Kraton Germans go for higher KV?

[Double Apex]

I've been reading a lot about the best motor/esc combo for the kraton EXB and am surprised about a difference between the German forums/YouTube channels and the Arrma forum.
In Germany the consensus seems to be that the HW Max8 + 2200 KV motor is the preferred combo.
Here on the Arrma forum a < 2000KV motor is recommended (Max6 +1650KV or similar).

Before reading German sites I would have dismissed the 2200 KV motor (not enough torque for off-roading). Now I'm not sure (plus the 2200KV combo is also mentioned a lot for the Corally Kronos). Are there any native Germans overhere that can explain the difference? Is it a cultural thing ?

 

[N.Mango]

Wow thats a great observation!
I'm sure the pro's will chime in soon, but I'm guessing it's just a cultural thing with gearing AND/OR Kv....???

 

[Yas]

For me, it will entirely depend on the application. I like the 2050kv in my Felony and have no reason to change it, but definitely prefer the larger can 1650kv HW motor in my Notorious. The higher grip and larger diameter tyres are more suitable for it. The stock 2050kv in my Noto would stutter at times in rapid, high torque situations i.e. when attempting to backflip

 

[Sandracer_NL]

I watched two German vids and both used the 2200kv with 4s. On 6s better go 1650kv-2000kv.
The max6 1650 combo can still lift front wheels on my Mojave, so I can understand when people say in a Kraton (shorter wheelsbase and lighter) they prefer a little less powerful combo on 6s such as the Hobbywing Quicrun / Max8 with a 4092/4082 motor in the 1650-2000kv range. Unless you like ->

 

[21STalion]

Maybe is has to do with access to higher quality batteries? It's a bit far fetched, but I'm pretty sure it's true. All the German made batteries I've ever used (Rare in NA) were better and lasted longer. It's just shipping is really expensive and basically only China has the stupid cheap shipping. Just a thought.

 

[Double Apex]

Im not sure if I understand why lower KV is better on 6s?

And to add to the (my) confusion: reviewers seems te be pretty impressed by the stock Corally 6s system which is very similar to the
HW max 8 system -> Same ESC but 2050KV in stead of 2200KV. It seems brilliant on both 4S and 6S in similar size and weight 1/8 cars.
(these reviews would also rule out te superior battery hypotheses)

 

[21STalion]

Im not sure if I understand why lower KV is better on 6s?

And to add to the (my) confusion: reviewers seems te be pretty impressed by the stock Corally 6s system which is very similar to the
HW max 8 system -> Same ESC but 2050KV in stead of 2200KV. It seems brilliant on both 4S and 6S in similar size and weight 1/8 cars.
(these reviews would also rule out te superior battery hypotheses)

I recently installed a castle 1717 combo system (1650kv) and I'm extremely happy with it. But in my research I noted that the 1650kv would be ideal for 5s.

I love running it on any S though, I run 3, 4 and 6 regularly. Never gets hot, but I don't have the space for full throttle runs often.
Here is one of the many charts I was using to figure it out. I do run this on the track and on the street/park.

 

[JvG]

Well this is always debatable but in general small light cars have small high kV motors and large heavy cars have large low kV motors.
Small cars run on 7.4volt (2s or less) and large cars on 29.6volt (8s or more).
Everything in between depends on weight and gearing (speed) resulting in in esc/motor temps.

I don't think it's a cultural thing. There are overlapping area's for the applications we use.
Say a heavily upgraded k6s exb is a lot heavier than a stock v5. So to get the same speeds out of it you need a more powerfull (larger and lower) kV system in the exb.
Also the more powerfull systems make it easier to rotate the car in the air (backflips).

 

[Jerry-rigged]

I think the difference is Germans like to do it the "Right" way, or even the "Best" way.

Americans just want to Over Power everything.

