Throttle Body Butterfly Inefficiencies

[al_roethlisberger]

I don't know if anyone has ever noticed, but if you take a gander at the TB intake butterflies, the left side opens away from the injector, and a mid/part throttle is actually deflecting air away from the injector <_>

 

Many of you may have noticed this effect while trying to balance the TBs where at part throttle things become uneven when the left side is getting a less efficient airflow/atomization .... but at full throttle both butterflies would be wide open.... at least that is a theory

 

I doubt this has much impact, or maybe it is the cause of our mid-range dip ...who knows.

 

This is just speculation at this point, and it would take a good bit of re-engineering to even attempt to change the direction the left butterfly opens, to test and even verify any potential benefit.

 

But I think it is interesting food for thought

 

 

al

[callison]

I don't know if anyone has ever noticed, but if you take a gander at the TB intake butterflies, the left side opens away from the injector, and a mid/part throttle is actually deflecting air away from the injector  <_>

 

Many of you may have noticed this effect while trying to balance the TBs where at part throttle things become uneven when the left side is getting a less efficient airflow/atomization  ....  but at full throttle both butterflies would be wide open....  at least that is a theory 

 

I doubt this has much impact, or maybe it is the cause of our mid-range dip    ...who knows.

 

This is just speculation at this point, and it would take a good bit of re-engineering to even attempt to change the direction the left butterfly opens, to test and even verify any potential benefit.

 

But I think it is interesting food for thought 

al

50952[/snapback]

 

Darn you Al. Now I'll spend hours pondering an effective method to test your theory.

[dlaing]

The mid-range dip occurs at WOT.

But the valve inefficiencies is an interesting topic.

Are other bikes better designed in this respect?

 

 

 

 

"You're a butterfly

And butterflies are free to fly

Fly away, high away, bye bye"

-Bernie and Elton

[Paul Minnaert]

I have a 916 throttle body at home,I will check how that works.

[helicopterjim R.I.P.]

I don't know if anyone has ever noticed, but if you take a gander at the TB intake butterflies, the left side opens away from the injector, and a mid/part throttle is actually deflecting air away from the injector  <_>

 

Many of you may have noticed this effect while trying to balance the TBs where at part throttle things become uneven when the left side is getting a less efficient airflow/atomization  ....  but at full throttle both butterflies would be wide open....  at least that is a theory 

 

50952[/snapback]

I'll stick to my theory of 2 throttle positions. Parked and WFO!

[callison]

I'll stick to my theory of 2 throttle positions. Parked and WFO!

50970[/snapback]

 

Well, you can. When I go WFO on my V11 Sport, the ECU fuse blows and WFO becomes WTF??? I did ride it to work and back once last week, but it's not a lot of fun when you have to gingerly apply throttle to avoid coasting to a stop.

[al_roethlisberger]

I have a 916 throttle body at home,I will check how that works.

50966[/snapback]

 

 

I have heard, but not *confirmed* that because of the physical arrangement of the cylinders and TBs on an engine like the Ducati, the injectors end up on the same side of the TB as the "opening" side of the butterflies.

 

It appears that MG simply either:

 

1) Didn't think the engineering through on this issue, and have mirror image TB butterfly assemblies for both sides, with reverse linkage, etc...

 

or

 

2) Had to engineer as best they could given a budget, and used off-the-shelf TBs

 

 

And to reiterate, who knows if in practice this really makes any real difference in performance. I have no idea, but just at a glance it seems that at part throttle, it would introduce some degree of inefficiency for the left cylinder. But maybe it doesn't. Only detailed testing( = time and $$) would tell.

 

But I'd love to know, and if there is improvement, it would be really cool to have a "kit" to flip the butterfly on the left But I think that's putting the "cart before the horse" at this point of course

 

 

al

[Paul Minnaert]

Al, the 916 set does the same as guzzi. Just as much thinking put into it.

If it hurts? But you noticed that there is a difference!

[al_roethlisberger]

Al, the 916 set does the same as guzzi. Just as much thinking put into it.

If it hurts? But you noticed that there is a difference!

51009[/snapback]

 

 

Interesting on the Duc....

 

BTW, *I* didn't notice this. The credit should go to Julio at Moto Italiano, one of the technicians there. He noticed it and we ended up discussing it at length

 

al

[DeBenGuzzi]

You ought to slap him now we got something else to worry about trying to tweak. Like I don't think about my guzzi enough already, ehhhhhh. I'll worry about that bridge when I get there I just need my bike back now.

[al_roethlisberger]

You ought to slap him now we got something else to worry about trying to tweak. Like I don't think about my guzzi enough already, ehhhhhh. I'll worry about that bridge when I get there I just need my bike back now.

51037[/snapback]

 

 

Well, keep in mind.... this doesn't belong on the "worry" list at all

 

 

This would fall squarely into the "improved performance - tinkering" list on non-essential issues

 

 

As an aside though, during the same conversation, we did find that one can(if careful and diligent) work the K&N filters over the stock velocity stacks that normally run into the airbox. So if one is of the mind to be concerned about airflow, and wants to use the stock velocity stacks/runners with their pods, you can... with generous lubrication and patience.

 

 

.... oh, and get your heads out of the gutter for Pete's sake

 

al

[DeBenGuzzi]

Well, keep in mind.... this doesn't belong on the "worry" list at all 

This would fall squarely into the "improved performance - tinkering" list on non-essential issues 

As an aside though, during the same conversation, we did find that one can(if careful and diligent) work the K&N filters over the stock velocity stacks that normally run into the airbox.  So if one is of the mind to be concerned about airflow, and wants to use the stock velocity stacks/runners with their pods, you can... with generous lubrication and patience.

.... oh, and get your heads out of the gutter for Pete's sake 

 

al

51041[/snapback]

My worry is more about being able to afford all the mods I want to do let alone the possible breakdowns. not soo much in the break down cat at least. I feel very confident about my goose like an old tractor that just needs a little talking to if she fails to start. Anywho you already covered the sexual reference so I'll just be going now.