Academic question about carburetors

[Air4Life]

I can appreciate the added efficiency/power of having individual carbs for the corresponding cylinders, but is that the reason why it is/was done?

[tvrla]

I think you're right - it's a performance thing. Some guys with two cylinder nortons and triumphs swap out the two carbs for a single.

On the airhead beemers, the intake runners become too long trying to use just one carburetor.

[Justin B.]

I thought about plumbing in a Weber 2 bbl years ago but never got past the "pondering" stage...

[Motu]

The long manifolds would cause icing without some attention. Fuel injection with a central throttle body would work very well though.

[Air4Life]

I don't have a clear picture of a VW engine of the past.  How'd they minimize this problem?  It was of course in a cowled environment...

[Barry]

Twin carbs are only of real benefit in chasing maximum horse power. Further down the rev range  they are inferior to a single carb generally because if an engine is over carbed then lower velocity through the carbs means poorer atomisation of the fuel.

Old brits would run smoother with a single carb but notice they are 360 deg twins like an airhead. 180 deg Jap twins didn't like single carbs because of the unevenly spaced induction strokes.

[Justin B.]

One of the first things I used to do to an MG was to pull the SU carbs and swap in my intake and Weber setup.  When I sold it I pulled it off and put the twin carbs back on!

[Air4Life]

I'm kinda of surprised i haven't seen a version of this done before; but as with most of my ideas, it has been questioned long before I was born.

http://www.advrider.com/forums/showthread.php?t=672689  

It's not that the current setup is not working for me; it just adds the opportunity for part failure, added maintenance and costs.  Getting a simpler setup would really be the thing to do.  I wish I had the know-how and workplace to at least attempt to develop something like this.      

If the difference in power is not that great, I would also add that the interval between routine adjustments of the current setup has too fall out of efficiency along the way, and this would possibly minimize any of those suggested efficiencies over the questioned carb. setup ...obviously a total guess on my part.

[Justin B.]

A simple controller and TBI sounds interesting...

[Barry]

I read the AVrider thread and the main concern seemed to be the long length of the inlet tracts.  It depends what you want from the engine. If it's smooth tractability your after rather than instant throttle response then look at any modern car engine and you'll see very long inlet tracts. In some cases they can be tuned with a valve to shorten or lengthen the tract according to the revs being used. Long inlet tracts are reckoned to be a good thing for low/mid range torque.

One negative I can think of is the possibility of poor cold running performance because the mixture would be more likely to condense out before it got to the head. That would be what the reference to a heated manifold was about.