VW fans

AZmiik

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I was wondering if any one had a guess on the CFM a vw fan puts out. I was thinking about going electric with a custom fan shroud and late model charging system.

Mike
 

ntsqd

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What do you think, you Engineers out there, for a rough idea could you measure the pressure drop at the intake at full song with a manometer and calc the air volume demand based on that and the size of the opening ?

I seem to recall seeing that number in a Hot VW's many years ago. Maybe they know where to look for it.

TS

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Kritter

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Use a Balometer. Insert it in the flow path and it gives you the CFM reading. Buy a fan with double the reading to be conservative, and you have a bitchen cooling system....2x better then the current one Now you ask..what is a balometer? It is an instrument used to measure volumetric flow rates...CFM. Find a friend in the HVAC industry or swing by a HVAC place and see if you they will do it up for you.

Kris
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AZmiik

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How would you suggest inserting this meter into a vw fan shroud to recive the best results. I can you just place this meter in front of the fan intake and recive a reading from there.

Mike
 

Kritter

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I have only seen one of these instruments and I am not sure if they are all the same. The one I saw used probes and it seemed that you would put them in the flow path and it gioves a reading. HVAC people use it to accuratly record the CFM of ducts or as feedback logic for a digital controlled system. I am not very versed with this instrument so thats all I can offer....sounds like a simple solution though if you can get somebody to do it for you.

Kris
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michael_loomis

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be careful you dont use a fan with too much draw on the alternator or else the load will be equal to what your replacing
 

MNotary

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600 liters/sec at 4000 rpm. It has been tried. It isn't that it couldn't be done, but Porsche never did it, so it may not be worth looking at.
 

Kritter

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Liters Per Second..I hope you took that out of an imported manual! 600Lps is equivalent to about 1271 CFM...this is America. We dont use no stinkin metric system.

Kris
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FABRICATOR

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Interesting idea but it would take one hell of a fan and a fairly big alternator. You could try a quick dyno run with and without the fan belt, to see the H/P requirement. Maybe run the fan with an electric motor while testing. I would assume the OEM fan to be fairly efficient. Hmmm

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partybarge_pilot

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The OEM fans aren't the most eficient things around, plus you have the frictional losses in the v-belt. Also you can set up electric fans on a thermostatic switch so they don't run all the time. You don't need all that much air to keep a VW cool. I've seen alky buggies without fans at all!
 

MNotary

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"I hope you took that out of an imported manual! "

If you stick a guy with a mullet 2 feet in front of the fan and his mullet is x inches, the angle of....

Didn't Gore invent the metric system???

Yea, 1200 plus.

I don't think it can be done and get what you are after. I know any VW motor that has the CR raised needs additional cooling.

If it would give more power or reliability Porsche would have done it.
 

FABRICATOR

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Re:"If it would give more power or reliability Porsche would have done it."

Yes, or someone else. And just how does an electric fan get around the V-belt losses??


<font color=orange>The best ideas are the ones that look obvious to the casual observer.</font color=orange>
 

Kritter

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"And just how does an electric fan get around the V-belt losses??"

In an electric fan you have bearing losses, stator losses, rotor losses, brush losses, etc..most dc motor specs claim to be in the 90 percentile for efficiency but I dont believe it for a second in real conditions. V belt losses are supposedly around 90% efficient too, but from differnet the work or calculations I have done I do not believe in any mechanical, hydro, or electrical system with an efficiency greater then 60% and even that's high, but that is becasue I am conservative. So instead of belt friction losses you get motor losses. The advantage of an electric fan is that the extra power required by the alternator to run the extra load is usually less then the power taken by a mechanical fan. Maximum HP I have seen from a direct drive mechanical fan is 8 HP and with a fan clutch it is in the 2-5 HP range. Electric fans are also nice because you have the option of turning them off which is not an option with a mech fan and you can mount them however you wish too.

Kris
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mgobaja

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Before removing a stock VW fan I would take into consideration how much Time and Money the Germans spend developing this work of art. They may not be the latest in technology but they do work very well for what they were designed to do. It is a rare occasion when they fail and if they do have problems it's not something thats tough to resolve or troubleshoot.
 

AZmiik

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Thanks for everyones input. I got a smoken deal on an Alt conversion so I am going to stick with the stock VW parts. Unless anyone has a porshe fan shroud just laying around they need to get rid of.

Mike
 

FABRICATOR

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Damn, and we almost had this one figured out!

<font color=orange>The best ideas are the ones that look obvious to the casual observer.</font color=orange>
 

Kritter

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They are one piece? I have no VW experience but that is pretty cool...as stated earlier...the Germans are truly some of worlds greatest engineers

Kris
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AZmiik

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Yup one piece. The fan is attached to the Alt or Get which has a long output shaft on it. Kinda tricky
Mike
 
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