Replace fan with electric blower??
JonTurner
Greetings,
Just an idea I've been chewing on for a while... would it be resonable to
replace the type 1 upright cooling fan with a pair of electric fans
located above the cylinders? Would I be able to move a high enough volume
of air to cool sufficiently?? Would the electric fan reduce drag onthe
engine? If it did work, I could add a timer to run the fan after engine
shutdown (much like the turbocharger cooler kits) and help keep my engine
comfortable during these hot North Carolina summers.
Am I crazy or could this idea work?
Jon Turner
Chapel Hill, NC
P.S. Don't worry -- this would be applied to a kitcar I'm building. I'm
not about to go screwing up my '66 Beetle! :)
Sean Bartnik
I highly doubt that would work too well. VW probably thought of it
somewhere along the way and tested it and found it didn't work :-)
The design of the stock cooling fan is such that it really moves a LOT
of air, and the shrouding and internal ducting is already set up to work
with the fan in its stock location. You'd probably have to modify all
kinds of stuff to get your idea to work well. Not that you probably
couldn't get it to work, just that it'd be a lot of time, trial and
error, engine sacrifices, and a huge amount of money :-)
I'm sure some of the fluid dynamics folks can give you a better answer
than this, but the above is just my gut feeling.
Sean
Sterlng007
If you figure out a way to make it work, let me know. I'd trust a fan
thats hooked to the chargeing system better than electric ones. What I
mean is, if the fan belt breaks or comes loose then the chargeing light
comes on and would let you know of cooling problems.
MARC TOUSSAINT
JonTurner wrote:
>
> Greetings,
>
> Just an idea I've been chewing on for a while... would it be resonable to
> replace the type 1 upright cooling fan with a pair of electric fans
> located above the cylinders? Would I be able to move a high enough volume
> of air to cool sufficiently?? Would the electric fan reduce drag onthe
> engine? If it did work, I could add a timer to run the fan after engine
> shutdown (much like the turbocharger cooler kits) and help keep my engine
> comfortable during these hot North Carolina summers.
>
> Am I crazy or could this idea work?
>
> Jon Turner
> Chapel Hill, NC
>
> P.S. Don't worry -- this would be applied to a kitcar I'm building. I'm
> not about to go screwing up my '66 Beetle! :)
--
marc toussaint
http://www.angelfire.com/biz/slugbug
slugbug - parts and restoration vw parts hotline: 972.313.0085
1119 Luke Street #113
Irving, Tx 75061-4059
John Connolly
JonTurner wrote:
>
> Greetings,
>
> Just an idea I've been chewing on for a while... would it be resonable to
> replace the type 1 upright cooling fan with a pair of electric fans
> located above the cylinders? Would I be able to move a high enough volume
> of air to cool sufficiently?? Would the electric fan reduce drag onthe
> engine? If it did work, I could add a timer to run the fan after engine
> shutdown (much like the turbocharger cooler kits) and help keep my engine
> comfortable during these hot North Carolina summers.
>
> Am I crazy or could this idea work?
>
> Jon Turner
> Chapel Hill, NC
>
> P.S. Don't worry -- this would be applied to a kitcar I'm building. I'm
> not about to go screwing up my '66 Beetle! :)
the fans don't have near enough volume for the engine.... in addition,
the increased electrical load isn't to good since the electrical system
isn't exactly brimming with extra juice ..... I use the electric fans on
my race engines, but they barely get me back to the pits after a
pass.....Just figure that the engineers did their homework.... the stock
cooling system can't be beat... especially for the money...
John
Ben Knorr
In article <19970716224...@ladder01.news.aol.com>,
jont...@aol.com says...
> Greetings,
>
> Just an idea I've been chewing on for a while... would it be resonable to
> replace the type 1 upright cooling fan with a pair of electric fans
> located above the cylinders? Would I be able to move a high enough volume
> of air to cool sufficiently?? Would the electric fan reduce drag onthe
> engine? If it did work, I could add a timer to run the fan after engine
> shutdown (much like the turbocharger cooler kits) and help keep my engine
> comfortable during these hot North Carolina summers.
