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tinkering with my supercharger from HK via ebay, $14 posted twin vanes at each end of the painted-to-look-anodised tube. I wouldn't dare fit it to intakes so tried it on exhaust as it was same diameter.
Start to ask question...is the intake cfm gonna be much different to exhaust cfm ? through same diameter pipe ?

I ask coz this supercharger did not appear to wind up anything much at all with exhaust at the tail pipe, sort of got a speed at 2000rpm and not seem to change speed beyond that - like exhaust was just blowing through the vanes

It did not also make the whirring noise I thought it made on a youtube clip - that may have been a crapped out bearing on the demo Honda

CFM is gonna be much higher out the tailpipe compared to the intake because it is 40 times the temperature. A quick calculation gives me 3.8 times the volume.

So for every litre of air the engine ingests, it spits 3.8 litres out....but.... not including the small amount of fuel, that 3.8 litres of hot air weighs the same 1.2 grams as the 1 litre of air that entered the engine.

So yes your pinwheel should spin faster in the exhaust than it would in the intake, this is the reason a turbo charger is able to compress the same volume of incoming air as what is actually powering the turbine out the exhaust. If your exhaust gas exited the engine at the same temperature it entered, a turbo wouldn't create boost