Tiny electric motor can produce more than 1,000 horsepower
238 comments
·November 3, 2025davedx
jayanmn
> According to YASA, this is achieved without using exotic or expensive materials, so the design could actually be scalable once the demand kicks in.
That is ever more special
electrograv
> In 2025, after a £12m investment, YASA opened the UK's first axial-flux super factory, in Oxfordshire.
It’s a little sad to me that fundamental innovations in electromechanical engineering like this get just a few million in investment, yet if this had been yet another derivative software startup with “AI” in the pitch, they’d probably have 10x+ or more investments being thrown at them.
lunias
I wish more people on the road realized the extent to which weight reduction improves all aspects of the driving experience... it really does compound unlike any other change that you can make to a vehicle. IMO heavy vehicles are a scam and the antithesis of the direction we should be moving.
ehnto
I agree with you however I believe weight and safety are in a complex relationship right now, which has nothing to do with performance and handling.
Unfortunately I feel much less safe in a Fiat 500 when a significant portion of cars in the road weigh nearly 3 tonnes and perhaps can't even see me. I suspect most people are in SUVs because they're the pragmatic trade off between safety and convenience, not because they were hoping for excellent performance.
schiffern
Classic prisoner's dilemma.
Everyone who can will naturally choose "defect" unless there's some sort of external coordination mechanism.
ajuc
Tax SUVs out of existence.
rounce
Absolutely and on top of that far lower pollution from tyre and brake dust, and less damaging to the road top surface.
rpozarickij
Driving Volkswagen e-up for the first time was a very unique experience to me. My brain needed to adjust that a car can be that nimble and responsive due to its small size/weight and instant torque from the electric motor.
amelius
But EVs are already heavy because of the battery. I suppose percentage-wise the motors don't make much of a difference (?)
nmehner
The issue with this type of motor is that it is part of the unsprung weight since it is inside the wheel. This is probably why savings here matter a lot more (or at least in a very different way) than the battery weight.
rob74
Ok, now I understand why this motor is only used in supercars - installing four (or even only two - according to https://www.mercedes-benz.de/passengercars/technology/concep..., even the AMG GT-XX has "only" three of them) hub motors with twice the power of a Tesla Model 3 in any other car would be ridiculous. So, the actual challenge is to make this motor even smaller while keeping the same power to weight ratio, so it can also be used for regular cars? That is, if they want to build something for the mass market, not only for an exclusive clientele?
Zanfa
I might be wrong, but I don’t think these motors are intended to be used inside the wheel. That would add a ton of additional requirements in terms of physical durability as well as constrain optimal torque and RPM of the motor design.
bidatzi
Why would it have to be unsprung? They are not unsprung in the vehicle shown in the article.
close04
YASA doesn't call it a hub motor specifically but that's one place where it helps to save as much weight as possible. And for the cars most likely to have 1000+HP weight matters too. A Tesla motor weighs 100-200lbs, so saving that much weight down to 28lbs on a supercar is highly desirable.
I think large drones will be another place where a downsized version of this motor will make a huge difference, assuming the power scales nicely with size.
jama211
Where does it say it’s inside the wheel? Not sure about that
Braxton1980
I believe caring about unsprung weight only matters for handling not efficiency
Kaibeezy
See also the Saab Emily GT project. Even with an older, heavier gen of these axial flux motors they found significant performance gains by controlling each wheel via its own motor.
https://electrek.co/2023/04/27/saab-engineers-develop-secret...
DrScientist
It compounds. If you have a lighter more efficient motor you need a smaller battery for the same range, that combined weight loss means you meed lighter brakes etc etc, and because the car is now lighter you size of your motor you need is less.....
They claim, this compounding effect works out to basically double the effective weight saving from battery and motor.
ie if you save 50kg on motor, and save 50kg on battery, you end up saving 200kg over all. Still only about 10% of a typical electric car.
