velocity stacks

[Guest slowpoke]

I cleaned my K&N pods the night before and lo and behold I forgot to put them back on the next morning and the bike ran alot better (I think). Yes I do believe it did. There was not as much hesitation-herky jerky I call it- in the low rpm's in traffic. It seemed to have as much power and well... just smoother. Anyone out there have experience with velocity stacks on a Moto Guzzi? I believe some have done it to their Centauro's (once again-I think). The only problem with them is one would need some sort of gauze or screen to keep out debris. I may be just hallucinating because the Guzzi seems to feel different everyday that I ride it. I think that is what is called "character".

[helicopterjim R.I.P.]

Try this link - about half way down the page you will find some Centauro/Daytona velocity stacks that may work for your V11.

Sport Cycle Pacific

 

P.S. My SFC has velocity stacks!

[Paul Minnaert]

the daytona/centauro ones have a bigger diameter. But verlocity stacks should be on the bodies, not the k&n's direct mounted.

[Baldini]

...the Guzzi seems to feel different everyday that I ride it...

 

Weird isn't it....mine's the same, so are the old ones. One day it feels so good, next day it feels rough. Nothing in tuning or faults - just seems bike reflects how I am, how I'm riding. Better shut up now. But I've not ridden anything felt same way, but then I've not ridden anything as much to get to know it so well.

 

KB

[al_roethlisberger]

Yeah, the velocity stacks linked above only fit the 4V engine setup...

 

I've inquired(do a search on velocity stacks )

 

 

But, you can fit your K&Ns over the stock plastic velocity stacks. One of the mechanics at the local shop did just that, and with a little lubricant and patience, you can work the filter over the OEM stack, and bolt it all back up to the TB easily. You'll just end up with a slightly "longer" solution, and hence the stock side covers will probably never fit again(if like me you had rigged up a frame to support them).

 

I planned to fiddle with this sometime later after the move.

 

al

[big J]

Weird isn't it....mine's the same, so are the old ones. One day it feels so good, next day it feels rough. Nothing in tuning or faults - just seems bike reflects how I am, how I'm riding. Better shut up now. But I've not ridden anything felt same way, but then I've not ridden anything as much to get to know it so well.

 

KB

55218[/snapback]

Thank god for that, I thought it was only mine that was like that. Checked all the TPS ,tappets,etc,etc. Still rougher than a badgers arse. Take it out next day, fine. Next day, rough again-WTF?! I was beginning to believe Luigi had tuned my ecu to Mandello local radio,if there's good news at home,she's happy.

[Guest slowpoke]

So I'm not the only one that has this affliction. Some times the bike just purrs and other times it's, well...weird. I did find a possible velocity stack solution from www.velocity-of-sound.com. The 48mm inside diameter should fit with some sort of sleeve and hose clamps. The outside measurement of the throttle bodies are 50mm and 48mm + approximately 2mm thickness for the velocity stacks should be pretty spot-on for the fit. Now if I can just figure out what kind of screen to use...hmmm

[Guest tinyelvis]

I got a pair of prototype velocity stacks for my V11 from this guy.. guzzidave@hotmail.com they're AWESOME.. They weren't too expensive either, shoot him an email. Great guy, really nice and great feedback via email. Can't say enough good things.

 

Here is a pic of my Guzzi with the stacks on her.. This is on our way to Mid-Ohio for the vintage races.. camping gear baby!

 

TinyE

 

[Mike Stewart]

Tiny,

 

Looking Good!

 

Mike

[Guest ratchethack]

I cleaned my K&N pods the night before and lo and behold I forgot to put them back on the next morning and the bike ran alot better (I think). Yes I do believe it did. There was not as much hesitation-herky jerky I call it- in the low rpm's in traffic. It seemed to have as much power and well... just smoother. Anyone out there have experience with velocity stacks on a Moto Guzzi? I believe some have done it to their Centauro's (once again-I think). The only problem with them is one would need some sort of gauze or screen to keep out debris. I may be just hallucinating because the Guzzi seems to feel different everyday that I ride it. I think that is what is called "character".

