teknicalissue said:

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?

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I'm not sure exactly what you mean here. In my last post, I was referring to two motors driving the same 14b compressor wheel.

Jim

jim95redgsx said:

I'm not sure exactly what you mean here. In my last post, I was referring to two motors driving the same 14b compressor wheel.

Jim

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If I understood the formula, it was for only 1 motor correct? the have one motor that produces 10kw of power. in which give you approx. 10PSI based on the math. I was thinking what if I had build two of these e-turbo's and put them side by side. so one motor one one compressor and another motor on another compressor. would that mean that we would generate 10psi per e-turbo? or are we saying each turbo can hold up to 10PSI ? meaning if I had two, would I end up with a 20PSI system or a 10PSI system all together

Just an afterthought here. You would be far better off running a normal turbocharger off the exhaust manifold and piping the compressor outlet into your E-turbo (1 motor). This should give you near instant spool-up and high boost. This may even be as good as nitrous for launching an auto tranny car off the line. Maybe a marketing tool here. Just speculating, of course.

Jim

jim95redgsx said:

Just an afterthought here. You would be far better off running a normal turbocharger off the exhaust manifold and piping the compressor outlet into your E-turbo (1 motor). This should give you near instant spool-up and high boost. This may even be as good as nitrous for launching an auto tranny car off the line. Maybe a marketing tool here. Just speculating, of course.

Jim

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That's actually a great idea. a 14b/16g compound e-assist would rock. Especially in autox. Also @jim95redgsx keep the math coming its great to see this layed out properly.

So I got in contact with the company and they said they would help the project by lending me a one of their 5kw motors. now, I know this isn't the 10kw one but their reasoning was that they want to see it do something before they go out and front $900. I think that's pretty fair. considering that I'm not loosing a dime. @jim95redgsx , how much PSI can we expect from the 5kw motor? They want to see it work before they are willing to help with more expensive items

teknicalissue said:

So I got in contact with the company and they said they would help the project by lending me a one of their 5kw motors. now, I know this isn't the 10kw one but their reasoning was that they want to see it do something before they go out and front $900. I think that's pretty fair. considering that I'm not loosing a dime. @jim95redgsx , how much PSI can we expect from the 5kw motor? They want to see it work before they are willing to help with more expensive items

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Well thats about 6.7 hp so 405 cfm X 5.5psi / 229 X .70 eff = 6.8 HP or 5,071 watts. I believe that's correct by looking at the compressor map but its fuzzy on my old laptop. But you're really not looking at to much boost either way with that.

Chumpaumpalumpa said:

Well thats about 6.7 hp so 405 cfm X 5.5psi / 229 X .70 eff = 6.8 HP or 5,071 watts. I believe that's correct by looking at the compressor map but its fuzzy on my old laptop. But you're really not looking at to much boost either way with that.

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I'm not expecting too much boost with the 5KW motor. They said they would provide a 10KW motor if I proved to them that the 5KW motor produced half the amount of pressure we're talking about. meaning, my prototype with this motor generates 5.5PSI, they will be willing to invest in a 10KW motor for the project which would then give us 10PSI

I'm not complaining, it's a free motor and it hepls me set up a decent control to compare too.

Chumpaumpalumpa said:

That's actually a great idea. a 14b/16g compound e-assist would rock. Especially in autox. Also @jim95redgsx keep the math coming its great to see this layed out properly.

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I was actually thinking of this! Imagine attaching this turbo directly to the throttle body? that's less space it needs to fill when you give it gas! BUT! would that become a problem when the bigger turbo starts building pressure above 10PSI? turbulence?

EDIT: I also can't help put thinking that these formula's might be a tad different in my application (just a speculation..). How so? well.. it isn't exhaust driven and there will be less weight on the shaft. without the turbine wheel and the extra thickness of the shaft, I imagine the weight of the shaft will be lighter by almost half. This would in theory mean that the shaft will get up to speed a whole lot quicker than a turbine shaft because of it's weight and motor. Just a thought though.. no evidence or proof behind this.

teknicalissue said:

I was actually thinking of this! Imagine attaching this turbo directly to the throttle body? that's less space it needs to fill when you give it gas! BUT! would that become a problem when the bigger turbo starts building pressure above 10PSI? turbulence?

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The small turbo (High Pressure and exhaust driven) feeds the large one (lower pressure) in a compound setup.

This illustrates the process fairly well.

Chumpaumpalumpa said:

The small turbo (High Pressure and exhaust driven) feeds the large one (lower pressure) in a compound setup.

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Actually, you have it backwards. The large turbo compressor feeds the smaller one. The air is already compressed by the large turbo, resulting in a smaller volume. The smaller turbo then further compresses it, increasing the pressure ratio.

Now, on the exhaust side, you're right. The exhaust feeds the smaller turbo first and then goes on to the larger turbo. Take a close look at the picture you posted. You'll see that's the way it's hooked up.

