My 5687 1100KV MAX6 / Castle Mamba X8S build (Outcast 8S EXB)

[sebcbien]

Bought some gensacearespammers Bashing Pro 8000 80C, they jumped on me at a second hand website .
I really had a blast today, impressed by that truck !
With punch at lowest settings, it rips my backyard weed down to the soil !
I'm not sure if I can put a 21 tooth but I think it will be more easy for the motor like that.
I thing this because there is no cogging, but still the start is not smooth.

 

[3d-rc.myshopify.com]

I run that setup in my kraton 6s. It's an absolute animal and I love it.

 

[sebcbien]

Thanks !
your setup is with 21 or 23 tooth pinion ?

 

[BashingBrian]

My O8s is currently running 30/47 no extra fans and temps are supercool, real top speed of 51mph.
I may go back to 28T or try 29T though as the 30T just didn't feel as good.!!

 

[sebcbien]

There is something I do not understand, how can you run 30/47with good temps.
Here is around 20°C outside and I was 86°C at the motor after 10 min in my backyard with 23/47. I also had to re-glue the tires.
The truck is an animal !!! On concrete I riped/damaged the tires studs at the first run with 29/47 and it was really difficult to not wheelie and go on the roof (I did it with the new body )
Maybe there is a different transmission ratio with the EXB ?
I'm an experienced driver, I have an X-Maxx with a MAX-6, TEKNO MT410 on Castle, Kraton 6S, Typhon 6S, e-Revo etc, but this is another game.
I will try to go to 20T.
I will also try to measure the speed with my phone, (I do not have a gps) to be able to make a comparison.

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In the meantime I made mud Guards for the outcast 8S/Kraton 8S (they are the same)
I modified some existing mud guards who where too thick
Here are the files:
https://www.thingiverse.com/thing:4973580
There are also roof bars for the Outcast 6S /others on my design list. Have a look.

Seems to work as intended

 

[BashingBrian]

Have a look at this, it was the gearing and heat I had..

https://www.arrmaforum.com/threads/gearing-and-or-speed-issue-🤔.42830/

 

[sebcbien]

So, after I found second hand Castle Mamba Monster X8S on ebay I've made my home work with logs.

Now I've put a 20T pinion (47T Spur). The startup is finally smooth now
I measured top speed when doing a "speedrun" on a cement road: 67km/h (41miles/h)
Here is the log:

And here is a log when bashing:

Values of the 1100kV 5687 deducted from the HW specs:
1100kv x 8S = 36960 Tr/Min
5800W / 33.6V= 172A max

I'm a beginner at this, but what I think I can read from those logs:
1) Max RPM is reached 36700RPM at the speedrun
2) Max amps when bashing are almost reached (160A)
3) Max Watt was 4778W instead of the 5800W possible.
3) Motor temp when bashing: 70°C max measured at the motor (temp gun). Outside temp is low 10°c (50°F), No fan on the motor
4) ESC Temp is cool, the fan was rarely spinning.
So I Think I'm in the good "constructor specs" range with 20T to 22T pinions, 25T if I want to go fast but it's a maximum in my mind.

Questions:
How can be 30/39 right ??? Even if the motor can handle it with turbo/noisy fans, if I can hit 67km/h with 20/47, with 30/39 it should be 121km/h !!! (75miles/h)
Or some people are crazy driving at more than 100km/h a monter truck or it's way over geared. Right ?

Please explain what I'm missing here !
I didn't measure the speed when I was running the 29T pinion but, by applying ratios, it was a theoretical top speed of 97km/h ...

Maybe my truck is not standard ? a different transmission ratio in the diffs or something else ?

Thanks for your help explaining this mystery

 

[sebcbien]

Hello,
I've put a 23T pinion with the Castle Mamba Monster X8S .
First thing I noticed is how smooth the start is compared to the MAX6... wow, unbelievable, the Max6 with the 1100KV is so brutal!
Second I made a speed run, it was on wet concrete road. I clocked 77km/h
The gain of speed is still linear with the gear ratio.
- 67km/h with 20T = 3.35km/h per tooth (41mph)
- 77km/h with 23T = 3.348km/h per tooth (48mph)
The power output however is not.
- 93A with 20T = 4.65 A per tooth = 1.39A per km/h
- 124A with 23T = 5.39 A per tooth = 1,61A per km/h
Here is the log of two speedrun.:

I didn't had the time to bash it to check the temps.

 

[sebcbien]

Here is a bashing log with the 23T pinion as like the previous post.
10 minutes of play, stopping at 3.8V per cell (no more time) could probably had lasted 2 more minutes.
We are here over the 200Amps maximum on the HW specs of this motor:

• 1100kv 8S = 36960 Tr/Min
• 5800W / 33.6V= 172A max
• C at the M.O.P = 200A (Maximum output Power)

Stats for all parameters:

The motor temp was 72°C (162°F) without fan, outside temp is 10°C (50°F)
Esc temp is ridiculous (53°C - 127°F) , I do not remember hearing the fan running.
The car is very enjoyable, the startup is definitively way smoother than with the MAX6.
I will keep this setup for now, an maybe find a temp activated fan, efficient but as silent as possible.
Conclusion (for now) : 25->29T pinion and 39T spur are way overkill for the 1100KV 5687 (my humble advice)
Hope this helps future buyers not to buy "crazy YouTubers pinion setup" ... like I did
20T is conservative for the battery and motor. 23T is really fun, allows more air control, infinite wheelings and backyard digging .
And one of my tire unglued on 1/3 of the rim unfortunately.

It feels like this, or maybe a little more puch: