Jump to content


Welcome to Ultimate Subaru Message Board, my lurker friend!

Welcome to Ultimate Subaru Message Board, an unparalleled Subaru community full of the greatest Subaru gurus and modders on the planet! We offer technical information and discussion about all things Subaru, the best and most popular all wheel drive vehicles ever created.

We offer all this information for free to everyone, even lurkers like you! All we ask in return is that you sign up and give back some of what you get out - without our awesome registered users none of this would be possible! Plus, you get way more great stuff as a member! Lurk to lose, participate to WIN*!
  • Say hello and join the conversation
  • Subscribe to topics and forums to get automatic updates
  • Get your own profile and make new friends
  • Classifieds with all sorts of Subaru goodies
  • Photo hosting in our gallery
  • Meet other cool people with cool cars
Seriously, what are you waiting for? Make your life more fulfilling and join today! You and your Subaru won't regret it, we guarantee** it.

* The joy of participation and being generally awesome constitutes winning
** Not an actual guarantee, but seriously, you probably won't regret it!

Serving the Subaru Community since May 18th, 1998!

Guest Message by DevFuse
 

Photo
- - - - -

Supercharger for EA81


  • Please log in to reply
35 replies to this topic

#1 Dante

Dante

    Eat, Live, Breath Subaru

  • Members
  • 333 posts
  • Seattle

Posted 29 August 2004 - 02:36 PM

I picked up a copy of Sport Compact on vacation because it included an article on my first Japanese car--a 1972 Datsun 510. While perusing the magazine, I saw an add for Procharger superchargers. That got me thinking.

I assume the prochargers cost too much to put on a $1,300 car. All the dealer websites I visited said "call for pricing." However, I stumbled on hints here and on a couple aircraft sites that someone might have retrofitted a Mazda supercharger onto an EA-81. Anyone have any details?

#2 Scoobywagon

Scoobywagon

    Evil Genius (tm) for Hire

  • Members
  • 1,044 posts
  • Bremerton-like

Posted 29 August 2004 - 03:45 PM

Don't know about a Mazda Supercharger, but Ive sorta been working on retrofitting an Eaton M90 (Thunderbird SC) to an EA81. So far, I need a custom manifold (working on it) and some better carburetion. I'm thinking about using a pair of weber side drafts for that. Not real sure, but I suppose we'll see what we shall see.

#3 Frank B

Frank B

    Subaru Master

  • Members
  • 2,226 posts
  • VA

Posted 29 August 2004 - 04:49 PM

Well other than the manifold, drive belt, and fuel management, It would probably be in your better interest to start with a turbo engine. This way you have the block and internals designed for the forced induction. But you could easily get by with lower compression pistons, or just run low boost. But if your going thru all the trouble with the modifications to the induction set-up. you will want to run high boost to take FULL advantage of the supercharger.

I believe the Eaton supercharger is on the buick 3800's too, as well as some Jaguar XJ6's, so they are available.

#4 Scoobywagon

Scoobywagon

    Evil Genius (tm) for Hire

  • Members
  • 1,044 posts
  • Bremerton-like

Posted 29 August 2004 - 04:55 PM

I'm starting with what I have, mostly as a proof-of-concept. If I can get it to work more or less the way I want it, then I'll move up to turbo goodies and start tweaking on it to get engine management all tuned up. Mostly, I thought this might work as a means to boost low-end torque for more 'wheeling goodness.

Either way, I'm just in the planning stages at the moment.

#5 carfreak85

carfreak85

    Temple of Fuji

  • Members
  • 5,020 posts
  • Cascadia

Posted 29 August 2004 - 08:36 PM

You might look for superchargers that were originally installed on small cars or used ones for british cars like MGBs and Midgets, etc.

#6 Dante

Dante

    Eat, Live, Breath Subaru

  • Members
  • 333 posts
  • Seattle

Posted 31 August 2004 - 10:00 AM

Well other than the manifold, drive belt, and fuel management, It would probably be in your better interest to start with a turbo engine. This way you have the block and internals designed for the forced induction. But you could easily get by with lower compression pistons, or just run low boost. But if your going thru all the trouble with the modifications to the induction set-up. you will want to run high boost to take FULL advantage of the supercharger.

I believe the Eaton supercharger is on the buick 3800's too, as well as some Jaguar XJ6's, so they are available.

