(non-Ebay) Electric Turbocharger (Supercharger?)

[teknicalissue]

Greetings!

I've been away but managed to get some print time and printed test fitment blocks!

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Now, you may be wondering what took so long; well, I've been printing and playing around with what settings work best with this application. Take a look at the scraps:

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all is well. I've been playing around and still haven't received the gears but should have enough now to print a unit and attach the gears later. I've also figured out how I'm going to handle the shaft/rod and the placement. I will be using two bearings, one close to the compressor wheel and the other within the gear box i'm making. I'm hoping this would share the stress on just one bearing. the turbo shaft will have to be custom made (if you guys have any contact, let me know!). I'd need a rod 6mm OD with a flat section on one end (for gear mounting) and a compressor wheel thread on the other end.

Does anyone here know the exact thread/pitch on a 14b turbine end shaft for the compressor wheel nut? diameter would also help!

 

[teknicalissue]

SO as I'm building this gearing system. I'm realizing theres a little more work involved but I'm not planning to give up. I have to definitely hire someone to create an custom aluminum shaft as the default one will simply not work for this new set-up. anyone know someone who can do this before I start reaching out to companies?

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[teknicalissue]

Motor section is almost complete! Motor screws in now

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[Chumpaumpalumpa]

Awesome. Hey what material were you using for the gears I dont think I ever inquired about that.

 

[teknicalissue]

Brass gears! Should do fairly well for the application as long as it's properly lubricated.

 

[91-GS]

Looks like you need to either slow the print speed down or increase flow rate some. That will give you a much more solid surface.

Don't think that was asked before, but how will this motor be cooled?

 

[teknicalissue]

Looks like you need to either slow the print speed down or increase flow rate some. That will give you a much more solid surface.

Don't think that was asked before, but how will this motor be cooled?

I've printed better quality parts before. I'm still printing for the sake of fitment; Nothing for the prototype yet. The XYZ is a bit slow, the bad of a quality took 6 hours to print. I'm sure the gear oil would fall right through this if I attempted to put some in it

As far as the cooling goes; I don't know yet, I know it'll get hot but I don't know how hot until I finish with the prototype. If cooling is necessary; I may look in to taping the coolant lines or adding vents or something of the sort. Once the prototype is complete, we can assess cooling options.

 

[mbyoung424]

I'm not smart enough to know what is required in making a shaft that small, but there are a number of people on the forum that have access to shops who have made larger aluminum pieces like bushings. Some of them may be willing/able to help. There is a member in BC that comes to mind that I talked to about making some bushings, Lowell is his screen name. Best of luck.

 

[jim95redgsx]

I think that you are seriously underestimating the horsepower required to drive a 14b compressor wheel.
A 14b is usually rated at 405 CFM at a Pressure Ratio of 2:1 (around 15 psi boost) at 65% efficiency and just over 130,000 RPM.
http://www.stealth316.com/images/td05h-14b-cfm.gif
This is just under it's max rating @ 60% eff.
At 150,000 RPM and a PR of just under 2.6:1 (around 22 psi boost) it will supply 405 CFM @ 70% eff.

A very basic equation for horsepower to drive a centrifugal compressor is:
CFM X PSI (boost) / 229 X compressor efficiency
This equation does not take temperature into account, nor does it include motor or gearing efficiency.

405 cfm X 15 psi / 229 X .65 eff = 17.25 HP
405 cfm X 22 psi / 229 X .70 eff = 27.25 HP
1 HP = 746 Watts (amps X volts)
17.25 HP = 12,869 Watts
27.25 HP = 20,329 Watts

Your original test with the compressor outlet blocked off with a boost leak tester is invalid because it's producing zero CFM. Your test @ 100-110 amps at 14.8 volts is only producing around 2 HP.

Jim

 

[91-GS]

Upgrade printer firmware to Repetier and use Repetier-host for the computer. It will give you much more control over the printer.

Working backward from that math i calculated that at 2 HP motor and 22PSI pressure output will be around 30 CFM. Does that mean only around 2 PSI at 405 CFM? I can't math very well this late at night, so someone should probably double check this. Still, if this fellow wants to go through with the project then best of luck to him. He might end up building a nice blower that is too small for a car, but will work great for a motorbike or a snowmobile or some other small engine.

Almost forgot: that link gives a 403 error, might want to look into that, or post it as an image here insead of a link.

 

[jim95redgsx]

http://www.stealth316.com/images/td05h-14b-cfm.gif
That link seems to be working again.
It's just a 14b compressor map that has been converted to read in CFM instead of the units that Mitsu uses.

