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17.5t Motor comparison using only dyno data

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17.5t Motor comparison using only dyno data

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Old 07-16-2018, 11:08 AM
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Originally Posted by Cain View Post
What is the factor (assuming something simple like the skyrc analyser is being used) that you are looking at as far as the numbers not changing much?

Is it basically the RPM you are looking at?

So for example, motor A each time you do a run on it you see it gains RPM of 500 or so each timing degree change.

Then, you suddenly see its only going about 200 RPM change. is that the factor or are you basically saying "I'll go 1 more degree once I hit that point and leave it there".
Thanks for any info!
Im comparing all the numbers .I don't have a set RPM or timing.. I try to get the best overall performance I all numbers together. If I you from 4 to 5 amp draw . I only 1000 rpm... Maybe 100 kv. I use the amp draw as the bench mark.. 25% increase in amp draw . How much did I increase performance. Definitely not 25% increase in RPM.. and so on . I look for lowest amp draw to performance. And can adjust with gearing. of course i use laps times and feel on the track to see if i can get any more out of it. and temperature. but im usually very close coming off the analyzer to where its just a gear change.
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Old 07-17-2018, 05:59 AM
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Originally Posted by dgrobe2112 View Post
i am by no means an expert when it comes to these spec motors, and such. i for one, do not believe in the set it at 50 and go. i do have an motorlyzer, and have used it many many times on my own motors, and helped others as well. here is what i have found.
#1, the higher the amp draw, the more temp in the motor, and the more fall off i noticed in the motor/battery in races. sometimes the jumps are hard to make later in the race, having to run wide.
#2, each motor is different (duh) but 50 degrees on one motor, vs the next the performance is alot different in the numbers.
#3, RPM is not that huge of a thing. you can always adjust that with a tooth or 2 on the pinion to get the top end out of the car.

Basically what i have done, is i will have fully charged batteries, usually 2 or 3, just to ensure the performance stays the same. i will do a number pull with the motor at 30 degrees timing, then another at 50 degrees timing. i will even max out the motor to see what the highest numbers i get, KV, Amp Draw, RPM,. i will see what my lowest and highest are, and start adjusting. once i start seeing numbers not changing much performance wise for power ouput, is where i start stopping. why run at 5 or 6A draw to get extra 200 RPM in the motor, and risk the heat. when you can run at say 3.5, or 4A draw, cooler motor, less pull on the battery, less fall off in the race, and you can adjust gearing to get the speed if needed.

There are countless people who came to me with their cars, same chassis and everything are like, my motor is running too hot.. i give them my gear ratio.. they say if i run your gear ratio my car is too hot.. or too slow.. or whatever.. different motors, brand and all that.. different ESC.. everything. they ask what my timing on the motor is, i say its 40.. they are running 55. so, just to prove it.. i take their motor, pull it out, put it on the analyzer, and see that they are running 50+ timing, Amp draw like 7A, RPM nothing spectacular.. so.. i do some changes.. get it where i think it is most efficient.. most times its around 4-5A draw, give it back.. with some suggestions on gearing and all that.. they come back happy.. tell them.. if you want to change it.. just change timing by a little bit.. but you should be close now that a pinion tooth will be all you need..

like i said, im no expert.. sure i may not have it down to a science. but i have figured out enough to get it in the ball park..
After testing on the dyno I think 50 degrees timing is the optimal setting on my Fantom FR1 V2R 17.5 motor. 51 degrees may be better on tracks with really long straights and flowing corners due to more power above 10,000 RPM but the efficiency is getting pretty low at 51 degrees. From running on a track with a fairly long straight (50M with a full throttle banked curve 30M) I found 51 degrees gave better lap times at the expense of more heat. I could have stayed at 50 degrees and maybe tried going up a pinion or 2 but ran out of rounds. The dyno results show 51 timing shifts the peak power into a higher RPM range at the expense of low range torque.


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Old 07-17-2018, 08:34 AM
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When I tested my Wurks R1 V16 17.5 I got the following results. I settled on 50 degrees being the optimal as it gave very similar low power and torque as 48 and 52 but was the middle of the 3 for overall peak power and high end power. Again maybe 52 would be better on a very flowing track with long straights.




