I've got to replace a fan & alternator I lost, so my question is, are all Porsche fan combinations the same dimensions? Or do I have to work out what size my fan shround needs and work from there to get a matching setup? (it was a OG fan & alternator not one of the CSP machined down fans with golf alternators)

Hi Jim. I would give Lee at La Performance a ring,he does alot of porsche fan kits.
Lee.

I think all alternator casings have to be machined down to the same OD. I have a 964 one, which is now a little thin. I can measure the OD of it, and the ID of the BAS shroud and the mould I have if you want?

The alternator I had wasn't machined, nor was the one that Orb had. Though the GSF replacement didn't fit his fan as the mounting bolts weren't long enough.

edit:

Oh, do you mean the ring needs machining or the actual alternator?

Could you measure up please, that would help.

The outer ring has to be machined

Its up in the loft, I'll try and get up there this evening

the od of the alternator on the 11 and 5 blade units is the same but the depth they back in to the fan ring is different much deeper on the 90 amp units

paul_f wrote:The outer ring has to be machined

Its up in the loft, I'll try and get up there this evening

No rush. Thanks.

For the BAS and I assume all the others (except the Sharpebuilt which takes standard sized ring) it is machined down to 260mm
as per the Ahnendorp website
B.A.S. Porsche-Style Lüfter
Bearbeitet auf 260 mm Ø mit eingebautem Regler

= B.A.S. Porsche style fan
Edited to 260 mm dia with built-in regulator

but just reread your post and you actually want to know the original size
oh well this might be useful to someone

some shrouds want a ring of 255mm
i.e. you cut the flutes off - just touching the casting numbers
if you will - the lower mounting ones - its only slighyt want 255
-the 260's are a tad taller
-i had 3 rings cut at 260mm
-when i then found they needed to be 255mm

Cool, I guess that's good then, if most need to be machined down to 260mm, (or 255mm) then it wouldn't really matter what year / model vehicle the fan and alternator comes off, so opening up the chance of getting a good priced one.

I'll measure mine tonight, but I doubt a 964 one could be machined down that extra 5mm

oh
you mean types available, well then
there are ones with 901 on them and ones with 930 on them

-they are however both alternators - the 901's if you like are a smaller alternator - pre 1974 when the internally regulated alternator didn't exsist

so any 911 up to 1974 = 901 it will have an external regulator - note type 3 are rated 50 ampherererers, but the porker ones are 55amp

-they then go to an internal regulator from 1975
-part number on the ring changes to 930 - the fans are the same - the ring is deeper i think - the rear deflectors change a wee bit too

-so all the 911's up untill i think the 964 are therefore 930

-the 964 may then have a 964 part number - as these are the last aircooled motors with the fiffering style fan and twin pulleys - i have never had one

the problem though is realistically you want the fan as low as possible
-
i have one of them there rear deflectors on e-bay ay the min.

-they kind of have a channel in the 'if you like' too funnel air to the opil cooler

while we are on.....
-do you know the bestest thing to do would be?
-try this
-get a shroub and cut it in half
-make a fan ring prop in the shape of the shroud arcing from the back of the enngine to the top of the ring
-channel air to the oil cooler
-biggedy bomb
-have the shroud in 2 bits