55201[/snapback]

Hey Slowpoke, this is interesting, but don't you think you might be treating the symptom instead of the cause by going after the "herky jerky" thing by going to velocity stacks? Not to condemn what you've done - different strokes and all that - and I'm sure you've weighed all the considerations. However, others reading this thread may not fully understand that of course there's a very important tradeoff involved here. There's a reason that mfgr's put air filters on engines, and it isn't for cosmetic purposes, or to decrease performance. It's to give them a reasonable operating life.

 

On the racetrack or pursuing a speed record, it makes sense that stacks are the way to go for performance reasons. There's no denying that open trumpets will make any engine run stronger if it's properly tuned for running this way. With race engines, the performance gains of open intakes offsets the substantially accelerated engine wear caused by unfiltered air, because race engines typically get rebuilt or thrown away before the cumulative scouring effects from ingested road grit, dirt, dust, salt, sand, etc. can take a performance toll during the relatively short lifecycle for which the engine has been built.

 

On the road, however, where presumably you're racking up thousands of miles with no (or very little) expectations of rebuilding the engine, for many if not most non-racing Guzzisti, it would seem at least questionable, if not unwise, to remove this fundamentally important means of protecting the engine. For comparison purposes, I would consider that going without an air filter is likely even harder on an engine in terms of shortening it's lifespan than going without an oil filter.

 

This is just me, but I wouldn't run my car, or even my lawnmower for that matter, without an air filter - let alone my precious Guzzi - not for even a minute. I plan to ride for many many years without the need for a rebuild. I've bought a dozen used bikes. If I had any indication that any of them had ever been run with open stacks, (or even K&N's, which are far superior to stacks as far as engine protection, but nevertheless allow passage of destructive particle sizes up to 3X the size of the best quality air filters) I'd have let 'em pass. Just my

 

And jeez - what's to prevent such items as rocks, insects and small birds from being sucked into the tremendous hurricane vortex of the wide-open V11 throttle bodies at full chat!?

[Guest tinyelvis]

Tiny,

 

Looking Good!

 

Mike

55738[/snapback]

 

 

THANKS!! They're awesome and damn does the bike sound good....

[al_roethlisberger]

Interestingly, from an aerodynamic sense, some of the benefit I've heard that a well designed velocity stack, is the the air it draws up and around around the "flare"/"bell" edge as well... not just a direct shot down its throat.

 

So, if one bolts a filter directly to the end of a VS, in theory some of that benefit is lost.

 

In fact, if you look at our stock plastic VS that goes into the airbox, you will see that it protrudes an inch or more into the volume of the airbox, allowing it to draw air from all around the bell, not just a direct shot.

 

How much benefit does this provide?? I honestly don't know, but have heard that it is significant.

 

So, as I mentioned in another thread, I am very interested in shoving my big K&N filters over the stock VS, such that the "flare"/"bell" is inside the volume of the filter cylinder.

 

An acquaintence mechanic at a local dealer has done this, and it is feasible, although shoving/working the K&N over the end of the flare is a bit of a trick, and takes patience.

 

 

al

[Guest slowpoke]

Ratchethack, I realize that there is a lot of debris that can potentially flow up into the intake either from the rear wheel or just happenstance from the atmosphere. But I'm a (former) sailboater. And when any wind force is sent over a curved surface one side becomes the negative and one side becomes the positive. Well it seems that the pods are not formed that way and whether or not they are getting the correct air pressure in lieu of the pressurised airbox that was intended with the original configuration is open to debate. The gentleman that is at Orange County Motorsports says that the reason for my inadequate dyno test is because I have the pods, (and no airbox) the Quat-D and no crossover and dual pipes. Well, I noticed a change in the performance with the pods removed. Could this be that when riding the bike an air flow occured over the throttle bodies creating a negative pressure that enhanced air flow into the cylinders? Perhaps it did and perhaps not. I would still like to try them-with some screens-and do a test. Also, thanks tinyelvis for the info on the velocity stacks I'm definitely going to contact. Thanks again guys.

