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Old 07-22-2018, 04:41 PM
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Tom Vaught Tom Vaught is offline
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Join Date: Dec 2001
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Personally I am a fan of the carbs with Annular Booster installed.
These carbs would be the 850 CFM carbs, or in some small engine cases, the 750 cfm double pumper carbs. But now you are getting into 750 cfm carbs that actually only flow 730 cfm. These would be street engines wanting excellent drive on the streets or Ski Boats, where you want the engine to respond immediately to the throttle (to pull the skier out of the water).

So for ideal DISTRIBUTION you want:

a) Vaporize as much fuel as possible so that the minimum amount of liquid fuel is present in the cylinders.

b) Use fuels with the correct Volatility for the ambient temperature and altitude conditions.

c) Ensure that the Charge Velocities are kept high in the intake manifold by using the smallest possible passages consistent with the desired volumetric efficiency and Hp.

d) Provide good atomization in the carburetor by selecting the proper venturi size (and carb flow capacity).

e) Avoid at all cost, Heads and Intake manifold constructions which allow fuel to separate out of the mixture due to sharp corners, "S" bend passages, and severe changes in the cross-sectional area.

f) Provide Turbulence in the manifold and head design to ensure that the fuel and air are kept well mixed during their passage to the cylinders.

g) Provide Manifold Heating, or heating of the air, to ensure that the fuel is well vaporized.

Tom V.

Note: Boosted Engines (especially Centrifugal Superchargers and Turbochargers) when used to pressurize carburetors (by using Inter-coolers) can optimize the conditions for proper Fuel/Air Vaporization.

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