By most metrics, a 4075 is probably the "right" size motor - big enough to have a lot of power, but small enough to not weigh a ton. 2200kv is great - loads of power, and good legs to give you nice top speed. The MAX 8 is a great ESC - not too big - that match well with the 4075 motors. This probably is the Goldilocks combo, if there is one. If you look at the racing side of the hobby, this is probably the most common racing motor size and KV for 1/8 truggy, both in EU and in USA. Great power, not too heavy.

But the 4985 motor is just brutally powerful in a 8s Truggy. More power than you need, more power than you can use, more power than the truggy tires can put to the ground. The 1650 KV is a bit low, but the motor has such a large amount of power, it can turn a huge pinion with no issue, so top speed is not an issue.

 

[Sandracer_NL]

Im not sure if I understand why lower KV is better on 6s?

And to add to the (my) confusion: reviewers seems te be pretty impressed by the stock Corally 6s system which is very similar to the
HW max 8 system -> Same ESC but 2050KV in stead of 2200KV. It seems brilliant on both 4S and 6S in similar size and weight 1/8 cars.
(these reviews would also rule out te superior battery hypotheses)

The Team Corally 6s esc is a rebranded Max8. Apart from the better esc TC uses, another reason why some reviewers say that TC on 4s is about as fast as an Arrma on 6s is the gearing TC uses.
More power can be fun, but the Max6 is basically for 1/6th scale (hence Max6). The Max8 is made for, you probably guessed it 1/8th scale.
The Kraton, being 1/8th scale, with Max8 combo with a 4s lipo, is quite a bit lighter than with the Max6 combo with a 6s lipo. So for a nimbler handling car the lighter Max8 combo on 4s can be better.

 

[Jerry-rigged]

Im not sure if I understand why lower KV is better on 6s?

Lower Kv in and of itself is not better or worse.

For any voltage, there is a range of KV that will work best. Best is a combo of top speed, low end torque and speed. For 6s, in a 1/8 chassis, this range is around 1500kv-2400kv. yes, you can go higher or lower, if you have a reason, but the drawbacks start to be large.

Assuming we are talking same motor SIZE-
Lower KV gives a bit more torque, and a bit less heat.
Higher KV gives a bit more total power, and a bit less torque, but more heat.

With the same gearing -
the 2200kv will be much faster, and have a lot more heat.
the 1650 will have very low heat, but run very slow.

With gearing to match top speed -
The 2200 will have a better chance of cogging off the line and still have more heat.
the 1650 will be smoother off the line, and run a bit cooler, but not have as much punch on the top end.

When geared for max speed - the 2200 will have a higher top speed, as it has more total power.


BUT - Comparing the MAX8 motor to the MAX 6 motor - you have a 4075 vs a 4985 - the MAX 6 is a much bigger motor, so it is much more powerful, regardless of KV. The highest KV offered for the 4985 is the 1650kv. If there was a 2000kv option, people would be buying that one.

 

[Yonic]

2200kv on a Kraton or Outcast is not really desirable simply because of gearing. the gearing on this platform when running such a bit tires is already on the edge of being over geared, not having the option to gear down is less than ideal.

The minimum pinion on this platform is 12t, so when running a 2200kv motor you'll end up with minimum gearing that gives you more than 55mph, without an option to go lower..

Ideally you'de want to use a KV value that will sit most of the time in the middle of the gearing range of the platform, lets say 15t pinion or something like that, so you could gear up or down.

 

[rotauq]

Motor can size is power/torque.

KV is 'just an electronic gearbox' with the most important function to get the motor rpm right, matching the desired input voltage with the application (diff ratio/tiresize).
Only in extreme application kv can make a difference.

 

[Aiosin]

One of the biggest RC retailer in Germany is selling the Arrma Rollers with the Max8/2200kv Combo cheaper as a set.

Maybe most german RC beginners just take a Set and think that the 2200kv is most fitting for their EXB?

Well, at least i did. But switched in the meantime to a lower kv.

 

[milehighspeed]

Not sure if its universally true that folks in Germany are tending toward higher KV motors or set ups but with so many variables could be anything…even product availability and cost can factor in. Hopefully German users on the forum could provide more data.

