Limitless Finding the 200 mph motor for the Limitless/Infraction GT

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You must keep in mind while designing your vehicle that there is a physics term known as 'power to weight ratio'. I cannot overemphasize this factor as it plays an extremely important part in what is the top speed of any vehicle.
Yes, that is what I am thinking what is going to kill me with my 1/10 build I am going to have trouble running 6s (it is an ECX) so if I made it only be able to have 3s my ESC/motor would be 33% lighter and my batteries would be half the weight. So, is 6s going to be faster than if I would have made it for 3s? We will see.
 
Yes, that is what I am thinking what is going to kill me with my 1/10 build I am going to have trouble running 6s (it is an ECX) so if I made it only be able to have 3s my ESC/motor would be 33% lighter and my batteries would be half the weight. So, is 6s going to be faster than if I would have made it for 3s? We will see.

You can go really stinking fast even on 3s. Ultimately I left my 4tec 2.0 10th scale build because there were too many compromises and weak points.
Building my own custom car was the inevitable final destination I was headed for.
 
Liberty,

You know you have have my utmost respect on this forum. I apologize my last reply to you was cut of. I had made s similar point in other posts. My only addition to this topic is that, other than aerodynamics (I would never presume to debate you on that), the size of a powered vehicle has it's limits due to (you mentioned it before s well), is Power to Weight Ratio. I used the crazy analogy by imagining a paper aeroplane powered by a Hemi engine. The results are very predictable as the vehicle hasn't enough mass to handle the power. I also mention the opposite, and also crazy comparison, that if the Howard Hughes Grey Goose had on 2 engines installed....well, you get it.

I realize, as scientists, we are on the same page. I always look forward to your contributions to this forum. But many can dream with considering the physics involved.

Great day, Dave
 
Liberty,
I see that you are using a xlx2 with a TP, what do you think about this I know that it is probably 3x more money and that more power doesn't always mean more speed, but do you think that this would be a good 200mph combo or is it going to be too much power and you should stick with 8s?
https://www.mgm-controllers.com/en/top-speed-12s-esc-motor-combo-en-10
Ps: Thanks for the input Sloclone, I am not experienced with triple digit speed running (PB 94) and I am trying to learn what I can.
 
You must keep in mind while designing your vehicle that there is a physics term known as 'power to weight ratio'. I cannot overemphasize this factor as it plays an extremely important part in what is the top speed of any vehicle. Simply put the equation for PTWR is: power-to-weight ratio = power / weight. No, armed with that dangerous information, let's make it simpler to understand.
Take a paper airplane. Now strap a 5 Liter Hemi engine to it. (if you could).. The engine would shred the paper airplane apart.
So, when you increase power, you must increase mass. After all E-Mc2.
Point it you are limited in speed when you factor in power and mass.
I think aero is more the limiting factor, scrubbing off speed, if not slippery enough at mid to high level speed runs. Sustained max RPM's becomes more important than torque at some point. Aero drag fights the torque and makes the most difference. Body choice and its setup matters mostly IMHO.
 
Liberty,

You know you have have my utmost respect on this forum. I apologize my last reply to you was cut of. I had made s similar point in other posts. My only addition to this topic is that, other than aerodynamics (I would never presume to debate you on that), the size of a powered vehicle has it's limits due to (you mentioned it before s well), is Power to Weight Ratio. I used the crazy analogy by imagining a paper aeroplane powered by a Hemi engine. The results are very predictable as the vehicle hasn't enough mass to handle the power. I also mention the opposite, and also crazy comparison, that if the Howard Hughes Grey Goose had on 2 engines installed....well, you get it.

I realize, as scientists, we are on the same page. I always look forward to your contributions to this forum. But many can dream with considering the physics involved.

Great day, Dave

What we talk about mostly is theory. No need to apologize.
Without wind tunnels and big budgets for simulations/engineering the best we can do is take information from other applications and try our best to apply it to RC Cars.
Even with land speed vehicles we can see that different teams all take different approaches. There is no single answer of what works best. That makes it fun and interesting!!!