I'm sure you are right. I wanted to put a dual-range tranny in a turbo car and lift it, but I wanted an EA-81 NOW more ;)

Here is a link to the thread on the supercharged EA-81 with pics:

http://subaru.sonik....pics/18786.html

Looks like it was a Toyota supercharger on an EA-82.

#7 oddcomp

oddcomp

    Subaru Master

  • Members
  • 1,763 posts
  • longview ,wa

Posted 31 August 2004 - 02:13 PM

hmm thats all mad maxish and stuff
as long as the s/c is not too big
you can get a custom drive pulley made for it
to provide the correct s/c rpm for x amount of boost

#8 MorganM

MorganM

    Do you Subaru?

  • Members
  • 8,390 posts
  • TwinCities

Posted 31 August 2004 - 03:52 PM

TURBO

#9 RAD

RAD

    Advanced Member

  • Members
  • PipPipPip
  • 64 posts
  • SoCal

Posted 11 September 2016 - 04:35 PM

I want a blower/super charger, the kind that comes up through the hood and looks cool, like on the engine in th eoriginal Mad Max movie - is this possible? What is it and where can I get one?

Thank you.



#10 Crazyeights

Crazyeights

    Crazyeights

  • Members
  • 1,369 posts
  • Pacific Northwest

Posted 11 September 2016 - 06:42 PM

The supercharger on the Mad Max car was for looks only. It didn't actually work.



#11 dfoyl

dfoyl

    USMB Regular

  • Members
  • 193 posts
  • Victoria, Australia

Posted 11 September 2016 - 09:11 PM

Tweety had a SC12 from memory on a stock EA81. I think these were found on "Z" badged Corolla's and similar. Fairly cheap and easy to fit from memory. Fuel economy was pretty terrible though.

 

Link : http://www.ausubaru....ead.php?t=23606


Edited by dfoyl, 11 September 2016 - 09:16 PM.


#12 iceageg

iceageg

    USMB Regular

  • Members
  • PipPipPip
  • 61 posts
  • Denver, CO

Posted 12 September 2016 - 08:16 AM

I want a blower/super charger, the kind that comes up through the hood and looks cool, like on the engine in th eoriginal Mad Max movie - is this possible? What is it and where can I get one?

Thank you.

You can find an Eaton M60 supercharger for fairly cheap on ebay.  That will have the look you want and may be small enough to still work efficiently on your motor.  To work and stick out of the hood the way you want you will have to fabricate an application specific intake manifold.  You would be better off with one of the newer, smaller centrifugal units on the market but they rule out the mad max look you want.  It can be done but I'm pretty sure you will be treading some new water hear so expect to do some trial-and-error fact finding along the way.  If you are carburated you may want to consider switching over to fuel injection also.  Both can be done but both tuning and fuel economy will be much better injected vs. carburated.



#13 skishop69

skishop69

    If it ain't broke, you're not trying.

  • Members
  • 1,235 posts
  • Puyallup

Posted 12 September 2016 - 09:42 AM

You'll need a smaller SC. The one Scooby is going to use is way too big. It needs to come from an engine of similar displacement. He'll have to more than double the size of his crank pulley to bring the volume of air coming out down to a usable amount. Doing so is going to increase the HP lost to run it and effectively kill the bottom end torque he's trying to gain. I believe there is a factory SC from a Mini Cooper that would work.



#14 RAD

RAD

    Advanced Member

  • Members
  • PipPipPip
  • 64 posts
  • SoCal

Posted 12 September 2016 - 01:27 PM

Ok... Two developments that at least for me are MAJOR. Preface: Even though it could be cheaper and more available, I am not considering "turbo". There was a very good discussion or two inhere somewhere about why Superchargers are better than Turbo, chiefly, because Superchargers operate directly in relation to either what you are doing with the throttle, or the engine/RPM, whereas Turbo does things slightly differently, and if I recall right, it was said that a drawback with Turbo is that it can kick in when you may not want it to, like in the middle of a tricky turn. That was what changed my mind to not wanting Turbo, with the caveat that of course, I could get some wrecked Subaru with a turbo engine and do a swap, and doing so could be fairly easy and cost effective.

HOWEVER, specifically if/since I am in love with the EA81 for its simplicity and lack of any timing belt/chain and want to stick with it, and not have to modify things just to put it in my Brat, Turbo is out of the game for me.