>
> Am I crazy or could this idea work?
>
heavy electric motors to your car? Your engine already has a constant
supply of "coolant", and it just increases as engine speed increases.
Bingo! Who could ask for anything more!? The motors would just add
weight, extra wires to mess with, take up space in the engine
compartment, and do little to help the engine run better (they run just
fine with the fans hooked up to the generators).
I suppose if you wanted to, anything is possible, but I don't see any
benefit to it.
/ben
'69 beetle
Joe Cali - Next Generation
You don't get free power- The electric fan draw power from the battery
which gets charged - the alt or gen has to work harder- notice when you
turn your light on - the idle drops. So the engine has to work harder.
JonTurner <jont...@aol.com> wrote in article
<19970716224...@ladder01.news.aol.com>...
> Greetings,
>
> Just an idea I've been chewing on for a while... would it be resonable to
> replace the type 1 upright cooling fan with a pair of electric fans
> located above the cylinders? Would I be able to move a high enough volume
> of air to cool sufficiently?? Would the electric fan reduce drag onthe
> engine? If it did work, I could add a timer to run the fan after engine
> shutdown (much like the turbocharger cooler kits) and help keep my engine
> comfortable during these hot North Carolina summers.
>
> Am I crazy or could this idea work?
>
JonTurner
Hiya Ben!
I asked:
>>Would the electric fan reduce drag on the engine?
>> Am I crazy or could this idea work?
You responded:
>The motors would just add weight
Yeah, I guess that they would add a few pounds, but keep in mind that I'd
be removing the stock fan. I dunno how heavy it is, but it looks like it
might weigh 5 pounds or so. Modern radiator fans (such as the type used on
air conditioning condensors) are small and relatively light (about 5-10
pounds each), while capable of moving a tremendous volume of air. Net
change, probably +10 pounds.
>extra wires to mess with
True.
>take up space in the engine compartment
Not if I removed the upright cooling tin which shrouds the fan and
fabricated a pair of tins over each cylinder head, using dual electric
fans.
I guess that I *would* need a separate blower motor for use with the
heater boxes, though. Something like the twin-outlet blower found in the
VW bus would do nicely, and then I would have a steady stream of heated
air inside the vehicle regardless of RPM. I would consider this a benefit.
You responded:
>I suppose if you wanted to, anything is possible, but I don't see any
benefit to it [electric fan replacing generator mounted fan].
I presume that one benefit would be decreased drag on the engine,
ESPECIALLY at high RPMs. It doesn't take much effort to turn over the
dynamo, but the amount of drag created by turning that fan at, say,
3500RPM must be fairly large. If you've ever broken a generator belt while
accelerating, you'll know what I'm talking about here.
I guess that what I'm after here is a "HP to the rear wheels" gain.
Although the dynamo will spend more time charging the battery, the
electric fan could free up some HP to the wheels.
I asked:
>>If it [electric fan] did work, I could add a timer to run the fan after
engine shutdown (much like the turbocharger cooler kits)
By continuing to cool the engine for, say, a minute after shutdown, I
think that would reduce the likelyhood of the temperature shooting up
after I switch off the engine. How much, I just don't know but I wouldn't
be surprised if it reduced maximum post-shutdown temps by 30% or so.
A very definite disadvantage to using electric fans is decreased
reliability. I don't know what the MTBF (mean time before failure) is for
radiator fans, nor do I know what the duty cycle (maximum running time vs.
cooldown time) for these motors is. It's hard to beat a mechanical driven
fan for reliability. Those belts last a long, long time and when it goes
it's very noticable. I'd need some sort of pressure switch (like those
used as safety systems in gas furnaces) that would sound an alarm or shut
off the engine if a fan failed to move a sufficient volume of air.
Sorry if I didn't word my originial post clearly. Thanks for the reply,
Jon Turner
Sudjim
Racers use "squirrel cages" for short term cooling. There must be at
least some benefit if Racers use them. You would need much stronger
motors to cool the engine, but there would be a HP gain. You could get
rid of, or relocate the generator and shroud. This could look very trick,
maybe win a trophy...
