Why V-Boost?

[MaxMidnight]

So my question is, why have a V-Boost system? Why not have slightly bigger carbs and inlet manifolds?

Engines are made up of a lot of compromises.

One example is the choke size of the carb(s). You want to keep the airflow as high as possible as this gives better atomisation of the fuel which = more power.

But there is a problem. If we select a choke size which maximises low and mid range power then as the revs ris there will be a point where you can't get any more air through the orifice. You will limit power at higher revs.

So lets put larger carbs on! Good idea but....the aiflow will be slower at low to mid revs therefore poorer atomisation and less power. You don't get 'owt for nowt.
This is well demonstrated by the dyno charts wich shows a reduction in low to mid range power if V Boost is opened earlier.

As we know those clever Yameringha folk sidestepped this conundrum with V Boost which maximises the power (or more correctly, torque) throughout the rev range.

 

[ninjaneer]

Engines are...

Thanks MM, I was waiting for this kind of answer! Love this site--learning something new every day.

regards from my tapatalking android...

 

[ricko]

When I installed my Kerker 4-1 and Stage1 in 87, the Vboost came out and straight tubes went in. That was so long ago I don't even remember what I did with the parts. Now I'm wondering how much effect it's having on getting the A/Fs tuned and synchronizing since I just rebuilt the carbs? Do I have to pull the carbs, block the tubes to tune and pull them off again to unblock?

 

[KJShover]

When I installed my Kerker 4-1 and Stage1 in 87, the Vboost came out and straight tubes went in. That was so long ago I don't even remember what I did with the parts. Now I'm wondering how much effect it's having on getting the A/Fs tuned and synchronizing since I just rebuilt the carbs? Do I have to pull the carbs, block the tubes to tune and pull them off again to unblock?

It definately makes getting them synced interesting. But it can be done with the webber sync tool. I can imagine an A/F issue would be harder to chase being you have two carbs to tune instead of 1 carb/1 cyl.

Others leave the Vboost intact but just unplug it when it opens the butterflys. This way you can close them when it comes time to sync the carbs.

 

[ricko]

Too bad this, what would have been futuristic site, didn't exist back then. Hell, I guess that was even before Al Gore invented the internet!