While I didn't check any of your math, it seems to be well off of the compressor map. To get any reasonable results, you have to keep the calculations on the map and out of the surge and choke areas.

Jim

 

[teknicalissue]

I think that you are seriously underestimating the horsepower required to drive a 14b compressor wheel.
A 14b is usually rated at 405 CFM at a Pressure Ratio of 2:1 (around 15 psi boost) at 65% efficiency and just over 130,000 RPM.
http://www.stealth316.com/images/td05h-14b-cfm.gif
This is just under it's max rating @ 60% eff.
At 150,000 RPM and a PR of just under 2.6:1 (around 22 psi boost) it will supply 405 CFM @ 70% eff.

A very basic equation for horsepower to drive a centrifugal compressor is:
CFM X PSI (boost) / 229 X compressor efficiency
This equation does not take temperature into account, nor does it include motor or gearing efficiency.

405 cfm X 15 psi / 229 X .65 eff = 17.25 HP
405 cfm X 22 psi / 229 X .70 eff = 27.25 HP
1 HP = 746 Watts (amps X volts)
17.25 HP = 12,869 Watts
27.25 HP = 20,329 Watts

Your original test with the compressor outlet blocked off with a boost leak tester is invalid because it's producing zero CFM. Your test @ 100-110 amps at 14.8 volts is only producing around 2 HP.

Jim

I'll have to go over my original results once I'm done with this prototype. Heck if this was easy, everyone would be doing it right? No matter; If this doesn't work, I can find a 27kw starter motor (BMW 450 I believe) and go with a more advanced gearing system. That should be more than enough to fit the math side of things correct? Still would like to re-try my original test and double check my readings (I believe someone here suggest using a GM MAF to read the voltage to calculate airflow).

When there is a will there is a way!

EDIT: Just stumbled upon these motors: http://www.goldenmotor.com/goldshop/product/173.html that have a peak of 20KW and rated at 10KW. This should work for short burst of power that I'm looking for. A tad expensive though but seems to be like the proper solution to fit the math.

Upgrade printer firmware to Repetier and use Repetier-host for the computer. It will give you much more control over the printer.

Working backward from that math i calculated that at 2 HP motor and 22PSI pressure output will be around 30 CFM. Does that mean only around 2 PSI at 405 CFM? I can't math very well this late at night, so someone should probably double check this. Still, if this fellow wants to go through with the project then best of luck to him. He might end up building a nice blower that is too small for a car, but will work great for a motorbike or a snowmobile or some other small engine.

Almost forgot: that link gives a 403 error, might want to look into that, or post it as an image here insead of a link.

That's the spirit! haha if this doesn't work for a car; I'll find a way. I can't remember the name of the electric turbo company that produced a turbo with 6hp on direct drive. If only they put that on gearing system! I'd love to figure out what motor they're using.

 

[jim95redgsx]

http://www.superstreetonline.com/how-to/engine/0406tur-knight-turbo-electric-supercharger/

Read this Super Street article on the Thomas Knight Electric Supercharger. He used to use three rewound starter motors with a turbo compressor before he switched to a Eaton roots blower.

I would question your use of brass gears and an aluminum shaft at this power level. For your shaft, why not use a stock 14b shaft with the turbine wheel cut off and a small flat spot ground into it for your set screw. You'll need an oil seal anyway, to prevent the compressor wheel from sucking all the oil out of your gear case. I "think" the diameter of the stock shaft is 6.5mm but I'm not 100% sure.

Both the GM and Mitsu MAF's use a frequency output to determine airflow. You'll probably need an ECU to decipher it. There used to be some old vane pressure type MAFs that used a voltage output but I don't remember which makes/models

Jim

 

[teknicalissue]

http://www.superstreetonline.com/how-to/engine/0406tur-knight-turbo-electric-supercharger/

Read this Super Street article on the Thomas Knight Electric Supercharger. He used to use three rewound starter motors with a turbo compressor before he switched to a Eaton roots blower.

I would question your use of brass gears and an aluminum shaft at this power level. For your shaft, why not use a stock 14b shaft with the turbine wheel cut off and a small flat spot ground into it for your set screw. You'll need an oil seal anyway, to prevent the compressor wheel from sucking all the oil out of your gear case. I "think" the diameter of the stock shaft is 6.5mm but I'm not 100% sure.

Jim

Very cool read! perhaps multiple motors is the answer! I'm hoping that when I get a prototype working, I can reach out to companies and request stronger motors so this is something to think about.

