting in decreased air flow and higher negative intake pressures at WOT than the stock setup.

 

Now some o' the Jap "appliance volume" mfgr's. have the engineering capability, and I've no doubt that they have the entire wherewithal to come up with significant results. But then, we're riding dinosaurs made in a small European village where some of the manufacturing design and factory techniques are hold-overs from those of medieval armorers.

 

The Luigi's at Mandello don't seem to've found a reason to make use of their wind tunnel for this purpose yet, so I reckon they figure the return on investment in terms of performance gains just isn't there.

 

I gotta agree.

 

But o' course, that's just me.

 

. . . .is there any difference between K&N filters and the BMC's?

The filter substrate of both K&N and BMC is made by the same supplier, but is evidently a different specification, the same way that oil filter substrates made by the same supplier for different OEMs have different specifications, depending on the application. The BMC air filter tests I've seen have put them in the "middle category" with the rest of the more generic high-efficiency filters in terms of performance and longevity, while K&N's have always been for the most part off on their own in the results, as illustrated by the Duramax ISO 5011 series of tests.

[guzzijack]

Art, your evidently well-qualified comments are appreciated.

 

You ask an interesting question.

 

When I think of "ram air effect" I think of a positive pressurization of the intake over ambient -- or at least less negative intake pressurization than would be the case otherwise, created by airflow over the vehicle at speed, that can be maintained with throttles open, even at WOT.

 

I don't think there's anything about the stock setup that could result in significant enough positive airbox pressurization at speed to keep airbox pressurization more positive (or less negative) than otherwise at any throttle opening up to and including WOT. But o' course that's just reasoned speculation on my part, lacking much of any likely potential for ever finding valid measurements (anywhere).

 

IMHO, unless you've got a wind tunnel - (like the one at Mandello!) , and want to chase boundary velocities and eddy currents using some pretty sophisticated analysis & design tools, trying to come up with air plumbing on a Guzzi to create a ram air effect presents a whole raft o' difficulties best left to the Pro's. . . . IMHO, the most likely outcome of garage plumbing for a ram effect has a greater probability of resulting in decreased air flow and higher negative intake pressures at WOT than the stock setup.

 

Now some o' the Jap "appliance volume" mfgr's. have the engineering capability, and I've no doubt that they have the entire wherewithal to come up with significant results. But then, we're riding dinosaurs made in a small European village where some of the manufacturing design and factory techniques are hold-overs from those of medieval armorers.

 

The Luigi's at Mandello don't seem to've found a reason to make use of their wind tunnel for this purpose yet, so I reckon they figure the return on investment in terms of performance gains just isn't there.

 

I gotta agree.

 

But o' course, that's just me.

 

No not just you

 

As a spinoff to his work on the Daytona 4 valver, there's a whole heap of historical information out there about Dr John Wittner's adventures in positive pressure airbox land with the 1100 Sport Carb - one of the forerunners to the V11Sport. My (perceived) reading of it is that for the sake of a minimal increase in BHP at WOT the tradeoff was a stuttering pig at real world riding levels. This was something that Dr J and the Guzzi engineering department couldn't overcome given the time and financial constraints that they were operating under at the time. As a fer instance they would have preferred to use at least Mikuni Flatside carbs instead of the 'ancient' Dells, (Keihen FCRs would have been the icing on the cake!), but Mikuni did not have an R&D facility in Europe to assist with emmissions compliance and there were probably contractual and financial considerations as well.

 

FWIW here's what I've done with the similar airbox on the Centauro (with acknowledgement to Phil A). Take off the right angled intake pieces. Using a heat gun on the intake 'schorkels' get them hot enough so that the plastic is shiney and then gradually bell them out with a suitably sized bottle neck - HP Sauce suited me! - until you have an ID of 50mm. It may take a few heat/ream/cool cycles to get there but the end result should be a smooth intake bellmouth. Then drill two 25mm or thereabouts holes on the top rear of the airbox just in from the corners with another positioned centrally and slightly forward of them - this, according to others more educated in these matters than myself, removes a disruptive harmonic that occurs in the standard box which manifests itself when you wind it on big time.

