Kraton EXB - "Tame" ESC/Motor combo that won't overheat?

[Steveoarrma517]

The 1717 blew the kevlar wrap off the rotor on my first attempt at 8S. It was a defect with the early models. The 1717 took a month or so to get replaced so I stuck the 1250kv in there with a 29T pinion and it is just as powerful. I only run it on 6S as it is already a tires shredding monster. No need to add weight.

The 1717 is now at home in my other K6S build that I call Beef Mode. It has yet to make an appearance as weather has been two of the following three lately

Wet
Cold
Windy

Tire shredding beast,boy can i relate to that. Been shredding tires since 2016. Some cheep rim centers too. Not mention spur gears.

 

[jondilly1974]

Same here! I got a solid week straight in but in the last week it's been bitter cold and windy and either raining or snowing.

Last question (I hope) for you. Do you have any issues with the 29T pinion making you push the motor too close to the side of the EXB such that it rubs the body? I know the K8S heatsink can be have tow fins trimmed off it and then mounted on the engine, and that the 50mm fan will likely rub in the corner. That's okay, I'm more concerns with the hot motor front edge (pinion side) touching the body and melting it.

Can you speak to the body rub potential? Does your engine even get hot enough to worry about melting the body? I'm not sure what type of plastic it's made of, so I'm not sure if this is worth worrying about. Plus I assume the K8S motor runs cool at 6S.

Thanks Man!

PS - I'm watching videos on your channel. The 119mph in a (heavily modified) Typhon 3S is INSANE!!

Yes the body does rub, but melting isn’t my concern. I worry about the paint being rubbed off. I do have the PPS mount, diff holder, cover, and roll bar attachment. Basically the whole PPS 9 yards. Not sure if the 29/50 fits the stock mount or not, but I believe I have read it does not. I have the stock mount on my Typhon 6S but only run 20/50 gearing on that. My Infraction has the PPS setup too.

 

[L3phturn]

"around 50mph on 1-2" grass (where I do most of my driving)."

Yeah - 1-2" grass is a very high drag and high traction surface. You need MORE thad n stock power, not less. You need shorter gearing and more torque. Choose a bigger but lower KV than stock motor and gear it conservatively. You will need good ESC and motor fans.

The 8S ESC and motor would mean more weight as well as more power, and more weight is going to mean more heat. I would go with a bit longer 40mm or a 42mm. For example: https://www.aliexpress.com/item/1005001407712908.html
A 4082 or a 4092 from 1250 - 1720. You'll need to wait a while for it to arrive but it's tough to beat for that price. You can run that on a Max6 or a Max8 just fine. Cool it and gear it low enough and you can manage heat. Get yourself a set of 5 pinions so you can start low and work up. I'd get a set of 3-5 pinions from say 15 to 21 or 23 to start with. Don't start at 25 tooth - start low and work your way up. Monitor temperatures and get a good fan on it.

 

[DKPatriots]

You need MORE thad n stock power, not less. You need shorter gearing and more torque. Choose a bigger but lower KV than stock motor and gear it conservatively. You will need good ESC and motor fans.

Fully agree. I realized after just a few responses from people, and some more research, that to run in grass and keep temps cool I should oversize. This is what led me into being interested in the Kraton 8S Electronics, even though I would only use the truck in 6S.

A 4082 or a 4092 from 1250 - 1720.

I actually started looking at the Hobbystar and Leopard variants of the 4082 and 4092 today. They are available on eBay shipped from the USA, so it wouldn't take weeks, but would cost about 15-20 dollars more.

Doing the Hobbywing research led me to believe that I would also need new batteries to run whatever motor I choose. My Typhon 3S has no issues with the SMC DV 5200mAh 3S batteries that I have (I have 4 in 3S and two in 2S). After seeing that the Hobbystar 4092 1480kv is rated for 150amps max... I am concerned that the batteries can't supply that kind of power and would fail. The Typhon 3S is 80 max amps, and the batteries do fine on that, but the 4092 is almost double, and I assume the spektrum 1250kv 4685 is likely around the same.

Now I have so many questions and thoughts going through my head...