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Old 07-17-2018, 08:41 AM
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Looking closer at 50, 51 and 52. I think 52 may be the better overall as it gives almost the same power curve up to 14,000 RPM but more power above this. 51 gives exactly the same power curve as 50 but with slightly less torque and higher current.
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Old 07-22-2018, 12:25 AM
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So what’s the best 17.5 motor to buy?
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Old 07-22-2018, 06:14 PM
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Originally Posted by riceball777 View Post
So what’s the best 17.5 motor to buy?
Not that simple, do your research as we have all had to. Whats suitable for you may not be right for someone else. A fantom driver will recommend a fantom motor, Randy Pike will recommend Tekin etc. They are all very close to each other now.
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Old 07-22-2018, 06:30 PM
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Originally Posted by nexxus View Post
Not that simple, do your research as we have all had to. Whats suitable for you may not be right for someone else. A fantom driver will recommend a fantom motor, Randy Pike will recommend Tekin etc. They are all very close to each other now.
He probably doesn't care, he's bumping up his post count, lots of one sentence posts in all of the forums.
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Old 08-29-2018, 01:12 PM
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Default Best motor to buy :-)

Its been awhile since Ive been on RCtech, but Ive been following threads. I've been tweaking motors since the 80s. But this brushless motor is a different beast to tackle. I started using the SkyRC/GForce analyzers, then got a Motolyser v1, then the v2, Now I have the MiniPro. All read different and must be used with care. I'm partial to Trinity motors, but I'm always hearing people claim their motor is better. Even seen results to support their claims. So I decided to dump some money to make my own comparisons and see which one is better.


Current list of motors (all 17.5), Trinity Monster Max Certified Plus ($165), Trinity Monster Max Cerified ($130), Tekin Spec-R ($100), SchuurSpeed Xtreme SPEC v4 ($110), Reedy S+Plus ($97), R1Wurks v16 w/1650 rotor ($100), Maclan MRR Team Edition v2 ($120), HobbyWing Xerun G3 V10 Competion ($95), also one more coming from Fantom ($150).


Testing criteria:

1) buy the best offered to the common racer (not factory sponsored)

2) Test motors out of box, no tweaking

2a) Test on Motolyser, SkyRC analyzer, miniPro.

2b) Test on the track, minimum 2 cars, 2 drivers, same gearing, same day so conditions are equal.

3) Test motors for peak performance via gearing, find the gearing that each motor likes best.

4) tweak the motor for max efficiency

5) tweak the motor for 6 amps


I'm still awaiting one more motor and it maybe November before I can travel a 100 miles and spend the day testing.

But this is out of the box results so far using the analyzers and motolyser and miniPro dyno:

RPM range @ 5v 10630 - 12549, most right around 11000.

KV range @ 5v 2868 - 3380, most around 3000.

Timing avg, 21-52, throw out the high and low and the rest were 42-44 degrees.

Timing deviation .3 - 2.3, most around 1.2

Asymetry .5 - 9.4, most about 2.

The MiniPro results of efficiency was an average of 60%.


What does all this mean? Well out of the box (using testers) most motors are equal and can be made competitive by adjusting the gearing.

But the true test will be on the track.


Some notes: I took the motor out of one my race cars and the motor is extremely strong and fast. The efficiency was around 67%, I played with the timing and found by reducing the timing from 51 degrees to 45 and got it to 71%. Then I installed non-magnetic screws and shims. RPM increased by only 250 rpm, but the efficiency jumped from 71% to 85%! I did run it 12 times to be sure and got the same results. Now this was only on one motor and maybe an anomaly so I have more non-magnetic kits coming and will install on more of my current race motors to see if the I get the same results.
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Old 08-29-2018, 01:24 PM
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Good info.. and like you in your notes.. i noticed that my motors were most efficient around 40-45 timing.. Tekin, trinity, tell everyone to put it at 50 timing... but i always have temp issues that way.. thats when the Amp Draw is around 6.0. i usually get my amp draw around 4, and dont notice any issues, with heat, or power.. and no fall off in battery.
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Old 08-29-2018, 02:24 PM
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Thumbs up Good amp setting 4-5