 

(1) I and others should study up on the similarities, differences, pro's, con's - what are the differences concerning "Superchargers" "Blowers" and other possible similar hardware.

 

(2) The possible game changer for me, was when I realized the possible potential for doing something different - a blowers, superchargers, etc. are basically about forcing dense (cold?) air into the engine, therefore, I could possibly put a glorified shop vac motor on my carb and make a difference - I know, that would not necessarily work, and reasons for it, etc. HOWEVER, what if one could use an ELECTRIC based blower? Such a thing could be far less expensive, much easier to get, mount, fabricate, etc., and if the right blower/motor was found, for one thing, a variable speed motor/blower, it could be controlled in/by different means, relating to your use of the throttle, the engine RPM, etc.  What I am in the initial stages of checking out, is mounting a second alternator where the air conditioning used to be, and using that to power some kind of electric blower, and possible an alternative form of air conditioning/cooling, likely using Peltier devices in some way....

I will have to find out what the CFM?/ Cubic feet per minute of say, the beloved Weber Carburetor is or can be, and using that as a minimum/base requirement for the blower. I am off-the-bat considering something with a cool looking scoop of some sort, using two roller type fans right at the front or it, with a removable grill/filter, which, if the fans had blades that can be chromed, would look super vicious ultra cool, lol...


Holy Carp! I think I already figured it out! I also happen to be a freak about private/hobby/commercial drones, and RC aircraft, in that realm, they use certain motors called EDF's, Electric Ducted Fans, which are by nature and requirement very power efficient, extremely high RPM, and built from inception to efficiently blow a high volume of air at high speed. On the aesthetic side, they would also give it a Jet engine whine type of sound that would probably sound a lot better than the average 'Turbo' sound, and look just as cool if one mounted say three of them side-by-side in a cool looking scoop!

 

I will be checking this out immediately!!!

 

Found an article:

http://electricsuper...r.blogspot.com/

 

UPDATE: This is looking just too good...


cnc-aluminum-90mm-12-blade-fan-unit-8.jp

 

65edf.jpg

90mm%20edf.jpg

 

- Now, also, it is said to have dense, COOL air forced into the system, so when I find....

SUXFLY-X-FLY-font-b-brushless-b-font-fon

3650-3660-Aluminum-Water-Cooling-Jacket-

- A cooling jacket for such motors, (Actually for RC boat motors, but if it fits and bolts on/in...) I wonder if I could use these water-cooling fan shrouds to super-cool the intake air! Who knows, maybe not necessary, but if it makes a real difference (in other than winter conditions) then I know these babies exist, and there is more than one way to inject cold water or whatever through these....

- And then, mount them in something as affordable as possible or improvised, such as this:

s-l1000.jpg


Edited by RAD, 12 September 2016 - 03:07 PM.


#15 skishop69

skishop69

    If it ain't broke, you're not trying.

  • Members
  • 1,235 posts
  • Puyallup

Posted 12 September 2016 - 04:21 PM

There is a reason there are no electric SC's. The power requirement necessary to move X-amount of CFM at Y-amount of pressure = TFM. (You figure the meaning. lol) It's very much like E=MC2.The faster you spin it, the more resistance you get pressurizing the air. The more resistance you get, the more power you need to feed it. You can see the ugly loop here. Utilizing 12v from an automotive source will not suffice based on the size of a 12v electric  motor to flow the necessary CFM and pressure. Simple horsepower ratio. Maybe a 300A alternator converting to 120v AC, stepping up to 480v AC and then converting to 3-phase. The short. It can't be done with 12v.



#16 iceageg

iceageg

    USMB Regular

  • Members
  • PipPipPip
  • 61 posts
  • Denver, CO

Posted 12 September 2016 - 04:34 PM

How to follow that . . .

