Fan Sizes

[chris_seven]

I have searched for a thread which describes the different fan size options but haven't found anything definitive.

I see refernec to 225mm, 226mm, 245 and 250mm.

Dose anyone have a definitive list with pulley ratios and the outer diameter of the housings?

I am tring to build an R replica motor and want to fit an amber shroud for a small fan but it would be great to understand the complete plicture.

Thanks

[304065]

Chris, your countryman from Bournemouth is the resource on this!

http://forums.pelicanparts.com/porsc...ate-motor.html

Here is the most "civil" version of the Fan Debate in which I post some actual data.

http://forums.pelicanparts.com/911-e...an-debate.html

Hope this helps. for a 911R I believe Olivier is reproducing the little housing, the fan can come out of a 79SC.

[chris_seven]

Hope this helps. for a 911R I believe Olivier is reproducing the little housing, the fan can come out of a 79SC.

This is the cause of my concern.

I realise that there is a shroud for a small fan housing but how does this then fit correctly to the engine casing - or did the 910/20 and 901/21 have a different fan housing location.

All very confusing.

[Flieger]

Could the outer diameter be the same, just with different inner diameters?

[chris_seven]

That's what I thought but then I was offered a choice of Amber shrouds - one for a 245mm fan and the other for a 225mm fan.

This is when I started to realise that I couldn't answer the question with confidence, hence ...

The shroud supplier can't seem to throw any light on the problem either.

[chris_seven]

Well,

I managed to get a 906 Fan and housing earlier today so my puzzle is resolved and I will make some detailed measurements.

The first photo is the 225mm fan and housing next to a 245mm fan.



The second picture just shows the casting number



The third picture shows the fan hosuing sitting on a sand cast case with an early engine shroud - note the gap.



The final picture shows how the lower part of the housing increases in diameter so it mates correctly to the engine case.



Obvious really and I am sure many people already know this but it was new to me and resolves all the questions I had.

I am pleased to have found this part as it now allows me to fit my Marelli S121 Dizzy without any mods to fan housings etc. and helps the quality of the 911R Replica we are planning.

[gled49]

The distributor won't hit the fan housing. If it hits anything it will be fan housing support on the case with the fan strap. Gordon

[chris_seven]

Gordon,

I agree it is touch and go but the S121 is just about 115mm long from the clamp face on the engine casing to the bottom of the distributor cap mounting face and I think this just clears the 'saddle' on the casing. The diameter of this portion of the dizzy is 110mm.

I bought the S121 out of a 1965 engine which had a standard fan. The fan had been modified to clear the dizzy.

I tried in the motor which was fitted with the small fan I picked up today and it cleared.

[v-8]

The distributor won't hit the fan housing. If it hits anything it will be fan housing support on the case with the fan strap. Gordon

I can confirm this. I also have an original magnesium 906 fan house + fan on a 901/03 block for my R project. The dizzy is a converted SC distributor with original Bosch rotor and cap. We have had to take a few mm of the fan housing support on the case to make the dizzy fit and turnable for adjustment.

I do not know if the Marelli dizzi is the same size?

[chris_seven]

I do agree that its is very, very close but my distributor is just long enough to clear the case but not quite long enough to miss a standard early fan housing.

There is a guy on Pelican with exactly the same problem he has a converted 30mm dia CW dizzy which is identical in size to the 30mm version of the Marelli and it hits the fan housing before it bottoms into the case.

I will take some photos over the weekend and try to make some better measurements.