i have been doing research for my eventual turbo project, and i have a thought about too small of a turbo.

if you have a turbo that is too small, it will fall off at high RPM due to a lack of flow, but what if you added a check valve that fit between the turbo compressor and the throttle body, that opened when that section was under vacuum, and allowed air in to let the motor operate as a naturally aspirated engine when the turbo could no longer keep up with demand?

i am thinking this would improve lower rpm power by reducing turbo spool times and give boost at low rpm, but not cause a small turbo to be a flow restriction at the top end

A turbo running way out of it's efficiency zone will still be making boost and flowing more air than a naturally aspirated system.

When that 'too-small' turbo is falling off the power at high RPM it is pumping heat and pressure into the intake charge but not moving much more actual mass of airflow.

Venting the pressurized side of the turbo at high load would send it immediately into the surge zone and destroy it.

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