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before we balance the rotating assembly, I wanted to remove some blades from the fan.

I have seen them anywhere between 4 blades, 12 blades, 20, etc.
Any suggestions?

thanks,
dr

To start I would recommend just every other to be removed. As you progress you can remove more and I can rebalance.

Whoa!, never heard of this. This must be a type 4 deal?

stock fan cavitates above 4500, removing blades makes it more effient and less drag. We run continuously over 5000 rpm.

dr

Absolutely.... Removing blades increases the stock fans cooling efficiency at high revs on production engines...

Or you could run a DTM! LOL

What's wrong with a simple power pully?

TIV fans run directly off the crank, no pulleys involved.

dr

Yep, it runs 1:1

Does this fan surgery do anything for street driven engines? Would it hurt more than help?

not good on the street. We only idle for a few minutes max on the grid and then its up and down the rev counter between 4500 and 7000.

Its hard to do that on the street.

dr

On the street it will increase temps till you are running 5K. Also the F Prod cars run tighter gearing and the engine has less load applied than on the street. This helps with cooling.

On Marks FP car he is running his DTM at only 1.24:1 drive and the engine won't go over 325 unless he is in fifth and on the straight then it hits 350 for a second... with the 911 fan it was running 375-400 all the time!

Where is the crossover of reduced engine load vs increased air flow and less cavitation by removing teeth?
Remove one tooth per sector?

Thaks,
L. McChesney
[email protected]

I removed 6 blades per 1/4, or per the space in between the mounting bosses. Some have removed all but 2 blades per 1/4 and some have left only the mounting bosses making essentially a 4 blade fan.

With 20 blades total, I thought that was a good place to start.

dr

Ok...here is an odd related question I have been wondering about for some time.
What if you reduced say every other blade for the street...then added an outer set of "stator" type blade like the type 3 fan combination has?

Also, he 4 main posts on the type 4 fan that hold the alternator pulley ring to the fan...could be "faired" better...maybe extended to be slightly longer towards the center of the fan. Either way, they should offer less resistance and turbulence to incoming air.

I have been speculating on machining a type 3 outer fan pulley to be bolted onto the outer end of a type 4 fan just to see what happens. Ray

Wow, It seems like my type3's stock cooling system has more in common to a type4 than a type1? I'm assuming all this removing of blades is strictly a racing thing?