Electric engine fans

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Scott V
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Re: Electric engine fans

Post by Scott V »

cvair4life wrote:I just e-mailed Keith to see if he's done any real bench testing on his fan. Says he's an Engineer so he may have data to back it up. We'll wait and see.
thats very cool & i hope he gets back to you. he has data posted on his web site - this data is posted in this thread. what other data are you looking for? oh............i just looked @ his site & he has removed most of the data that we are asking about. i guess that says alot - was the data real/valid.

his statement that "The mechanical belt driven fan consumes 25hp at 3000rpm......" is wrong also & needs to be corrected. the stock fan consumes 1.1 hp @ 3000 rpm.

this isnt meant as a dig - but i wonder what kind of engineer he is. most of his claims/data he has for the fan kit makes no sense based on any simple engineering or science foundation.
cvair4life wrote: If not..... maybe I can talk him into sending me one of his setups and I'll do a full fledged bench test myself. I may not have a lot of skills in life... but being a nerdy bench scientist is one of those rare skills I do posses.
that would be great & would help a ton. what type of bench test/tests would you do? do you have a way to measure cfm & pressure?

-Scott V.
USAF_vair
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Re: Electric engine fans

Post by USAF_vair »

Hello, it has been a while sense i been able to look into the electric conversion of the Corvair fan. I kind of ran into a wall with the engineering behind the engine. Correct me if i am wrong, but the engineers changed the style of the corvair fan between the early and late models. The reason for this i concluded was the increased performance the engine was producing. The design of the late fans has the blades close from say "1-4 o'clock” and further apart as it goes around. The question i have is why would they do this? is it because the fan then would create like a tornado effect under the cowling, with air force higher on one side of the engine, "BUT Rotating around with the fan" With this the CFM's the fan is pulling in is divided differently among the "8" cooling sections between the cylinders. This increased Air Force would cool the far reaching areas of the motor better than an electric fan would.
Does this theory hold water? Why did the engineers change the fan design?
Scott V
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Re: Electric engine fans

Post by Scott V »

im guessing here but i think the engineers changed the fan design to make a lighter fan & maybe a less costly fan.

the curved blade steel fans worked well but where heavy & a heavy fan leads to tossing fan belts. all the 3 different fans move about the same amount of air @ near same pressures & need about the same power to drive the fan but the straight blade mag fan is much lighter.

the cast mag fan was probably less expensive to make - even w/mag being more expensive than steel. casting/injection molding is less expensive for a part like this cuz the steel fan is made w/lots of little samped parts & then welded together.

-Scott V.
145236
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Re: Electric engine fans

Post by 145236 »

The change was made because of the inertia of the steel fan, its weight exacerbated fan belt problems. The original plan for 64 was the same design as the magnesium fan, but in delrin. Turns out when the generator was putting a good charge into the battery at speed tiny droplets of acid were expelled from the battery and these reacted with the delrin fan to produce formaldehyde fumes which then got shoved right into the heater, causing great discomfort to the driver. I'll try to find the original engineering papers on this, I seem to remember that the old steel fan moved more air than the later mag version.
miniman82
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Re: Electric engine fans

Post by miniman82 »

Sounds like a strong case for relocating the battery to the trunk.
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4carbcorvair
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Re: Electric engine fans

Post by 4carbcorvair »

I'm suprised no-one, that I know of, has looked at using a ford Taurus fan. I installed one in my jeep cj, no cooling issues with the v-8. http://www.go.jeep-xj.info/HowtoTaurusFanInstall1.htm It's a two speed fan. Approximately 2,500 cfm on low, 4,500 on high. The thing will suck small children up against the grill If it running. It is a large fan tho.....
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145236
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Re: Electric engine fans

Post by 145236 »

The stock fan moves enough air for even the wildest high-horse motors. The parasitic HP loss is negligible. With a top quality belt properly installed it is as trouble free as any part on the car. Why put on a part that adds chances of failure to on/off switch, electric motor failure, requires addition of very high output alternator, and does not have benefit of over 50 years of extensive road testing?
As mentioned above, power needed to move air is pretty much the same if direct from crank to fan as it is from crank to alternator to motor to fan. Can't see any benefit myself. I have seen a high output alternator in a jump-started Corvair put such a load on the belt as to MELT the belt.
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azdave
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Re: Electric engine fans

Post by azdave »

4carbcorvair wrote:I'm suprised no-one, that I know of, has looked at using a ford Taurus fan. I installed one in my jeep cj, no cooling issues with the v-8. http://www.go.jeep-xj.info/HowtoTaurusFanInstall1.htm It's a two speed fan. Approximately 2,500 cfm on low, 4,500 on high. The thing will suck small children up against the grill If it running. It is a large fan tho.....
I have five of those popular Taurus fans squirrelled away for future use and two of them are in operation in my Corsa V8. They are powerful fans but are not good at building air pressure in my opinion. A single Taurus fan pulls close to 35A at full speed.

Most automotive fans are designed to suck air through the radiator, not blow. I think they would operate poorly as a blower fan once they are trying to build air pressure under a shroud of any type but until someone does more testing it's just my guess. I am happy with the cooling arrangement on my stock Vairs and have no desire to change.
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USAF_vair
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Re: Electric engine fans

Post by USAF_vair »

I agree with the changes to the fan for weigh reasons. the question still is why was the fan designed with fan blades close on one side and farthur apart on the other side? one would think that there is a weight difference in the fan. if the far apart blades pull more air there would be greater forces on that side of the fan. this would create a load on that side of the bearing. so is did GM design the blades closer on the oppsite side to creat a counter weigh to reduce the rotating forces put on the fan's center bearing?
Scott V
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Re: Electric engine fans

Post by Scott V »

USAF_vair wrote:I agree with the changes to the fan for weigh reasons. the question still is why was the fan designed with fan blades close on one side and farthur apart on the other side? one would think that there is a weight difference in the fan.
oh - i understand what you are asking now. the fan blades are not evenly spaced to cut down on fan noise. it doesnt affect the fans performance. the factory balanced the fans so you dont have a weight differance in the fan.

