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Volumetric efficiency

EFI Tuning Fundamentals

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Is everything over 100 percent forced air induction or am I missing something here.

It is possible, with very carefully optimised engine designs, to approach 150% VE with NA engines as some F1 engines managed before the current turbo' era. Two big parts of the optimisations is tuning the pressure waves in the inlet and exhaust systems to maximise filling and scavenging by the lengths of the tracts, and the diameters of the ports to maximise the velocity and volumes of the gases. This is actually where the expression 'tuning' originated, with steam engines.

However, do not confuse actual VE with the VE BS used by tuners with forced induction - they are quite different things! perhaps the easiest way to explain why I have a problem with this is if you have an engine with poor, true VE that is consuming a specific amount of air and fuel, you rework the head(s), valves, camshaft, etc, and improve the VE and you will find that if tested with the same air and fuel being fed to the engine the boost will drop and power/torque will increase because the engine is more efficient - yet, using the 'tuner'definition the "VE" will be the same.

I would describe VE as a scaling factor to cylinder filling efficiency when the engine is NA, some sort of mechanical and design efficiency - how good the cylinder is fed with air due to the engine geometry and choice of components. Adding boost does not change any of those two things but simply forces more air in cylinders. That is not increasing efficiency(VE) but mass flow.

Thanks for the reply

Thank you,Georg, that is exactly my point and why I, also, consider it should be MA, Mass Efficiency used for the correction factor.