No, at speed. Check it out.
While they themselfs have no parrasidic loss, they amount of power to drive one is a loss to the engine since the exhaust gasses spin the unit, a certain amount of pressure is required to maintain and accelerate the turbo.
This is back pressure. Last time I checked, back pressure was not good for N/A engines, why is it different for a turbocharger.
Heres a trick for you. Try this sometime.
Use a external source for pressure and then hook up the turbo/centrif/charger to the engine to mirror the same boost levels through out the dyno run and see the difference.
You will never again honestly say, "Turbo power is free power." because you can't ... honestly say so.