First, it is obvious that you either A) have not decided what your primary objectives are or B ) are looking forward to a multi-phase, long term research project along the lines of a high school science fair entry. If you actually want to be able to drive your brat in the near future you need to sit down with a pad and paper and write down your goals, then cross out the ones that conflict. For instance, going back to your Mad Max post above . . . if the Mad Max look is 100% required you are stuck using a twin screw blower of some kind. There are very few on the market that are designed to work efficiently on a motor our size (MR2, Mini S, etc.) and they are much smaller than you are probably hoping and may not provide the "WOW" factor you are looking for. Larger ones can be made to work but you will trade performance for the big, bad, Mad Max look. In that example you would have to cross out "best performance" in order to keep "Mad Max look". I'm not trying to crush your enthusiasm but you did go full keyboard diarrhea of thought in your last post. If you want to put in the work to compare various options and dedicate your car to being a full time test bench I will shut up and get my popcorn.

Second, if you have dedicated your project to carburation then you need to do some reading up on "draw through" and "blow through" systems. Depending on the amount of boost you want to create you will have varying levels of complexity setting up and tuning your carburator. If you are just going with a mild 3-5psi setup you may be fine with a simple blow through setup. Any more than that and you will need to relocate the carb pre-blower or set up a pressurized blow through housing. Either way don't expect to just bolt it on and have a daily driver. Remember that a carburator is nothing more than a calibrated vacuum leak. When you start changing the airflow through it relative to what the engine is asking for you are going to count on some adjustments being needed. Fuel injection makes this process much easier and more flexible.

For your item #1, this is a large topic. To large to get into in detail here so I will attempt the cliff notes version. Assuming we are talking about engine driven units, twin screw blowers (like Mad Max) are the absolute best option for low end response. They get into usable torque before any other traditional option and they just look awesome. The downside is you have almost no options for mounting location and extremely limited options for intercooling if you are pushing enough boost to need it. The efficient range for most of these is also designed to operate best on lower RPM engines. Many (possibly most) of these are also positive displacement, meaning if the belt breaks your car stops because no air is getting through.

Centrifugal blowers offer very predictable throttle response but their power is not available as soon in the RPM range as a twin screw. They do however give you quite a few more mounting options, are much easier to intercool and there are more units to pick from on the market. Having more options you may have better luck finding one with an efficient range that matches your CFM and RPM needs than twin screw units adapted from other applications.

All of this ignoring (by your request) any information or comparisons to the obvious alternative of turbocharging.

For your item #2, "blowers, superchargers, etc. are basically about forcing dense (cold?) air into the engine, therefore," . . . No. They compress a volume of cold dense air into a smaller volume of warm/hot air that still provides more total combustible oxygen even though it is warmer. Things like intercoolers are used to cool the warmer air charge back down but without the help of something like a CO2 element freezing the intercooler it will never get back down to it's original ambient temperature. There are some other tricks but I am still trying for cliff notes.

Alternate drive sources like electric or chain saw motor (yes, I've seen it done) offer yet more mounting location options but I think you are going to have an extraordinarily difficult time getting them to work with a carburator. For instance a one speed electric motor will always be trying to flow the same amount of air. The carb meters fuel based on how much air is flowing through it. If the engine only wants XXX volume of air at say idle, but the blower is providing YYY you are going to have to do some creative engineering (variable speed electric motor, extra butterfly vavle, etc) to automate your way around it or simply remember never to flip the switch unless you floor the accelerator peddle. These options will convince you that fuel injection is an easier option.

Leave blowers have been proven to make a difference but every setup I have ever seen has taken up far more room than it was worth and turned out only to be a gimmicky "because I could" temporary joke. Roadkill even did an episode dedicated to it that is well worth the watch if you want a laugh or just to see what lessons others have learned on the topic. I have never heard of anybody using drone engine/prop. My guess is they won't flow enough CFM and might even prove to restrict flow by being in the way of an already greater flow. Once again for reference, the 110 cubic inches in your EA81 your engine at 6000 RPM will require roughly 170CFM of air to operate normally at full throttle normally aspirated. Any fan you are looking for will need to exceed that.

I don't mean any of this to discourage you from trying. Just make sure your attempts align with your end goal. Good luck and I look forward to watching your progress.


Edited by iceageg, 12 September 2016 - 04:41 PM.


#17 skishop69

skishop69

    If it ain't broke, you're not trying.

  • Members
  • 1,235 posts
  • Puyallup

Posted 12 September 2016 - 05:17 PM

+1 and very well written. One thing to add on your requirement of roughly 170 CFM at full throttle. That number is based on near static (freeflow) airflow. Meaning you have very little vacuum at this point and no pressurized airflow. In order to build the pressure necessary to create an actual boost to engine power, there is a lot more math involved and in keeping to your Cliffs Notes style, we'll say a minimum of triple that amount at WOT with a minimum boost of say 4-5psi.



