Here is the supercharger I would start with...
- Thread starter AlexLTDLX
- Start date
InitialAuto
Member
are the p2s out of stock now? amazon link you put in the vid says they are. what are they selling for @AlexLTDLX ?
try this link:
P-2 Centrifugal Supercharger Polished Head Unit | eBay
This is accomplished by compressing combustion air before it enters the cylinders, which increases density. This results in improved cylinder filling, allowing more air and fuel to be burned in the combustion cycle, with dramatic increases in torque and horsepower.
www.ebay.com
or this:
P-2 Centrifugal Supercharger Polished Head Unit | eBay
This is accomplished by compressing combustion air before it enters the cylinders, which increases density. This results in improved cylinder filling, allowing more air and fuel to be burned in the combustion cycle, with dramatic increases in torque and horsepower.
www.ebay.com
gnaah ... I have a serious problem getting batteries from china.
The first seller had to return my money because of "shipping irregularities" (fake shipping, fake tracking number, but AliExpress stepped in).
The second seller is trying to sell me something else than what I had chosen from his offerings (of course for double the money, and shipping quote still pending).
The third seller gave me a price on option one, but twice as expensive and does not yet come back on the shipping question too ...
I will start machining the pulleys and the simple mounting fixture once batteries are secured/on the way!
Then ... maybe enough time has passed for Trampa to come out with the better high amp VESC targeted for the end of this year ...
MkngStffAwesome
Active member
i can't get batteries into the country too.. there is literally no option.. Im guessing when we start letting people back into the country mid next year then i might be able to get them in 
cmoalem - can you confirm the timing belt size/pitch for this blower? Is it indeed a T5/25? Is the 260mm length good, or could it be a little shorter or longer? I literally can not find anything that'll work in the US from my usual channels. I can say the shaft pulley has 19 teeth.
Alex ... it is 18 teeth! (mark a tooth with a sharpy and count again
, and 18teeth seems to be kind of standard step!)And the MEDWAY T5-260 25mm wide is perfect! see post #31 and following
(shoot ... MEDWAY pdf is too large for upload)
Last edited:
and here some more shots:
as you can see with the 260 length the pulley bore (TP motor axis) ends up approx at those empty threaded bolt holes on the blower backplate.
BTW ... although we need T5 pitch pulleys as well I was curious and ordered some M5 pitch pulleys which I found here:
The great thing about them: they are available with the right D shaped 8mm bore and setscrews. Tight still sliding on fit! Very nice.
I assume for testing purposes the rounded M profile is ok. But belt longetivity of my T5 belt might suffer ...
I will use the M pulley as "work order/sample" to machine my T pulley accordingly at the machine shop eventually ...
as you can see with the 260 length the pulley bore (TP motor axis) ends up approx at those empty threaded bolt holes on the blower backplate.
BTW ... although we need T5 pitch pulleys as well I was curious and ordered some M5 pitch pulleys which I found here:
5M Timing Belt Drive Pulley 15-25T D-shaped Bore 5mm Pitch for 15/20/25mm Belt | eBay
Find many great new & used options and get the best deals for 5M Timing Belt Drive Pulley 15-25T D-shaped Bore 5mm Pitch for 15/20/25mm Belt at the best online prices at eBay! Free shipping for many products!
www.ebay.com
The great thing about them: they are available with the right D shaped 8mm bore and setscrews. Tight still sliding on fit! Very nice.
I assume for testing purposes the rounded M profile is ok. But belt longetivity of my T5 belt might suffer ...
I will use the M pulley as "work order/sample" to machine my T pulley accordingly at the machine shop eventually ...
Last edited:
You're right - even though I used a silver pencil to mark a tooth, somehow I miscounted - it's 18 teeth. Thanks for the pics. I happened to find a Gates 280mm belt on Amazon for $6... for that price delivered, I figured "close enough." I did also find pulleys on McMaster-Carr here in the states. With shipping, 1 pulley was just under $30 - a bit steep for what it is, but both will be here by Friday. I went with a 22 tooth motor pulley. A D-shaped hole is certainly preferable; I might try to make a "gib" of sorts that the set screw pushes against; a set screw straight on the shaft isn't the greatest idea, I've discovered. I'm fortunate enough to own a small lathe and mill, so that shouldn't be too difficult. Hopefully the larger pulley diameter makes up (at least somewhat) for the 20mm longer belt.
My thinking with the 22 tooth motor pulley is to get a bit of "step up," since max output power seems to be roughly in the middle of a brushless motor's rpm range; and torque increases at lower rpm. My TP Power motor is rated for 40,000 rpm, and we've been able to hit about 28,000. If we can hit the same motor speed (which is probably doubtful), then we could hit 32,000 impeller rpm. Doesn't sound like much, but that would be the difference between 650 and 750 hp on my car's engine. Realistically, if we could get to just over 30,000 rpm, that would still be 700 hp.