1. Am I going to need to spend 300+ dollars to get 4 new 3S batteries to run this in 6s in my EXB?
2. I know I don't want a "tame" EXB anymore, but do I want the Kraton 8S electronics or to grab the hobbystar 4082/4092?
3. Would the Hobbystar run on the SMC batteries I have? If so I should go with that to save a ton of money. I can always upgrade the motor later since I'll get a Max6 ESC.
4. Would the Kraton 8S ESC and motor run on the SMC batteries i have? If so, I should go with that since it's more powerful than the Hobbywing 4092 anyway.
5. Can I fit the pinion size I want using the Kraton 8s electronics? I know to start at 20T (50mph - like my Typhon) but can I fit a 24-25T without having to buy a new mount? The goal was 60mph capable EXB so that it has room to grow.
6. If the Kraton 8S won't fit a 25T pinion with the stock hardware, I should go with the Hobbystar - but which one? The link above was to the 1480kv which is the middle ground between the 1730 and the 1300 (1250kv is only available from China). The 1730 seems to be more popular, but it's also 160 max amps, 10 higher than the 1480, and it would run hotter.
7. It's the same price to buy the Kraton 8s electronics or a Max6 esc and a hobbywing 4092. But the hobbystar is less powerful, though it may give me the room to grow that I'm looking for due to pinion size. It would also run hotter.
8. Maybe I should have just bought the Kraton exb Notorious J had for sale in the classifieds last week.
9. Maybe I should find out if my batteries will work in the stock Kraton 6S and start upgrading parts to EXB ones as they break, and eventually grabbing a new motor and ESC, and getting new batteries along the way. This is more expensive in the long run, but cheaper in the short term. It will also take much longer to reach "trophy car" levels.

I'm not expecting answers to these questions (though battery insight would be nice). I'm just giving an example of what's running through my mind here.

I thought I had it all figured out and was ready to order/buy everything at my LHS this weekend (I like to support small local businesses). But then the Hobbystar research began, then the potential (and likely) battery issue came up when I realized the amperage these larger motors need, that concern was followed by pinion sizes above 20T probably not fitting when using the Kraton 8S electronics and stock motor mount. The "plan" I had has unraveled, as they often do. I still want a Kraton EXB, but amount of uncertainty has grown, as has the scope of the project, the options I have, and the cost. I was okay with $1000 for the Kraton EXB, Firma 160 Amp Combo, Spektrum DX5C transmitter and receiver combo, heatsink, fan, and DS3225 servo. But $1300-1400 (maybe more) after batteries, potential motor mount, several pinions, etc is harder to justify.

Rant over! That was a lot of typing hahaha

I love this hobby! There's so many options! The only problem is that there's so many options!

 

[3d-rc.myshopify.com]

Max 6
Hobbywing 5687
Pps mount with 30t pinion.
I couldn't heat this thing up doing back to back speed passes at 70mph.
Zero fans

 

[L3phturn]

The issue with the K8 electrics is the added weight of the much larger motor. I’d look up the weight difference. That said, more torque = less heat on the same gearing. It’s a balance. Price matters to me, so I might go the K8 electrics route from Jenny’sRC if available if the price is right. You could also just get the Spektrum 160a and a cheap 4092 and probably be fine. If you do, I suggest the Rocket motors for the machined fins on the can. No heat sink needed, just a bracket to hold a powerful fan. No heatsink stuck on a smooth can will work as well as fins machines into the can itself IMO.

Those are 70C rated good quality 3S batteries. You can use matched pairs of them for any of the setups you are considering.

 

[DKPatriots]

Yes the body does rub, but melting isn’t my concern. I worry about the paint being rubbed off. I do have the PPS mount, diff holder, cover, and roll bar attachment. Basically the whole PPS 9 yards. Not sure if the 29/50 fits the stock mount or not, but I believe I have read it does not. I have the stock mount on my Typhon 6S but only run 20/50 gearing on that. My Infraction has the PPS setup too.

Is this the correct motor mount?

https://practicalproto.com/collections/backorders-and-preorders/products/v4mountbackorder

 

[jondilly1974]

Is this the correct motor mount?

https://practicalproto.com/collections/backorders-and-preorders/products/v4mountbackorder

Yep. And you’ll also want the following too

https://practicalproto.com/products/backorder-arrma-v4-6s-blx-differential-mount

https://practicalproto.com/products/bopo-differential-cover-cap-for-arrma-v4-6s-blx-platform (WITH ROLL BAR MOUNT)

 

[DKPatriots]

Yep. And you’ll also want the following too

https://practicalproto.com/products/backorder-arrma-v4-6s-blx-differential-mount

https://practicalproto.com/products/bopo-differential-cover-cap-for-arrma-v4-6s-blx-platform (WITH ROLL BAR MOUNT)

Thank you so much! I saved those links for when I finally get an exb.

Can I ask what batteries you use in your EXB when you run it in 6S mode? I'm concerned that my SMC Truespec 3S 5200mah batteries may not be up to the task of running a Spektrum 1250kv motor.