#18 RAD

RAD

    Advanced Member

  • Members
  • PipPipPip
  • 64 posts
  • SoCal

Posted 12 September 2016 - 05:45 PM

For not trying to discourage, which you are not, you are doing quite a job at an unintentional attempt! lol...
I am almost certain that I will go for the EDF option. It is easier, far less expensive, super cool looking and sounding, and has great potential as far as I can see so far, especially considering that it could potentially be controlled by some compromise between being based on the RPM and being based on actual throttle use/position, or use of both. Using throttle position as the basis for an electronic control is the biggest problem I can see here, and not necessarily required.

If all I did was put some scoop on the hood, that would adequately seal onto the carb or filter below on the engine, there would be no problem caused that I can see, and although that alone would probably not improve performance by any real extent, it would definitely not make performance any worse, provided that there was some adequate filtration of some sort.
Beyond that, some minimal forced air flow would almost certainly begin to improve things functionally, the question being just how much force/volume/speed of air would work best, and because it would be electronic, an adjustment tune-in would likely be nothing more than turning a knob (Potentiometer) - if I spelled that right, lol
EDF motors could absolutely and easily keep up with the pressure and speed of the car at any speed it could possibly be expected to reach, as EDF motors are incredibly high RPM themselves.

As far as a scoop, I have already pretty much dismissed buying any conventional racing scoop, as they are all unnecessarily expensive. I could improvise with several kinds of stainless steel items, which I already have a number of, such as particular kinds of serving trays, "steam table" trays, which are a little "Boxy" looking despite their well curved corners, and even my secret weapon, an upside-down stainless steel bed pan! I got that not only because it looks GREAT on the hood, but because I presently have a small normal height air cleaner which is a bit too tall, and gets sandwiched down by the hood. The idea was to cut a hole in the hood, mount the upside down bed pan on the hood, so that the top of the air cleaner would technically be fluch with the top of the hood, but have the clearance it would need anyway, and of course, I would be cutting one large oval hole, or three round holes in the front of it, and installing some kind of grille or heavy chrome or stainless or brass mesh.

Also, as far as I can tell, I would likely be able to use the base of the little air cleaner I have now for the basis of a seal when the hood comes down, and that seal would likely be some form of soft rubber or foam rubber, so that tolerances and clearance will not be a problem, and I can freely drop the hood to slam down and not worry about if things went together right or not.

Although I do not have all the details down yet, and will obviously need some kind of electronic controller for such a unit, I feel 100% confident that two or three 70mm - 90mm EDF motors will blow as much air as I could possibly need, as fast as I could possibly want, to be tamed down to what works best (tuning), therefore in concept I am sure it will work if I choose that option, which I likely will, because it is SO much less expensive and easier than the traditional method.
Especially with three 90mm EDF motors winding up, my Brat would almost certainly sound just like a freakin' jet about to take off, and my only concern would be that I more like the sound of what could come out of my exhaust more than the jet sound of the intake, and would want to possibly balance the volume between them to have the best sound.

In fact, I think  the only way this will not work for me is if :
(1) I just decide to do something else reason - which would not be a 'Fail'.
(2) Somehow large scale, heavy-duty 90mm EDFs cannot produce the volume/speed of air needed, which is highly doubtful.

(3) I cannot arrange for a useful controller for the unit, which is the only real problem I face, and the right person with the right skills would certainly be able to tackle that, and as it turns out I have a Dupont electrical/mechanical engineer for a friend, and the variable there is getting him interested enough or making a good enough deal for him to do so, because I know he has far more than enough skill, talent, knowledge and experience to do such a thing.

Beyond that, worst case scenario, if all I have is the equivalent of a volume knob in the dash, I adjust it to where things work and sound best, to be altogether crude about it, lol...





 



#19 RAD

RAD

    Advanced Member

  • Members
  • PipPipPip
  • 64 posts
  • SoCal

Posted 12 September 2016 - 05:49 PM

+1 and very well written. One thing to add on your requirement of roughly 170 CFM at full throttle. That number is based on near static (freeflow) airflow. Meaning you have very little vacuum at this point and no pressurized airflow. In order to build the pressure necessary to create an actual boost to engine power, there is a lot more math involved and in keeping to your Cliffs Notes style, we'll say a minimum of triple that amount at WOT with a minimum boost of say 4-5psi.

