What brushless motors are being chosen?

WB projects said:
But I changed for a castle creation motor
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thank you for the update WB. I was going to order a 4070 CM today, but curious if I should hold off for a better option. Could you share your thinking on why you are moving away from the TP 4070? Any watch outs? I have a similar sized engine to yours (2.0 liter 4 cylinder and am angling for a similar sized turbo). And which castle creations motor you are switching to? Is it one in the list above or a different model? And what was your rationale for the castle model you selected? if you would be so kind as to indulge us. Thank you!
 
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A Garrett T04E-40 compressor wheel would be a good fit for a 2.0L engine. There are Chinese clones on Ebay dirt cheap.

At 6000 rpm I'd estimate about 19 lbs/min of air flow with 5 psi of boost. The compressor would demand about 5.7 kW from the motor. The required rpm would be about 73,000. The 4070CM is rated for 5 kW continous and 9 kW peak and may work for these conditions.

When I do an electric supercharger, I'll looking for more boost. 5 psi is not going to get you a lot more power. 10 psi requires close to 13 kW from the motor.
 
AlexLTDLX said:
WB - are you coming out of your winter deep freeze? :)
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HAHAHAHA yes! I just get out of my igloo! The ESC is out for 7months now and I should get the first diagnostic from MGM this week. Not their fault but my shipping company. Anyway I hope get it back soon in a month we should get sumer temperature!
Btw remember my forged wheel? They are done! This is a trip to miami last month
 

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GTHound said:
thank you for the update WB. I was going to order a 4070 CM today, but curious if I should hold off for a better option. Could you share your thinking on why you are moving away from the TP 4070? Any watch outs? I have a similar sized engine to yours (2.0 liter 4 cylinder and am angling for a similar sized turbo). And which castle creations motor you are switching to? Is it one in the list above or a different model? And what was your rationale for the castle model you selected? if you would be so kind as to indulge us. Thank you!
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Honnestly you can try and hope having a real CM version because I don’t! I still manage to get 7psi with my normal 4070 but I damaged my ESC.. the castle creation I get is the 1721 I think
 
Thanks for the input. Here is an updated chart of motor options. Adding the LMT and Castle 1721.


Motor RPM maxMax VoltsWatts Cont / PeakCost
TP 4070-CM75K12S = 48V - 54V5,000 / 9,000$189+ship
TP 5670-CM85K10S = 40V8,000 / 12,000$399
Castle 2028-1700KV60K8S is this an issue??$299
Castle 1721-2400KV90K8S is this an issue??$239
Hobbywing 70125 560KVmy calc = 48 x 560KV = 27K?6-12S= 25V - 48V300A/2000A = 12,000 / 88,000$350
LMT 3010050K - too low for direct drive?40,000
Amazing power handling 		$615 hard to get
Neomotor 3030 too low for direct drive?15,000/30,000
Big power handling
 
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It is interesting about the max S we «can use» on the 1721 motor. I talk with a guy of castlecreation and he suggest me to not over volting the motor. I don’t know why but anyway I have cells in spare so I can upgrade it in the futur if 8s is not enough. But what I did is I add cells for the voltage drop! So with rhe drop, I should be “perfect“
 
I can't speak for Castle but on a NeuMotor the maximum voltage is a limit to keep from spinning the motor past its rated EPMs. The problem with low voltage is that the amperage for a large kW motor is going to be high and that means a more expensive ESC and also lots of batttery capacity to get a high enough C factor to support the high amperage.
 
So, I really want to close the loop and get my motor ordered to free my mind and get it on its way. I am down to 2 lead options. A) castle 1721 and B ) TP 2070-CM.

I like the high RPM limit (90K) and power handling of the castle, and clearly a sensored motor. Although after talking to their tech service it sounds more like 90K is blow apart speed than a usable one. On amazon reviews some had the rotor come apart after a few runs ant 72K. But hopefully it can just be dialed down with the right pwm signal. Another concern is the lower voltage (8S max). I can’t seem to get clear on the max wattage even after talking to castle tech service, although they say some racers have been hitting 15KW for 10 second bursts.

On the TP-4070 CM option, it doesn’t rev quite as high (75k) but still significantly north of 50K limit. It does take 12S, which is great. But sounds like WBs was not the real deal and could not rev past 55K and it may have contributed to a blown ESC. I can’t seem to figure out if the TP is a sensored motor based on their web site. If it is not sensored, then I will go with the castle for now and upgrade the motor and batteries in a year or 2 as the tech gets more affordable.

Any votes from the veterans who have ran these or similar variants?
 
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I think the real deal of the 4070-cm should be enough. BUT I have better hope with the 1721 castle motor! They call it « the TP killer ». But like you said the 8s worries me too. I still have couple week till I try it but we will see!
 
WB projects said:
I think the real deal of the 4070-cm should be enough. BUT I have better hope with the 1721 castle motor! They call it « the TP killer ». But like you said the 8s worries me too. I still have couple week till I try it but we will see!
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Thanks WB. Was your TP 4070 sensored? My hunch is that it is not, else probably would have been advertised as such. I just can’t seem to get a good picture to see if it has the sensor port or find any info on their website.
 