 

[olds97_lss]

I run a max6 and the blx2050kv in my outcast. Has plenty of power while delivering it very smoothly. I went with the max6 over the blx185 because I wanted to gear it up a bit. While the max6 let me go 1T bigger, it would still overheat. But, the BEC in it is better, which I run at 7.2V, and the power delivery is smoother.

I run the same motor/esc/servo in my ERBEv2.

I run a powerhobby dual fan motor cooler in both as well with 30mm alloy framed fans on it and on the esc. The stock HW fans suck and die quick. The alloy framed ones hold up much better for me.

 

[DKPatriots]

I run a max6 and the blx2050kv in my outcast. Has plenty of power while delivering it very smoothly.

I run a powerhobby dual fan motor cooler in both as well with 30mm alloy framed fans on it and on the esc. The stock HW fans suck and die quick. The alloy framed ones hold up much better for me.

This PowerHobby dual fan and heatsink combo?

Looks like it would work great, but it says it is 40.8mm diameter. Did you find that it fit loose at all on your 40mm 2050kv?

Any idea if it would fit a 42mm diameter? I was thinking about going with Spektrum firma 160 combo (Max6 rebrand) with the Spektrum 4685 1250kv motor and the Arrma heatsink and fan, or the Max6 plus the Hobbystar 4092 1480kv motor (or maybe the Hobbystar 4092 1730kv). The Hobbystar is 42mm because it has fins, so I'm wondering if the Hobbypower can be stretched a bit to fit the 42mm of the hobbystar.

 

[jondilly1974]

Thank you so much! I saved those links for when I finally get an exb.

Can I ask what batteries you use in your EXB when you run it in 6S mode? I'm concerned that my SMC Truespec 3S 5200mah batteries may not be up to the task of running a Spektrum 1250kv motor.

I have a few different packs. Yowoo 5000mah Graphene works well. Turnigy Graphene Panther 5.0 is about the best you can buy. I also own HRB 4S packs for if/when I decide to try 8S again.

 

[olds97_lss]

This PowerHobby dual fan and heatsink combo?

Looks like it would work great, but it says it is 40.8mm diameter. Did you find that it fit loose at all on your 40mm 2050kv?

Any idea if it would fit a 42mm diameter? I was thinking about going with Spektrum firma 160 combo (Max6 rebrand) with the Spektrum 4685 1250kv motor and the Arrma heatsink and fan, or the Max6 plus the Hobbystar 4092 1480kv motor (or maybe the Hobbystar 4092 1730kv). The Hobbystar is 42mm because it has fins, so I'm wondering if the Hobbypower can be stretched a bit to fit the 42mm of the hobbystar.

It fit fine on the arrma blx2050kv motor with the ribs on it. Without those though, it would be sloppy without putting something under the bottom plate.

 

[Ypsi]

Will the castle 1717 1260kV fit in the EXB with the PPS mount pieces? I don’t have to go super fast, but I like having room to grow and with as much money as these power systems are, I’d rather just buy once. I like the build philosophy of running cool too.

Downloaded that speed calculator spreadsheet and a 25 tooth pinion would push that combo just over 70mph on 6S?

I’ve been searching the forum, but haven’t been able to find out where you guys are buying your pinions. Is there a link somewhere?

 

[DKPatriots]

I have a few different packs. Yowoo 5000mah Graphene works well. Turnigy Graphene Panther 5.0 is about the best you can buy. I also own HRB 4S packs for if/when I decide to try 8S again.

Well... I bought a Kraton EXB with Kraton 8S electronics in it from RCProponent yesterday, so I'm back to looking at batteries.

The Yowoo are priced incredibly well, and are supposedly 48mm wide, though it seems that they may actually be closer to 50-51mm. I know the Turnigy batteries are 51mm. In your experience, are the Yowoo 5000mAh 3S and 4S batteries actually 48mm wide?

Have you ever had an issue running soft packs? I've always only run hard packs.

 

[jondilly1974]

Well... I bought a Kraton EXB with Kraton 8S electronics in it from RCProponent yesterday, so I'm back to looking at batteries.

The Yowoo are priced incredibly well, and are supposedly 48mm wide, though it seems that they may actually be closer to 50-51mm. I know the Turnigy batteries are 51mm. In your experience, are the Yowoo 5000mAh 3S and 4S batteries actually 48mm wide?

Have you ever had an issue running soft packs? I've always only run hard packs.

Mine are 50x50x150mm and all I buy are soft packs anymore. I’ve had too many hard packs swell up and go bad. Might just be a coincidence but no soft packs have done that yet.