I had my hands tied as the gear manufacturer working with me could only make the gears brass. I don't expect the prototype to last more than a year. The final product (If I ever get there) I'm sure will have better internals. Maybe I should rephrase the word prototype and use the word "model". I need a working/semi-working model to move forward. As far as the aluminum shaft is concerned; I can't use the existing shaft as it steps up for the turbine wheel (can't remember by how much off the top of my head). Cutting the shaft at the step up would result in a far too small shaft for the application. I'm using aluminum because it's cheap and custom machining won't cost me an arm and a leg (this is all out of pocket for me... just a side project ) but going forward, I'll look in to stronger metals for longevity.

 

[Chumpaumpalumpa]

Upgrade printer firmware to Repetier and use Repetier-host for the computer. It will give you much more control over the printer.

Working backward from that math i calculated that at 2 HP motor and 22PSI pressure output will be around 30 CFM. Does that mean only around 2 PSI at 405 CFM? I can't math very well this late at night, so someone should probably double check this. Still, if this fellow wants to go through with the project then best of luck to him. He might end up building a nice blower that is too small for a car, but will work great for a motorbike or a snowmobile or some other small engine.

Almost forgot: that link gives a 403 error, might want to look into that, or post it as an image here insead of a link.

Lets not forget that he is NOT directly driving the compressor. Spinning brass gears will also take some power to spin and take some RPM off the top end so your theoretical 150,000 Rpm might not be possible with your existing motor. I'm thinking 110,000-125,000 RPM range with no extra load (building boost).

 

[91-GS]

EDIT: Just stumbled upon these motors: http://www.goldenmotor.com/goldshop/product/173.html that have a peak of 20KW and rated at 10KW.

Such motor itself weighs close to 40 lbs. By the time you add a gear box, batteries, and the blower itself the sustem will probably be close to 100 lbs. Don't know if many people would want to use something this heavy on a racing car.

Speaking of concepts, some time ago company Dyson made Airblade, a 'bladeless' household fan. The idea was that a blower pushes air out of a slot in a duct (that was more like a ring really) and that air grabs surrounding air and moves it too. IIRC it's called "Venturi effect". Having said that what if a source of air, be that a blower or a tank, forces air through a slot in part of the intake and pulls more air in with it? Then again with amount of air needed it will probably take something like a scuba tank (3000 psi reduced down to a hundred or so for output) to make it work for a drag race. And if that works then it will most likely weigh as much, if not more than an electric blower.

 

[Chumpaumpalumpa]

Such motor itself weighs close to 40 lbs. By the time you add a gear box, batteries, and the blower itself the sustem will probably be close to 100 lbs. Don't know if many people would want to use something this heavy on a racing car.

Speaking of concepts, some time ago company Dyson made Airblade, a 'bladeless' household fan. The idea was that a blower pushes air out of a slot in a duct (that was more like a ring really) and that air grabs surrounding air and moves it too. IIRC it's called "Venturi effect". Having said that what if a source of air, be that a blower or a tank, forces air through a slot in part of the intake and pulls more air in with it? Then again with amount of air needed it will probably take something like a scuba tank (3000 psi reduced down to a hundred or so for output) to make it work for a drag race. And if that works then it will most likely weigh as much, if not more than an electric blower.

The way that works is because of the shape. The airplane wing shape causes the air to accelerate and create negative pressure that more air fills in that spot and since it it moving it pulls more air with it. Idk how you would do that on an intake tract.

 

[teknicalissue]

Lets not forget that he is NOT directly driving the compressor. Spinning brass gears will also take some power to spin and take some RPM off the top end so your theoretical 150,000 Rpm might not be possible with your existing motor. I'm thinking 110,000-125,000 RPM range with no extra load (building boost).

from a numerical stand point, I would be using a 5050kv motor with a rating of 11 volts. We can assume that on paper the motor will spin at 55,550 RPMS. With the gearing system I found, I will be stepping up by 4 giving the shaft a total of 222,200 RPMS total. I think If we add friction plus the gear and Oil, it'll bring it down to 130 - 150;/ I can't imagine it being bogged down by 50% but then again; I'm no engineer building boost is another variable we need to take in to account; the more air being compressed the harder the motor would have to spin in which to jim95redgsx's point; Would require a more powerful motor. I'd be curious to know what would happen when the motor can't compress air anymore.. would it stall? or bog down? hmm...

Such motor itself weighs close to 40 lbs. By the time you add a gear box, batteries, and the blower itself the sustem will probably be close to 100 lbs. Don't know if many people would want to use something this heavy on a racing car.