Jim Orce (sud...@aol.com)
Bill Crick
MARC TOUSSAINT wrote:
>
> JonTurner wrote:
> >
> > Greetings,
> >
> > Just an idea I've been chewing on for a while... would it be resonable to
> > replace the type 1 upright cooling fan with a pair of electric fans
> > located above the cylinders? Would I be able to move a high enough volume
> > engine?
SNIP...
Yes it would reduce 'drag' on the engine, as long as you don't get the
electricity to
run the fan from the engine;-)
I think you would be suprised to see how big the fans would be, and how
much power
they would suck.
You also would have trouble with the extension cord for the fans getting
tangled
up in overpasses, adn around lamp posts.
Bill Crick
76 Type 1.99998
Sterlng007
Your best bet is to reengineer the fan system. The idea is to create a
positive pressure going into the fan instead of a negative one. This would
releive the load on the fan, and in turn release more horsepower for the
engine. The problem is how to do this. The wind going by the car down the
highway is a good source of energy. You would have to create a duct system
from somewhere on the car to catch the air and direct it to the fan
opening. BMW had a great idea on a concept car where they put a duct
opening above the rear window (flush mounted) and had it go through the
back window (2 sheets of glass with a air pocket between) and into the
engine compartment. You don't have to get this fancy, but a duct running
from the front to the back, under the car, very wide and slim (say 24" by
3") that would take some of the air going under the car and put it to good
use. Another thing is to create a wider opening where the hot air comes
out, createing a vacuum pulling the air through faster. All of this would
help the fan that's already there. Just a thought.
Ron
66 single cab (undergoing full restoration)
73 beetle (being customized eventually)
JonTurner
To:
Newsgroup,
John Kuthe,
John,
Your response was well composed. I do want to continue the discussion
further, however. Just a couple of points...
>Why not just look at the situation from an *energy* standpoint??
Good. You're right, that's the proper way to look at this situation.
>There is a certain amount of energy used to drive the stock fan,
>right? And the goal is to save using this energy, to put it to use
>driving the transaxle input shaft instead, right?
Exactly.
>OK, that means, to maintain the same cooling air effect, that an equal
>amount of *energy* is going to have to come from some type of electric
>setup, electric fans, blowers, etc.
Probably equal, but only if there is an equivilant efficiency betw. the
two systems. Some impeller/propeller designs are not as efficient as
others at different speeds. I don't know whether the VW mechanical fan is
as efficient as modern variable-pitch, low inertia nylon bladed radiator
fans.
>And where's the energy gonna come
>from to *drive* those electric motors??!! THE GASOLINE MOTOR ITSELF,
Yep. I'm still with you.
>You ain't gonna drive those electric blowers
>from big batteries charged up at home (energy in), right?)
That's what the hamster treadmill in the boot is for. :) Jokes, aside. No,
I plan to run it off the engine's alternator. You're correct.
Here's the crux of my idea: The alternator is always turning, producing
mechanical resistance to the engine and converting that mechanical energy
to electrical energy, at least above 1000 RPM or so.
Here's the key point: The alternator puts drag on the engine all the time,
and 'produces' energy all the time. Most of the time, the battery is not
being charged and only a small portion of the energy 'produced' by the
alternator is used to power the vehicle's electrical components. (At other
times, such as when idling, the battery's 'surplus' of energy is tapped to
temporarily make up for the energy shortfall.) MOST OF THE TIME there is
an energy surplus from the alternator.
Since we're already converting the engine's mechanical energy to
electrical energy via the alternator, why not use that surplus to power an
electric fan, rather than introduce ADDITIONAL resistance by means of the
stock VW mechanical fan?
Am I on track so far? Or does the alternator introduce a variable amount
of drag depending on current drain? (I doubt this to be true.)
To make matters far worse for the mechanical fan, the VW fan is 1:1
linked to the alternator shaft resulting in an exponential curve where
drag increases as a function of RPM. Using an electric fan would at least
flatten the curve, freeing up HP at the top end and providing additional
cooling at low RPMs. If I wanted to get really fance, I could use a
variable speed circuit to modify fan speed as RPM changes.
