Author Topic: 77 Reed Block  (Read 7164 times)

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HeavenVMX

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Re: 77 Reed Block
« Reply #30 on: January 08, 2017, 03:44:24 PM »
Like I said depends on application
orifice size depics flow rate, all pretty simple really as long as it is not mixed up in its application and mediums
once confusion regns no amount of explanation will sevice
cheers
oh look a squirrel
You are trying to relate venturi effect as setting flow rate.

A venturi is a measuring device which allows you to measure flow (we are discussing air flow which is a compressible medium) by generating a representative signal (in the case of a carburettor this is the vacuum applied to the jetting system to draw fuel in) which is proportional to air speed through the venturi this 'signal' is then compensated for air density and cross sectional area. This is achieved via the jetting in a carburettor. There are many ways to measure airflow besides a venturi as seen in fuel injection systems.

in industrial instrumentation situations every venturi design has it's own characteristic table which is a relationship between the differential pressure across the venturi to medium speed for a specific medium, medium density and cross sectional area. This is converted into a flow constant graph which is used to convert the differential pressure across the venturi to a calculated flow in KG/sec or some other unit of quantity.

Anyway I am busy herding my pigs that keep flying away so over and out.

Offline GMC

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Re: 77 Reed Block
« Reply #31 on: January 08, 2017, 05:15:23 PM »
The confusion with the straw statement comes from the misunderstanding between volume and velocity.
Volume being the amount of air that travels through the straw / tube and velocity being the speed at which it travels through the straw / tube.

A larger carby will allow more air to travel through it but it will travel at a slower speed thus not having the same venturi effect so may not draw in enough fuel, especially at lower RPM

Ultimately volume and velocity must be in harmony with each other
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HeavenVMX

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Re: 77 Reed Block
« Reply #32 on: January 08, 2017, 05:20:58 PM »
Thank Christ!!! The voice of reason.

The volume/velocity harmony is relevant, as you say, for the operation of a carburettor not when considering flow in isolation.

Offline shelpi

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Re: 77 Reed Block
« Reply #33 on: January 14, 2017, 09:55:50 AM »
The confusion with the straw statement comes from the misunderstanding between volume and velocity.
Volume being the amount of air that travels through the straw / tube and velocity being the speed at which it travels through the straw / tube.

A larger carby will allow more air to travel through it but it will travel at a slower speed thus not having the same venturi effect so may not draw in enough fuel, especially at lower RPM

Ultimately volume and velocity must be in harmony with each other
thank you