 

This modification apparently passes some 5% more air than the O/E configuration but allows the retention of the standard airfilter, (or K&N or Amsoil flat plate replacement), with a slight but enjoyable increase in intake honk. The real world result is that I am experiencing a noticably smoother ride, better throttle response with no glitches or stumbles and an enhanced aural experience

 

To get back on track with Greg's start to this thread - yes OK there was a lot of crud in the standard filter after X amount of miles some of which were on dirt roads, but I happen to run an 'internal' K&N which will give the same results - dirty filter and clean airbox. Why? because I clean and oil the filter every 6k miles (every 2nd service interval) and don't leave it to run for zillions of miles before maintenance. My filter, including the cost of a bottle of cleaner and oil, will pay me back over the cost of O/E paper filters within a year or two of bike ownership without increasing engine wear.

 

Comments anyone?

 

Graham

[Greg Field]

Graham:

 

I clean and oil my K&Ns on the Eldo at about 4,000-mile intervals. They were ridden through the same roads as Billy Bob. The K&Ns appear to have stopped a very small fraction of the dirt the paper filter stopped. In fact, the K&Ns still looked pretty clean, whereas the paper filter looked loaded with dirt. I'm going to construct a custom airbox so I can run a paper filter on the Eldo.

[DeBenGuzzi]

I'm just not worried about it untill someone shows me some solid evidence that I'm hurting my engine with K&N pod filters, There seems to be plenty of proof it filters more but show me how that matters besides just "well it does" argument.

[Tom M]

On ram air, here's a decent article on it from 1995:

 

http://www.sportrider.com/tech/146_9508_ram/

 

...and a couple more:

http://www.sportrider.com/tech/146_9910_ram/index.html

http://www.sportrider.com/tech/146_9912_ram/

 

In a nutshell they concluded that ram air indeed works, but it doesn't make much difference until you exceed ~120mph. That was in '95. I expect the technology has been refined since then but I bet a state-of-the-art system still probably doesn't help until your past 100mph.

[ArtD]

On ram air, here's a decent article on it from 1995:

 

http://www.sportrider.com/tech/146_9508_ram/

 

...and a couple more:

http://www.sportrider.com/tech/146_9910_ram/index.html

http://www.sportrider.com/tech/146_9912_ram/

 

In a nutshell they concluded that ram air indeed works, but it doesn't make much difference until you exceed ~120mph. That was in '95. I expect the technology has been refined since then but I bet a state-of-the-art system still probably doesn't help until your past 100mph.

 

Great stuff here!! Every one of these articles confirms my gut feeling that the STOCK airbox on the v11 series puts out more power than ANYTHING else, including hacking holes in the damn thing, throwing parts of it away, etc. As for "It doesn't make much difference until you exceed 120", to that I would say, "yes (comma) but"........ notice how in the Kawi test their manometer starting showing pressure at 70mph! Now, I can't speak for everyone, but I know that I spend a fair amount of time at or above 70 What every one of those tests showed was, modern Motorcycle airboxes look like crap and make serious HP :!: Now... did the Guzzi boys do any testing to come up with their Box for the V11's?? I think there was some engineering involved, I'll believe that until I see proof to the contrary. Notice how all of the tests tried to duplicate speed riding not just smoking tires on the local guru's dyno? Bottom line: I admit, the K&N pods LOOK slicker than Owl crap, but, are they REALLY better, from a performance viewpoint? Does a lustly "honk" from the vicinity of what used to be an airbox mean the motor is happier? As for paper vs K&N, go to the K&N site and take a peek at the FAQ's, and read K&N's interpatation of the federal warranty laws. Notice how nowhere do they say "our filters filter better than the stock filters". You use K&N filters for two reasons: One- over the long haul, if you keep the vehical (or bike) for many years and many miles, you will save money on filter replacement costs; and Two- they will flow more air then a stock paper air filter will. End of story. My very humble seems to be use the stock box with a K&N or BMC filter PROPERLY lubricated........except when going for rides on dirt roads covered with the volcanic ash of Mt St Helens

[helicopterjim R.I.P.]

Paper, scissors, rock. Your choice!

[DeBenGuzzi]

Paper, scissors, rock. Your choice!

not a very convincing argument.