 

Thank you very much for your input, and where the notation above your profile pic in your reply is concerned:
"If it ain't broke, you're not trying." is about the best understanding of the spirit of older Subaru's and their drivers that I have thus far seen! - How do I get such a signature or notation over my profile pic in a reply?!?!?!?!??????
Thank you.



#20 RAD

RAD

    Advanced Member

  • Members
  • PipPipPip
  • 64 posts
  • SoCal

Posted 12 September 2016 - 05:56 PM

There is a reason there are no electric SC's. The power requirement necessary to move X-amount of CFM at Y-amount of pressure = TFM. (You figure the meaning. lol) It's very much like E=MC2.The faster you spin it, the more resistance you get pressurizing the air. The more resistance you get, the more power you need to feed it. You can see the ugly loop here. Utilizing 12v from an automotive source will not suffice based on the size of a 12v electric  motor to flow the necessary CFM and pressure. Simple horsepower ratio. Maybe a 300A alternator converting to 120v AC, stepping up to 480v AC and then converting to 3-phase. The short. It can't be done with 12v.

 

I respectfully and joyfully disagree.
These motors are used in RC aircraft that do not have the CCA of a car battery, much less the potential for the right alternator for a second alternator. I would though interject that one caveat not expressed thus far would be the possible trade-off of power between the performance output and the engine power needed to drive that alternator. - However, in disagreement with my own caveat, again, these motors azre used in RC aircraft, running entirely on battery, and their batteries' power does not even come close to what a cars' battery or alternator puts out in most scenarios.

Thus, I think as far as your concern is concerned, the question would be about actual "Pressure".


I possibly ignorantly ask: Does it really need "Pressure"? If air is being forced in at extremely high speed, it might make the difference, like how a .223 bullet is small, yet can cause significant damage, or how speed vs. torque are imagined. As has been pointed out to me in another thread, Subarus' are not like muscle cars with the low RPMs and torque providing the power, they are more like high RPM motors working with speed rather than torque. They cannot haul an extremely heavy load like a truck, but if kept light, they can shoot past that heavy torque truck, especially if carrying a load while both are going up a grade.
Is there any potential to my guesswork on this point?

Also, if nothing else, I could just use drone parts and components for a lot of this, including the control of the unit, with a voltage converter of some sort, and then the unit would become an "Intelligent" unit, with more potential than most commercial airliners, with the spill-over of thus also making my Brat intelligent... Oh, the unintended, accidental potentials that are rapidly bubbling to the surface of this concept, lol....

OMG... I might just end up turning my Brat into some form of Drone, lol...


Edited by RAD, 12 September 2016 - 06:07 PM.


#21 iceageg

iceageg

    USMB Regular

  • Members
  • PipPipPip
  • 61 posts
  • Denver, CO

Posted 12 September 2016 - 06:42 PM

. . . Does it really need "Pressure"? If air is being forced in at extremely high speed, it might make the difference . . .

 

The answer to that is yes, it does.  Staying with the cliff notes theme, Bernoulli's principle explains to us that high velocity = low pressure, low velocity =  high pressure.  In addition to that, simply throwing high velocity air at a restriction (in this case a carburator) will simply make the air slow down because only so much air can pas through the restriction . . . unless you have pressure forcing the compressed mass of air through the restriction.  This I think is the main point you are missing when talking about the drone rotors.

 

Remember my reference to "positive displacement" when talking about twin screw blowers above?  After the air is compressed by the supercharger there is NO path for the air to escape backwards and if the engine was not accepting the compressed air fast enough it would eventually explode due to over pressurization.  Put one of those twin screw units on a sealed box and turn it by hand.  Eventually it would build up so much pressure that you would not be strong enough to hand crank it anymore.  If you put the rotor blade from a drone on the same opening you could spin it forever because it is not moving any air.  The restriction simply causes air to "stack" up and eventually the propeller blade starts to cavitate like an over sped boat propeller.  It doesn't create velocity or pressure past a point.  I hope I explained that adequately.

