Safe kv for the blx 185?

[JAM]

JRC had them in stock so I didn’t waist any time snagging one for a 3s typhon build I’m planning. I want to run 3/4s only but I’m not sure which direction to go KV wise. Would this be too much power for a geared down 3200kv blx motor? Is it a safer idea to pick up something more in the 2200-2800kv range instead? I want to stick to the 36mm diameter range.

Also there was a thread that I thought was stickied with a list of escs and there comparisons to other renamed brands. Can’t find it now if someone has it.

 

[suchtragedy]

ESC thread: https://www.arrmaforum.com/threads/esc-rebrand-conversion-guide.9960/

BLX185 is larger than the BLX100/120 and so you're going to have to cut off the receiver box section to fit it under the Typhon body. I can show a pic to show how large if you want.

As far as KV if you want to stick to the 36mm size I would go 2200-2600kv, I think 3200kv would be too unusable power wise on 4s.

 

[LibertyMKiii]

I would agree something in the 2200- 2800 kv range. Think of 2200 running cool all day but slower, and 2800 kv going fast, but getting hot (pick your poison )

 

[JAM]

Thanks fellas. I’m thinking of these 2 options below. Minimum gear being 15T. I’ll run a motor fan.

Would there be an added benefit to going up in motor diameter?

@suchtragedy sure on the pic.

I wonder if I should move my 120 from my K4s and use that instead and put the 185 on that.

 

[suchtragedy]

@suchtragedy sure on the pic.

Here's my 3s Typhon with the BLX185 with the 4074 6s motor. I cut most of the receiver box off to fit the esc and made a 3D printed lid/side piece to make a mini receiver box in the small space I had left. Also the BLX185 mounting tabs I had to cut off because it was too wide to fit in the chassis with them on. If I cut out the receiver box entirely I think I could have left the tabs and moved the esc closer to the servo. The part that was rubbing in my application was the center drive shaft bearing against the esc so with esc further forward it might have cleared without cutting off the tabs and turning it 90 degrees. Again this is all because of the low clearance of the Typhon body so you might have an easier time with it in the 4s Kraton stacked on top of the receiver box.

To answer your question about diameter benefits....basically bigger motor diameter and/or length = more torque. Like you see in my pics the 40mm 6s motor fits but if you go the 40mm route just make sure it has standard 3mm mounting holes available. The arrma 6s motors have both 4mm and 3mm holes for mounting but not all motors are like that.

 

[JAM]

@suchtragedy ah I remember this build now. You also had the sweet 3D printed vents over the fans.

How’d you like the end result? Were you mainly doing speed runs? I appreciate the info.

 

[suchtragedy]

@suchtragedy ah I remember this build now. You also had the sweet 3D printed vents over the fans.

How’d you like the end result? Were you mainly doing speed runs? I appreciate the info.

I originally intended to do speed runs but then I got a Limitless converted to Infraction so my focus has been on that platform instead. My Typhon has a 22T pinion with the 4s slipper and it's great on 4s, not breaking any speed records but it's still pretty quick. On 6s and that pinion it's too much juice and it's more of a burnout machine unless you are easy on the trigger, so I worry about the plastic diffs holding up to that kind of abuse over time so I have stuck to 3s and 4s only.

So for now I don't really know what to do with it so my plans were to keep an eye out for a Kraton or Talion roller for cheap and transplant the 6s system from my Typhon to that and then revert my Typhon back to a blx120 and 2400kv motor and stay 4s.

 

[Peteyk49]

I run a 3674 2950kv motor with the blx 185 in my sons brcc. We mostly run it on 3s and it’s awesome. 4s is just insane! The temps stay under 140 with the cheap arrma cooling fan

 

[JAM]

@suchtragedy sounds like you have some options if you come across a good deal. I appreciate the feedback. I may pull the blx120 out of my K4s and use it in my project instead. Think I can get that in under the body without much trimming? Should be same as the blx100 right?

I may just hold onto the blx185 since arrma just dropped this new roller concept. Could be good to throw in there if I can find funds.

I run a 3674 2950kv motor with the blx 185 in my sons brcc. We mostly run it on 3s and it’s awesome. 4s is just insane! The temps stay under 140 with the cheap arrma cooling fan

Hey good to know. What pinion are you using?

 

[suchtragedy]

Yeah blx120 is same footprint size as the blx100 so fitment in the Typhon is a direct swap.

I just ordered the XBR Kraton after I saw it so my Typhon 6s system will now have a new home lol

 

[JAM]

Hahaha that didn’t take long ?

 

[Peteyk49]

@suchtragedy sounds like you have some options if you come across a good deal. I appreciate the feedback. I may pull the blx120 out of my K4s and use it in my project instead. Think I can get that in under the body without much trimming? Should be same as the blx100 right?

I may just hold onto the blx185 since arrma just dropped this new roller concept. Could be good to throw in there if I can find funds.


Hey good to know. What pinion are you using?

We are using a 17t pinion. I’ve been told 18t is the sweet spot. I plan to try that next. I want my son to get used to his new build before making even faster ha

 

[JAM]

We are using a 17t pinion. I’ve been told 18t is the sweet spot. I plan to try that next. I want my son to get used to his new build before making even faster ha

Nice! I have a hobbystar 3674 3000kv motor in our senton but with a 15t pinion. I agree with you on the speed. He only gets it on 2s. I know it would be nuts on 3s and a 18/20t pinion.