-Scott V.
USAF_vair
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Re: Electric engine fans

Post by USAF_vair »

how does the air pressure between the stock corvair fan and the air pressure of this electric fan compair? for people with after market headers this i have read is not an option. this is due to the air forces that are coming up from under the car and acually pushing back against the" now opened portions of the heads and cylinders.
Scott V
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Re: Electric engine fans

Post by Scott V »

USAF_vair wrote:how does the air pressure between the stock corvair fan and the air pressure of this electric fan compair?
no one knows cuz no real/valid info has been posted for his fan. the stuff on his web site said his fan moves 4596 CFM @ 4 PSI. that would be about 3x the cfm & 11x the pressure of the stock fan - & he is doing it w/about 10% of the power that the stock fan needs. id think that is kind of impossible.

-Scott V.
USAF_vair
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Re: Electric engine fans

Post by USAF_vair »

true sir,

you bring up a good point. Laws of conservation of energy. takes energy to create it. and 4596 cfm is a lot of air and would take lots of power to move. really would be great seing a dyno chart of the converstion or at least some type values for proof of the power gain.

i work in the air force and even some the the jets and cooling systems on the planes air not producing near enough cfm's. the only parts that due move the amount of air needed to cool the corvair uses a engineered hydraulic motor.
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Canyon Man
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Re: Electric engine fans

Post by Canyon Man »

I've used a electric fan (perma cool 2500cfm?) on my sandrail for 10 years (never failed) and I think there is a difference in horsepower. Turning it on or off there is no noticable draw on engine (through alternater) at idle, compare that to another rail I had with a "electric clutch" on the balancer which uses the stock fan/belt and at idle engaging the fan would almost stall the engine and more importantly when disengaging it would relieve the engine (rev slightly higher).
Luke Geis
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Re: Electric engine fans

Post by Luke Geis »

I have tried two different electric fan designs. I have had no luck........... The second design utilized the popular permacool 2500 cfm fan. It says it will push the 1800 cfm needed, but I didn't have luck. Getting the shrouding to fit well enough to lock the forced air down over the engine was the major issue. The 14" wide fan left a huge gaping hole in which it would just cavitate as it tried to push air through the engine. Where it did excel was at idle. It would run cooler at idle all day than when running down the freeway. You could drive for quite some time before the engine would get upset, but anything more than a cruise around town was too much for it. The first design was a fail from the start........

Now I do believe that if you could drive the stock fan @ the peak RPM with an electric motor then there should be no worries of overheating. The engine RPM is what we base the peak performance of the fan at. The 3000 RPM that the motor turns would mean that the fan is turning faster because of the pulley system. This is where is see an issue. If you could find an electric motor and directly drive the fan up to an RPM well in excess of 3000 RPM, then there may be a case for the electric cooling fan system. The issue I see is that it will be pretty hard to find a motor that will turn 5000 + rpm that may be needed and have enough power to turn the fan.

Now if..........................this fan can produce more cfm and PSI. with a lower fan speed and or less power required to do so, then it again is viable. I see it being likely that the fan is a better design and is fully capable of producing better numbers than the stocker, but the question is really if the motor turning it will finish the job? For example, you could use the same fan ( electric design ) with the conventional belt system and use different pulley's to reduce power draw and still achieve the 100% cooling needed all the time. The current stock system isn't broke, but it does rob a noticeable amount of power. I don't see any reason to be really worried about the loss it does create unless for performance driving. But if a reliable electric fan system was available I would be interested. I have known of this system in question for a while, but it does seem too good to be true. I don't doubt that it is capable, but it would sure be nice to see it in action and with some actual hard data to support it's claim.
Scott V
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Re: Electric engine fans

Post by Scott V »

the electric fan question can be roughed out in a simple way...............the stock fan takes about 3 hp @ 3K engine rpm.

the stock fan is not real bad - design wise - but lets say you can make a really great fan & matching tin to fit the engine. lets say you can make it 2x better than the stock fan - not likely - but lets just say. you would need a 1.5 hp electric motor to drive the fan.

ok - lets now say that since you will drive it direct you will save power not having the fan belt run over the pulleys. how much power would that save? 10%? 30%? lets guess & say youd save 1/2 a hp - again just guessing. you need a 1 hp electric motor. if you will be using the cars 12v system - start looking for a 1 hp 12v motor - thats the minimum size that even makes sense.

guys that are selling/pimping kits w/motors that are 1/4 or even 1/3 hp are either fooling themselves or looking to make a fast buck on the backs or others - maybe both. gg.

there are lots of other things to put in the mix & im not saying you cant cool a vair engine w/a electric fan. buggys, auto-x cars, drag cars, etc....these can be cooled w/a electric fan as they dont run w/the same conditions as a car.

if you want to cool a vair engine w/a electric fan in a stock type vair car & cool it at all temps/driving conditions like the stock fan does - you are going to need @ least a 1 hp motor if using a very much improved fan & engine tin. if you want to use the stock fan & engine tin you probably need a 2 hp motor.

-Scott V.
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