Power Flat Spots

[Phil A]

John,

Yes I did remap at the lower rpm settings, especialy under half throttle. This is where I found some of the greatest gains.

 

This also applied to the 1100 sport I did.

 

The rideability issue was my main motivation for all of this with the V10. My bike will now willingly walk away from 1500rpm in top gear. This is not something I make a habbit of, but it will.

 

I have remapped every piont of the original map.

 

Greg,

you will be surprised how much difference the teardrop holes will make all the way through. You will get as much or more gain than the original 3 holes gave, and will probably fill in the deficiency? you found over the cut away lid setup.

 

This improvement came as a vision at 2 am one morning, (why I keep a notepad and biro near the bed!) It took some time to test and get a design I was happy with.

It took me a while to understand why it works, but there was a logical explanation once I worked it out.

 

Probably wont bore the masses with it.. Im guessing you can work it out if you look at it long enough.

 

Phil.

[pete roper]

.

 

Probably wont bore the masses with it.. Im guessing you can work it out if you look at it long enough.

 

Phil.

 

Well, I'm too dim you bastard so how about giving me a hand up?

 

Pete

[pete roper]

Well, I'm too dim you bastard so how about giving me a hand up?

 

Pete

 

And yes, the teardrops are 'Beard Shaped!'

 

Pete

[Greg Field]

So what I gather is that between 3800 and 7500 RPM, the gauze filter and cut off lid gave immediate power and torque gains at between 3500 and 7800 rpm compared to Phil's modified airbox with a paper filter, even without optimizing the map for the former.

 

For me, that's the range of primary interest.

 

I still prefer the paper filter with Phil's modification for the reasons you state, but want to clear up my understanding. BTW, I like dirt roads too, but worry about riding on tires designed for the Autobahn.

 

Yes, this is what the chart showed. The torque increase was, to my eyes, astonishing. There were no torque hole in either configuration, but the "plateau" in the midrange was much higher with the gauze filter. Perhaps with the teardrop holes they'll be even in power? I will try it.

 

V11s do fine on the dirt, unless it's deep and loose. Respring for your weight, first, though.

 

Greg,

you will be surprised how much difference the teardrop holes will make all the way through. You will get as much or more gain than the original 3 holes gave, and will probably fill in the deficiency? you found over the cut away lid setup.

 

This improvement came as a vision at 2 am one morning, (why I keep a notepad and biro near the bed!) It took some time to test and get a design I was happy with.

It took me a while to understand why it works, but there was a logical explanation once I worked it out.

 

Probably wont bore the masses with it.. Im guessing you can work it out if you look at it long enough.

 

Phil.

 

I must try it, then. And please bore us with your story. I love a little mysticism with my bits and bytes and cfm.

[Skeeve]

 

***warning speculation follows, please ignore***

I would not be surprised if a better runner design could make the pods work better. I suspect the stock runner is not the ideal length for the pods, and also how the runner pushes the pods towards the frame puts a limit on what size pods can be used with the stock runner.

The V11Sport has only been out for a few years, eventually someone will test some runner tuning lengths beyond the two most obvious configurations.

I'd love to completely re-design the air box.

Phil has impressively maximized its potential by flaring open the intakes and cutting critically placed holes.

I wonder how much more power can be gotten out of a better designed airbox.

Larger filter area,

longer straighter runner,

filter placement so that gravity does not dump and trap crap in filter pleats,

Larger snorkles with tuned length and positive ram air positioning.

***speculation over, please return to your regular reading***

 

[emphasis added above]

 

Well, the airbox we're working with is basically Dr. John's update of the airbox Umberto Todero came up with for the LMIII back in the late 70s, so it stands to reason that there's room for improvement. Only, there's literally no room for an improved airbox, unless we want to go back to the mono-posto original Daytona, w/ the airbox in the tail! Alternatively, we could revert to the Tonti frame, w/ some slight redesign, drop the fuel tank down where it belongs [for mass centralization] between the cylinders, and put a larger volume airbox under a false "tank" cover a la' Buell & the MGS01.

 

But on our spine frames, the spine & shock are filling the space that our airbox & gas tank needs to occupy, so I'm thinking Phil A's mods to the stock airbox [that between U. Todero & Dr. John, probably already have untold man-hours, if not man-months or even -years of time spent in optimization within the space- & noise-constraints imposed by frame design or govt. edict] are about the best that can be done under the circumstances.

 

Of course, I still entertain the thought of rigging up some sort of ram-air intake on my LeMans, since the fairing is just there taking up space anyway, but then what am I going to do w/ the darn headlight?

 

[Skeeve]

Well, I'm too dim you bastard so how about giving me a hand up?