Liberty,
I see that you are using a xlx2 with a TP, what do you think about this I know that it is probably 3x more money and that more power doesn't always mean more speed, but do you think that this would be a good 200mph combo or is it going to be too much power and you should stick with 8s?
https://www.mgm-controllers.com/en/top-speed-12s-esc-motor-combo-en-10
Ps: Thanks for the input Sloclone, I am not experienced with triple digit speed running (PB 94) and I am trying to learn what I can.

I have been very interested in MGM and running 12s up to 16s, but I cannot afford to try it.
The fact that no one has ever successfully run an MGM ESC at high speeds has me very concerned. RC Boat guys talk highly of MGM and Lehner motors, but boats are so very different.

I figure everyone should cut their teeth with TP Power and Castle. IF you get to 160+ then experiment with more expensive equipment....
The fact that an XLX2 and a 56mm motor in 2 different 1/7 cars have gone into the 190's tells us Castle is an excellent ESC. We all have a long way to go to get to those speeds.
 
What we talk about mostly is theory. No need to apologize.
Without wind tunnels and big budgets for simulations/engineering the best we can do is take information from other applications and try our best to apply it to RC Cars.
Even with land speed vehicles we can see that different teams all take different approaches. There is no single answer of what works best. That makes it fun and interesting!!!



I have been very interested in MGM and running 12s up to 16s, but I cannot afford to try it.
The fact that no one has ever successfully run an MGM ESC at high speeds has me very concerned. RC Boat guys talk highly of MGM and Lehner motors, but boats are so very different.

I figure everyone should cut their teeth with TP Power and Castle. IF you get to 160+ then experiment with more expensive equipment....
The fact that an XLX2 and a 56mm motor in 2 different 1/7 cars have gone into the 190's tells us Castle is an excellent ESC. We all have a long way to go to get to those speeds.
Thanks for the info. What is the reason that on one as got serious about top speed running? I know that we are using prebuilt chasses and making new top speeds (for that modal) every week. But we have got the tech now that we (speed runners) are running heavy 1/7 cars on 16.8 less volts and getting 6mph slower than the world record. dose no one have the desire, the money, and the time to do it?
Also, what is the car on your profile page?
 
Thanks for the info. What is the reason that on one as got serious about top speed running? I know that we are using prebuilt chasses and making new top speeds (for that modal) every week. But we have got the tech now that we (speed runners) are running heavy 1/7 cars on 16.8 less volts and getting 6mph slower than the world record. dose no one have the desire, the money, and the time to do it?
Also, what is the car on your profile page?
James McCoy could break the world record with his car. I have zero doubts.... We just need to get him and his car on an airport. (it is not such an easy thing to pull off)
The speeds he is doing on such a short road is simply amazing.

I am not moving very fast finishing the car, but I have 100% confidence my custom built car will do 200+
The car on my profile page was called the "Unlimited project" basically a stretched Limitless.

Unlimited thread

200+ thread
 
Yes, it is amazing how close they are getting to the world record with such non custom builds.
And thanks so much for the links I will look it all over, I am working on a 130mph Felony build if you would check it out that would great!
 
Kind of on the topic here but did anyone else notice/ think it was odd that McCoy, Raz and innovation rc(his was cutting out running 34/34 gearing) did their runs testing the 2400 1721 motor and getting people hyped for the motor and then after their videos posted they quickly moved on to other builds and haven’t really said anything about the motor since
???
This was my observation, I may be mistaken just wondered if anyone else noticed this. I’m wondering if they all fried the motors😁 a personal friends lasted 4 runs not running overgeared on 8s.

On the topic of a 200mph motor, a super solid battery supply to me seems just as important as the motor.
 
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Kind of on the topic here but did anyone else notice/ think it was odd that McCoy, Raz and innovation rc(his was cutting out running 34/34 gearing) did their runs testing the 2400 1721 motor and getting people hyped for the motor and then after their videos posted they quickly moved on to other builds and haven’t really said anything about the motor since
???
This was my observation, I may be mistaken just wondered if anyone else noticed this. I’m wondering if they all fried the motors😁 a personal friends lasted 4 runs not running overgeared on 8s.

