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[roofeditor]

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The supercharger robs power from the crankshaft to generate the boost thus decreasing fuel efficiency. Why take power from the crank that can go to the flywheel when you can just use free energy in the exhaust?


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Nope......Driving a turbo causes exhaust back pressure which in turn causes higher cylinder pressures on the exhaust stroke...It's not free energy, but the increase in power outweigh the losses if properly designed.


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It's not entirely "free" but it does not take as much power from the engine crank shaft to drive it as the power you are getting out the compressor side. Most of the power from an exhaust driven turbocharger is taken from the extra energy of the exhaust gases and not the engine crank shaft. Now a mechanically driven supercharger takes 100% of its energy from the crank shaft and therefore is not an "energy scavenger" like the exhaust driven turbo.

Birken


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I was gonna say, so what! If I have 10 lbs of exhaust backpressure and I add 12 lbs of manifold pressure on the intake stroke, am I not offsetting the increased backpressure with increased intake manifold pressure?

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You're kidding? [img]/ubbthreads/images/graemlins/shrug.gif[/img]