Not matter what happens, this is by far the easiest way to build one of these things and we also need to know if the belt will hold up. I'm not really sure about that, but we'll see. These rpms are well beyond what these belts are supposed to be able to hold, but the torque seems to be within spec.
My thinking with the 22 tooth motor pulley is to get a bit of "step up," since max output power seems to be roughly in the middle of a brushless motor's rpm range; and torque increases at lower rpm. My TP Power motor is rated for 40,000 rpm, and we've been able to hit about 28,000. If we can hit the same motor speed (which is probably doubtful), then we could hit 32,000 impeller rpm. Doesn't sound like much, but that would be the difference between 650 and 750 hp on my car's engine. Realistically, if we could get to just over 30,000 rpm, that would still be 700 hp.
Not matter what happens, this is by far the easiest way to build one of these things and we also need to know if the belt will hold up. I'm not really sure about that, but we'll see. These rpms are well beyond what these belts are supposed to be able to hold, but the torque seems to be within spec.
BTW, my 22 tooth pulley showed up; along with the belt. Looks like a 280mm belt isn't a bad choice either; at least not with a 22 tooth motor pulley. The center bore of the pulley overlaps the 8mm holes in the back plate by about 75% on the holes that are a little further out, and by about 50% on the ones a little further in. I'm going to assign this weekend to some "me" time; so I might be able to get this running, at least on low power on the VESC.
WB projects
Active member
Do the side tension on the motor shaft with the belt will be a problem?
Because it's a toothed belt it shouldn't need much tension. On top of that, if you look at cmoalem's pics, you can see the steel wires inside the belt (my belt is a Gates belt and not transparent, but it's supposed to have steel wires inside it too).
I'm not really worried about side tension, or really load capacity (we're right on the edge of the belt's max load rating) - what I am worried about is max rpm. The highest rpm I've seen a T5 belt rated for (on the faster turning pulley) is 14,000 rpm. We're looking to at least double that, if not more.
Just like most things throughout this whole process - only one way to find out - run it!
Worst case scenario, if the belt doesn't hold up, I'll go back to direct drive - I may even machine my own impeller shaft. But I do hope this works, because playing with different pulley combinations should help us maximize impeller rpm. I have a feeling that "sweet spot" is somewhere between a 1.2-1.5 to 1 ratio step up.
I'm not really worried about side tension, or really load capacity (we're right on the edge of the belt's max load rating) - what I am worried about is max rpm. The highest rpm I've seen a T5 belt rated for (on the faster turning pulley) is 14,000 rpm. We're looking to at least double that, if not more.
Just like most things throughout this whole process - only one way to find out - run it!
Worst case scenario, if the belt doesn't hold up, I'll go back to direct drive - I may even machine my own impeller shaft. But I do hope this works, because playing with different pulley combinations should help us maximize impeller rpm. I have a feeling that "sweet spot" is somewhere between a 1.2-1.5 to 1 ratio step up.
Regarding step up or down : depends a lot on your eMotors specs and what voltage u r running and where you want to end up with your impeller rpms.
I intend to run the TP power 1000KV motor I have here with around 48V (or so after voltage drop) ...
I think Alex wants to run his 750KV TP power ...
My assumption for my motor I can actually afford a step DOWN ... for my engine/displacement I am totally fine with 32k impeller rpm! ... (and the step down actually unloads the motor ... lower gear ... higher torque)
From the experiments Alex ran with his Si trim Vortech somehow I got the impression we need more TORQUE to overcome the 28000 impeller rpm barrier.
So ... I have a 18 T pulley, a 15 T pulley and even a 12 T pulley to play around with
Alex goes bigger ... I go smaller
I intend to run the TP power 1000KV motor I have here with around 48V (or so after voltage drop) ...
I think Alex wants to run his 750KV TP power ...
My assumption for my motor I can actually afford a step DOWN ... for my engine/displacement I am totally fine with 32k impeller rpm! ... (and the step down actually unloads the motor ... lower gear ... higher torque)
From the experiments Alex ran with his Si trim Vortech somehow I got the impression we need more TORQUE to overcome the 28000 impeller rpm barrier.
So ... I have a 18 T pulley, a 15 T pulley and even a 12 T pulley to play around with
Alex goes bigger ... I go smaller
Your thought process makes sense; but here's why I went the way I did (right or wrong, dunno yet - as always, only one way to find out for sure):
This is just a typical brushless motor torque chart vs speed. If I can lower the motor's rpm into it's peak torque region, then perhaps that overcomes the step up torque loss. Since my TP Power motor has a max speed of 40k rpm, and we were already hitting just short of 30k rpm, I'm assuming that's in the declining region of the torque curve. Again, I really don't know if this will play out that way, but I'd certainly like to find out. If I can keep the motor to maybe at least 26,000 rpm, then that would give me an impeller speed of about 32k.
