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Help with motor selection

Help with motor selection

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Old 02-09-2012, 12:34 PM
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Default Help with motor selection

I'm trying to figure out which motor I want to get for a 1/10 2wd buggy.
I thought I had figured out that I wanted an 8.5...but that seems to be rather different across various brands, and even within brands.

For example, what is the real difference between Fantom's Apex and ION3 series? They offer what look like the same options on both series of motors in the same turns, at basically the same price point.

Then I saw elsewhere differences in KV across brands and how that would make an ESC or the motor hot, or draw your pack down quicker, etc...but no explanation as to which would do that.

Can somebody put this into an easy to understand format such that X stat as it goes higher, means Y, and may vary based on Z? This would make it much easier to compare various companies motors for given applications.
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Old 02-09-2012, 01:51 PM
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To be honest most of them run the same.

I really doubt you'd notice +/- 100kv in any motor.

Buy a motor you like and go have fun!

Most of the differences are cosmetic. Things like connectors how you adjust the timing and general construction of motor.

Try to buy something you can change the stator in if you decide you need more motor down the road.

In general the more kv the lower you gear.

Hope that helps!
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Old 02-09-2012, 02:01 PM
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You probably won't notice much difference in a 2wd buggy between motors that are the same number of winds or close at least. Much of any extra power will be lost in the slipper, or you'll just constantly wheelie if the slipper is too tight. It doesn't seem to matter quite as much in offroad like it does in high traction onroad where you can really make use of the extra power. As long as you have enough motor to clear the largest jumps at your track, you should be fine.

Fantom Apex is a re-branded Trinity ReVtech


Good motors, but I'm biased.
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Old 02-09-2012, 03:21 PM
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Originally Posted by locked View Post
Fantom Apex is a re-branded Trinity ReVtech
I've read that before, but I've also seen people post stats of the two side by side to show there are large differences in kv.

For instance, the RevTech shows 6000kv @ 8.5T
http://www.trinityrc.net/shop/index....product_id=142
While the Apex seems to not have kv info available at all.

The same has been said about the ION3 being a rebranded D3, but they are actually quite different, not just 100 or so kv like was mentioned (and I would've expected), so including the RevTech above, we have anywhere from 4000-6000kv in an 8.5t.
LRP Vector X-12 8.5turn 4200kv
Tekin Redline 8.5turn 5300kv
Novak Ballistic 8.5turn 5000kv
Novak SS Pro 8.5turn 5000kv
Viper VST 8.5turn 4000kv
Trinity D3 8.5turn 5800kv
Fantom ION3 8.5turn 4000kv
(other numbers from here)

So...the whole choose your favorite motor...I don't have one...just coming back into the sport after 15 years out, and none of the numbers quite make sense to me yet as to what I should expect and use to compare.


Originally Posted by onefast8
In general the more kv the lower you gear.
So how does that affect things now? Should I expect more or less heat (on esc/motor), endurance, etc by going with a higher kv and lower gear vs a lower kv and higher gear?
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Old 02-09-2012, 04:17 PM
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kv ratings in (in ROAR spec sensored motors at least)are like the motor equivalent of battery C ratings. Largely a steaming pile of male bovine excrement. Have a look at 2 cell shorty packs. They're all the exact same size and weight, but the numbers they print on the packages vary hugely. I'm pretty sure they're all the same inside.

The majority of motor manufacturers do not dyno every motor(some "tuners" do). The rotor's distance from the sensor as well as the rotor strength can be very different even between two of the exact same motor. So don't pay much attention to those kv ratings. They can give you a rough idea of how fast a motor is, but are generally meaningless and when you use advanced timing, the numbers are completely meaningless

Even if they were extremely accurate, that tiny bit of difference won't make much difference at all on the track and if you are worried about a minor performance increase, throw a 7.5 or a 6.5 in. I'm sure you'll realize pretty quickly that you can't actually use any of that extra power. At this level of performance, most drivers will do slower laps with faster motors.
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Old 02-10-2012, 12:46 AM
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Well, everything says to ignore the turn equivalent numbers too...so what numbers actually matter?

Basically I want something I can run forever non-stop, yet still reasonably race. I fully expect to run a packs back to back to back to run for several hours, and then let the quad charger catch up over lunch, and do it again until dinner.

So generally what should I look for to make sure the motor won't run too hot, or make the ESC run too hot? How can one get a general feel for performance from numbers as well, if all the numbers are junk numbers anyway? How about being able to tell how efficient the motor is (which should equate to longer pack times and less heat)?
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Old 02-10-2012, 08:22 AM
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Watts (or some other measure of power) are what matter. Kv is only half of the equation of power, also need to consider torque. Don't believe watts are readily available, and if they are may well be taken under different test conditions. Trying to make a purchase decision from spec sheets is likely not very productive, if not outright maddening, as others have alluded to. All the brands mentioned are more than capable, plently of guys go fast with each.

Turns are for racers, Kv are used primarily by bashers. Why you will never see agreement on the forums, as both have their place.

You want to run nonstop, suggest at least a 10.5, if not a 13.5, and use conservative timing, etc. A 8.5 can be difficult to keep cool for long runs.
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Old 02-10-2012, 11:00 AM
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Thanks Dave. Is there a good way to grab a comparison spec for the torque?
Maybe I'll get an 8.5 for race days and a 10.5 for the all day runs where I just want to work on control and rhythm.
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