 

Pete

 

Well, Pete, here's my guess [hopefully, Phil will chime in to say how close or far off I am... ]:

 

the holes in the back corners of the box help delete the harmonics reflecting off those corners [a sawed off corner of a cube being the optical basis of the retroreflectors they put on the Moon for laser-ranging of that satellite, and molded into the back of clear amber or red or white bits of plastic are affixed to bicycles the world over] - so that's why they're where they are.

 

The central hole is there partly for increased airflow thru the filter, and also because being 1/2 the area of the other two holes, it deletes the harmonic that their presence would create.

 

The teardrop shapes work because they're essentially a whole range of holes [excuse the pun] .o0O so that the harmonics between all three teardrops are kind of "self-tuning" in eliminating themselves.

 

Anyway, that's all I can figure from my limited knowledge of high-school physics and Aristotlean logic [known for being fallible beyond all others! ]

 

Really looking forward to Phil A giving us more details of his 500cc dry-lake racer: it sounds quite interesting!

[dlaing]

[emphasis added above]

but then what am I going to do w/ the darn headlight?

Mount it on your helmet!

Yes there is not much room under the tank.

A lower gas tank does seem to be the way to go.

But that would be a major modification.

Some ideas I have had are to raise the tank, put airbox over tank, put airboxes under cylinder heads, and putting airbox under seat.

The ideal intake point is probably about the headlight.

One could probably replace the headlight with two smaller, somewhat fashionable lamps, letting the air flow presumably into two tubes, probably routed outside the triple clamps and forks, down along the path of the exhaust pipes, under the cylinder heads where there would be one of these beautiful air filters

http://www.bmcairfilters.com/infoCDA.asp A pair of the CDAxx-130 would have little filter element resistance.

on each side of the bike and then bent around in a perfectly tuned bend to the throttle bodies, possibly with a X-over between the throttle bodies.

But again getting all the tuning done right is key.

It boggles my mind how Phil came up with his modification design.

Belling the snorkels made sense, but the holes seem to be more counter intuitive.

Maybe if I try to explain what I think is going on, Phil will set me straight.

If he did not drill the holes the performance would be better than stock, but still there would be a venturi effect robbing the performance. The snorkels direct the air flow over rather than at the filter element. This has a tendency to reverse the flow of pressure. But if the air is headed to the filter element from above, through the tear drop holes, it can be drawn directly through without the counter productive venturi effect.

If he had simply removed the airbox lid the draw through would be direct and he would also make more power than stock, but the filter element would be less protected, it would draw in more hot air at low speeds, and there might be more turbulents, and the tuning length effects would be different. This could be why Greg Field got more high RPM power when he headed in the direction of Phil's design, as the snorkel's tuning length kicked it into supercharged mode at a higher RPM.

Does that make sense? Phil? Anybody?

[Phil A]

I know am a constant source of amusement to you Pete, but ya cant argue with the horses i can find that are tied up inside these things just waitin to be let loose

All of the comments made on this last page sound fairly valid to me however due to time constraints I wont try and answer each one.

One thing I will say, is that that I believe that once the bike is moving, the temperature difference between the front of the airbox and the top of the box is minimal.

 

I will just try and give you a simplified version of the logic that went into each modification.

Thinking time was over aperiod of months and months. No I dont sleep.

 

The bellmouths I think, speak for themselves. There is heaps of data published on this topic.

 

The principles I use have been used forever. It is the application to which it is applied that usually requires the thinking.

In this case it was the fact that 30mm snorkels wont supply 50mm throttle bodies! That is a no brainer.

 

Because the air box adds resistace then you would need at least 2 x 60mm supplies. Is it really that hard?

The bell mouths can only be made so big. We still have a deficit to make up.

 

Ok ok we now get to the holes.

As previously mentioned, we have a wayward harmonic screamin around inside the air box.

 

As the supply holes to the box (30mm) are smaller than demand (50mm throttle bodies) then there must be a low pressue situation in the box. The lowest pressure is going to be in that back corner of the box.

 

Try and imagine that you are diving head first into the engine (via the airbox). What is the shortest route to the cylinder? It aint via the furtherest corner of the airbox I can tell ya.

 

Sooo......... if we put a couple of holes in the corners of the box lid, we might just let out a bit of that errant harmonic, and if we are lucky the low pressure condition in the rear of the box might let some extra air in.

Double bonus.

Now....... the shape of the individual holes and the formation of the holes is exactly the same explanation, but it is the hardest to explain and understand.

 

As the air begins to fall into the begining of the teardrop it forms a slight low pressure around its extremeties. IT being the "bit" of air that is falling into the hole. This in turn "sucks" more air into that low pressure area, which creates a bigger low pressure area which sucks more air etc etc.

You need to try and visualise this in 3D. It makes a little tunnel of air or a tube of air heading into the hole.

 

The first hole effectively creates a low pressure area around the extremeties of this tunnel of air (which it has stolen from the air travelling between the box and the tank) forcing the remaining surrounding air to move towards the centre and down towards the lid. As it moves toward the centre and down, we put two more holes in its path to further entice it down into the box as described above. Effectively the first hole has created a low pressure area moving down and in, behind it. Does this make sense?