Ideally, we'd have actual dyno graphs of these TP Power motors, then we wouldn't have to guess.
This is just a typical brushless motor torque chart vs speed. If I can lower the motor's rpm into it's peak torque region, then perhaps that overcomes the step up torque loss. Since my TP Power motor has a max speed of 40k rpm, and we were already hitting just short of 30k rpm, I'm assuming that's in the declining region of the torque curve. Again, I really don't know if this will play out that way, but I'd certainly like to find out. If I can keep the motor to maybe at least 26,000 rpm, then that would give me an impeller speed of about 32k.
Ideally, we'd have actual dyno graphs of these TP Power motors, then we wouldn't have to guess.
MkngStffAwesome
Active member
That is a pic of a Servo ( which yes is a brushless motor )
In say a 3d printer it is desirable to have a flat torque curve to allow for fast printing without loss of steps.. in that example it has the same torque below 2000rpm..
This is achieved by providing a low inductance motor WHILE limiting motor current this flattens the torque output out..
If that motor was not Current (torque) limited it would have had max torque at 0 rpm.
With the VESC you were able to do this by implementing the "current" limit.
In say a 3d printer it is desirable to have a flat torque curve to allow for fast printing without loss of steps.. in that example it has the same torque below 2000rpm..
This is achieved by providing a low inductance motor WHILE limiting motor current this flattens the torque output out..
If that motor was not Current (torque) limited it would have had max torque at 0 rpm.
With the VESC you were able to do this by implementing the "current" limit.
Last edited:
My understanding is the linear relationship between torque and rpm is only valid as long as you're not magnetically saturating the motor. I've empirically discovered that my particular TP Power motor seems to saturate just under 14 kW. So that's a relatively known quantity - more or less. This guy gives a really good explanation of the rpm/torque/saturation relationship:
In any event, most of the motor graphs I've found show that plateau of torque in saturation starts to drop off right around half of the motor's max rpm. So in the case of my TP power motor, that's around the 20,000 rpm ballpark - thus my statement above of having a "step up" ratio of up to about 1.5:1. Real world will tell the real story, though.
I'm actually working on the belt drive again tonight. It's cold as heck in the garage, so it's taking a while - I'm assembling/laying out on the same desk I shoot my "talking hands" videos on, but popping out the the garage to do the actual work. I just have standoffs to make on the lathe and still have to layout the motor's bolt pattern on the motor plate. I'm also discovering that I'll need some sort of small diameter headed 10mm bolt to make things work. I'm trying to keep everything as compact as possible, and was hoping to use studs with nuts as I don't like repeatedly torquing bolts into aluminum, but it is what it is. I can only do the stud trick on one side. The other will need a socket head cap screw with the head turned down from 16mm to 14mm. At least there's plenty of room for a load-spreading washer given the tapered front plate design on the motor. It'll make sense when you see it.
In any event, most of the motor graphs I've found show that plateau of torque in saturation starts to drop off right around half of the motor's max rpm. So in the case of my TP power motor, that's around the 20,000 rpm ballpark - thus my statement above of having a "step up" ratio of up to about 1.5:1. Real world will tell the real story, though.
I'm actually working on the belt drive again tonight. It's cold as heck in the garage, so it's taking a while - I'm assembling/laying out on the same desk I shoot my "talking hands" videos on, but popping out the the garage to do the actual work. I just have standoffs to make on the lathe and still have to layout the motor's bolt pattern on the motor plate. I'm also discovering that I'll need some sort of small diameter headed 10mm bolt to make things work. I'm trying to keep everything as compact as possible, and was hoping to use studs with nuts as I don't like repeatedly torquing bolts into aluminum, but it is what it is. I can only do the stud trick on one side. The other will need a socket head cap screw with the head turned down from 16mm to 14mm. At least there's plenty of room for a load-spreading washer given the tapered front plate design on the motor. It'll make sense when you see it.
MkngStffAwesome
Active member
That video did not at all contradict what i said. Which is that a Servo motor is limited by their controllers to a certain current to achieve the same torque across a wide range of RPM. This is desirable to have the same predictable acceleration / Torque. Having predictable acceleration is very useful in motion control. It will also stop the motor from melting when being held stationary.
That Video deals with a few things moving from the world of theory to reality.