Jim

jim95redgsx said:

405 CFM is way off the compressor map at these low boost levels. I'm assuming 100% VE at around 5500 engine speed and 350 CFM. This is still off the compressor map. Small changes in actual volumetric efficiency and engine RPM will have relatively large changes in CFM in this area. Actual boost pressure will vary greatly just with weather conditions,altitude and temperature at these boost levels.

I would say around 6 psi boost with around 4100 usable Watts from the motor:
350 X 6 / 229 X .60 = 5.5 HP
5.5 HP = 4100 Watts
This is at a 1.4 Pressure Ratio and about 100,000 compressor RPM.
Boost will be much higher at lower engine speeds and drop off sharply at higher engine speeds.

I'm assuming that this is the Castle 2028 motor ($280). Castle rates this 45,000 RPM max and 12s batteries. There is a serious discrepancy here.
12s X 3.7 volts = 44.4 volts
44.4 volts X 800kv = 35,520 RPM
In any case, I would gear this motor to obtain around 100,000 RPM compressor speed.

I looked at a couple of RC car and boat forums. It seems that some people are pushing these motors to 10-12 HP (but probably for VERY short amounts of time).
Castle doesn't seem to want to release the exact specs (amps, watts, efficiency, etc) to the public. I believe there is even a water cooling jacket for this motor.

Jim

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Hey Jim!

Just wanted to let you know that Castle is a distributor of the motors. The people who actually make the motors are http://neumotors.com/NeuMotors/2200_12_series.html.

The specific motor being given to me will be the 2217-12 - 725KV model you should have all the specs and if not, I can get them for ya! Also keep in mind that we too will be pushing peak power at short times. I'll have logic built in that after X seconds of WOT, to gear the motor back to regular operating temps outside of its peak.

I noticed you mentioned "Small changes in actual volumetric efficiency and engine RPM will have relatively large changes in CFM in this area." how does this rule change now that we have an electric motor powered the turbine instead of an engine pumping out exhaust?

I also thought i'd be cool to put this here I got the main drive gear on the motor and it's a perfect fit! even gave it a tiny test run

jim95redgsx said:

Actually, you have it backwards. The large turbo compressor feeds the smaller one. The air is already compressed by the large turbo, resulting in a smaller volume. The smaller turbo then further compresses it, increasing the pressure ratio.

Now, on the exhaust side, you're right. The exhaust feeds the smaller turbo first and then goes on to the larger turbo. Take a close look at the picture you posted. You'll see that's the way it's hooked up.

Jim

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My bad you're right got those mixed up.

I think you should put the turbo far enough away to have some time to cool the charge air. Maybe you could try using a Peltier junction intercooler, check out this electric supercharger system.

teknicalissue said:

Hey Jim!

Just wanted to let you know that Castle is a distributor of the motors. The people who actually make the motors are http://neumotors.com/NeuMotors/2200_12_series.html.

The specific motor being given to me will be the 2217-12 - 725KV model you should have all the specs and if not, I can get them for ya! Also keep in mind that we too will be pushing peak power at short times. I'll have logic built in that after X seconds of WOT, to gear the motor back to regular operating temps outside of its peak.

I noticed you mentioned "Small changes in actual volumetric efficiency and engine RPM will have relatively large changes in CFM in this area." how does this rule change now that we have an electric motor powered the turbine instead of an engine pumping out exhaust?

Click to expand...

I tried looking up that motor on the Neu website. The nearest I could find was either 850kv or 640kv. Maybe this is an older model. There is a 2220-12 motor rated at 725kv. This led me to trying to learn more about brushless motors.

It turns out that I didn't know as much about brushless motors as I thought I did. I had always assumed that the KV rating was the RPM that the motor was designed to run at. This is not the case. The KV rating is the NO LOAD RPM. Putting a load on the motor will pull down the RPM an increase the heat. You have to find a balance between the load and overheating the motor. It seems that a lot of people recommend loading the motor down to around 70-80% RPM of it's KV rating, but this is far from true in all cases.

You can throw out all my previous recommendations on gear ratios as they were based on running the compressor RPM at the KV rating of the motor. Maybe you should send an e-mail to Neu, to see what they recommend for this motor.

Since you already have a gear set with a 4:1 ratio, I would try that first. You still want a compressor RPM of around 110,000 RPM or maybe a little higher or lower.
44.4 volts X 750 kv X 80% rpm x 4:1 gear ratio = 106,550 compressor RPM

As for CFM required for the engine:
Displacement (122 cu in) / 1728 X RPM / 2 X volumetric efficiency = CFM

You can probably expect an increase in VE without a turbine wheel in the exhaust.