Dont forget that all this is taking place in a shape that is dictated buy the airbox lid and the fuel tank, therefore this is aided by the fact that we have a "relatively" captive supply of air needing to go somewhere.

 

The teardrop shape definitely improves the flow for two reasons. One is utilising the vacume or negative supercharger effect, and the other is that it keeps the air from tumbling over itself at the edges as it does through say, a square hole in a flat plate.

 

Hope this helps.

[Tom M]

Phil A,

would you mind sharing the length and width of your teardrop cutouts?

[motoguzznix]

 

 

 

Maybe this will explain things a little clearer.

These mods will make your engine run lean so I dont recommend them them to anyone who does not have the provision to add more fuel to compensate. ie My16m or similar.

 

Pierre, exhaust rear mufflers are 2'' straight through. Centre muffler is stock.

 

For the mods described no modifications were done to the bell mouths or the ram tubes attached to the throttle bodies.

 

YEP, pods on stock runners with airbox removed and these airbox mods give similar hp figures.

 

YEP, this was a "noise and filtration driven approach "

 

Regards,

 

Phil A.

Sorry but I cannot see the pictures on my Computer - is there anybody out that can provide them in a different format?

Would like to see how the teardrop shape is executed.

Thanks

[dlaing]

Sorry but I cannot see the pictures on my Computer - is there anybody out that can provide them in a different format?

Would like to see how the teardrop shape is executed.

Thanks

Try viewing them here:

http://s109.photobucket.com/albums/n78/PhilA_02/

[Skeeve]

Just one question remains:

 

 

How do you do this? Dip the intake horns in boiling water? Blowtorch? Clicking your heels together & saying "I want to go home, I want to go home, nah I changed my mind, I want a better airbox lid instead?"

 

After spending an altogether unreasonable amount of time struggling to get the darn fuel tank off[1], I finally managed to work my way down to accessing the lid. Now what?

 

 

 

[1] We should start a FAQ titled "Things You Ought To Know About Your Guzzi That Make No Sense Whatsoever." In it we can put answers to such questions like "Why does Guzzi use a really great connector on the red/black pair of wires, & then use this impossibly annoying different style on the blue/white pair? Instead of just reversing the good connector, Guzzi chose to utilize this square block w/ a clip that can only be lifted to release the halves. Only, lifting the little arm of the clip doesn't release it, pressing it down does. Only you *can't* press it down because of the little plastic post beneath it. Get some needle nose pliers and rip out the post. Of course, even being able to see what the problem is while fiddling around beneath the tank is what makes this whole FAQ necessary...

 

Anyway, once the post is torn out, you'll be able to press down on the little arm, releasing the connector. Then you just need to run to the hardware store for 1/4" & a 3/16" hose barbs so you can cut the overflow & vapor recovery tubes & make the job easier for yourself the next time you take off the tank.

[Tom M]

Just one question remains:

 

 

How do you do this? Dip the intake horns in boiling water? Blowtorch? Clicking your heels together & saying "I want to go home, I want to go home, nah I changed my mind, I want a better airbox lid instead?"

 

 

I warmed the bellmouths up with a heat gun and flared them to 50mm with a beer bottle, per this thread: http://www.v11lemans.com/forums/index.php?...=8924&st=30

[Greg Field]

Seems apropos in this thread, so I'm posting the dyno charts here, too.

 

 

This one is the chart after mapping the PC III. Configuration is '04 Ballabio with Mistral cans and crossover and airbox cut per Phil A.'s earlier recommendations, using round holes. If there's a torque dip, the chart appears not to show it.

 

 

 

This one's an imperfect comparison of the mapped configuration used on the first chart with nothing else changed except that I swapped on a BMC filter and fastened it with an airbox top that was completely cut away save for the rim. Surprising to me was how much more midrange torque it made with the BMC but that the paper filter produced more peak power. Both are contrary to what I would have expected.

[motoguzznix]

Seems apropos in this thread, so I'm posting the dyno charts here, too.

 

 

This one is the chart after mapping the PC III. Configuration is '04 Ballabio with Mistral cans and crossover and airbox cut per Phil A.'s earlier recommendations, using round holes. If there's a torque dip, the chart appears not to show it.

 

This one's an imperfect comparison of the mapped configuration used on the first chart with nothing else changed except that I swapped on a BMC filter and fastened it with an airbox top that was completely cut away save for the rim. Surprising to me was how much more midrange torque it made with the BMC but that the paper filter produced more peak power. Both are contrary to what I would have expected.

Greg

 

For me it is still hard to believe that the measured Power/torque difference is caused by the filter element. It seems more to be related to the differences in the air box design. I beleive the difference caused by the filters themselves will be unmeasurable.

Swap the filters in the airboxes and measure aigain to be sure.