Automotive Related Ducted Fan Question - RC Groups
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Sep 05, 2001, 12:30 PM
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Automotive Related Ducted Fan Question

I just purchased a We-Mo-Tec fan from for my car. I don't really know what you guys will think about using an electric ducted fan as an "electric supercharger" but I can tell you that it added about 10-15HP to my car. No kidding. The problem is that this fan makes a whole lot of volume but very little pressure. I am trying to find a better fan blade (12 blades hopfully) as well as a brushless motor that will spin faster and draw more current. I have "unlimited" available current so that is not an issue. I am limited to about 13-volts though. I browsed Aveox's web site but I am not sure what motor I am looking for. Any suggestions as to which motor would be a good upgrade for this fan? Thank you!
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Sep 05, 2001, 03:42 PM
Registered User
You have calibrated Dyno results.. Before AND after to substantiate this.. (on first glance unbelievable) claim???
Sep 05, 2001, 03:47 PM
aka: A.Roger Wilfong
gnofliwr's Avatar
You should be able to just use a 12v automotive vacuum cleaner, hook a hose in place of the bag and force feed the air cleaner snorkle. Cheep and dirty - worked with a carb in the 60's (required a little tuning), don't know what it would do with today's fuel injectors and electronic controls.

- Roger

[This message has been edited by gnofliwr (edited 09-05-2001).]
Sep 06, 2001, 08:24 AM
Registered User
I have no verification of any HP gain other than my "butt dyno" which is a huge variable I know. The e-ram made a noticable difference in first and second gear at higher RPM's. It made a little difference in third, but no difference in fourth and fifth. I am still looking to upgrade the fan blade and electric motor to see if I can get a little more "boost" from this thing. As far as the vacuum cleaner suggestion: A centrifugal supercharger would be much better for this application than an axial flow ducted fan for sure. I guess if I was going to try that I would start with a good leaf blower and get a power invertor. I really want to see how far I can take this using only 12-volts though. I am still looking for a better fan blade and electric motor...
Sep 06, 2001, 10:25 AM
No "R" !!!!!!!
Fitz Walker's Avatar
What kind of car did you put it in?

Sep 06, 2001, 11:02 AM
Registered User
2000 Subaru Impreza 2.5RS. It has a 4" cold air intake feeding the WeMoTec. From there it goes to a 3" pipe all the way to the throttle body.
Sep 06, 2001, 11:08 AM
Registered User
Oh yea, the air filter is located AFTER the fan. It is in the factory airbox but is a very large, high-flow air filter. If the fan comes apart I don't want it going through my engine.
Sep 06, 2001, 11:15 AM
Registered Electron User
CharlieS's Avatar
I saw the video demo where a guy had the fan running off of the car battery while holding it in his hand. He let go and it shot upwards. Do you know what fan and motor are being used and do you have a guess at the thrust? The website did not give much info in this respect. Is the moter brushed? Is the fan really a WeMoTec?

Sep 06, 2001, 11:41 AM
Registered User
The fan assembly is a WeMoTec MIDI 3 1/2" fan. The motor IS a brush motor. I want a better electric motor, maybe brushless. I have "unlimited" current at 12-volts. What Aveox motor would be the best replacement?
Sep 06, 2001, 12:19 PM
jbourke's Avatar
Originally posted by subarumantoo:
The fan assembly is a WeMoTec MIDI 3 1/2" fan. The motor IS a brush motor. I want a better electric motor, maybe brushless. I have "unlimited" current at 12-volts. What Aveox motor would be the best replacement?
What you want is a motor with a higher Kv than the current motor and also more mass (which should translate to a higher thermal limit - allows more torque). Both are needed for your application.

So basically a big motor with a low number of winds is the ticket. It doesn't really have to be brushless because it doesn't sound like efficiency is the issue.

The disadvantage of brushless is that you will need an expensive controller that is designed to drive a brushless motor. You can't just hook up the brushless motor to a positive and negative wire. I believe Aveox makes a suitable controller, but I have never looked at their industrial parts.

The advantage of brushless in your case is basically that you get more torque per ounce of motor. If you want the most suction, brushless is going to win out over brushed.

A higher solidity fan is going to make a big difference for you. The reason is that it will cause more of a load which will allow you to go to a lower Kv motor. But, realistically, I think you will be happy with just switching motors. Playing around with different fans will be a pain.

