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Posted by: synthesisdv Apr 7 2004, 08:30 AM

Just separated the fan wheel from the big steel pulley ring. FYI, it takes the same 8mm 12pt bit that the CV uses. They were harder to get out than the CV bolts.

Anyway, I don't think I have a saw or airtool that will get in-between those blades. There is only like 6mm in between. Any suggestions?

TIA
dr

Posted by: URY914 Apr 7 2004, 08:48 AM

What are you trying to do?
Remove some of the blades?

Paul

Posted by: Mueller Apr 7 2004, 08:52 AM

pliers or a screwdriver...the blades should break off near the bottom.....

Posted by: tat2dphreak Apr 7 2004, 08:55 AM

pardon my ignoragce(normal state)... but why remove fan blades?

wouldn't that change the air volume being pushed?

Posted by: cha914 Apr 7 2004, 08:59 AM

Lotsa racers do it so the engine will rev better...

Dave, I imagine this would work:



usually called an air body saw, basically an air powered mini sawsall...useful for many other things also...

Tony

Posted by: tat2dphreak Apr 7 2004, 09:02 AM

ahh, like lightening the flywheel, only this will make the engine run hotter too correct?

Posted by: URY914 Apr 7 2004, 09:02 AM

I removed some of my blades. I'll post a pic tonight. One was already broken off so I removed the one across from it to balance it out.

The thorey is it will make the fan lighter but you'll be removing very little weight by removing blades. Crank, rods, pistons, flywheel are where the bulk of the weight is.
An aluminum blade don't weight much.

I know, I know, every oz counts. Look who's talking.

Paul

Posted by: ArtechnikA Apr 7 2004, 09:15 AM

not necessarily...

there are many who feel the OEM fan is -too- efficient for high speed operation, and actually tries to pump more air than can be pushed through the available openings. it's not efficient to compress air wit this kind of fan.

so the racers remove 'some' blades to balance the air delivery with what can be squoze out.

so it doesn't cool any worse at the high speeds that race-track cars operate at, but it does consume way less power.

they do tend to run hotter at idle.

in general (broadstrokes generality warning) aircooled engines are overcooled at idle so they'll be at proper operating temp at cruise. watercooled engines are undercooled at idle which is why they used to have so many overheating in traffic problems - before the widespread adaptation of the thermostatically switched electric fan. pretty much for the same reasons - it takes a lot of power to turn the fan...

Posted by: tat2dphreak Apr 7 2004, 09:21 AM

ahh, ok, that makes a lot more sense then... thanks!

Posted by: Jake Raby Apr 7 2004, 09:47 AM

To do it right, you need a milling machine to take them all to the same depth...

Please don't leave them uneven when you send it to me, it creates alot of work.

Posted by: synthesisdv Apr 7 2004, 10:16 AM

the stock fan is made to run optimally at <4000 rpm. A race motor lives above 5000 rpm where the fan cavitates and looses efficiency. Removing blades puts less of a load on the motor and allows better flow at high rpm.

Its really not about weight.

The pic is not what mine looks like.... yet.

dr


Attached image(s)

Posted by: Jake Raby Apr 7 2004, 10:35 AM

Those are a BITCH to balance BTW...

They air moves differently through the blades and my computer sensors pick the air up as imbalance. I have to make a cover for the fan inlet and cover the blades with masking tape to actually get balance numbers...

Posted by: thesey914 Apr 7 2004, 02:10 PM

I thought the balance machinery rotated quite slowly must still move enough air though

Posted by: Jake Raby Apr 7 2004, 02:19 PM

The balancer rotates at 500 RPM, but the air disturbs it enough to aggrevate me.

Posted by: thesey914 Apr 7 2004, 03:38 PM

Jake, I salute your attention to detail......wonder how many other builders go to these legnths??

Posted by: brians914 Apr 7 2004, 03:42 PM

Wow, over my head!

Posted by: lmcchesney Apr 7 2004, 08:53 PM

Is there a optimal number of blades to remove?
What pattern do you use?
I had previously see the pictured blower blade, but I thought it excessively radical.
L. McChesney

Posted by: Jake Raby Apr 7 2004, 10:11 PM

I normally remove every other blade, but have ran some with only the 4 impellers that hold the fan together!

My track fan for my car has every other one removed...