Speaking of concepts, some time ago company Dyson made Airblade, a 'bladeless' household fan. The idea was that a blower pushes air out of a slot in a duct (that was more like a ring really) and that air grabs surrounding air and moves it too. IIRC it's called "Venturi effect". Having said that what if a source of air, be that a blower or a tank, forces air through a slot in part of the intake and pulls more air in with it? Then again with amount of air needed it will probably take something like a scuba tank (3000 psi reduced down to a hundred or so for output) to make it work for a drag race. And if that works then it will most likely weigh as much, if not more than an electric blower.

You are 100%! after I posted that I looked at the weight and the size (half of the diameter of a motorcycle wheel) and realized that motor would be incredibly silly. I did look around and found a 20 pound and somewhat smaller motor. it's still beefy, but small enough to tuck somewhere under the hood unlike the 40 pound motor. and when all else fails, we have the starters

The way that works is because of the shape. The airplane wing shape causes the air to accelerate and create negative pressure that more air fills in that spot and since it it moving it pulls more air with it. Idk how you would do that on an intake tract.

hmm.. I wonder if I could utilize the venturi effect somehow. this would require a custom compressor housing but it's a good thought to bounce around.

 

[Chumpaumpalumpa]

I'd be curious to know what would happen when the motor can't compress air anymore.. would it stall? or bog down? hmm...

hmm.. I wonder if I could utilize the venturi effect somehow. this would require a custom compressor housing but it's a good thought to bounce around.

It would stay at a continuous RPM, like an electric car reaching top speed. I do not believe the work load needed to compress air is linear, but rather exponential, just like trying to reach top speed. That is why I was suggesting e-assist because you're gunna need one hell of a motor to generate 27psi or something where you make some really good power. Also, on a side note, I stumbled across Vortex tubes which use the 1st and 2nd law of thermodynamics to create a temperature differential and uses no moving parts. We're talking well below freezing in some cases. Thought it might be a cool (pun intended) replacement for an intercooler.

 

[jim95redgsx]

from a numerical stand point, I would be using a 5050kv motor with a rating of 11 volts. We can assume that on paper the motor will spin at 55,550 RPMS. With the gearing system I found, I will be stepping up by 4 giving the shaft a total of 222,200 RPMS total. I think If we add friction plus the gear and Oil, it'll bring it down to 130 - 150;/ I can't imagine it being bogged down by 50% but then again; I'm no engineer building boost is another variable we need to take in to account; the more air being compressed the harder the motor would have to spin in which to jim95redgsx's point; Would require a more powerful motor. I'd be curious to know what would happen when the motor can't compress air anymore.. would it stall? or bog down?

That doesn't sound like a very good motor for this application. I did a quick Google search for 5050kv motors. The biggest one I found was a Leopard, rated at 11 volts, 120 amps and 1300 watts. This won't get you very far. You'll want a motor that's wound for the RPM range that you want with your 4:1 gear ratio. Trying to load the motor down to reduce RPM will reduce efficiency and result in a tremendous heat increase.

You can't spin a 14b compressor to 222,000 RPM. If you look at the compressor map, you'll see that it's limited to 170,000 RPM. When the compressor wheel tips reach the speed of sound, no more air will flow.

A few notes on centrifugal compressors:
Volume (CFM) goes up directly with an increase in RPM.
(RPM1 / RPM2) = Change in CFM

Pressure (PSI) goes up with the square of the RPM increase.
(RPM1 / RPM2)^2 = Change in Pressure Ratio

Required Horsepower goes up with the cube of the RPM increase.
(RPM1 / RPM2)^3 = Change in required Horsepower

Jim

 

[Chumpaumpalumpa]

That doesn't sound like a very good motor for this application. I did a quick Google search for 5050kv motors. The biggest one I found was a Leopard, rated at 11 volts, 120 amps and 1300 watts. This won't get you very far. You'll want a motor that's wound for the RPM range that you want with your 4:1 gear ratio. Trying to load the motor down to reduce RPM will reduce efficiency and result in a tremendous heat increase.

You can't spin a 14b compressor to 222,000 RPM. If you look at the compressor map, you'll see that it's limited to 170,000 RPM. When the compressor wheel tips reach the speed of sound, no more air will flow.

A few notes on centrifugal compressors:
Volume (CFM) goes up directly with an increase in RPM.
(RPM1 / RPM2) = Change in CFM

Pressure (PSI) goes up with the square of the RPM increase.
(RPM1 / RPM2)^2 = Change in Pressure Ratio

Required Horsepower goes up with the cube of the RPM increase.
(RPM1 / RPM2)^3 = Change in required Horsepower

Jim

Good note with the motor winding I dont see how that slipped my mind hurr durr . Anyways my guess is you need somewhere in the 10's of hp to spin and flow enough to make some decent power, that is why I suggested the motor I did at first. The NeuCastle 2028 or maybe the Castle Big Block Would work well, but they are not 12v motors. Still compact and light though.