(Water cooled cars achieve this by using a fan clutch to slip the fan at
high RPM's -- where the fan is no longer as mechanically efficient (due to
airfoil turbulance) to avoid the additional drag at the high RPM range.)
I understand the prinicples of energy conversion, but since the alternator
is already turning (and thus producing 75 or so amps of energy with the
hi-perf models) I'm not convinced that it would add additional drag to
the engine to power a high-volume fan off of the electrical current
produced by the alternator.
I don't know if I've expressed myself well. Hope all that came thru. I
look forward to your response.
Sincerely,
Jon Turner
John William Kuthe
In article <19970716224...@ladder01.news.aol.com>,
JonTurner <jont...@aol.com> wrote:
[re: an idea about replacing the stock cooling fan with some type of
electric fan]
You people! I'm talking about all the ones who responded to Jon,
saying things like "they'd have to be real big motors" and "the volume
of air moved by the stock system can't be beat" (not direct quotes),
sheesh!!
Why not just look at the situation from an *energy* standpoint??
There is a certain amount of energy used to drive the stock fan,
right? And the goal is to save using this energy, to put it to use
driving the transaxle input shaft instead, right?
OK, that means, to maintain the same cooling air effect, that an equal
amount of *energy* is going to have to come from some type of electric
setup, electric fans, blowers, etc. And where's the energy gonna come
from to *drive* those electric motors??!! THE GASOLINE MOTOR ITSELF,
one way or the other!! (You ain't gonna drive those electric blowers
from big batteries charged up at home (energy in), right?)
Now, as any first year physics student learns, whenever you change
energy from one form to the other, e.g. mechanical to electrical, you
LOSE some, because no energy form change is 100% efficient!! And
you're talking here about going from mechanical (the car's engine) to
electrical (one BIG alternator), *back* to mechanical (the blower
motors)!! In addition, you're talking about one *whopping* amount of
electrical energy, too!! How many watts of "energy" (power) does
anyone estimate it takes to drive all that cooling air from the stock
cooling system??
And since the car's motor will be driving this big alternator, at
*least* as much energy is going to come out of the car's motor and be
put to cooling the engine as with the stock mechanical fan!! And
surely more, due to transfer losses!!!! (What? You thought it took NO
energy to drive an alternator? Hey! Energy, like matter, is neither
created nor destroyed! It just changes form!!)
The bottom line is that NO type of electric blower could EVER provide
the motivating energy to move enough cooling air as the stock motor,
without taking EVEN MORE energy out of the car's motor!! Not without
the input of energy from outside, or another source (maybe a small
nuclear generator in the car!! ;-) )
--
John Kuthe, aka jw...@cec.wustl.edu, St. Louis, Missouri | MWA Homepage: |
First Job of Government: Protect people from govermment.| /www.missouri.edu/ |
Second Job of Government: Protect people from each other.| ~c681357/mwa.html |
It must *never* become the job of government to protect people from themselves!
Tony Huguley
This guy has a scientific approch.. I like that...
The idea may work, but think about what this guy is saying. Do the math,
even if it does work out in your favor, using the "physics" this guy is
talking about, and you figure out that you DO use less energy using the
electrical aproach.. Do the math and figure out that what you saved was
1/3rd hp? Is all the work, and expense to prove this scientific mind maybe
wrong WORTH the gain, if there is any?
Do the math, Math never lies...
Tony
John William Kuthe <jw...@ritz.cec.wustl.edu> wrote in article
<5qo24n$9...@ritz.cec.wustl.edu>...
David M. Brodbeck
JonTurner (jont...@aol.com) wrote:
: Am I on track so far? Or does the alternator introduce a variable amount
: of drag depending on current drain? (I doubt this to be true.)
--> Yup. The more current drain on an alternator (or generator) the harder
it is to turn. Ever heard of 'dynamic braking' on diesel-electric locomotives?
