Big Rock Motor upgrade!

[ransom 65]

Need opinions!

I'm upgrading the motor on the big rock next month. I'm only looking to run 4s, but don't mind having a bigger system if it operates better. Looking to run something that can handle a heavier rig with all the metal and bigger tires. Any suggestions??

Stock spektrum from the 4 or 6s line?
Hobbywing Max 10 or 8?
Castle 1515?

Needs to be for something up to 9lbs or up to 11lbs. Thanks!

 

[dure16]

Will your big rock really be 11 pounds? You might be fine with a smaller system and saving weight is always good.

Good: Arrma 2400kv combo
Better: Castle Mamba X 2400kv combo
Best: Castle Monster X 2650kv combo

P.S. have you considered selling the big rock and buying a 6S car? It would probably cost less than all those upgrades and would definitely perform better.

 

[ransom 65]

Will your big rock really be 11 pounds? You might be fine with a smaller system and saving weight is always good.

Good: Arrma 2400kv combo
Better: Castle Mamba X 2400kv combo
Best: Castle Monster X 2650kv combo

P.S. have you considered selling the big rock and buying a 6S car? It would probably cost less than all those upgrades and would definitely perform better.

It's not 11 lbs, no. After everything installed it'll probably be closer to 8 1/2-9. Just didn't want to be at the top of the suggested rating is all.

I plan on getting a 6s eventually, but I'm staying in the lower ranges right now for reasons lol

What size pinion would you consider running on those? I don't plan on doing speed runs. Just trying to have reliable power, similar to stock speeds without it getting overheated.

 

[dure16]

What size pinion would you consider running on those? I don't plan on doing speed runs. Just trying to have reliable power, similar to stock speeds without it getting overheated.

I would start small and monitor temps closely. Increase pinion size if motor/ESC stay cool and decrease pinion size if they run hot.

 

[ransom 65]

I would start small and monitor temps closely. Increase pinion size if motor/ESC stay cool and decrease pinion size if they run hot.

Why is the 2650 hv better than the 2400? And which "measurement size is that one, the 1515?

 

[Hector_Fisher]

I assume you're coming from a stock system?

Honestly nearly anything you get will be an improvement over stock. Get a 3670 size motor around 2500kv and pair with any 4s capable ESC (with the appropriate size pinion) and you will have way more power than you know what to do with on that tiny truck and plenty of torque to snap diff gears and strip driveshafts.

IMO, the castle 1515, max8, or any 6s combo are way overkill for this truck. Weight alone from those big systems would be big factor to consider. I wouldn't personally spend $200 to 300 on an upgraded system when you could get away with something much cheaper and still get more power than you know what to do with.

If i were looking for a combo, I'd consider the max10 G2 combo. You'd get a bigger motor and sensored, for less than $200.

 

[dure16]

Why is the 2650 hv better than the 2400? And which "measurement size is that one, the 1515?

The 2650kv is better because it’s bigger. Just note that means it’s also heavier which can cause other issues.

Castle measures internal motor components in inches unlike most manufacturers who measure outside dimensions in millimeters.

In Castle terms, 14 series motors are 36mm diameter and 15 series are 42mm diameter.

The 2400kv motor is a 3670. 36mm diameter and 70mm long.

The 2650kv motor is a 4268. 42mm diameter and 68mm long.

 

[ransom 65]

I assume you're coming from a stock system?

Honestly nearly anything you get will be an improvement over stock. Get a 3670 size motor around 2500kv and pair with any 4s capable ESC (with the appropriate size pinion) and you will have way more power than you know what to do with on that tiny truck and plenty of torque to snap diff gears and strip driveshafts.

IMO, the castle 1515, max8, or any 6s combo are way overkill for this truck. Weight alone from those big systems would be big factor to consider. I wouldn't personally spend $200 to 300 on an upgraded system when you could get away with something much cheaper and still get more power than you know what to do with.

If i were looking for a combo, I'd consider the max10 G2 combo. You'd get a bigger motor and sensored, for less than $200.

Yeah I'm coming from a stock system. Just trying to find something reliable that can handle a little more weight than a 3s system. It's already pretty heavy as it is. I was just worried about the max 10 being at the top end of its performance capabilities pushing around 8-9 lbs. figured it would be better to play it safe, but that's why I'm here asking for help lol

The 2650kv is better because it’s bigger. Just note that means it’s also heavier which can cause other issues.

Castle measures internal motor components in inches unlike most manufacturers who measure outside dimensions in millimeters.

In Castle terms, 14 series motors are 36mm diameter and 15 series are 42mm diameter.

The 2400kv motor is a 3670. 36mm diameter and 70mm long.

The 2650kv motor is a 4268. 42mm diameter and 68mm long.

That's good to know that castle measures differently, thanks! So I've heard the fan length "determines" torque. Does the can diameter measure the same performance wise?

 

[Hector_Fisher]

Yeah I'm coming from a stock system. Just trying to find something reliable that can handle a little more weight than a 3s system. It's already pretty heavy as it is. I was just worried about the max 10 being at the top end of its performance capabilities pushing around 8-9 lbs. figured it would be better to play it safe, but that's why I'm here asking for help lol

That's good to know that castle measures differently, thanks! So I've heard the fan length "determines" torque. Does the can diameter measure the same performance wise?

Fwiw, I've run the stock 3660 motor for extended periods before on 4s. Currently running it in my Tekno SCT410 on 4s. It requires more frequent motor bearing change out and a motor fan, but definitely gives more power than on 3s.

I wouldn't worry about maxing out the 140a max10 g2 performance on 4s for the big rock. It's predecessor, the max10 SCT, has been known to power the 4s kraton and mt410 (much bigger and heavier trucks) just fine. I have run a 4068 motor in the big rock before as well. The motor was cheapo brand, so it wasn't long before the low quality solders desoldered themselves.

All in all, considering you're likely to need to start upgrading the big rock drivetrain when you go 4s, I would invest in a cheaper 4s system to get started and test out the waters. The 130a spektrum ESCs from jennysrc will do the trick just fine for cheap (just have to sign up for notifications for when they come in stock). My next pick would be the 140a max10 G2 ESC for only $100. Add a 3670 or 3674 size Rocket brand motor and you would have plenty of torque and power. That'll put you less than $150 for a killer system that will even appease Rich Duperbash.

Can length and diameter both influence torque. Diameter slightly more so than length.