You need to match the motor power output to the power requirments of the supercharger. If you pick a motor what puts out 5 kW of power at 75,000 rpm but the supercharger consumes 10 kW of power at 75,000 rpm the motor starts to stall. The amps go through the roof and something burns up. Slowing the compressor to reduce power is necessary. However, BLDC moros do not produce their nameplate power when throttled back. At 50% throttle the voltage to the motor is reduced by half and to get the same power output the phase current goes up by a factor of two and something goes up in smoke. You want a motor with certain Kv so that at 100% throttle it has enough power to deliver the power required by the compressor at the full throttle rpm (KV*supply voltage).
 
Upon further reaearch an LMT 2280/5 motor and an MGM 25063-3 ESC look promising. LMT has an option for a carbon fiber sleeve on the rotor to extend the RPM range. It looks like this motor could do 9.3 kW at 73000 rpm with a 50 volt supply drawing 200 amps. The peak amps look to be 400 providing 18+ kW. The MGM ESC is advertised for 15S max, 250 continuous amps and 360 peak amps. All this comes with a price:

ESC - 596 euros
Motor - 424 euros
delivery to Texas - 88 euros

with current exchange rate - $1200
 
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88fiero said:
Upon further reaearch an LMT 2280/5 motor and an MGM 25063-3 ESC look promising. LMT has an option for a carbon fiber sleeve on the rotor to extend the RPM range. It looks like this motor could do 9.3 kW at 73000 rpm with a 50 volt supply drawing 200 amps. The peak amps look to be 400 providing 18+ kW. The MGM ESC is advertised for 15S max, 250 continuous amps and 360 peak amps. All this comes with a price:

ESC - 596 euros
Motor - 424 euros
delivery to Texas - 88 euros

with current exchange rate - $1200
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Good research on the motors. I like the find with the carbon fiber sheath for extra high RPMs. That motor is big bucks, but it looks like just what we need.
 
88fiero said:
Garrett clone T04e-50 turbofor $159.

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It is an interesting process to think through which compressor housing to use. Although using the same compressor maps, I am sizing quite different than a turbine powered turbo. I have found that the smaller diameter compressors for typical 4 cylinder engines require such high RPM > 100K, to get the right pressure that it is not practical for direct drive.

It seems that the larger compressor wheels, typically for larger engines, have a higher blade tip speed because of the larger diameter, so can build boost better at RPMs that are in the realm of direct drive.
 
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My target vehicle is a 2.8L V-6 in a 1986 Pontiac Fiero. This is a push rod engine that makes 140 HP at 4800 rpm. I have modeled it with DynoSim5 with a high efficiency centrifugal supercharger. With 10 psi of boost the inlet acfm is 306 at 5500 rpm redline. This equates to 21.6 corrected lbs/min. This is in the middle of a Garret T04E-50 compressor map running at 75,000 rpm with a 1.7 pressure ratio. I wouldn't think that a 4 valve 2.0L 4 cylinder is a lot different.
 
I agree with GTHound's thinking. Extremely high rpm means high ESC switching losses, which limits power in a non-linear fashion. However, WB Projects has had some success using a more conventional turbo on his setup. Though I do tend to side with GTHound on this point, there's still very little data out there to prove it, so who knows for sure. Plus, technology is continuously evolving.
 
An LMT 2280 is a 2 pole motor so running at 75,000 rpm is only 75,000 erpm. The MGM ESCs are rated for 200,000 erpm. APD ESCs are rated at 750,000 to 1,000,000 erpm. How can APD rate the ESCs for these high numbers if switching losses are a big problem? There is nothing in their documenation that says the ESC needs to be derated to run high erpm. And low rpm, high kW motors tend to have more poles so eventhough they run slower, the erpms don't change a lot.

The alternative to high impeller speed is to buy an oversized supercharger for a small engine like the P2. You can make boost at 30,000 rpm but that then you have to deal with turndown and avoiding surge with low engine rpms. This means configuring a blow-off valve that is positioned based on engine rpms and controlled by a microcontroller. The BOV can't be pressured controlled because the operating curve at 30,000 rpm is essentially flat at the flow rate range for a small engine.
 
Well - I'll stay this. I've blown up 2 APD ESCs and no MGM ESCs. And the VESC had major issues at high eRPM. Even Kelly controllers charges more for the same ESC running higher eRPM (they have two additional option levels - high rpm and ultra high rpm). It would be nice if there was a slightly smaller option for a compressor like the P2, but you really don't need blow off valves - you can simply control the electric supercharger. Your stock engine is right on the cusp. I've thought about buying one of those Fieros many times over the years, btw - just never found a good one when I was looking. If you could get 200hp n/a out of your engine, then I'd say just go for it and don't worry about it. You definitely don't want to run boost at low rpm anyway - that's a quick way to get a tiny tuning window and blow up a piston (a lesson I've learned the hard way many times).

I've been thinking about a universal control unit - it would run in several "steps" based on load, but with an rpm based trigger switch - so it wouldn't activate below a certain rpm - say around 3,000 rpm for most engines.
 
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