BMW now looking into electric turbos

[LiveWire]

Ford Lightning, Cobalt SS, Saturn Ion Redline were all supercharged and inter cooled from the factory. A standard roots type blower produces quite a bit of heat itself. It is an exponential curve to RPM. So past a certain point in RPM, they are very inefficient. As the rotors spin, the air is smashed against itself and squeezed out. The compressor side of a turbo is more of a smooth flow. A twin screw supercharger is far more efficient producing less heat. The air wrapping around the rotors is converging at an angle so it merges and goes out the one end. I think a sweet setup would be a turbo feeding a twin screw supercharger. You would multiply the compression ratios of the two. So say ((1.5x1.5)-1)x14.7psi atmospheric pressure=18.375psi boost. Total boost would be limited by a partial or complete bypass of the supercharger reducing the load on the crank. The power to drive the turbo is not free, but it is cheaper. The Turbo 660 Drakart is quieter than the NA 660. So you might be able to get away with a less restrictive muffler that would help efficiency.

[Carlriddle]

Centrifugal SC or twin screw seem much more efficient and reducing the air temp.  And most dont use intercoolers at modest boost.  Now most of this info is auto industry and will vary with bike engines.  But also see some autos running the turbo at end of exhaust greatly reducing the air temps too.

Based on what?   Its definatly harder to measure this drag VS a supercharger but how do you KNOW its less drag?

Fabr says so and his the Master.   

[fabr]

Ford Lightning, Cobalt SS, Saturn Ion Redline were all supercharged and inter cooled from the factory. A standard roots type blower produces quite a bit of heat itself. It is an exponential curve to RPM. So past a certain point in RPM, they are very inefficient. As the rotors spin, the air is smashed against itself and squeezed out. The compressor side of a turbo is more of a smooth flow. A twin screw supercharger is far more efficient producing less heat. The air wrapping around the rotors is converging at an angle so it merges and goes out the one end. I think a sweet setup would be a turbo feeding a twin screw supercharger. You would multiply the compression ratios of the two. So say ((1.5x1.5)-1)x14.7psi atmospheric pressure=18.375psi boost. Total boost would be limited by a partial or complete bypass of the supercharger reducing the load on the crank. The power to drive the turbo is not free, but it is cheaper. The Turbo 660 Drakart is quieter than the NA 660. So you might be able to get away with a less restrictive muffler that would help efficiency.

+1 Good points. I'm worn out trying to explain this @GD. I'll leave the effort to others here. LOL!!!!!

[fabr]

Centrifugal SC or twin screw seem much more efficient and reducing the air temp.  And most dont use intercoolers at modest boost.  Now most of this info is auto industry and will vary with bike engines.  But also see some autos running the turbo at end of exhaust greatly reducing the air temps too.

Fabr says so and his the Master.   

It's all just a big left wing conspiracy I tell ya!!!!!

[LiveWire]

I believe I read at one point BMW was looking at using a sort of steam engine ran off the heat that would otherwise go out the radiator. That in turn ran a compressor that pumped air into a tank. During acceleration, that air was fed into the engine. The article I read did not say, but I assume the air was fed through a venturi using a low volume of high speed air to draw in a high volume of low speed air.

[fabr]