are velocity stacks necessary?
 

I was wondering if most conversions require the use of a velocity stack? Also has anyone ever turned it backwards and tried to "supercharge" one...[X(]

RE: are velocity stacks necessary?
 

They are not absolutely necessary and you can try turning it whatever direction you want and see how it runs?

Enjoy,

Jim

RE: are velocity stacks necessary?
 

Velocity stacks get their name from the speed your money leaves your wallet on something absolutely useless and power robbing. here is a chart of their effectiveness ( or lack of)

RE: are velocity stacks necessary?
 

Most of the carb extensions that people are using are not actually velocity stacks but extension devices to try to contain the reversion plume of fuel mist that forms at the entrance to the carb. They just make the needle easier to set and the plane a litte cleaner.

At least that's my experience.

Enjoy,

Jim

RE: are velocity stacks necessary?
 

the spit back can be used to build some extra hp by utilizing whats called a hemholz resonator my tests have shown up to a 1200 rpm increase. i dont have a dyno but this also equates to a tork gain also. these have to be adjusted to case volume, port timing and rpm range. the example shown below is for a boat engine and was made from a simple plastic container. the shape isnt important other than you dont want it to flex or "oil can" one was made from a stock aircleaner housing and one other fabricated from a small extinguisher container

RE: are velocity stacks necessary?
 

They also give a little better gas mileage as it sucks that plume back into the engine instead of having the forward speed blow it away. Many chainsaws used them for the same reason.

RE: are velocity stacks necessary?
 

The simple velosity stack that I made for my Koritz, 40 cc, put 100 rpms extra on it. STeve