With the max8 and 2200kv and proper set up there is enough torque at 6s in the EXB to flip the car straight on its back right off the line and do doubles no problem, and the 2200Kv motor is going to move a typical Kraton at over 65mph which is cool, but maybe also not as necessary when hard bashing in rough terrain like the Kraton is suited for.

Therefore, the 1650kv motors seem to give more options for gearing and running cooler while only sacrificing high end speeds which most don't hit while bashing, which is why I think some prefer that set up and call it more "ideal". Its just a rule of thumb and not a rule but generally 35K rpm is a nice sweet spot for RC motors that typically places them in a balance between speed/torque/heat and the 1650kva sits right there…you see that in @21STalion chart.

The 1650kv basically provides a more "flexible" set up while only giving up high end speeds your unlikely to need while bashing an EXB.

 

[Double Apex]

thanks everybody for chiming in. It has become an interesting read and I learned a couple of things. I enjoy lightweight trucks so I hoped the Germans were on to something but I’m afraid it might be just as simple @Aiosin said:

One of the biggest RC retailer in Germany is selling the Arrma Rollers with the Max8/2200kv Combo cheaper as a set.

Maybe most german RC beginners just take a Set and think that the 2200kv is most fitting for their EXB?

Well, at least i did. But switched in the meantime to a lower kv.

 

[RC-Dude]

Don't think it's representative. Same physics over here.

The Max 8 combo is 189 EUR.
The Max 6 combo is 239 EUR.
Seems a lot of sellers push the Max 8 combo.

Or maybe we just go on the Autobahn without speed limits if we want speed while you guys put it in your rc cars.

 

[@9G]

Lower Kv in and of itself is not better or worse.

For any voltage, there is a range of KV that will work best. Best is a combo of top speed, low end torque and speed. For 6s, in a 1/8 chassis, this range is around 1500kv-2400kv. yes, you can go higher or lower, if you have a reason, but the drawbacks start to be large.

Assuming we are talking same motor SIZE-
Lower KV gives a bit more torque, and a bit less heat.
Higher KV gives a bit more total power, and a bit less torque, but more heat.

With the same gearing -
the 2200kv will be much faster, and have a lot more heat.
the 1650 will have very low heat, but run very slow.

With gearing to match top speed -
The 2200 will have a better chance of cogging off the line and still have more heat.
the 1650 will be smoother off the line, and run a bit cooler, but not have as much punch on the top end.

When geared for max speed - the 2200 will have a higher top speed, as it has more total power.


BUT - Comparing the MAX8 motor to the MAX 6 motor - you have a 4075 vs a 4985 - the MAX 6 is a much bigger motor, so it is much more powerful, regardless of KV. The highest KV offered for the 4985 is the 1650kv. If there was a 2000kv option, people would be buying that one.

To your last point...this is where companies like TP Motor, Neu Motors and Cordova Research make a killing! They offer a wide range of KVs (with different winds, amp totals, and RPM values) no matter what the motor size is. The options seem endless and you can mix and match depending on what you're trying to accomplish.

 

[RC-Dude]

The higher the KV the higher AMP load the motor can take and the less hot it gets. Look at charts of brushless motors of any manufacturer. Same weight motor with higher KV can handle more heat and Amps. If the KV is too high you'll have trouble finding a small pinion and tires are likely to burst if they can't handle the speed.

The bigger the Motor the better it can handle heat. Just more mass where the head can dissipate. That is why you don't need a fan on the Max6 combo. The motor does not get hot if driven with "normal" pinions.

 

[Jerry-rigged]

The higher the KV the higher AMP load the motor can take and the less hot it gets. Look at charts of brushless motors of any manufacturer. Same weight motor with higher KV can handle more heat and Amps. If the KV is too high you'll have trouble finding a small pinion and tires are likely to burst if they can't handle the speed.

I'd be interested in seeing a chart that says higher KV motors can handle more heat. Yes, they will GENERATE more heat (more amps = more heat) but pretty much all hobby grade motors have similar high heat limits, where the magnets start to get weak, and the wiring insulation starts to fail...