Or 'regenerative braking' on electric cars? The electric drive motors are
run as generators, and the output is soaked up by batteries (car) or by
a big resistor bank (locomotive).
Kenton Green
Hello Jon,
JonTurner wrote:
>
> To:
> Newsgroup,
> John Kuthe,
>
> John,
> Your response was well composed. I do want to continue the discussion
Well composed?!? He had an almost condescending attitude, and what he
wrote missed some important issues, to boot!
> further, however. Just a couple of points...
>
> >Why not just look at the situation from an *energy* standpoint??
> Good. You're right, that's the proper way to look at this situation.
>
So far so good...
> >There is a certain amount of energy used to drive the stock fan,
> >right? And the goal is to save using this energy, to put it to use
> >driving the transaxle input shaft instead, right?
> Exactly.
>
> >OK, that means, to maintain the same cooling air effect, that an equal
> >amount of *energy* is going to have to come from some type of electric
> >setup, electric fans, blowers, etc.
> Probably equal, but only if there is an equivilant efficiency betw. the
> two systems.
Yes, Jon, you are exactly right, and it seems John missed this point.
> Here's the key point: The alternator puts drag on the engine all the time,
> and 'produces' energy all the time. Most of the time, the battery is not
oops, here you went wrong. The alternator's drag on the engine is
proportional to the energy it is being asked to produce. The conversion
is 750 Watt (as in light bulb power) = 1 hp (as in engine power). Turn
on more electrical devices like light bulbs (or electric fans) and more
hp will be drawn from the engine.
> being charged and only a small portion of the energy 'produced' by the
> alternator is used to power the vehicle's electrical components. (At other
> times, such as when idling, the battery's 'surplus' of energy is tapped to
> temporarily make up for the energy shortfall.) MOST OF THE TIME there is
> an energy surplus from the alternator.
>
Nope, the alternator only supplies enough energy to run all electrical
devices presently on (assuming batt is fully charged).
John Knuthe said to look at it from an energy point of view, but
actually for you, that is wrong (I am assuming you are interested in
racing?).
You want to look at it from a HEAT/engine lifetime point of view. What
I mean by this is: if you are only doing quarter-mile drags, then screw
the cooling: right before the light turns green, cut the belt to the
alternator and fan! This is called total loss (and has the added
meaning of total loss for cooling as well). It should cut at least a
second off your time, if not more.
If you are a circle-racer, figure out how long a race usually is, and
how hot your engine can stand to be for that period of time without
dying, and run it that hot. (by shutting the fan off, or removing some
blades, etc) You may lose a race or two because your engine dies, but
then you have a much better chance of winning the ones that your engine
survives than you did before.
The stock system is meant to keep the engine cool enough to go 100,000
miles. You only care about one race. Your goals are completely
different than the factory goals, so why use their cooling system? The
neat thing about electric fans is that you can turn them off with a
switch while the engine is running, and you can run them at the rpm
where they are most efficient. Hook them up to a temperature sensor,
and run the engine at whatever max temp you are comfortable with,
without using silly flaps!
Of course, if the car is a driver, or you are not a real hard-core racer
and don't rebuild your engine often, then you will have to temper
everything I said.
Someone else mentioned "air scoops". Again, you can't get something for
nothing; they increase drag on the car, and so rob HP. It may be that
something can be designed that is more efficient than a given fan-driven
cooling scheme, but it needs to be carefully designed; you can't just
hang a few large snouts off the car and see adequate cooling with an
increase in hp.
<blabbering off>
Kenton
--
University of Rochester/Center for Optoelectronics
http://www.seas.rochester.edu:8080/ee/users/kgreen/
Bill Crick
Can someone explain how the electrical approach can save energy?
Unless the actual fan blade on the engine is very poor efficiency, and
your electric blowers have very well designed blades, it has to use
more energy due to the losses in teh alternator, and the motor.
Even if the engine fan blade is inefficient, the best solution would
be to replace it with a beeter blade?
Seems to me the stock fan drives on the order of 1700cfm, into
who knows what pressure. That is quite a bit of air!
