Help Me Choose a 12s Motor for 20+lbs savage

[Jahay]

As title says...

Currently i will attempt to push my 1520 to the max on 9s once i get my truck up and running. the 1520 has so much torque on 6s and didnt even break a sweat when the truck weighed 16lbs or so.

I have added a little more weight... mainly the baja wheels and tyres and a little more alloy parts....

I am wanting to get the most out of my 12s Ice HV ESC... So looking for an appropriate motor.

I am not so familiar, or know what to choose other than the usual 1717,1520,1518, etc....

These bigger motors are out of my knowledge area... and i do not know how they would cope.... or if they would fit in my Motor/Diff Mount.

I have been looking at the following...

Model RPM/Volt Weight/Oz Length/inches Maxrpm Cont Watts Surge Watts Max V

1509/3Y 1,200kv 7.48/7.94 2.1 60K 750 watts 1,500 watts 50 volts $199.00

1512/2.5Y 1,100kv 9.88/10.23 2.4 60K 1,000 watts 2,000 watts 54 volts $225.00

1515/2.5Y 850kv 12.00/12.7 2.7 60K 1,250 watts 2,500 watts 70 volts $249.00

1521/2.5D 1,200kv 16.93 3.3 60K 1,750 watts 3,500 watts 50 volts $269.00


Are there any other recommendations you could make? or advice to give when picking a motor?
Maybe there is something already available that does not need to be built by castle?

Thanks

Josh

[DrKnow65]

You need to pay close attention to KV vs. Max RPM.

I like my motors to push 45-60k rpm at max voltage, so 12S X 4.2v = 50.4v
50.4v \ 60,000rpm = 1190KV
50.4v \ 45,000rpm = 892KV
I also think bigger is better, but the 17xx series is only good to 45K rpm, so I'd stick with the bigger 15xx's.

So by MY standards, I would go with a 1521-1527 1.5Y Neu motor.
(I also prefer the wye winds VS the delta's because they make more power at higher RPMs versus lower).

[lincpimp]

For 20+ lbs I would suggest going to a 1527 motor.

A 1200kv motor will put you around 53000 motor rpm. That may be too fast depending on the gearing you can fit and the speeds you want to run.

A 1000kv motor will get you motor rpm around 45k. This may be a better choice, depending on your gearing limits and desired top speed.

Looks like a 1527 2D at 1150 kv would be a decent choice, or a 1527 2.5D at 925kv.

I really think a 1521 will be stressed too much with this setup.

There may be other motor choices out there, suck as a suitable leopard motor perhaps? I would stick with a 4 pole motor, as you want more torque.

[DrKnow65]

Hey Linc, didn't you have a 1527 for sale? I don't remember the wind though...

[BrianG]

Have you given this a try? I have been trying to tweak/improve it, but not much feedback so far.

[lincpimp]

Nifty tool you have there BG. Any chance you can increase the voltage range on the step 2 slider to go up to 12s fully charged?

When I crunched the numbers it came up with the 2d 1527 but that was at 37v. So 10s lipo nominal. A 1000kv motor seems like the best bet for 12s use for Jahay.

[Jahay]

Thanks for everyone chiming in asap

Brian, i havent used that calculator. Pretty kl tool!!! BUT it wont let me choose speeds of higher than 50mph and it wont let me choose up to 50V of power.....

Linc, i think you may be right regarding the motor... And due to my current gearing difficulties using a pinion which is too small.. the 1527 925kv would be ideal as it lets me use a larger pinion...

Differential Ratio: 3.2222222222222223 - Savage BP Diffs
Transmission Ratio: 1 - Centre diff
Other Ratio: 1
Spur Tooth Count: 47
Pinion Tooth Count: 15
Total Voltage: 44.40 - 12s @ 3.7v
Motor KV: 925 - Neu 1527 2.5d
Tire Diameter (inches): 6.88 - Baja bow ties
Tire Ballooning (inches): 0
Motor Current Draw: 0
Motor Coil Resistance: 0
Spur/Pinion Ratio: 3.13 : 1
Total Ratio: 10.0963 : 1
Tire Circumference (inches): 21.61 inches (549 mm)
Rollout: 2.14:1
Total Motor Speed: 41070 RPM
Vehicle Speed: 83.26 mph (133.74 km/h) -
Effective KV Value: 925
KT constant: 1.46 oz-in/A

I believe this should be achievable with my 18-20lbs savage. Considering there is a guy on here running a baja 5t weight 29lbs on 12s geared for 80mph without any heat problems at all....