On the topic of a 200mph motor, a super solid battery supply to me seems just as important as the motor.
Raz does some rather sneaky stuff in his videos. I don't believe it really went 190.

I talked to James and Raz about that motor. Both said it is a good motor solidly capable of 180mph, but not the best for 190+ goals.
Both said it really has to wind up to 60k+ Rpms and needs lots of road.

56mm 1/5scale motors are better. Both really wish we had some 4 pole 56mm motor options in higher KV (due to the de-sync issues with 6 pole motors over 1400kv)
 
is it a torque or an RPM problem, with the 1721?
If it takes a while to spool up, it sounds like at the gearing needed for top speed, it is lacking torque. Makes sense that it fits between the 1717 and 2028 cans in performance, as typically within the same manufacturer relative size equates to relative watt output, be it in KV or Torque
 
Think if tp came out with a 46mm 113mm long motor. TP4680CM 1850KV..6AWG MOTOR LEADS ..200MPH MOTOR???I think 46mm 4 pole is the key..🤷‍♂️🤷‍♂️
5680cm will still outperform it. Since the larger motor has a higher watt output, it is outright more powerful. The only real question is if gearing for a lower KV, larger can will be possible for the required driveline RPM to hit 200+. On the Limitless chassis this may present an issue with possible/total tooth count, but running something like a Neu with one of their output transmissions may work to get a 56xx class motor at ""2400KV"" (motor will be lower, but the output transmission will increase the effective output KV before it even hits the motor mount.)
 
5680cm will still outperform it. Since the larger motor has a higher watt output, it is outright more powerful. The only real question is if gearing for a lower KV, larger can will be possible for the required driveline RPM to hit 200+. On the Limitless chassis this may present an issue with possible/total tooth count, but running something like a Neu with one of their output transmissions may work to get a 56xx class motor at ""2400KV"" (motor will be lower, but the output transmission will increase the effective output KV before it even hits the motor mount.)
I smoke alot of pot,don't now what this means☝..I do now I feel like the 56mm motors are heavy,an loads of torque.the 40s just don't have enough..45-50mm in the middle seams just right
 
I smoke alot of pot,don't now what this means☝..I do now I feel like the 56mm motors are heavy,an loads of torque.the 40s just don't have enough..45-50mm in the middle seams just right
General rule of thumb, the bigger the motor from the same manufacturer, the higher the watt (power) output.

Oversimplified:

Watt (power) output can divided to rotation speed (KV) multiplied by turning force (torque).

So, by using the same watt motor, with a lower KV, you will have a higher torque, since KV*Torque=Watt. OR, if you have a higher watt motor (bigger can), with the same KV, you will have a higher torque.

If you combine these 2 things and have a higher watt motor with a lower KV, you will have much greater torque.

Once you have a high enough watt output, you can change the gearing to convert torque to RPM. If you do this, the amount of torque you have left over will determine how fast you can get up to the RPM you need.


Again, this is an extreme oversimplification of the process, but the concept stands. Additionally there are exceptions, like comparing motors from different manufacturers may not follow the "bigger is higher power" rule (a Castle 1717 may have more power than a Leopard 56mm can)
 
is it a torque or an RPM problem, with the 1721?
As @ABabyEater mentioned its a torque difference as to why. Remember we are comparing a 180mph motor vs a 190mph motor. That is around a 5% difference.

There was mention of Neu motors. The issue is that they only really have good options for 40mm motors. Their motors are more efficient and tent to net about a 2-5% increase in output. Their larger motors are not made for high rpm use.

For now the 56mm and 58mm diameter motors from TP Power seem to be the best. I still don't know what motor James had in his top speed car. It was all black and did not have the same end caps as TP Power.

If you are going to spend money on a motor, for now I would say focus on the TP 1/5 scale motors and shop in the 1100-1400kv range. Unless you have a big budget and want to try the MGM & Lehner combo.
 
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