Yeah, I'm not disputing that there's a performance increase to be had, i'm just warning against talking in terms of power increases as people selling these sort of pullies often do.
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As I said before the only way that a different pulley can increase power is if that pulley causes alternators/water pullies etc to be underdriven thus reducing the amount of power sapped by those accesories.
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Tiny
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- see above, it's the underdrive aspect which gives rise to power gains.
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You get no power by reducing mass.
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If you want another way of thinking about it:
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Would you expect fitting a CF bonnet give you more power?
What about replacing the undriven wheels with lightweight ones?
What about the driven wheels?
Driveshafts?
Gearbox input shaft?
Flywheel?
Crankshaft?
Crank pulley?
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Whilst replacing any of those components with lighter ones will give you a faster accelerating car it's the reduced mass that that allows this.
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None of them will give you more power.
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The only difference with the rotating components is that the performance benefit per kilo removed is higher because the mass has to be accelerated both linearly and rotationally for the car as a whole to accelerate.
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There are exceptions where lighter engine components can give you more power but these are typically reciprocating rather than rotating parts
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(such as valves, followers, pistons, conrods etc) the reduced mass allows you to run to higher speeds without increasing the loads involved in acclerating/decellerating those parts.
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