DrScientist
What's a bit of a shame is they are no longer an independent company ( ie wholly owned owned by Mercedes ) - so that might mean we are less likely to see these motors combined with solid state batteries any time soon.
poniko
Yea that's the thing right, the battery is so very much of the weight that optimizing the other parts are "meh" at this point. What is cool is that the 600Wh/kg solid state batteries seems like they are really finally here soon :) i.e removing 200-300kg from a car in one go will be a game changer.
bbarnett
No wonder electrics don't sell well in the US. People weigh more, you're basically saying that leaving grandma at home, is a "game changer".
klabb3
Manufacturers may just keep the battery size and market the improved range instead? Smaller cars in urban and suburban environments have always had lots of benefits, but since many of them are collective in nature, it has largely fallen on tragedy of the commons, and we got larger cars with larger hoods instead.
davedx
Not true. Tesla themselves said the way they got the Model 3 to be so efficient was by optimising every single part exhaustively. It’s expensive at design stage but results in the most efficiency gains across the fleet - so worth it (especially something like the motors)
thesz
Tesla Model Y's battery is 771 kg. The motor in Model Y weights about 45 kg, about three times as much as the motor in the article. By reducing dual motor configuration weight from 90 kg to 28 kg, we reduce total powertrain weight by 7%.
JKCalhoun
I'm more excited about light electric vehicles. (Bikes, tuk-tuks, what-have-you).
linsomniac
...with 1,000 horsepower. =:-)
cesaref
I don't see the weight reduction being very significant.
If we take a Tesla model 3, I believe it weighs 1611kg, and the motor shows up at 80kg if you google it (no idea if this is correct). This YASA motor by comparison weighs 14kg. So, this would drop the vehicle weight by 66kg out of 1611, so that's a 4% saving.
linsomniac
I assume that means it would be more like an 8% savings on the dual motor variants? At what point does it become significant?
jcims
Better for robotics as well.
chris_overseas
A link to the press release https://yasa.com/news/yasa-smashes-own-unofficial-power-dens...
fainpul
> 59kW/kg
At this point why don't we get rid of the k prefix and write 59W/g?
Edit:
I was half joking, but various answers mention kW being standard for motors, kg being the SI unit for mass etc. All true, but as used here in a combined unit, which means "power density" it still would make sense IMO. It's not like the "59" tells you that it's a strong motor and hence you want kW to compare it to other motors. You can't, it's just a ratio (power to weigth). W/g just reads much nicer in my head. Or we could come up with a name, like for other units. Let's call it "fainpul" (short fp) for example :)
59 fp is a new record for electric motors!
floo
Because kg is the fundamental unit of mass and kW is typically used for electric motors.
Same reason you wouldn't use m²/s³ even though that's also technically correct.
kibwen
Amusingly, given the other thread in here with people sniping each other over the metric system, I'm obliged to point out that kg, not g, is the fundamental unit of mass in SI, because even metric can't get away without some silliness.
samdjstephens
kg is the SI unit for mass, I think that would be why
youngtaff
Comparison with other motors
larodi
Much better you should post it and somebody mark the banner ridden one for deletion.
rtaylorgarlock
'Supercarblondie' manages to hit everything I dislike about automotive marketing online all at once.
thenthenthen
Yeah wasnt blondie the name of a dog belonging to a certain historical figure?
1234letshaveatw
So can I jet ski from NY to London in a few hours?
varjag
The new YASA axial flux motor weighs just 28 pounds, or about the same as a small dog.
But how many footballs a small dog weighs?
rob74
Not sure about that, but if you ask me, a really small dog only weighs up to 7 pounds - or otherwise said, this motor weight as much as four fat Chihuahuas ( https://en.wikipedia.org/wiki/Chihuahua_(dog_breed) )
ordu
Lol. I was confused by it also. I have no idea how much is 28 pounds, and I could imagine how a small dog can be anything from 1 kg to 10 kg. It happens that the motor weight is ~13kg, but I'm still not sure that 13kg dog counts as "small".
neilv
New performance ratio: horsepower:dogweight.
aleph_minus_one
> But how many footballs a small dog weighs?
