# racing BMWs in reverse...



## riba2233 (Apr 29, 2015)

LOL, this proves absolutely nothing, he could just put more power in that car with in wheel motors. Also electric motors work absolutely same in both directions, so the video is very misleading. Same result could have been achieved with both hub motors and standard motors with differential or any other combination.


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## brian_ (Feb 7, 2017)

That's amusing. Elaphe Propulsion Technologies claims in the caption "an improved center of gravity and exceptional weight distribution", which is a complete load of crap. The centre of mass of the in-wheel motors is located (vertically and longitudinally) at the centre of the wheel, while an inboard motor can be located ahead of, behind, above, at, or even below the wheel (axle) centre. Yes, the in-wheel location allows other components to be where the inboard motors might be, but every production EV places batteries within the wheelbase and low, so this is not an improvement.


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## brian_ (Feb 7, 2017)

riba2233 said:


> LOL, this proves absolutely nothing, he could just put more power in that car with in wheel motors.


I agree that it doesn't prove anything, and I don't even think the in-wheel location allows more power. There's not much space in a wheel, and Elaphe's highest-power product does not have higher output than readily available (to OEMs) inboard motor.



riba2233 said:


> Also electric motors work absolutely same in both directions, so the video is very misleading.


True for any motor which would be used in a modern production EV; however, brushed DC motors are routinely setup with asymmetric timing, which means they don't work as well (if at all) in reverse.



riba2233 said:


> Same result could have been achieved with both hub motors and standard motors with differential or any other combination.


True!


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## riba2233 (Apr 29, 2015)

DC motors with interpoles and neutral brush timing work same in both directions, but yeah, most of them have advanced timing and work well in one direction only.


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## Karter2 (Nov 17, 2011)

Hmm ? ...something doesnt add up here ?
....can someone explain how a 70Nm motor ...or even 4 of them...fitted in wheels , can come anywhere near to the performance of a single GM Bolt motor at 400Nm driving through a 4:1 reduction to the wheels ?
.....and if they can , we will move on to the Tesla, with 1100Nm and a 9.7:1 drive ratio !


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## brian_ (Feb 7, 2017)

Karter2 said:


> ....can someone explain how a 70Nm motor ...or even 4 of them...fitted in wheels , can come anywhere near to the performance of a single GM Bolt motor at 400Nm driving through a 4:1 reduction to the wheels ?
> .....and if they can , we will move on to the Tesla, with 1100Nm and a 9.7:1 drive ratio !


It can't, even four of them could not, but the motors are presumably the L-Type, with (according to the manufacturer's specs) peak torque of 1500 Nm... and peak/continuous power ratings of 110 kW / 77 kW (with liquid cooling). Each one of the in-wheel motors would be roughly comparable to the single Bolt motor, or half of those Tesla specs (which are presumably be for a P100D in "Ludicrous+" mode).

Even the smaller M700 motor - intended for vehicles such as the Smart ForTwo - puts out (as the name suggests) 700 Nm... as it would need to in order to be useful.


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