With
"Why do i need a bigger motor at all why can't i just apply a billion watts to a tiny motor and expect it to move a billion KG load"
While you can theoretically apply a unlimited amount of electrical power to a motor ( assuming the coils dont melt ) that does not result in endlessly increasing torque out from the motor. If that was the case then there would only be one motor and it would be tiny. It gets to a point where that motor is not able to convert that in to useful magnetic power due to Stator saturation (inpart). The answer then to increasing torque is to increase motor size.
Saturation point does not have anything per say to do with RPM but the Power the motor is pulling at that rpm.. As RPM increases back emf increases that therefor current pulled is less and therefore Power/ Torque is reduced as Motor RPM increase. So as motor RPM increase power being pulled starts to drop below saturation point.
Stator saturation basically does not change if you gear it or not because gearing it does not change the physical parameters of the motor and therefore the power the motor can convert.. gearing it will affect the load on the motor and therefore how close you are to the saturation point.
Gearing the motor will result in lower motor RPM ( because of the increased load caused by the gearing) while hopefully providing higher impeller RPM.. Due to the lower motor rpm therefor will be less back EMF and therefor more current will be drawn and therefore you are applying more "Power" than before ( Great ! ) . If the motor is already at or close to saturation point then gearing it will not result in higher impeller speeds but just more power consumed. If that is the case then your only option is to get a "bigger" motor.
The question then becomes are we at or near Saturation now.. I don't think we can categorically answer that as i dont think any real testing has been done on that. However i believe that since that "loaded" RPM is high relative to max theoretical rpm ( unloaded ) then we can't be operating to near "saturation". (What was max theoretical again Alex KV * LOADED Voltage ?)
So gearing it should result in more power being pulled and more boost being made.
Now the last thing i would say is... "What about efficiency", which i think cmoalem was alluding too. For alex it's a drag car so he doesn't care but for the rest of us efficiency is a big deal... Im certainly not smart enough to tell you what will be more efficient between X or Y gearing. However at a guess id say that Alex's gearing would result in less efficiency. In saying that we care about complete system efficiency not just motor efficiency. Impeller efficiency is not a constant at all RPMs so while we maybe losing motor efficiency if at the same time we are gaining more impeller efficiency then maybe there is little difference with the comparison with watts consumed V boost, which is really what we care about.
FYI this is all assuming that the gearing is with the smaller pulley on the impeller and the larger one on the motor.. as this is what i assume is being proposed.
That Video deals with a few things moving from the world of theory to reality.
With
"Why do i need a bigger motor at all why can't i just apply a billion watts to a tiny motor and expect it to move a billion KG load"
While you can theoretically apply a unlimited amount of electrical power to a motor ( assuming the coils dont melt ) that does not result in endlessly increasing torque out from the motor. If that was the case then there would only be one motor and it would be tiny. It gets to a point where that motor is not able to convert that in to useful magnetic power due to Stator saturation (inpart). The answer then to increasing torque is to increase motor size.
Saturation point does not have anything per say to do with RPM but the Power the motor is pulling at that rpm.. As RPM increases back emf increases that therefor current pulled is less and therefore Power/ Torque is reduced as Motor RPM increase. So as motor RPM increase power being pulled starts to drop below saturation point.
Stator saturation basically does not change if you gear it or not because gearing it does not change the physical parameters of the motor and therefore the power the motor can convert.. gearing it will affect the load on the motor and therefore how close you are to the saturation point.
Gearing the motor will result in lower motor RPM ( because of the increased load caused by the gearing) while hopefully providing higher impeller RPM.. Due to the lower motor rpm therefor will be less back EMF and therefor more current will be drawn and therefore you are applying more "Power" than before ( Great ! ) . If the motor is already at or close to saturation point then gearing it will not result in higher impeller speeds but just more power consumed. If that is the case then your only option is to get a "bigger" motor.
The question then becomes are we at or near Saturation now.. I don't think we can categorically answer that as i dont think any real testing has been done on that. However i believe that since that "loaded" RPM is high relative to max theoretical rpm ( unloaded ) then we can't be operating to near "saturation". (What was max theoretical again Alex KV * LOADED Voltage ?)
So gearing it should result in more power being pulled and more boost being made.
Now the last thing i would say is... "What about efficiency", which i think cmoalem was alluding too. For alex it's a drag car so he doesn't care but for the rest of us efficiency is a big deal... Im certainly not smart enough to tell you what will be more efficient between X or Y gearing. However at a guess id say that Alex's gearing would result in less efficiency. In saying that we care about complete system efficiency not just motor efficiency. Impeller efficiency is not a constant at all RPMs so while we maybe losing motor efficiency if at the same time we are gaining more impeller efficiency then maybe there is little difference with the comparison with watts consumed V boost, which is really what we care about.
FYI this is all assuming that the gearing is with the smaller pulley on the impeller and the larger one on the motor.. as this is what i assume is being proposed.