Jim

jim95redgsx said:

I tried looking up that motor on the Neu website. The nearest I could find was either 850kv or 640kv. Maybe this is an older model. There is a 2220-12 motor rated at 725kv. This led me to trying to learn more about brushless motors.

It turns out that I didn't know as much about brushless motors as I thought I did. I had always assumed that the KV rating was the RPM that the motor was designed to run at. This is not the case. The KV rating is the NO LOAD RPM. Putting a load on the motor will pull down the RPM an increase the heat. You have to find a balance between the load and overheating the motor. It seems that a lot of people recommend loading the motor down to around 70-80% RPM of it's KV rating, but this is far from true in all cases.

You can throw out all my previous recommendations on gear ratios as they were based on running the compressor RPM at the KV rating of the motor. Maybe you should send an e-mail to Neu, to see what they recommend for this motor.

Since you already have a gear set with a 4:1 ratio, I would try that first. You still want a compressor RPM of around 110,000 RPM or maybe a little higher or lower.
44.4 volts X 750 kv X 80% rpm x 4:1 gear ratio = 106,550 compressor RPM

As for CFM required for the engine:
Displacement (122 cu in) / 1728 X RPM / 2 X volumetric efficiency = CFM

You can probably expect an increase in VE without a turbine wheel in the exhaust.

Jim

Click to expand...

I meant the 850kv not the 725kv sorry!

In regards to the gearing, you are correct! This is why we've been saying that the Rpms are much lower if you take friction, oil, and load in to the equation.

So with a lighter shaft we get better VE... I like that.. That also means that the motor needs to exert less energy to spin the lightweight shaft as well...

I managed to get a quote on the shaft so I should have that soon! After that, I'll test fit everything and give it a run with better quality printed parts. We're getting really close to this guys!

The only time that a lighter shaft will have any effect is during acceleration/deceleration. It won't have any effect at a steady RPM. You are eliminating the weight of the turbine wheel but you are adding the weight of the gears and the motor moving parts. I don't think that you'll see any measurable effects. It won't have any effect on CFM. It's the lack of a turbine wheel, partially blocking the exhaust, that will do that (less backpressure).

I assume that you'll be doing all this testing on the bench (for now). You will need some method of measuring the CFM. You'll also need some way to vary the CFM and to measure the boost pressure. To vary the CFM, you could hook up a butterfly valve (old throttle body?) to the compressor outlet. To monitor motor temperature, you could probably use an infrared thermometer. I assume that you already have a boost gauge. Measuring the CFM would be harder.

If you have a means of measuring frequency (some higher end DVM's have a frequency scale) and can get hold of a 2G MAF, I may be able to help with a frequency vs CFM scale. I'm already logging MAFRaw (frequency) and lb/min airflow with ECMLink. It may not be exact without barometric pressure and temperature inputs but it should be close enough for what you're doing.

Jim

Could possibly use an Arduino board to convert pulses to numbers (this: http://www.instructables.com/id/Arduino-Bike-Speedometer/?ALLSTEPS might help to get you started). Or build a simple PWM-to-constant voltage converter and use a volt meter (and a conversion table) as a gauge. As a matter of fact, some fancier volt meters can measure pulse-width modulation directly. Not sure how you would calibrate it though, would need two sources with known CFM.

If you want a lighter assembly, a lightweight shaft won't help much. Instead you can drill some holes in the large (and possibly small) gear to make it lighter, similar to this:

While lighter rotating assembly won't increase flow, as mentioned above, it will decrease power required to get the assembly going. That reduction will slightly decrease size of batteries required, and obviously decrease weight of the entire unit.

91-GS said:

Could possibly use an Arduino board to convert pulses to numbers (this: http://www.instructables.com/id/Arduino-Bike-Speedometer/?ALLSTEPS might help to get you started). Or build a simple PWM-to-constant voltage converter and use a volt meter (and a conversion table) as a gauge. As a matter of fact, some fancier volt meters can measure pulse-width modulation directly. Not sure how you would calibrate it though, would need two sources with known CFM.

If you want a lighter assembly, a lightweight shaft won't help much. Instead you can drill some holes in the large (and possibly small) gear to make it lighter, similar to this:

You must be logged in to view this image or video.

While lighter rotating assembly won't increase flow, as mentioned above, it will decrease power required to get the assembly going. That reduction will slightly decrease size of batteries required, and obviously decrease weight of the entire unit.

Click to expand...

And of course the point of this exercise is to eliminate lag, that would be worth doing and balancing the gears.

91-GS said:

Could possibly use an Arduino board to convert pulses to numbers (this: http://www.instructables.com/id/Arduino-Bike-Speedometer/?ALLSTEPS might help to get you started). Or build a simple PWM-to-constant voltage converter and use a volt meter (and a conversion table) as a gauge. As a matter of fact, some fancier volt meters can measure pulse-width modulation directly. Not sure how you would calibrate it though, would need two sources with known CFM.

