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 pete wood
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 posted on April 4th, 2006 at 03:32 PM |
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Flat electric cooling fans?
Trying to think outside the box and I've been thinking about this for a while. Has anyone ever used thermatic type cooling fans on an aircooled motor
ala porsche racer?
Check the pic below.
Aside of the whole, "I need an alternator issue" [not a drama in type 3 or 4] I would have though this could work quite well given the right
ducting. Not only that, but with computer controllers (on an EFI motor) you could stack up to 4 on top of each other and bring them into use as the
need arose. What do people think?
It's a good way of losing a nasty power sucking fanbelt.
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Oasis
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| posted on April 4th, 2006 at 04:02 PM |
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another one with a fan belt...
Don't know how efficient this is but it looks fantastic.
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"Tell him 'We've already got one'"
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pete wood
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| posted on April 4th, 2006 at 04:25 PM |
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yeah that's a german kit for type 4's, unfortunately, it has the same issues as corvair motors. 
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modulus
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| posted on April 4th, 2006 at 04:47 PM |
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| Quote: | Originally
posted by pete wood
It's a good way of losing a nasty power sucking fanbelt.
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You can't make the need for power to drive the fans go away just by giving it a new source...
Let's say you have a 55 amp alternator, and about half that's needed for start battery drain replenishment, lights, wipers etc.
That leaves you, say, 27 amps @ 13.5 V, say
370 watts. Is less than half a kW enough to drive the fans?
Clearly not, because we know that the power requirement for the fans is of the "nasty, power-sucking" sort. So you'll need several nasty,
power-sucking alternators. The 1st Law of Thermodynamics is, paraphrased, that you can't win, you can only break even - the energy has to come from
somewhere. (The 2nd law, paraphrased, is that you cna't break even either, but that's another topic...).
The one way you could gain through this scheme is in drag racing; where you might be able to start with a charged battery and end with a discharged
battery, not running an alternator or generator, but this exceptional case is obviously not extendable to continuous operation.
hth
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cram
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| posted on April 4th, 2006 at 05:20 PM |
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thinking laterally, how about a petrol-powered fan!
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modulus
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| posted on April 4th, 2006 at 06:31 PM |
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| Quote: | Originally
posted by pete wood
...but with computer controllers (on an EFI motor) you could stack up to 4 on top of each other and bring them into use as the need arose.
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Reading Pete's post more carefully, there is a lot to think about in this suggestion. You might use standard cooling but *supplemented* with some
electric fans for, say, a large-bore motor and control their operation through the ECU and some load management sensors (e.g. temp.). Consequently you
might be able to reduce total cooling power requirement by only turning on the extra when needed. My previous post was a bit premature and
ill-considered.
hth
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pete wood
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| posted on April 5th, 2006 at 08:08 AM |
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I have seen a car in HotVWs with an eletric fan setup some years back. Now it was really a show car, but I figured, with the efficiency of modern
radiator style fans, that they might be a better option than the mechanical setup VWs usually have. Lot's of race cars use eletrically driven water
pumps, what's the difference?
The electric fan also offers other benefits, for instance, when warming your engine up, it would be better and faster to go without the fan, but the
belt driven one runs all the time. I know people are gonna tell me there is a thermostat, but most people's VW engines are missing this these
days.
I guess part of the key would be scooping air into the engine, rather than pumping it in, and then using the fans to aid the effect.
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MickH
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| posted on April 5th, 2006 at 08:52 AM |
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you can buy electric fans that go where the fan housing is (one on each side) from somewhere in the states...will look again tonight for
pictures,it's been a while since i've seen them for sale.
tssnq.com.au
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pete wood
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| posted on April 5th, 2006 at 09:49 AM |
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you mean the barrel fans the bergs use. I know what you mean, but they're more of a short term drag racing type thing.
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Joel
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| posted on April 5th, 2006 at 07:21 PM |
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one year brookvale spares i think it was brought that circus beetle (two fronts joined at the middle) to valla and it had an upright motor with no
shroud or genny just a kombi heater fan ducted to both cylinder banks
guess what beelte was on the side of the road in the parade with smoke coming out of it
Joel
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pete wood
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| posted on April 5th, 2006 at 07:47 PM |
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that was the smoke machine in it :P
yeah, well. of course that won't cool a VW motor properly. :o
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rocknrob
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| posted on April 5th, 2006 at 10:22 PM |
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Your theoretical car could benefit from scoops funnelling all that fresh air rushing past as you cruise down the road at 100 klicks...worked well on
motorbikes....
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shaihulud
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| posted on April 16th, 2006 at 07:04 AM |
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modulus's post says it all.