Originally Posted by dgrobe2112 View Post
Good info.. and like you in your notes.. i noticed that my motors were most efficient around 40-45 timing.. Tekin, trinity, tell everyone to put it at 50 timing... but i always have temp issues that way.. thats when the Amp Draw is around 6.0. i usually get my amp draw around 4, and dont notice any issues, with heat, or power.. and no fall off in battery.
I have noticed too that I get the best performance around 5 amps, sometimes 4. Then I just gear it up.
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Old 08-29-2018, 02:34 PM
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Originally Posted by Mudcat981 View Post
5) tweak the motor for 6 amps
Everything else was good, but then I saw this bit. Don't bother, that's not optimal for current gen motors.
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Old 08-29-2018, 02:37 PM
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Wink All part of testing

Originally Posted by gigaplex View Post
Everything else was good, but then I saw this bit. Don't bother, that's not optimal for current gen motors.
I have included this to debunk the 6 amp methods. Because like you I don't believe in the 6 amp rule, but others do. So to satisfy them I am including this testing to see the effects and performance gain or loss.
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Old 08-29-2018, 06:11 PM
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I am not a fan of this self made 6 amp rule which seems to have started from Nick Adams youtube clips. I find the "optimal" timing mark is just before when a further increase in timing increases amp draw disproportionately to rpm.

And it varys from motor to motor. The new Maclans, don't like being over 50 degrees timing, the Actinium V2 Team Powers, always seemed to settle around 36-37 degrees and unloaded were only pulling 2-3 amps, but on the dyno and more importantly on the track that's where they worked best.
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Old 08-30-2018, 04:37 AM
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Originally Posted by nexxus View Post
I am not a fan of this self made 6 amp rule which seems to have started from Nick Adams youtube clips. I find the "optimal" timing mark is just before when a further increase in timing increases amp draw disproportionately to rpm.

And it varys from motor to motor. The new Maclans, don't like being over 50 degrees timing, the Actinium V2 Team Powers, always seemed to settle around 36-37 degrees and unloaded were only pulling 2-3 amps, but on the dyno and more importantly on the track that's where they worked best.
From all my testing with the MinPro Dyno nearly all the 13.5 and 17.5 motors give out maximum power when at or very near to 6A. I have tested each motor with 30 degrees up to 55 degrees in 5 degree increments and watched for when the peak power starts to fall off. I then test each motor in 1 degree steps around the peak power output to determine the best setting. I then go back and check the unloaded current draw on the SkyRC analyzer and each motor is usually between 5.3 and 6A.

Once I've found the max power setting for each motor I check the efficiency graph from the dyno output and find the max efficiency point on the curve. If you check the RPM at max efficiency - 15% and then gear so this is your max RPM on track (you will need an ESC with data logging).

So far this method seems to get me close to the optimal settings for each track. I can fine tune during the day and keep an eye on temps. I never see motors coming off hotter than 70C even on hot days of 30C+ (We actually had a heatwave this summer in the UK!)

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Old 08-30-2018, 04:43 AM
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Originally Posted by Mudcat981 View Post
I took the motor out of one my race cars and the motor is extremely strong and fast. The efficiency was around 67%, I played with the timing and found by reducing the timing from 51 degrees to 45 and got it to 71%. Then I installed non-magnetic screws and shims. RPM increased by only 250 rpm, but the efficiency jumped from 71% to 85%! I did run it 12 times to be sure and got the same results. Now this was only on one motor and maybe an anomaly so I have more non-magnetic kits coming and will install on more of my current race motors to see if the I get the same results.
Thats's a nice group of motors!

Why are you tuning for max efficiency and not max power or was this just an observation? Efficiency will always increase as you reduce the timing to a point, but they will not be fast. I have found that motors I have tested are giving out max power around 60% efficiency. Strangely I hadn't seen any measurable improvement in torque, power or RPM by changing to alu motor screws on 2 motors I tested.

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