 

[teknicalissue]

That doesn't sound like a very good motor for this application. I did a quick Google search for 5050kv motors. The biggest one I found was a Leopard, rated at 11 volts, 120 amps and 1300 watts. This won't get you very far. You'll want a motor that's wound for the RPM range that you want with your 4:1 gear ratio. Trying to load the motor down to reduce RPM will reduce efficiency and result in a tremendous heat increase.

You can't spin a 14b compressor to 222,000 RPM. If you look at the compressor map, you'll see that it's limited to 170,000 RPM. When the compressor wheel tips reach the speed of sound, no more air will flow.

A few notes on centrifugal compressors:
Volume (CFM) goes up directly with an increase in RPM.
(RPM1 / RPM2) = Change in CFM

Pressure (PSI) goes up with the square of the RPM increase.
(RPM1 / RPM2)^2 = Change in Pressure Ratio

Required Horsepower goes up with the cube of the RPM increase.
(RPM1 / RPM2)^3 = Change in required Horsepower

Jim

I agree, Just for clarification though.. I said that the motor would spin the custom shaft at 220,000 RPM from a numerical stand point BUT! I mentioned that after friction and such; I'd only expect it to spin the shaft at 130,000RPM - 150,000RPM.

Good note with the motor winding I dont see how that slipped my mind hurr durr . Anyways my guess is you need somewhere in the 10's of hp to spin and flow enough to make some decent power, that is why I suggested the motor I did at first. The NeuCastle 2028 or maybe the Castle Big Block Would work well, but they are not 12v motors. Still compact and light though.

That's why I have the 3D printer, if/when this motor doesn't work, I'll find one that does! once I have the basic shape and prototype and shaft, switching out the motors and/or gears should be rather fast!

Once I have a good model, then we can start swapping out parts; for my OCD's sake, I just want to start with some kind of base

EDIT: I Sent the castle people an email about their motors. Their 10k watts (which would be amazing for this application) are $900.00. These could be the motors I'm looking for though.. hmm @jim95redgsx; what do you think? you seem to have the engineering degree among us I should be clear that I'm looking for 10 - 15 PSI..

The castle motor spins at 40k RPM and with my gears the result would be 160k rpm. BUT! I can get less teeth on the smaller compressor gear to bump up the ratio to 1:6 to total at 240,000 RPM. adding friction loss could put us at the 170k sweet spot. keep in mind that these are electrical motors too, so if we are overshooting the RPM's we can tone down the motor to spin less.

EDIT2: holy cow! I just realized that I could fit 2 of these motors to spin the compressor... does this mean it will total to 20kw of power?... because if this is the case, you realize that we could generate 20PSI on the fly right?

 

[Chumpaumpalumpa]

EDIT2: holy cow! I just realized that I could fit 2 of these motors to spin the compressor... does this mean it will total to 20kw of power?... because if this is the case, you realize that we could generate 20PSI on the fly right?

Yes sir and good point on the base, I suppose that's a good idea. I'll do some more motor research as well later today.

 

[jim95redgsx]

You DO NOT want to gear up your compressor speed. Efficiency loses are released in the form of HEAT, not RPM reduction. You will bog down the RPM or possibly stall the motor completely if the required HP of the compressor exceeds the HP of the motor. Again, this will show up as heat in the motor and will "let the smoke out" of the motor.

170,000 RPM is not the "sweet spot" of the 14b, it's the absolute maximum.

That Castle 10k watt motor may be just what you need to get started. That 10k watts is usually the input power to the motor. Brushless motors usually have between 80% and 90% efficiency. Lets assume 85%. Spur gears are rated between 94% and 98% efficiency. Lets assume 95%.
10,000 X .85 X .95 = 8075 watts output power
8075 / 746 = 10.8 HP

For the compressor, lets assume 350 CFM (around 5500 rpm engine speed) and a 1.7 PR (around 10 psi) at 120,000 compressor rpm and .70 efficiency.
350 X 10 / 229 X .70 = 10.7 HP

With a 40,000 motor rpm, you'll have to change your gear ratio to 3:1 to get a 120,000 rpm compressor speed. DO NOT gear it up to 6:1.

You could design your motor mount to hold two motors and two gear sets and just run it on one motor/gear set for now. Just make a block off plate for the second motor.

Jim

 

[teknicalissue]

just for kicks.. if I were to set this up with two 14b's side by side and two motors.. are we saying we can generate 20psi at two different intervals?