[GuzzTim]

I would still like to try them-with some screens-and do a test.

 

I wouldn't worry about a little debris during the test...

 

Hell, some central valley guys I know throw their Guzzi's over a cliff, let 'em cartwheel 100ft, yank them back up by a towtruck, then ride 350 miles on it the next day...

 

What's a little road debris !!!

[Guest ratchethack]

Ratchethack, I realize that there is a lot of debris that can potentially flow up into the intake either from the rear wheel or just happenstance from the atmosphere. But I'm a (former) sailboater. And when any wind force is sent over a curved surface one side becomes the negative and one side becomes the positive. Well it seems that the pods are not formed that way and whether or not they are getting the correct air pressure in lieu of the pressurised airbox that was intended with the original configuration is open to debate. The gentleman that is at Orange County Motorsports says that the reason for my inadequate dyno test is because I have the pods, (and no airbox) the Quat-D and no crossover and dual pipes. Well, I noticed a change in the performance with the pods removed. Could this be that when riding the bike an air flow occured over the throttle bodies creating a negative pressure that enhanced air flow into the cylinders? Perhaps it did and perhaps not. I would still like to try them-with some screens-and do a test. Also, thanks tinyelvis for the info on the velocity stacks I'm definitely going to contact. Thanks again guys.

55783[/snapback]

Slowpoke, I'm also a bit of a sailor (NA 40, Silvergate YC, Shelter Island - 5 of 7 first places in our class last season) . But I'm missing something in your ref. to positive and negative air pressure. As Pete Roper pointed out recently in the discussion on crankcase breathing, air pressure is a relative measurement. He thinks of pressure as always positive with regard to engine operation ("there is no such thing as a 'sucking force'".) , in terms of always-positive differences relative to ambient (1 ATM, or 14.7 lb./sq. in. at sea level - there's your sailing connection ).

 

The stock airbox isn't ever pressurized relative to ambient. I don't know that there's any debate over this, as only supercharged and turbocharged engines have a positive intake pressure differential relative to ambient. In conventionally aspirated engines, air pressure will always be negative in the airbox (or less positive than ambient as Roper would say) as long as the engine is running, increasing in the negative direction with increased flow via throttle opening and engine RPM, pulling against the resistance of the airbox plumbing and/or filter element(s). The interior of the pods will similarly never be higher pressure than ambient, always lower whenever the engine is running. Stacks simply allow less negative pressure upstream of the TBs relative to ambient because they have no resistance of plumbing and/or filter media to pull the air through.

 

The Gent at OCM may have been referring to the way the engine-pulse wave resonance "signature" on the intake side with the pods (which seems to be considerably different than the wave resonance signature of the stock airbox) interacts with the unique resonance signature on the exhaust side of the Quat-D (without front crossover, as you noted) to influence overall flow through the heads. The output results of this interaction would map out on the torque and power curves on the dyno. If the resonance signatures on each side don't complement each other very well, your curves won't tend to be very impressive. I suspect this is the case with the Quat-D and pods.

 

Again, In almost any configuration or state of tune, I'd expect an overall improvement in dyno results by going to velocity stacks - except in the case where the change to stacks creates an over-lean condition. Any change that decreases air intake restriction will tend to make the bike run leaner unless the FI map has been adjusted accordingly.

 

My main point was to attempt to illustrate that there's a cost for the performance gains of open stacks for those who may not otherwise understand this. In any case, the relative torque and power benefits of stacks in real-world operation actually only apply to the purpose for which velocity stacks are designed - running at WOT, which happens to coincide with the way engines are typically evaluated on the dyno.

 

In my case (for one) it's another example of how dyno results don't always line up with the real-world use of motorcycles. I think of it this way: With air filters, at anything less than WOT, if you need more power, just crank in more throttle, and you've more'n likely got it. Me, because I'm just a Road Geezer, free of any (well, almost any) Boy Racer aspirations , I almost never run at WOT, and when I do, not for more than a few seconds at a time, but that's just me...