 

Last, as skishop69 noted above, if the engine normally consumes 170cfm you will need something that flows MORE than that to see any benefit.  Anything that flows less air would effectively restrict what the engine was already feeding itself.  So as long as your drone rotor moved more air than the engine normally consumed you could get some benefit out of it but because of the shape of the fan blade I doubt it would generate much boost pressure.  Please make sure you post your results if you go through with it (I know I have spent more time and money on failed experiments than I care to admit), but based on my experience you will probably be disappointed.

 

You won't find much technical information (mostly geared towards sales and generating phone calls) but you can check us out at http://www.forcedaeromotive.com/ if you want some eye candy and some idea of where I'm coming from.



#22 subarubrat

subarubrat

    1000+ Super USER!

  • Members
  • 1,439 posts
  • Bealeton, VA

Posted 12 September 2016 - 07:46 PM

An axial flow compressor CANNOT compress into a volume. I love electric ducted fans, they fly airplanes very well, but put one into a tube and cap the outlet and there will be no meaningful pressure on your hand, and RPMs will increase. The idea of an electric forced induction is a fools errand for the most part. You can use a rather large brushless motor with a large battery to spin a conventional supercharger, but the added complexity, lack of modulation and weight are pretty strong no votes. I considered super charging my EA81 but decided on a comparable HP NA build to keep it closer to stock looking. My choice would be an MP62 for a budget build or a TVS if you want to spend a bit more. Simply put EDFs will gain you no bump in performance, waste your money, and possibly damage your engine if it sheds blades into your intake. I have been in the aerospace field for 26 years and the physics haven't changed yet. The EA81 is one tough little motor, I think you will find great success in a conventional supercharger with draw through fueling.

 

This is a real electric SC for example; http://www.eaton.com...arger/index.htm


Edited by subarubrat, 12 September 2016 - 08:05 PM.


#23 superpoo93

superpoo93

    New User

  • Members
  • 205 posts
  • las vegas

Posted 12 September 2016 - 07:58 PM

Not EA81... Does have Mad Max feel :)

https://youtu.be/ng5xFzjf_JM

#24 DaveT

DaveT

    Subaru Nut

  • Members
  • 2,208 posts
  • Colchester

Posted 12 September 2016 - 07:59 PM

Yes, for any of these later ideas, start investigating how much power it takes to compress the CFM you need to supply at the boost pressure you want.

#25 skishop69

skishop69

    If it ain't broke, you're not trying.

  • Members
  • 1,235 posts
  • Puyallup

Posted 12 September 2016 - 09:13 PM

Do it as an experiment if you really feel the need, but EDF's will NOT work. Subarubrat beat me to it... Physics will not allow it. It can't be done. Read up on your basic physics for airflow, then dive into SC and TC principals of boost and follow it up with flow dynamics of intakes. Understand what you're trying to do before doing it, then, if you really want, build a small scale single EDF setup to see that it can't work. Here's the basics of why not: Like Subarubrat said, "An axial flow compressor CANNOT compress into a volume." Put the EDF in a tube. It already has it's own 'mini tube' which is it's housing, but this will help you see what will happen. Crank it up to full speed and seal the outlet. Not only will there be no pressure in the tube on the outlet side, but you will notice some air coming out the inlet side. Due to the space between the blades themselves and the housing around the blades, compressing cannot physically happen because too much air can escape. You will also notice and increase in RPM's of the EDF as previously noted by Subarubrat. Iceageg likened this to cavitation of a boat prop (great analogy) but what's actually happening is you're creating a void around the propeller where the air coming in equals the air trying to come out so in essence, a vacuum.

 

Now for your control issues. The EDF's themselves would have to be tied to a TPS that would control their speed in proportion to the throttle blade opening so that airflow out of them (IF they could compress which they can't) would stay within the correct flow ratio. You can't put a knob on the dash or just let them run willy nilly. Leave them up full at idle, too much ir, not enough fuel, you burn up the engine. Leave them too low at high RPMs, not enough air, too much fuel and you foul the plugs. Now lets cover the insane amount of bucking the engine is going to do if you try to manually control flow with the throttle blade constantly changing position as you drive. Most people who drive aren't capable of driving, chewing gum and changing the radio station at the same time let alone real time tuning which would pretty much be what you're doing. Actually worse since you're not using software to do it. It'd be like trying to manually steer the Enterprise at warp speed. :rolleyes: Yeah, I went there... :lol:






0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users