Is the 906/rsr 225mm(226) the smallest diameter fan used in an upright belt driven engine? This is not going into a porsche or VW but a bmw flat twin.
All I am looking for is the fan and alternator from the porsche as I will be making the mount out of billet.
225 906 fan question
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Re: 225 906 fan question
The fan used on the 225mm Fan Housings have the same central hub size as all of the other 11 and five blade fans.
They were first used on the 904 GTS and then the 906.
The means that a 245mm fan can be modified to operate in a 225mm housing but would need re-balancing as it runs at around 15000 rpm.
It is the housing depth that affects the capacity if the alternator not the fan.
The fan is held onto the alternator by the single central nut and there are three different sizes depending on alternator type.
Fan balance will affect the critical speed of the alternator which will be important for bearing life.
I would tend to use a genuine fan as they are proven from a fatigue life point of view.
Blade tip clearance will also be important as this will influence efficiency and noise.
They were first used on the 904 GTS and then the 906.
The means that a 245mm fan can be modified to operate in a 225mm housing but would need re-balancing as it runs at around 15000 rpm.
It is the housing depth that affects the capacity if the alternator not the fan.
The fan is held onto the alternator by the single central nut and there are three different sizes depending on alternator type.
Fan balance will affect the critical speed of the alternator which will be important for bearing life.
I would tend to use a genuine fan as they are proven from a fatigue life point of view.
Blade tip clearance will also be important as this will influence efficiency and noise.