Which kind of football: the British or the US-American one? :-)
eru
Australian rules.
jonplackett
123.5 cubic centi-litres
IshKebab
Not sure about footballs but 28 pounds is about the weight of a child, a bag of rice, or a dumbbell. Hope that helps!
beAbU
How much rice do you buy at a time?!
iambateman
Asian grocery stores carry 25 pound bags of rice and we use about 2 each year. If you eat rice regularly, it’s the way to go.
KingMob
American football or international futbol? If American, it's twelfteen furlongs.
antonyh
The questions I have mostly centre around how much precision of power delivery it has - it is an all or nothing proposition, can it deliver 0.1% smoothly for real world use, and what is the MTBF / duty cycle / failure mode? I would imagine the last thing anyone would want is a locked wheel, or only one wheel delivering that much power. I know this is unlikely, but as someone with a 22-year-old ICE vehicle I do tend to take the long view on these things and want to know how they will fail as much as how they work. Same applies to the Tesla motors - is there much information on failure modes publicly available?
boringg
Ok so whats the catch with the technology? Its more powerful, smaller, all readily available materials. Some kind of strange shape, longevity challenge? Difficult to make so costs are tough to bring down?
Just noticed that they are owned by mercedes benz- they will kill it accidentally. Corporate wont be able to roll it out. They will try and capture all the value and kill its potential
hwillis
Axial flux motors are difficult and expensive to make.
Motors need to be made of laminated steel sheets to reduce parasitic eddy currents. The laminations need to be thin in the direction of the direction of the flux. For radial flux motors you just punch out a shape and stack a bunch of sheets up. For axial flux you have to wind a strip: https://15658757.s21i.faiusr.com/2/ABUIABACGAAgmviFqAYozvPw-...
Each layer of that strip has a different cut in it, so its much more complicated to make. The shape and manufacturing method typically impacts efficiency; YASA avoids that by spending more money. Efficiency is an unavoidable requirement of high power density- heat is the limiting factor, and going from 98% to 96% efficient means double the heat.
The mechanical demands on the motor are also much higher- radial flux is balanced since the magnetic force pulls the rotor from opposite sides. Axial flux motors are usually one-sided, so the magnets are trying to pull the rotor and stator together with incredible force. That also makes vibrations worse. Extremely strong, expensive bearings are required to handle it. With permanent magnet rotors you need a jig to lower the rotor into place; they can't be assembled by hand. That also makes maintenance more difficult and expensive.
phkahler
>> Each layer of that strip has a different cut in it, so its much more complicated to make.
You can roll a spool of that material and then machine the shape out of it. I've seen this done for axial flux motors. There are other approaches as well, and the cost differences get even smaller if you throw automation at the production process. I used to believe axial flux motors were one of those oddities that won't win in the end, but now that I work with them I'm not so sure. They are at least competitive with radial flux machines.
gwbas1c
It's easy to forget that most of the weight in an electric car is the battery. It's ICE cars where a lot of the weight is in the motor.
That being said, could this be adapted so that a 2.8lb motor produces 100 hp? That would allow putting a small motor in each wheel, thus completely eliminating axels, driveshafts, and allow recapturing the space they used to occupy. It also wouldn't significantly impact unsprung weight.
neuroelectron
Is it really easy to forget?
ChrisMarshallNY
I'm curious as to the efficiency of the motor (basically, how much of the input electric power is converted to motive power).
If it isn't very good, then it might be excellent for drag races, but maybe not so many others.
Also, any power that doesn't turn into torque, is likely to be expressed as heat.
gcanyon
It would almost have to be very efficient -- they're saying it can do something like 500HP continuous, and it doesn't have enormous fins all over it for cooling.
