turbochargers also used a fixed position turbine that powered the centrifugal compressor directly. Because the turbine is located directly in the exhaust stream, the turbine is a huge exhaust restriction. This restriction creates a constant exhaust backpressure that decreases fuel economy even when the turbo is not in use. At high engine speeds, the restriction creates enough pressure in front of the turbine (back pressure) that the wastegate can no longer limit turbine power by bypassing the exhaust around the turbine. The result is that turbo compresses more air into the engine than is wanted. For example, a turbo was set to produce a maximum 12psi boost pressure, but during a period of sustained wide open throttle high engine speeds the turbo is n
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