No matter what you propose to do to cool the engine the Laws of Thermodynamics always come into play. If the fan is engine driven by belts, gears or
drive shafts, exhaust driven from a turbine, electric, air scoops, wheel driven from a drive shaft, etc., etc., it will require energy from somewhere
to do it. The Laws of Thermodynamics are very clear in this: "There ain't no such thing as a free lunch."
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tassupervee
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| posted on April 16th, 2006 at 04:13 PM |
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Wes did some figures on fans some time ago and from memory, the fan became a significant power soak after a certain rpm which, altho escapes me right
now, was surprisingly slow
Im thinking along the lines of drawing the air the other way into the fan housing and perhaps adapting a viscous fan coupling so the hot air drawn
thru the system controls the fan speed and load.
There is little reason the air cannot run in reverse thru the engine and the cylinder deflectors normally fitten underneath the barrels could be
fitted on top.
The only issue is is the fan coupling is pretty much disconnected there needs to be some kind of airflow up there to actually have an effect on the
coupling and make it drive the fan and control the temp adequately.
In a conventional car, this us usually taken care of by the proximity of the viscous coupling to the radiator.
Having said that, even when the couplings are fully disconnected the fans tend to idle over and even at very slow fan speed, this will draw sufficient
heat up thru the fan housings to have an effect on the viscous coupling.
If the fan coupling was fitted in clos proximity to the cylinders then radiated heat from the barrels would do the job. But, you are at the mercy of
having to change the direction of the fan belts as pictured above.
The addition of some simple air dams/scoop/ducts...blah blah would..... errrr. "encourage" airflow up thru the engine from underneathe the car when
it is moving forward.
Im really just thinking this out as i go along but this approach may be worth thinking further about.
l8tr
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Im not a complete idiot, quite a few parts are missing....
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koolkarmakombi
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| posted on April 16th, 2006 at 04:23 PM |
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If the engine was mounted in front, like an aircooled motorbike, then the air coming through whilst moving could be used to cool quite efficiently.
The problem is the airflow used like that is not clean flow, efficient nor reliable (crosswind etc)
With the engine in the back the air needs help to be drawn in and oven the engine. scoops like elephant ears on kombis help.
TSV has his thunkin cap on, as the tests that Wes showed proved, the fan only goes so fast then the belt slips. Using the themal dialed coupling
makes sense and has the advantage of slippage at high prm. A variable vane prop would help too.
Ram air type cooling has good effects but often stuffs the aerodynamics and is moot in traffic. My air cooled bmw gets a bit snotty if I get stuck
idling in the great Brisvegas car park too long.
kkk
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sinecure
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| posted on April 20th, 2006 at 08:17 PM |
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This may be a little outside the square, but I work with Mainframe computers and disk arrays, and the "Air Movement Devices" - fans - used in these
units are speed controllable, very lightweight, VERY efficient, high (up to 6000) RPM and VERY reliable.
They are usually 24 volt, but will run at 12, or use a step-up regulator kit. I have two here at the moment, aluminium frames, brushless, plastic
turbines, that if anyone would like to experiment with, they can have.
One's a 6 inch and t'others a 4 and a half. Keep in mind these fans are designed to move a LOT of air, and exist in VERY hot environments, and the
large one draws 0.58A @ 24V (approx. 14W), the small 0.25A @ 24V(6W).
Cheers,
Mick.
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pete wood
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| posted on April 23rd, 2006 at 05:10 PM |
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Now THAT is the sort of info I was looking for Mick. Tell me, are they expensive? And how long can they reliably run for at full load without
failing?
TAS I'm surprised, no one has put real effort into it in FVees yet. the cooling fan weighs quite a bit along with a VW genny/alt. if you go the
updraft thingo working properly, you could use a much lighter alternator, or ditch it altogether and rely on a good battery.
KKK, the trick is to have the fan working in traffic and airflow/ducting cooling the engine on the freeway.
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sinecure
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| posted on April 23rd, 2006 at 08:02 PM |
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They are relatively expensive new, but I have access to quite a supply of used one's free. These fans are designed to run full load 24/7/365 for a
minimum of 5 years. I personally have seen one fan out of around 50 fail. As with most mainframe gear, if it doesn't fail in the first 2 weeks,
it'll run forever. They're brushless, bearinged or brass bushes, so there's no electrical contact surface to create drag or sieze. I can't
remember seeing even a 12 inch that draws more than 1.5A at 24V.
They are fairly light, so if you want I can check a freight price to get them to you (ACTUAL freight price, not e-bay 'handling' LOL). As I said,
I'm happy to give them away.
The larger (12 inch) units are a little heavier, but if you want them let me know and I'll find out a freight price.
