Variable Venturi VS. Fixed Venturi carburetor?

[dat]

Which one did you guys prefer?and which one is the best application?

[lostforawhile]

i will post on here later with the links to my dual SU project

[2oodoor]

I believe one of the advantages of VV carb is you do not have to swap jets to achieve your desired stioch, you do have to have a VV carb that is matched to your particular engine's vacuum capability relating to the resistance of the plunger "venturi" piston though.
I wonder if that advantage sustains with barometric pressure changes and air temperature changes though. That is the biggest PITA with Holleys and Webers IMO.

[2ndGenGuy]

I believe one of the advantages of VV carb is you do not have to swap jets to achieve your desired stioch, you do have to have a VV carb that is matched to your particular engine's vacuum capability relating to the resistance of the plunger "venturi" piston though.
I wonder if that advantage sustains with barometric pressure changes and air temperature changes though. That is the biggest PITA with Holleys and Webers IMO.

Isn't there some kind of a needle valve on a VV carb that you can change out for your particular application to make it work right?

[2oodoor]

Isn't there some kind of a needle valve on a VV carb that you can change out for your particular application to make it work right?

Precisely
and the other concern I mentioned could be addressed by saying they use these on small aircraft

[2ndGenGuy]

My dad has a pair of big VV carbs on his motorcycle. I guess the throttle response is not quite as snappy with them, but they run much nicer and are far easier to tune. At least that's what I hear. No jetting to mess with. His bike has two 40mm carbs, and it's a 2 cylinder, 1000cc bike. I imagine a 4 cylinder, 2000cc car engine would take a set of 4 quite nicely.

[dat]

have you guys seen the variable venturi downdraft?(SU is sidedraft)...its comes from aisan japan?been used on Toyota if i'm not mistaken.
have any of u guys using it?