Understanding VBoost

[VS Bullet]

I read the FAQ and some other threads, but still have a question.
The Vboost is a tube with butterflies between the manifolds on each bank that opens at 6,000 rpm.
Does the VMax engine normally use 1 carb per engine side(or 2 cylinders), then when VBoost kicks in it opens an additional carb per side. or is it running off all 4 carbs all the time, if so where is the boost coming from?

Sort of like the old 4 barrel carbs worked, normally 2 barrell, then when the accellorator is depressed enough the other 2 kick in making it 4 barrell.

 

[VMAX1260]

there are 4 carbs . 1 for each cylinder. when the vboost open the butterflies allows one cylinder to take gas from 2 carbs thats why the raise of power. hope i helped.

 

[VS Bullet]

But if each cylinder is operating off 1 carb, what is the advantage of opening the manifold between the 2 carbs?
Unless - 1 cylinder is only using 1 carb during the intake stroke. If the intake strokes are at different times, then when the butterfly is open, 1 cylinder is taking air and fuel at twice the rate since the intake valve is closed on the other cylinder.

ok, I'm slow to catch on, but eventually i get it. LOL

Genius, and nobody ever thought of this before?

 

[98Redlne]

Under normal operation each of the 4 cyls draws from it's own carb.
The firing order is 1 3 2 4 (front left, rear right, front right, rear left)

When cyl 1 is sucking air and fuel through it's carb, cyl 2 is firing leaving the carb for cyl 2 to sit there doing nothing.
When the V-Boost opens, it allows cyl 1 to utilize both of the carbs for cyl 1 and 2 since the cyl 2 carb would have been idle anyway.

 

[Rusty McNeil]

Under normal operation each of the 4 cyls draws from it's own carb.
The firing order is 1 3 2 4 (front left, rear right, front right, rear left)

When cyl 1 is sucking air and fuel through it's carb, cyl 2 is firing leaving the carb for cyl 2 to sit there doing nothing.
When the V-Boost opens, it allows cyl 1 to utilize both of the carbs for cyl 1 and 2 since the cyl 2 carb would have been idle anyway.

+1, well done.....

BTW,......A Max with an Exhaust and open Vboost at idle will give you an erection unless your deaf.....

 

[VMAX1260]

+1, well done.....

BTW,......A Max with an Exhaust and open Vboost at idle will give you an erection unless your deaf.....

+1unk:

 

[MaxMidnight]

One of the many factors that affects the power that a motor can make is how well the fuel is atomized into the incoming air.
The higher the air speed the better the atomization, the smaller the fuel droplets, the better they burn, more power is made.

BUT...as in most things in life, the size of the carburettor venturi is a compromise.
If you want good power at low revs then you need a small venturi which will keep the air speed high. The downside of this is that at higher revs it can't flow enough air to satisfy the motor thus power will drop off.
So, you make the venturi larger so you can make power at the upper end of the rev range...but it will be too large at low revs so power will suffer.

Yameringha use carbs that are too small for maximum revs but overcame the limitation by letting a cylinder draw the air / fuel mix at higher revs from another carb once the V Boost butteflies start to open.

Manufacturers have used devices such as the power valve on two strokes and EXUP valve on a four stroke, and variable length inlets to perform a similar trick of spreading the power further over the rev range.

 

[2fear]

Great thread! I just learned a couple things myself....:cheers:

 

[satariel666]

One of the many factors that affects the power that a motor can make is how well the fuel is atomized into the incoming air.
The higher the air speed the better the atomization, the smaller the fuel droplets, the better they burn, more power is made.

BUT...as in most things in life, the size of the carburettor venturi is a compromise.
If you want good power at low revs then you need a small venturi which will keep the air speed high. The downside of this is that at higher revs it can't flow enough air to satisfy the motor thus power will drop off.
So, you make the venturi larger so you can make power at the upper end of the rev range...but it will be too large at low revs so power will suffer.

Yameringha use carbs that are too small for maximum revs but overcame the limitation by letting a cylinder draw the air / fuel mix at higher revs from another carb once the V Boost butteflies start to open.

Manufacturers have used devices such as the power valve on two strokes and EXUP valve on a four stroke, and variable length inlets to perform a similar trick of spreading the power further over the rev range.

Which is strictly done with DUAL THROTTLE VALVE sytems(named diffrently in diffrent brands) and "not so brilliant ideas" like Yamaha YCC-T and YCC-I.
As it goes with bikes of course.

As with cars - its nothing new from decades.