My 911 kit came with a 1.6-1 crank pulley, I bought a smaller pulley from Fat Performacne that is 1-1.
ken

For your info:

Latest dyno test showed that the fan took 6hp on Zen's engine.
If you get a pulley with a 1:1 ratio the Porsche shroud will NOT work that well.

Please wait a week or two.....I have some really good infos for my article.

Alex

Just picked up 11 blade fan kit, all for $320. Not bad hey?? Dry sump here we come, just gotta get the cash to finish the 2332 and it can all be installed

....
 

For sure you have to interchange pulley-diameters, just to get the correct ratio.

A safe thing, to be warned, that the diameter is too small is, if the generator light comes on! LOL


5 blades for president! 12 blades are good, but...! 11 blades provide best airflow, besides it's less noisy than the 5 blades! Problematic is, that you can't get the 11 blades new.

So there is no real problem running a 5-blade fan? I am having a hard time locating an 11-blade fan. Would it cause any problems or should I keep looking for an 11-blade?

Thanks,
fast70

Think about it this way, the 5, 11 or 12 blade was designed to cool a lot more power, cylinders, boost and heat than we will ever need.

The only problem with running a 5 blade fan that I can think of is as follows.

I dont like the look. Yes, if nothing else was available, I would run a 5 blade (almost did too), in all honesty, I REALLY REALLY REALLY REALLY like the 12 blade, but those cant be found in SA, so I opted with the 11 blade.

It all boils down to looks!!! They each have their specific design application, which is much more than we need anyway.

Yeah,
I don't know what I was thinking! As if the fan for a 6-cyl would'nt be good enough for a 4-cyl. Thanks for showing me the logic!

Thanks,
fast70

The 5 blade fan was introduced to the 2.7 911 in the mid 70's to make the engine run hotter in order to reduce exhaust emissions.
How do I know? I have a mid 70's 911 and every thing I have read about it tells me to upgrade to the 11 blade fan before the engine overheats and pulls the head studs out of the case.
So the 5 blade fan cools less.
To confuse things even more there were 2 sizes of pulley too.

Tim

Yeah,

I think I read that in a Porsche manual once. They did it in order to reduce emissions by making it run hotter.

fast70