24-01-2021, 03:53 PM
Not always! Sometimes there is a butterfly in the air intake. The faster the engine runs, or the more the butterfly is closed, the greater the vacuum in the intake manifold - and the vacuum operates a diaphragm which controls the fuel pump.
Running backwards, there would be no vacuum so the fuel pump would inject the maximum, whatever, and the engine speed would just ramp-up, even if inefficiently. Amie's theory is quite plausible.
The stop control operates directly on the fuel pump rack, so is independent of engine rotation direction - which is lucky as it turns out, and is very much in the spirit of this thread.
The butterfly system does have the advantage over the centrifugal weight system, that greater engine braking is available on the over-run - sucking air through a closed butterfly is energy-sapping, and is why petrol engines, despite lower compression ratio, are more effective at showing a vehicle down.
I'd hate to have no means of shutting down in emergency situation...
Running backwards, there would be no vacuum so the fuel pump would inject the maximum, whatever, and the engine speed would just ramp-up, even if inefficiently. Amie's theory is quite plausible.
The stop control operates directly on the fuel pump rack, so is independent of engine rotation direction - which is lucky as it turns out, and is very much in the spirit of this thread.
The butterfly system does have the advantage over the centrifugal weight system, that greater engine braking is available on the over-run - sucking air through a closed butterfly is energy-sapping, and is why petrol engines, despite lower compression ratio, are more effective at showing a vehicle down.
I'd hate to have no means of shutting down in emergency situation...
