aria! stock air box

[docc]

It is always *an event* when the V11 is apart and waiting for parts . . . things happen. There's no stopping it!

 

Preparing for a ride (five days out ) to the Barber Vintage Festival, I figured on installing my "spare" (incorrect) throttle cable. See the other threads for that cock-up.   . . . while performing, Beta testing, and revising the Tank Off Maintenance Checklist.

 

So, with the Sport poised like a willing *subject* in The La-BOR-atory, and the airbox lid at hand I couldn't ignore the findings of PhilA and the observations of Greg Field.

 

http://www.v11lemans.com/forums/index.php?showtopic=18909&p=100986

 

I have also retrieved the stowed electrical lead for the original electrical petcock (Fuse 8) to route forward a "Systems are GO" (Go_Winkie) indicator light, per Kiwi_Roy's encouragement.

 

My, my . . .

 

Wish me luck. Send beer . . .

[czakky]

Uh-oh, I don't see any "speed-holes" in the airbox lid? Is there an after shot?

[docc]

On 10/3/2015 at 5:11 PM, czakky said:

Uh-oh, I don't see any "speed-holes" in the airbox lid? Is there an after shot?

Stand by . . .

[docc]

Also, searching (diligently, I assure you, Sir!) for the correct glass mandrel to expand the "bell mouths" to a proper 50mm . . .

(I was hoping the "OLD LEGHUMPER" would do it, just for bragging rights.)

[czakky]

Ok good, there is a hammer in the background.... Scared me for a second.

[Gio]

Docc - please do not use that 1" bit on the air-box ... Geese are allergic to anything imperial - please find something marked mm ... (eg 27 x 10 mm holes should do the trick ... mmm)

[Admin Jaap]

I know we all are getting dependent on computers more and more, but for Pete Roper's sake, who needs a MacBook for drilling holes in the airbox lid?

 

[Scud]

The Macbook is an accoutrement - in silver to go with Docc's color-matched Sport.

 

@Docc - eager to hear whether the ear-dyno or butt-dyno confirm prior findings.

 

More seriously - I assume the computer is there so you can check/improve the Tank-Off Maintenance Checklist.  Thanks again for being the custodian of that.

[JBBenson]

Docc:

 

Since you and I have essentially the same bike (mine being slightly faster), and I assume the laptop is for working magic with Guzzidiag, can you share what exact cables etc that work with your bike and a Mac laptop....? If that is what you are doing.......?

 

Muchas Gracias de California,

 

Jésse

[docc]

@ Gio - I just cannot bring myself to make those holes! I am going to study up on NACA ducting, but will likely leave the lid sealed.

 

@JBB - The three cables cost me about $75US: 1) Caspers TPS breakout harness to set the baseline TPS with a voltmeter; 2) FTDI chipped OBD to USB like this one from ECS Tuning; 3) FIAT/Lancia 3 pin to ODB adapter cable.

[edit Jan 2020: No surprise the ebay seller for Cable#3, above, is long gone. Looks like Lonelec still offers the #2/#3 combo:

https://www.lonelec.co.uk/index.php?route=product/product&product_id=51]

 

Somehow, it just seems right to use both a hammer and a computer to tinker with the Guzzi! I really only had the Tank Off Maintenance Checklist    for reference and revisions (no guzzidiag  this time)

 

After some hours of using "glass mandrels" (which had to be first emptied! )  and a heat gun, I managed to give the inlets a nice, polished bell shape, but only opened them about 5mm (not the 11 mm specified by PhilA). I expect it to make no appreciable difference outside of my cognitive existentialism.

 

But they look nice!

[docc]

To be honest, I found the inlets to be a definite choke point. The more I worked with them, the more I realized how much they pinch down as the air goes in and how irregular the first 3"/75mm.

 

If the inlet started at 39mm, it must have pinched down to 35mm inside necessitating a lot of prying and shaping with glass mandrel #1 (EvilTwinBrewing YIN Imperial Taiji Stout) with final shaping and polishing with mandrel #2 (Austria's Hofstetten Granitbock). While mandrel #3 (Oregon's RogueXS Bitter Ale) had the specified overall diameter, I just could not take it out that far; ran out of time, steam, and gumption.

And beer.

 

The plastic of the air box is very stout (heh -  pun ; / ) and took quite a lot of careful heating and shaping to rework.

[Welshguzzi]

Question: will they look better with the tank on?

[docc]

Question: will they look better with the tank on?

"Therein lies the rub."

 

I think they're just gonna feel better, all smooth and polished and bell-mouthy . . .

 

Although, the right was palpably more restricted than the left. I wonder if the intake balance may have changed? Or the idle speed nips up a bit?

 

Otherwise, it's all largely a subjective exercise. I've always been a sucker for "velocity stacks!"

[JBBenson]

To be honest, I found the inlets to be a definite choke point. The more I worked with them, the more I realized how much they pinch down as the air goes in and how irregular the first 3"/75mm.

 

If the inlet started at 39mm, it must have pinched down to 35mm inside necessitating a lot of prying and shaping with glass mandrel #1 (EvilTwinBrewing YIN Imperial Taiji Stout) with final shaping and polishing with mandrel #2 (Austria's Hofstetten Granitbock). While mandrel #3 (Oregon's RogueXS Bitter Ale) had the specified overall diameter, I just could not take it out that far; ran out of time, steam, and gumption.

And beer.

 

The plastic of the air box is very stout (heh -  pun ; / ) and took quite a lot of careful heating and shaping to rework.

 

 

As the inlet is narrowed the pressure drops and it speeds up AKA the venturi effect. 

 

I would guess that the only time a larger inlet would make any difference is at idle or at the moment you crack the throttle. As the throttle is opened the only limitations at that point is the intake valve opening and speed.

 

Those are my thoughts. 

[GuzziMoto]

It goes both ways.

If the inlet narrows the speed increases and the pressure decreases.

If the inlet widens (as the stock ones do) the speed decreases and the pressure can increase (as long as the rate of area increase doesn't go up faster than the flow can fill it). An increase in pressure is good, but not in the pipe leading to the air box. You want that pressure increase in the airbox and not on the way to the airbox. An increase in pressure in the pipe leading to the airbox would likely reduce flow to the airbox.

I think the alteration to the airbox intakes that Phil did were mainly to address the very beginning of flow into the airbox. I think it was geared towards getting the air to smoothly enter the tubes, thus maximizing the flow into the airbox. A tube with an abrupt opening can develop turbulence around the opening. That turbulence can make the actual opening flow less air then it should. I think the alterations were trying to improve that first part of the flow.

Filling in those odd shaped "resonators" (at least that is what I assume they are) would probably also help, as would anything else you could do to make the area of the intake constant through out the length.