BUT on a side note... i am not sure if i want to spend $300 just yet on a setup i am not sure i will like

Are there any cheaper motors i could try which are of a lower price before i drop serious coin? Could i just look for most motors around the 900-1000kv range?
What would you recommend? anything from hobbyking i could try out?etc...

[BrianG]

Originally Posted by Jahay

... it wont let me choose speeds of higher than 50mph and it wont let me choose up to 50V of power.....

I guess I can unlock higher speeds. On the voltage thing; it will suggest a voltage, but you can use the slider (in step 2) to adjust it. Then, adjust the motor kv until everything is green. Once you do that, click the link to see the list of possible motors.

[Jahay]

What do you all think about leopard motors~?

Some like the low kv motors such as this 730kv 5692 motor
http://rc-fans.com/details.asp?prodid=2032

But it has a 6mm shaft!

[lincpimp]

Ok, used Brian's calc again (thanks for the updates BG) and a 950-1000kv motor with a 12t pinion would be my best suggestion. Also, if you do not have batteries may I suggest going with a selection of lipos that will allow for 10s and 12s. Maybe 2 5s packs and a 2s you can remove to get 10s... Or a 6s, 4s, and a 2s. I think 10s lipo would be better, and allow for a larger pinion, as the small pinions on a large spur wear much faster as they have to make so many more revolutions than the spur.

[BrianG]

Originally Posted by lincpimp

...thanks for the updates BG...

It's a temporary update. There is no top speed cap right now, but I think there should be some kind of limit, just not sure what. Voltage is now capped at 15s (55.5v). And, be aware that the suggested motor list is being generated only from the motors I have in my "database", but there may be other motors out there that could be suitable.

[Jahay]

nice one BG, but it didnt find any motors for my application :/

linc, i am not sure... but 12s may be too much. I could always just run and definitely be happy with 10s. Would mean that my truck stays lighter too, and it wouldnt stress the ESC either.

I was going to run 2x 3s lipos in the side battery boxes and a single 4s lipo in the rear tray, to make 10s. (i can fit up to 6s in the rear tray...all lipos are of 5000mah capacity too)

I could go for a 1000kv leopard motor
http://cgi.ebay.co.uk/BRAND-New-Leop...ht_2543wt_1031

which is half the price or so of the 1527....

what do you think?

any other options of motors?

[BrianG]

Originally Posted by Jahay

nice one BG, but it didnt find any motors for my application :/...

If that's the case, then it means there wasn't a motor in my database that had the kv and published power rating required for the setup. When you open the "motor recommendations" window, near the top it shows the recommended power range.

FYI: Since you are obviously shooting for high speeds, you can sort of ignore the fact the speed text is in red. Just try to keep motor rpms and rollout values green, or orange max.

After playing around with this tool, I can see a few ways to improve it. Looks like it's time for another update...

[Jahay]

THanks for this motor calculator brian... works quite nicely.

If i go for roughly a 1000kv motor running a 14-15t pinion with a 2:1 roll out on 10s, i get 70mph.

This would be a nice place for me to start, and i believe it would be quite safe for 10s, and i can adjust my gearing accordingly after that.

Just need to source a 1000kv motor....

BUT WHICH ONE... hmmmmmm

Any advice on a motor which is affordable apart from leopard? and has a 5mm shaft so i do not have to buy 6mm pinions from kershaw?

[JERRY2KONE]

Originally Posted by BrianG

Have you given this a try? I have been trying to tweak/improve it, but not much feedback so far.

I love this tool BG. Nice addition to your calc collection. Kind of fun to play around with and it really helps keep people in the range of their setups for chosing the right motor and batteries. Thanks for sharing.