Bennett project: Fan size question
 

Hi everyone,

We've hit a slight snag with the 11 blade fan for Barry/Jane Bennett's* car. The car is a 1976 2.7 which should have a (5 blade) 245mm fan according to Bruce Anderson's 911 Performance Handbook.
However, when we tried to replace the 5 blade with a later 11 blade fan it wouldn't fit - the 11 blade fan was too big.

B.A.'s book say the 5 blade fans only came in 245mm but upon measuring the 5 blade fan it was determined that it was a 226mm unit.

What is the story on upgrading the 5 blade fans? If the B.A.s book isn't also mistaken about the '78-79 SC fans, they are 226mm. Is this the fan people use for the upgrade?

Can we source a later fan housing (from Carrera for example) and use that with the 11 balde 245 fan we have or will there be alternator fitment issues?

thanks,
Chris

* See Bennett Project Update

All the 5 blades that I have ever seen in person are 245mm(the one on my '76 C3 most certainly was and accepted a late 245mm 11 blade perfectly.

But there were some 226mm 5 blades used on R models. Never seen one just heard of them.

If you want to proceed get, a fan housing from most any other '76 or '77

Thank Bill. Has anyone else got some ideas on using a later fan housing?
-Chris

Hi Chris,

Can you sleeve a 245 housing to obtain the correct tip clearance on the 226 fan? Just an idea.

Chris,
I'll call you, I think I have one that will work,
Dave

Grady Clay knows lots about fan interchangeability; you might PM or email him.

Chris,

I agree with Bill.

The solution is to use a production 245 mm fan housing from ’74 to ’77. Does the fan you got use the smaller pulley parts (hopefully.) Even in your clime, having a more powerful fan is desirable. The A/C works better, the heaters defrost better, and most important, the heads stay cooler.

Since you don’t know yet where the 911 will go, see if you can find the parts for an 11-blade 1.82:1 set-up. You can always trade for them or include the old parts.

Here is the fan ratio thread:
“Fan drive ratio”
http://forums.pelicanparts.com/porsche-911-technical-forum/170042-engine-fan-drive-ratio.html

One major issue is to make sure the alternator position is correct. There were several stages of larger, more powerful alternators where the fan housing was progressively deeper to accommodate the longer/larger alternators.

We are all proud of you all that are making this happen.

Best,
Grady

I have a 226 mm 11 blade fan that I don't use. Is in excellent condition. The fan use the smaller pulley. Was installed in a 1979 3.0 911. Send me a PM is you want it.

That would be great! You have a PM Nitro.

Does anyone see a problem with the above combination of an early 226mm SC fan and a 2.7L 226mm fan housing? It seems like a no brainer but that's what I thought last time when I believed what Bruce A.'s book said. I just want to be sure before Nitrometano goes to the trouble and expense of shipping it.
thanks,
Chris

Bruce's book is correct, someone over the years had to have swappped parts w/ a '78-79 SC

email me to neneloco55@hotmail.com

That could explain the 226mm fan housing but that doesn't explain the 5 blade fan which Bruce's book states:
"The 245-mm five-blade fan used for 1976 and 1977 only." (Picture caption on page 78.)
"The five-blade 245-mm fan with 1.8:1 drive ratio, as used on 911s for 1976 and 1977.) (Picture caption on page 79.)
Janes car has a five-blade 226mm fan. Did some SC's come with 5 blade fans?
-Chris

Again Bruce is correct, the genisis of your fan is the question, it is either a very rare factory race part or someone cut down a stock '76 77 5 blade and installed it in a 226mm shroud on the engine.

the 906 for one is a 225mm fan driven @ 1.3:1

Cutting a 5 blade fan down to size? Now that's crazy talk Bill. ;)
Nitro has generously donated an 11 blade 245mm fan, Thanks Nitro!
-Chris

EDIT: Sorry, I misunderstood. Nitros has a like new 226mm fan that he can sell us. What's a 226-mm 11 blade fan go for these days? Does anyone have a used one for sale cheap or that they'd be willing to donate?

Chris any part # on that thing?

I'll ask Ed.
-Chris

I haven't seen any pricing examples that I can reference.

I was asking around for a few months last year because I wanted one for my engine project and I couldn't find one that was anywhere near usable condition. Near as I can tell the only 226 mm fans which are left are those that have not yet been replaced on engines. In many cases they have chips, cracked blades and the sundry other issues which constitutes normal wear and tear.

Ed checked and the casting # is 901 106 101 5R. Does that shed any light on what's going on here?
-Chris

Chris

11 Blade Fan are selling for better than $300 for the assembly.

Unfortunately I gave my 245mm x5blade away a long time ago, maybe someone else in the audience.....?