I’ll most likely go this route, maybe 2500kv range with 18t. Pinion is on its way.

Having second thoughts on the esc. I may convert the typhon project I had planned to be able to fit a truck body so the 185 can fit. I may put the 185 on my K4s and put the 120 in the project. Not 100% yet. This info definitely helped though. ?

 

[Peteyk49]

Nice! I have a hobbystar 3674 3000kv motor in our senton but with a 15t pinion. I agree with you on the speed. He only gets it on 2s. I know it would be nuts on 3s and a 18/20t pinion.

I’ll most likely go this route, maybe 2500kv range with 18t. Pinion is on its way.

Having second thoughts on the esc. I may convert the typhon project I had planned to be able to fit a truck body so the 185 can fit. I may put the 185 on my K4s and put the 120 in the project. Not 100% yet. This info definitely helped though. ?

I wanted to be able to run 4s for kicks and keep the kv up for running 3s most of the time. I also figured a much lower kv would have too much torque for the plastic parts. I saw guys running a hobby star 3670 3050kv but couldn’t run 4s. I wanted My son to be able To smoke his buddies traxxas maxx at the 4H fair this year. the fair was canceled Unfortunately but at least his truck is dialed in

 

[JerryBoor]

The KV motor you run will depend on the LiPo cell you plan to use. As long as your RPM's on the stock motor stay below 50K and for low temp running below 40k, you can run a variety of KV motors. 2s LiPo's are about 8V, so anything below 5000 kv motor works. 3s is about 12V keep it blow 3300 KV. 4s is almost 17V, below 2400KV, and 6s is 25V, so below 2000KV. Now those rated KV motors will run hotter the larger pinion you put on or bigger tires. Cooling fans are almost a must for speed un cars. Many bashers don't like fans because it's another part to break or disconnect power on hard landings. Higher KV motors are good for speed runs or lower Kv motors have more torque for large buggies or tires. Lower KV motors need larger pinions to get to the top speeds a lot of bashers like. But they also like the torque for acceleration and wheelie style stunts.

 

[Knxwledge]

I run a 3674 2950kv motor with the blx 185 in my sons brcc. We mostly run it on 3s and it’s awesome. 4s is just insane! The temps stay under 140 with the cheap arrma cooling fan

How does it compare to stock? Less heat?I’m thinking of grabbing that motor

 

[Peteyk49]

How does it compare to stock? Less heat?I’m thinking of grabbing that motor

It has more torque and stays cooler. It has lots of raw power when you can put it down ha. I’m waiting for the tires to explode or rip off the rims. I vented them in 4 spots to help out. I had to upgrade the driveline. On 3s, It takes off faster than my k6s and is faster when we’re both running 4s. It’s a light truck so with any added power, you’re going to notice it ha. Last time we ran the brcc, the temp was 138 after a hard run on 3s 5200 80c lipo and 10 mins or so on 4S 5000 80c lipo before it broke the Metal 4s spur gear. It had maybe 2mins of cool down time between batteries. We were running it in our gravel driveway and thick grass in our yard. I want to get another max10sct esc at some point

 

[Knxwledge]

It has more torque and stays cooler. It has lots of raw power when you can put it down ha. I’m waiting for the tires to explode or rip off the rims. I vented them in 4 spots to help out. I had to upgrade the driveline. On 3s, It takes off faster than my k6s and is faster when we’re both running 4s. It’s a light truck so with any added power, you’re going to notice it ha. Last time we ran the brcc, the temp was 138 after a hard run on 3s 5200 80c lipo and 10 mins or so on 4S 5000 80c lipo before it broke the Metal 4s spur gear. It had maybe 2mins of cool down time between batteries. We were running it in our gravel driveway and thick grass in our yard. I want to get another max10sct esc at some point

Thats awesome! I will probably just stick to 3s. I don't wanna break the gears lol

 

[Peteyk49]

Thats awesome! I will probably just stick to 3s. I don't wanna break the gears lol

3s is fast enough! It’s better than stock for sure and stock was damn good. We just couldn’t get the 3 stock esc’s to work for us. We had the max10sct in for a week or so and my son fried it in a huge puddle. Then the motor bearings fried a week or so later after I put the blx185 in it. They were corroded big time because the puddle was in a retention basin after the New Jersey winter thaw and it was extra salty Haha. So with the current setup, there is not heat issues or no fake out low voltage cutoff . The $11 Arrma heat sink fan has held up so far. I stop myself from running my sons brcc hard and let him bash it. He’s 9 and not easy nice to it haha

 

[Knxwledge]

3s is fast enough! It’s better than stock for sure and stock was damn good. We just couldn’t get the 3 stock esc’s to work for us. We had the max10sct in for a week or so and my son fried it in a huge puddle. Then the motor bearings fried a week or so later after I put the blx185 in it. They were corroded big time because the puddle was in a retention basin after the New Jersey winter thaw and it was extra salty Haha. So with the current setup, there is not heat issues or no fake out low voltage cutoff . The $11 Arrma heat sink fan has held up so far. I stop myself from running my sons brcc hard and let him bash it. He’s 9 and not easy nice to it haha

I’ll most likely grab the Max10 SCT with it when I pick up the motor. I just really want more torque and just stick to 20T or 18T pinion.