Bill Crick
76 Type 1.999998
Tony Huguley wrote:
>
> This guy has a scientific approch.. I like that...
>
> The idea may work, but think about what this guy is saying. Do the math,
> even if it does work out in your favor, using the "physics" this guy is
> talking about, and you figure out that you DO use less energy using the
> electrical aproach.. Do the math and figure out that what you saved was
> 1/3rd hp? Is all the work, and expense to prove this scientific mind maybe
> wrong WORTH the gain, if there is any?
>
> Do the math, Math never lies...
>
> Tony
>
> John William Kuthe <jw...@ritz.cec.wustl.edu> wrote in article
> <5qo24n$9...@ritz.cec.wustl.edu>...
> > In article <19970716224...@ladder01.news.aol.com>,
> > JonTurner <jont...@aol.com> wrote:
> > [re: an idea about replacing the stock cooling fan with some type of
> > electric fan]
> >
> > You people! I'm talking about all the ones who responded to Jon,
> > saying things like "they'd have to be real big motors" and "the volume
> > of air moved by the stock system can't be beat" (not direct quotes),
> > sheesh!!
> >
> > Why not just look at the situation from an *energy* standpoint??
> >
> > There is a certain amount of energy used to drive the stock fan,
> > right? And the goal is to save using this energy, to put it to use
> > driving the transaxle input shaft instead, right?
> >
> > OK, that means, to maintain the same cooling air effect, that an equal
> > amount of *energy* is going to have to come from some type of electric
> > setup, electric fans, blowers, etc. And where's the energy gonna come
> > from to *drive* those electric motors??!! THE GASOLINE MOTOR ITSELF,
> > one way or the other!! SNIP....
STEPHEN EARLY
In article <19970718184...@ladder02.news.aol.com>,
JonTurner <jont...@aol.com> wrote:
>
>Am I on track so far? Or does the alternator introduce a variable amount
>of drag depending on current drain? (I doubt this to be true.)
Actually Jon, I'm pretty sure it does. I'm not able to describe the
physics behind it but I've experienced real-world examples. When I used
to work with gasoline driven generators and alternators, the load on the
engine increased as the power demanded increased.
--
Steve Early
'62 VW crew cab *for sale*, see http://udel.edu/~early
Kenton Green
STEPHEN EARLY wrote:
>
> In article <19970718184...@ladder02.news.aol.com>,
> JonTurner <jont...@aol.com> wrote:
> >
> >Am I on track so far? Or does the alternator introduce a variable amount
> >of drag depending on current drain? (I doubt this to be true.)
>
> Actually Jon, I'm pretty sure it does. I'm not able to describe the
> physics behind it but I've experienced real-world examples. When I used
I can explain the physics with a simple example, but first, to see the
relationship let me explain a small point about an alternator/generator:
An alt/gen supplies current at 12 volts to recharge the battery and
power everything else using the principle of moving magnets (to simplify
a little). Moving a magnet across a wire will cause current to flow in
the wire under the right circumstances. The more current that is pushed
thru the wire, the harder it is to push the magnet past it (i.e. the
stronger the opposing force).
Ok, real-world example. Take two small/weak magnets, like two
refrigerator magnets, and push together the sides that repel each
other. Feel the effort that it takes? Now replace one of those with a
stronger magnet, like the rare-earths from speakers or DC motors etc,
and again push together the sides that repel each other. Feel how it is
harder to do?
It is more difficult to push them together in the second example, and if
use your imagination, you may be able to see what your engine sees when
you turn on the lights, crank up your 200W stereo, etc. The larger
current drain demanded from the alt/gen makes the stator/armature look
like a stronger magnet, and it becomes harder for the engine to push the
field magnet past it (or for the field to be pushed past it if we are
talking about an alternator).
Therefore, to sum up, higher current draw (due to electric fan, lights,
etc) makes the magnet (stator or armature) inside the alt or gen
"stronger", which makes the alt/gen harder to turn, which loads down the
engine...
Got it? Good, 'cuz there's a pop quiz tomorrow. :)