Fan alternatives?

[undysworld]

Robin,
The electric fan blade assemblies that I've seen have, by and large, been pretty flimsy compared to the Pinz fan. As Profpinz noted, when they get submerged they get silent. I've heard that too. I'd worry that a less substantial fan blade (even without the electric motor ) might be damaged by the occasional swim. Water is just too thick. ??

Vince may have it, that the stock design is the best one. But I still like the idea of a scatter shield, especially when working with the doghouse off and the engine running (when possible).

[spandit]

I know the original is probably best but they are expensive and I don't know how many spares there are. Just musing on the possibility of an aftermarket solution

Pinz isn't the only vehicle that gets muddy...

[rmel]

OK, Robin, keeping the pulley in place for the alternator works.

Although you probably don't want the electric motor driven fan
running full tilt when it's not required -- too cold (or hot) is not
necessarily good for smooth running. I think you would also need
to consider fan speed control either based on RPM, or ideally,
Exhaust temp (on #3) ala Pyrometer.

[Jimm391730]

Last year my son (who was learning to drive a stick) grenaded the fan, probably by missing a shift. Fortunately all debris was contained within the doghouse. I had seen a CNC machine shop cutting stainless steel custom boat propellers and thought that an aluminum version would be desirable. But it seems that this has not been created, and even taking a chance and having 10-20 made they would probably be double the cost of a new stock fan (like $800-$1000). Discussed with Scott at EI, he had mentioned that some Porsche or similar fans might be adapted, but no one had done so (yet). So I just bought a new OEM fan (used fans were only marginally less expensive, and why take a chance with old plastic?) and all is well so far.

[rmel]

OK Jim, now you have me thinking :idea: I need a spare fan laying around!
EI has them, did you find another source of interest?

For the curious, a closed loop electric fan control is almost 1/2 done
with this: http://www.plxdevices.com/product_info.php?id=SEMOSMEGT.
Gives you a fancy Pryometer plus a linear analog output from 0-5V that
you could then connect to a relatively simple Vin to Fan speed out driver.
I'd put the sensor on #3 which runs the hottest due to limited airflow
around that cylinder, #1 is the coolest.

These PLX devices are great, I have one for Wideband O2 driving a SDS ECU.

[Jimm391730]

My concern with an electric fan is that I would guess that due to the pitch of the stock fan, number of blades, and rpm, it would probably take 1-2 HP worth of power to drive it. An electric motor of 1-2 HP would take 30-60 amps! And most electric fans that I've seen are probably in the 7-15 amp range, or 1/4 to 1/2 HP. This would allude to significantly less airflow. What I don't know is how much airflow the engine really needs; it might be perfectly happy with less than stock (meaning that it doesn't overheat, even in worst case conditions) in which case an electric fan might be just fine.

I actually took some quick measurements and photos of the new fan before I installed it, just for discussion points if I ever got to talking to a machinist about machining an all aluminum fan(plus I kept the old original aluminum fan hub). But I've no plans to pursue it at this time.

[spandit]

Can I be clear? I was trying to say that one could take a cheap electric fan from another vehicle, throw the motor bit away and adapt the FAN ONLY onto the alternator pulley. No electrics needed, no extra current drawn, just a different fan! :rolleyes:

[undysworld]

Can I be clear? I was trying to say that one could take a cheap electric fan from another vehicle, throw the motor bit away and adapt the FAN ONLY onto the alternator pulley. No electrics needed, no extra current drawn, just a different fan! :rolleyes:

Robin,
It's all semantics. You're from across the pond, so there's a language disconnect. You speak English. Over here we speak 'merkin.

(Yes, I know what I spelled.)

[Jimm391730]

Sorry, Robin, yes, I missed your point about using just the fan portion, separated from an electric fan assembly. However, I really was commenting on Ron's post (just above mine) regarding an electric fan controller (which implies an electric powered fan... ). I'm not trying to berate anyone, just kicking thoughts and ideas around!

[spandit]

Can I be clear? I was trying to say that one could take a cheap electric fan from another vehicle, throw the motor bit away and adapt the FAN ONLY onto the alternator pulley. No electrics needed, no extra current drawn, just a different fan! :rolleyes:

Robin,
It's all semantics. You're from across the pond, so there's a language disconnect. You speak English. Over here we speak 'merkin.

(Yes, I know what I spelled.)

Jus' the 'lectric fan, y'all. Have a nice day now!

[nicholastanguma]

Perhaps tellingly, Jack Raby (R.A.T.) is no longer willing to balance Pinz fan blades (or at least refused to the last time I inquired). He said he was afraid of damage to his machine if one did let go.

I found Jack Raby to be a rather self-important sort, and generally unpleasant. Many people in the aircooled VW scene claim the same in their own interactions with him. Thesamba.com is rife with complaints about his abrasive personality.

But I think it's because he knows he's truly one of the world's best experts on old aircooled tech. He's a jerk, but he's a jerk that's SMART and EXPERIENCED like almost no one else I've ever met in the scene. So as far as I'm concerned he can be a jerk all he likes when it comes to the equipment; meaning that if even he's concerned about grenading fans I really start wondering if I should be, too.

Are brand new replacement fans available from Puch or through various Pinz suppliers, or are they only old fans that have simply never been used?

[undysworld]

When I spoke with Jack, I too found him a bit off-putting. Let's say he didn't waste too much effort at being warm. But mostly he was just matter-of-fact about not trusting the Pinz fans on his equipment.

SAV still lists new fans, so I assume they are relatively easily available.

[GRCameron]

Imbalance of any rotating object is expressed in the same units as torque, ie. inch-ounces, foot-pounds, gram-centimeters, etc. It is not necessary to spin the object at full speed to balance it, but it requires more sensitive equipment to do it slowly. Check out the dynamic tire balancer when you get your next set of tires. It doesn't spin them at highway speed at all. Perhaps Jake Raby's equipment isn't sensitive enough to do it slowly.

Imbalance consists of two components: Static imbalance - where one side is heavy, and Couple imbalance, where the mass is not equally distributed along the rotational axis. Couple imbalance causes the object to want to rotate around a different axis from the one it is supported on. Couple imbalance is corrected by adjusting mass in two planes that are perpendicular to the rotational axis and separated by some distance along that axis. That is why your tires, when properly balanced, have weights on both the inner and outer rim perimeters. Tires are balanced by adding weights, but things like fans and crankshafts are balanced by removing mass at the correct two locations locations. This is a simplified explanation of the process, something I did back in the days when we balanced payloads to be launched on spin-stabilized sounding rockets.

[Stekay]

oh, and then there's the object's natural frequency and it's coupling to the assembly its attached to. Shall we continue? ... I think not.

[krick3tt]

Wow, you tech guys amaze me.

I found bits of fan blade behind the one there now. Must have been an incident at some time. Curious, curious.