If you want a lighter assembly, a lightweight shaft won't help much. Instead you can drill some holes in the large (and possibly small) gear to make it lighter, similar to this:

You must be logged in to view this image or video.

While lighter rotating assembly won't increase flow, as mentioned above, it will decrease power required to get the assembly going. That reduction will slightly decrease size of batteries required, and obviously decrease weight of the entire unit.

Click to expand...

I am going to use Arduino for this project as I have a bit of past experience with it (I build robots ). Reading the TPS voltage should be fairly simple and I could set up a calibrate button where someone would have to press the throttle all the way down (WOT) and then realize the throttle. The biggest hurtle for me is trying to decide on a battery solution. The neumotors take a ton of energy although they shouldn't be sucking too many amps unless you're planning to be WOT for 15 minutes straight. Currently I'm working on the section that holds the bearing and the turbo shafts. I decided that I'm going to utilize some of the turbo components and 3d print some of the components I need and then getting them machined. At this point based on the numbers and the design; I'm confident this will work and be compact enough to drop and go.

Some things to consider are the price of the motors and the ESC's for something this high a voltage/amp rating. I was really aiming for a cost effective solution but regardless, this will be an instantaneous boost gain in which I believe someone said could be possibly compared to nitrous (that would be assume) the closer to the manifold you mount this.

Just daydreaming here but don't Most rc speed controllers use a 0-5v signal? Isant the tps a 0-5v signal? possible to tap into the tps and have a nice proportional way to control the motor speed? But your going to want full power before full throttle so you can adjust the esc like castle's products with a adjustible throttle curve. Just throwing it out there.

jim95redgsx said:

Yes, batteries and the ability to balance charge them would be a major problem and expense. Maybe you should consider a major redesign here.

If you use four of your original motors, rated at 11 volts, 120 amps and 1300 watts, it should compare nicely to that Neu motor, as far as power is concerned. These motors should run on the car's 12 volt battery/alternator system, eliminating a major expense. It seems that these motors retail for around $60 each but you would need an ESC for each motor.

Of course, this would require a complete redesign of your motor mount/ gear system, which I would consider anyway. From your video, those tiny brass gear teeth look like shrapnel, ready to explode.

Jim

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This would be for the 5KW motors correct? I will be switching the 5KW to the 10KW motor once I prove the 5KW works so our end goal is still at least 10 PSI with the 10,000KW motor (But for now, 5 PSI on a 5,000KW motor). These gears were recommended to me by an engineer for which was explained the application and the speeds. Now what this "Engineer's" credentials are; idk, But thank you for the heads up. I'll be taking safety precautions when I first start this up at full speed (Outside bench with me far far away from the turbo. I'll have a camera recording so I can view results and such.) Because of this, I will be consulting with another person and get their thoughts as to what the proper gears are for this application

I tried to crack the math and ended up with 0.5 amps per second (for the 10,000 KW motor at WOT) which means that it will suck up 0.9 amps good for a honda civic 16 second quarter mile. so if I bought a 100 AMP battery, it would last 111 seconds or 1.8 minutes assume you are WOT for a full minute. A larger AH battery of 200AH will obviously double this whopping 3.3 minutes to 6.6 minutes . again.. this is assuming you are sitting with your foot on the pedal. if you are cruising at full charge and we drive with the motor at 1/4 kw (producing 2 PSI with a 10KW motor) would suck up 0.01 amps or 2 hours of none WOT throttle use. This is assuming a 100AH battery and the motor running at 47 volts.

xiteamxi said:

Just daydreaming here but don't Most rc speed controllers use a 0-5v signal? Isant the tps a 0-5v signal? possible to tap into the tps and have a nice proportional way to control the motor speed? But your going to want full power before full throttle so you can adjust the esc like castle's products with a adjustible throttle curve. Just throwing it out there.

Click to expand...

You are correct but what I don't want to happen is for the motor to run at different intervals due to the power consumption (75% throttle = 75% power = more consumption for little benefits. ). The way I was originally thinking this was having two set triggers which means that the motor will run in two stages: below WOT will run the motor at half speed. This should actually help with gas mileage (speculating here with fords ECO boost) and should last a below an hour. One of the things I was thinking about is what would happen if you run out of juice? the motor will stop and there will be a compressor wheel in the way of the intake; but for normal driving.. I don't see this as an issue (again.. my own speculation). Worst case scenerio I run the motor at 1/4 of the speed or less... I would still like for it to run for a bit.

The Second stage is WOT. This is when you hit the pedal to the metal and that little motor is sucking up as much juice as it can to generate power.

Anybody else have any thoughts? I could make it as @xiteamxi suggests and I can even sell it to people who would prefer it that way.. I'm just curious as to what would be more MPG friendly while at the same time efficient as far as battery draining is concerned.

EDIT: Maybe I should market this as Electric Nitrous XD