Re: Weber MAX CFMs
The point some people seem to be unable to understand is that with a common plenum air is flowing through the carb and as each individual cylinder draws on it, it has the full area and flow of the carb available to it. 90 degrees later the next cylinder is going through the same cycle and the airflow is comparitively consistent. There is overlap of the cylinders of course but in simple terms that is what is happening. At all times the full flow of the carb is available to the whole engine.
With the Weber or any other single choke per cylinder induction the cylinder only draws through the (relatively tiny compared to a 4bbl) carb for a small proportion of the 720 degree four stroke cycle. That is why Webers strangle big cube motors. The rest of the time, when the inlet valve is closed, the potential flow of the carb is not available to the rest of the engine. With injection larger throttle bodies are available and overcome the problem, but you can't use big enough venturis with Webers.
There are also significant revese pulses etc generated in a Weber system and these can act both to the benefit and detriment of the torque curve at different revs.
The point some people seem to be unable to understand is that with a common plenum air is flowing through the carb and as each individual cylinder draws on it, it has the full area and flow of the carb available to it. 90 degrees later the next cylinder is going through the same cycle and the airflow is comparitively consistent. There is overlap of the cylinders of course but in simple terms that is what is happening. At all times the full flow of the carb is available to the whole engine.
With the Weber or any other single choke per cylinder induction the cylinder only draws through the (relatively tiny compared to a 4bbl) carb for a small proportion of the 720 degree four stroke cycle. That is why Webers strangle big cube motors. The rest of the time, when the inlet valve is closed, the potential flow of the carb is not available to the rest of the engine. With injection larger throttle bodies are available and overcome the problem, but you can't use big enough venturis with Webers.
There are also significant revese pulses etc generated in a Weber system and these can act both to the benefit and detriment of the torque curve at different revs.
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