More top speed, suggestions?

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Marko R1

Active Member
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Location
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Arrma RC's
  1. Kraton 8S
  2. Kraton EXB
  3. Notorious
Hi guys

My K8S is running 39/39 with 780kv & 160amp esc…I wouldn’t mind more top speed but I think I’ve maxxed out my gearing?

If so, maybe I need to stop driving my Motonica pan car :)
 
you mean ztw 12s right?
Also an option. for your reference in terms of power:

(12S) 50.4V * 300A = 15kW
(8S) 33.6V * ~600A = 20kW

Flier:
(22S) 92.4V * 400A = 37kW

All those batteries still need to fit in the car though
I don't think we know the ESC is the limiting factor just yet.
I don't own a K8s but I imagine there must be a way to gear up? Can you reduce the spur gear size?
Good to check indeed. I used 'likely'
 
I don't think we know the ESC is the limiting factor just yet.
I don't own a K8s but I imagine there must be a way to gear up? Can you reduce the spur gear size?
Again, good call. But I still believe the XLX2 can never be a bad idea. Thanks for the shout-out. I was actually just trying to hold down the shop while waiting for you buddy!
 
Again, good call. But I still believe the XLX2 can never be a bad idea. Thanks for the shout-out. I was actually just trying to hold down the shop while waiting for you buddy!
Agreed, the XLX2 is the Bees Knees when it comes to ESCs, but if he is going 40mph and ran out of speed it may only need gears.
 
Can I run a smaller spur gear than 39?
I guess I could also run a larger pinion than 39?
…keeping in mind that I’m running 39/39 but if I did any of the above to run a taller ratio, would I run into over heating issues?
 
Can I run a smaller spur gear than 39?
I guess I could also run a larger pinion than 39?
…keeping in mind that I’m running 39/39 but if I did any of the above to run a taller ratio, would I run into over heating issues?

The question is what are your temps at now based on how you drive.
If they are decent (below 140 F) you have some room to change gears.
 
The question is what are your temps at now based on how you drive.
If they are decent (below 140 F) you have some room to change gears.
Good point - will check temps when I take it out next :)
Also an option. for your reference in terms of power:

(12S) 50.4V * 300A = 15kW
(8S) 33.6V * ~600A = 20kW

Flier:
(22S) 92.4V * 400A = 37kW

All those batteries still need to fit in the car though

Good to check indeed. I used 'likely'
So the 12s has 15kw whereas the 8s has 20kw? How is that? Due to difference in amps? I need to understand this :)
 
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Good point - will check temps when I take it out next :)

So the 12s has 15kw whereas the 8s has 20kw? How is that? Due to difference in amps? I need to understand this :)
Yes, amps are usually a much more limiting factor than voltage. But it takes amps times volts to get watts (AxV=W). So you can sure increase either side of the equation. But increasing amps comes at more of a premium as it creates more heat. But today, the XLX2 is still the best we have for a standard sized RC.
 
Yes, amps are usually a much more limiting factor than voltage. But it takes amps times volts to get watts (AxV=W). So you can sure increase either side of the equation. But increasing amps comes at more of a premium as it creates more heat. But today, the XLX2 is still the best we have for a standard sized RC.
Adding to what Jon mentioned here /\ the other part is that most 12s ESC go up in flames when you try to run the hard in speed applications.
Sadly you have 2 options. The XLX2 at around $250 or MgM which runs around $700.

With all the money thrown around in this hobby I have yet to see anyone go fast with an MgM, but the RC boat guys swear by those ESCs. Possibly for the same reason that people think MaxAmps batteries are good. (If its 3x the price it must be good)

Given that we have now seen 2 people hit 190 mph with the XLX2 with the Arrma 1/7 scale chassis it is clear that the XLX2 is up for the job.
 
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Adding to what Jon mentioned here /\ the other part is that most 12s ESC go up in flames when you try to run the hard in speed applications.
Sadly you have 2 options. The XLX2 at around $250 or MgM which runs around $700.

With all the money thrown around in this hobby I have yet to see anyone go fast with an MgM, but the RC boat guys swear by those ESCs. Possibly for the same reason that people think MaxAmps batteries are good. (If its 3x the price it must be good)

Given that we have now seen 2 people hit 190 mph with the XLX2 with the Arrma 1/7 scale chassis it is clear that the XLX2 is up for the job.
Which 2 cars hit 190mph? Impressive
 
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