ChrisMarshallNY
Looking at the picture, it looks like there may be a liquid input (cooling). Even a very efficient motor is going to need cooling (and lubricant).
nabakin
Exactly my thought as well. You can have all the horsepower you want but if it doesn't convert the electricity efficiently, it's not going to be useful for normal consumer cars.
FabHK
Outperformance metric is basically power density. The model described is some 13 kg and delivers 750 kW peak, 350+ kW sustained.
(That's 28 pounds, 1000 hp peak, 470+ hp sustained.)
The 40% improvement is actually 36% and is versus the previous model of the same company.
superxpro12
Peak power is a number that can be manipulated. You just dump short circuit current into a winding. Even if that peak lasts for 1 microsecond, you can "claim" eye-watering horsepower numbers.
I wonder if we defined peak as sustained peak over 100 milliseconds, or some more meaningful number, what that would do to the claims. You aren't really generating meaningful torque over 1 microsecond.
impossiblefork
I sort of wonder how well these things can be scaled down.
Wheel hub motors are obviously bad, for harshness reasons, but if you could have a motor like this weighing 1-2 kg, and put one on each wheel, that'd be okay.
Power-wise this would be okay if things are linear. 26 kW per wheel sustained power output is more than enough for a light car. The question is what torque a scaled-down machine can be expected to have.
ants_a
I'm wondering if it would make sense to integrate the rim, motor and wheel bearing into a single assembly to save weight and cost. That combined with the weight and packaging benefits of not having half shafts and differentials might make it worth it. Plus there can be additional benefits, like the extra maneuverability that ZF Easy Turn and Hyundai's e-Corner have demonstrated.
30kW sustained/60 kW per wheel peak power is easily enough even for large passenger vehicles. Sustained could take 3 ton vehicle up a 10% grade at 120 km/h.
vanderZwan
Thanks. Do you also happen to know the power density of the motors in the average EV car? Because the article uses "nr of Tesla Model 3" as a unit, which is meaningless without further details about it power density.
egorfine
> That's 28 pounds
or about the same as a small dog
alex_duf
There was a video on this motor recently: https://www.youtube.com/watch?v=r4OdH0ibOBk made by a phd in the field
tverbeure
That’s an excellent video!
NeroVanbierv
A similar company is based in Munich: https://www.deepdrive.tech/ They have cool testing facilities applying CI/CD practices to testing hardware!
molticrystal
It is great that Mercedes-Benz now owns a highly performant electric engine. But is this just an impressive lab breakthrough, or can it work in the real world for their cars? Which means enduring from freezing to high temps, hours of sustained driving, and years of that (or equivalent endurance testing).
Cthulhu_
It's not a lab model (according to the article), but it's likely aimed at performance cars. For consumer cars, 150 KW / 200 HP is enough and efficiency is more important than weight.
Of course, when consumer car efficiency increases, they won't necessarily get higher ranges because the manufacturers will instead try to downsize the battery.
Could lead to significant efficiency gains for EV's, because 1/4 of the motor weight means better power-to-weight ratio... a lot of things will automatically get better.
YASA was founded in 2009, a spin out from Oxford University following the PhD of founder and still CTO, Dr Tim Woolmer.
"Over the decades that followed both of these technologies were explored. But despite the potential for weight reduction, smaller size, shorter axle length and increased torque, it was the difficulty in manufacturing the axial flux technology that limited its commercial viability, because the motor could not be made by stacking laminations, as with radial machines."
"The breakthrough innovation came by segmenting the axial flux motor in discrete "pole-pieces", so the motor could be manufactured using Soft Magnetic Composite material.
SMC can be pressed at low cost into a wide variety of 3D shapes. This removed the need for the complex laminations, overcoming the major manufacturing challenge of the axial flux machine."
"In 2025, after a £12m investment, YASA opened the UK's first axial-flux super factory, in Oxfordshire.
The opening of this facility boosts YASA’s manufacturing capacity, setting new benchmarks in e-motor technology and quality, and enabling production to scale beyond 25,000 units per year."
This is awesome. Lighter motors also make electric flight more viable