My wife would love to see some of my collection go!
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tassupervee
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| posted on April 23rd, 2006 at 09:29 PM |
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| Quote: | Originally
posted by pete wood
TAS I'm surprised, no one has put real effort into it in FVees yet. the cooling fan weighs quite a bit along with a VW genny/alt. if you go the
updraft thingo working properly, you could use a much lighter alternator, or ditch it altogether and rely on a good battery.
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Pete, sadly unlike the US where they remove the fan housing entirely and simply rely on ram cooling alone, the F-Vee rules in Oz state we must have
the original fan. gennie, gennie stand and 40hp fan housing.
The gennies are gutted right out and dont do anything apart from support the fan and we run total loss ignition.
Way it is!
L8tr
E
Im not a complete idiot, quite a few parts are missing....
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seagull
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| posted on April 24th, 2006 at 01:13 AM |
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There was a guy in Perth that removed the fan , ran me to say how good it was going with out the fan conected .Three hours later he ran me to ask if
my car trailer was there as the motor stoped .
Looking for that special lady : PM me for coffee & cake
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tassupervee
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| posted on April 24th, 2006 at 10:32 AM |
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hehehehe U do get that on the odd occasions!!! LOL
L8tr
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Im not a complete idiot, quite a few parts are missing....
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pete wood
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| posted on April 25th, 2006 at 03:25 PM |
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| Quote: | Originally
posted by seagull
There was a guy in Perth that removed the fan , ran me to say how good it was going with out the fan conected .Three hours later he ran me to ask if
my car trailer was there as the motor stoped .
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special people eh? :o
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tassupervee
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| posted on April 25th, 2006 at 10:15 PM |
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Ummmm yeah!
L8tr
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Im not a complete idiot, quite a few parts are missing....
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pete wood
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| posted on December 13th, 2006 at 09:50 AM |
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I'm re-evaluating this theory. Might be time to have a go at it.
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Baja Wes
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| posted on December 13th, 2006 at 02:00 PM |
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| Quote: | Originally
posted by pete wood
KKK, the trick is to have the fan working in traffic and airflow/ducting cooling the engine on the freeway.
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Pete,
If you make really big ducts to ram air into the stock VW fan, then you'll eliminate the power draw anyway.
If you ram in as much air as the fan wants to suck, then it won't draw any power.
If you ram in more air than the fan wants to suck, then the fan will actually generate power.
The VW fan will draw somewhere around 1000cfm at 3000rpm. You need at least 4 x 12inch thermo fans (drawing 10 amps each) to push that much air
through the VW cylinders in an effective manner.
The VW has narrow fin spacing, designed for forced air cooling. Motorcycles have a much larger fin spacing, designed for non-forced air cooling.
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pete wood
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| posted on December 13th, 2006 at 09:21 PM |
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I only need something that can cool it for 10 min while the car is racing. I figure if I mate it with a large oil cooler I'll be ok.
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Baja Wes
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| posted on December 14th, 2006 at 08:22 AM |
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10 minutes is a long time at race pace. If the electric fans won't cool for an extended period, they won't cool for 10 minutes of racing either.
Your far far better off just using a power pulley.
When I was testing the stock cooling fan, we had a very long smooth intake connected to the fan so we could take the pitot tube (flow) measurements.
My staffy walked past when it was running and it almost sucked his head into the intake. Trust me, the VW cooling fan is much much more powerful than
any 12V electric fan.
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pete wood
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| posted on December 14th, 2006 at 02:45 PM |
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have you seen this race motor?
http://forums.aussieveedubbers.com/viewtopic.php?tid=55197
these guys do supersprints and autocross and use electric cooling fans on very highly stressed motors.
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Baja Wes
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| posted on December 14th, 2006 at 04:04 PM |
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Pete,
I can't figure out what those guys are doing. I can tell they probably live in some cold european country.
If they run methanol they don't need cooling at all. Who knows what they're doing?
Their engines will certainly survive running with reduced cooling, the question is for how long. And how much blowby do they get from cylinder
distortion from uneven cooling? I don't know. But I wouldn't do it.
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pete wood
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| posted on December 15th, 2006 at 12:40 PM |
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they're from germany or scandinavia I think, but even still, the cars seem to work fine. I know they have huge oil coolers in the front of the cars.
The cars are EFI too, so they might blowing raw fuel through on closed throttle to cool the motors ala V8 supercars. Also, the porsche flat 8 at the
beginning of this post ran fine with an electric fan. They were very successful cars. So it can't be all bad as long you know what the motor is
actually doing.
BTW, you mentioned something about Alcohol fuel cooling a motor. what the story there?
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