Typically, The 1409/1.5Y from Aveox is a good choice on the Midifan and 12 volts. If you can get Aveox to make you a 1409/1Y, that will be even better. You could also use a 1412/1.5Y or a 1412/1Y if they will make it for you.

Now the problem with these motors is that you are going to be running them for a lot longer than we typically do in our airplanes. That means that you will build up heat and there is about a 90% chance that these motors will not survive more than a 5 to 10 minute period of use. So what you really need is a bigger motor with the same Kv as the above motors.

Your goal is to find a motor that fits the minifan that has a Kv at or above 2000.

What motor is in the fan unit now?

I hope that helps.



Sep 06, 2001, 12:50 PM
Registered User
Thank you for the input! That is what I was looking for. I also think that the problem of running the electric motor for long enough to overheat it is really not that critical. The fan only runs for a few seconds at a time, plus there is always air moving across the motor because of the vacuum created from my engine. I am going to get back on Aveox's web site and do a little more investigation. Thank you again!
Sep 06, 2001, 03:52 PM
Registered User
The small volume of "boost' air as you call it is probably leaning out your mixture enough to give a performance boost, potentially enough to quickly wreck your engine.
The actuall volume (and pressure) of air that your engine requires under full load, wide open throttle operation is surprisingly high, so high in fact as to be the cause of 'Turbo Lag' in genuine turbo configurations... asuming that a model aiplane electric fan can generate even small percentages of the required air is optimistic given that a purpose designed turbo unit (the WRX unit for example) has to spin at 110 to 120,000 rpms to get the job done... tough to find a good brushless for that:-)
Sep 06, 2001, 04:23 PM
Gravity sucks.
mrittinger's Avatar
You must remember that an internal combustion engine is nothing more than an air pump.Anything that can be done to increase airflow in, or out, of the engine will increase performance.
However,the pressure created by a 40% efficient model EDF setup is minimal, and when the internal resistance felt by said accelerated air hitting the Air Filter, little if any benefit would be realized.
You notice that Turbos, most of the time, are AFTER the air filter.There is a reason for this.
You would be better to try getting cooler( denser, more efficient) air to the intake system.(this is why Hot Rodders Ice-Pack the intake manifolds on the car between races.)
I would say you should invest in rerouting the intake to a cooler air pickup position,and popping on a nice, open free flow exhaust.
The IDEA of forced air is a good one, one that has been used for a long time in turbines , Roots type superchargers,and turbos, but it takes a buttload of VOLUME and VELOCITY to get any benefits...
It might help to get cooler air through your EDF into the intake to cool it down after stopping the engine, thus giving better power after startup but before the heat transfers through the motor to the intake again.

Just my hot rod past experience $.02

Sep 06, 2001, 04:25 PM
Registered User
My car requires 230CFM at wide open throttle at 6250RPM. The WeMoTec MIDI fan makes over 700CFM using the little brush motor that came with it! That is over twice the required VOLUME. The problem is the fan doesn't make much pressure. As far as my engine running lean, my factory ECU is capable of managing about 3lbs of boost with no modifications what so ever. I am not even close to that. The best I can tell from my vacuum/boost gauge is that I am making about .75lbs of boost with the WeMoTec. My goal is 1.5lbs of boost. I found the Aveox 1412/1.5Y that looks promising. I have also spoke to someone who thinks I could actually stack 2 of the 6-bladed fans on top of each other using a special adapter. Any opinions on that?
Sep 07, 2001, 12:27 AM
Dieselized User
gkamysz's Avatar
Odds are that increasing the power to the fan will have little effect. My guess is that the fan is stalled. If the fan should be flowing 700CFM as you say, then the chances of it being stalled while being restricted to only 230CFM are very good. The solution is a better compressor. A single stage axial flow fan isn't going to cut it.

To make 1.5psi and flow 230CFM you would need over 3HP to the fan. A single stage fan doesn't allow for this at any RPM below 60k. Even then I don't think you could do it efficiently. BTW 3HP from 12V is 200 amps.

Mounting a blower before or after the filter has little to do with performance. They are always mounted after the filter for the obvious reason. To keep it clean, as dirt in a turbo or blower will quickly wear the tight clearances it is manufactured to. You aren't accelerating air, you are pressurizing it.