There may be a more effective mechanical fan available.
09-28-2005, 06:22 AM
#1
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There may be a more effective mechanical fan available.
It is my understanding that that a fan is most efficient when the edge of the blades are within a certain proximity to the tube or duct that surrounds them. The closer the proximity the more efficient the fan is going to be to a certain point given how it was engineered. I believe a ducted fan is more efficient than an open fan.
The typical mechanical fan blades are open at their edges.. the allroad has a ducted fan as the primary mechanical fan. There is an intergrated edge to the allroad fan which likely acts as a sort of velocity stack to smooth flow through the fan and increase efficiency.
Now the problem is that the allroad uses a different viscous coupling... which has a different outter diameter and only mates up to the inner diameter of the allroad fan blade.
Good news is that the allroad fan is the same diameter as the stock A4 fan.. so it should fit without any space constraints. The allroad coupling also threads onto the other V6 pulley assemblies. The overall height of the coupling is very close to the V6 one.
So..
If one were so inclined to acquire a allroad viscous coupling and a fan blade... one could replace their fan with it.
Coupling 4z7-121-350
Fan blade 4z7-121-301
bolt n-014-745-4 (4) [M6x14]
The typical mechanical fan blades are open at their edges.. the allroad has a ducted fan as the primary mechanical fan. There is an intergrated edge to the allroad fan which likely acts as a sort of velocity stack to smooth flow through the fan and increase efficiency.
Now the problem is that the allroad uses a different viscous coupling... which has a different outter diameter and only mates up to the inner diameter of the allroad fan blade.
Good news is that the allroad fan is the same diameter as the stock A4 fan.. so it should fit without any space constraints. The allroad coupling also threads onto the other V6 pulley assemblies. The overall height of the coupling is very close to the V6 one.
So..
If one were so inclined to acquire a allroad viscous coupling and a fan blade... one could replace their fan with it.
Coupling 4z7-121-350
Fan blade 4z7-121-301
bolt n-014-745-4 (4) [M6x14]
09-28-2005, 06:30 AM
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very correct
it's the same principal applied when trying to achieve more thrust. Reduce the diameter of the actual tube but keep the same fan size. So essentially you'd achieve more CFM based on a ducted system because there's less ways for the air to escape.
09-28-2005, 06:31 AM
#3
more pressure, but less volume though? I'd think you'd want more volume with a cooling fan?
Also keep in mind, the fan ONLY is effective BELOW say 40 mph. Over that, it's just another restriction for air flowing through the radiator. So keep that in mind when you crank down the venturi at the back of the fan.
09-28-2005, 06:39 AM
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are you speaking of a fan blade with a ring around it? (in basic terms)....
If so, I have that. My car has a fan that has all the blades connected with an outter ring.
or are you talking about a stationatry shround that goes around the fan?
is there a smaller one that the edges of the blades come closer to?
that would make less pressure loss around the outside of the blades rotating area.
or are you talking about a stationatry shround that goes around the fan?
is there a smaller one that the edges of the blades come closer to?
that would make less pressure loss around the outside of the blades rotating area.
09-28-2005, 06:42 AM
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maybe... but it would likely be better for the autocross where low speed and high RPM
also tracking any time below a certain speed it would aid.
Why are all of the electric fans we use ducted fans?
Why are all of the electric fans we use ducted fans?
09-28-2005, 06:51 AM
#7
The electric fans are ducted, usually because they are designed to be mounted directly to the rad...
the lock carrier has a duct built into it, that the stock fan sits in in the original config.
The ring around the edge of hte fins helps keep air flowing over the fins, in the intended direction, and keeps it from drawing air in from the sides (also what the shroud is there for).
Yeah, I'd think some nice electric fans would help a lot in an autocross, as would getting rid of the AC altogether. Since it's a track car and all.
The ring around the edge of hte fins helps keep air flowing over the fins, in the intended direction, and keeps it from drawing air in from the sides (also what the shroud is there for).
Yeah, I'd think some nice electric fans would help a lot in an autocross, as would getting rid of the AC altogether. Since it's a track car and all.
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09-28-2005, 07:20 AM
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yes, my mechanical fan has the blades connected by a comon ring....
it dosent look much like a "venturi" of any sort, looks almost liek its just more for strength or to keep the thing together.