Help me understand. - RC-Monster Forums

notnodak · **Help me understand. -** 01.03.2008, 03:33 AM

Here are the specs I can find for the Ammo motors in question.
Ammo 36-56-1800 motor
SPECS: Motor Diameter: 1.42" (36mm)
Motor Length: 2.2" (56mm)
Shaft Diameter: .197" (5mm)
Shaft Length: .591" (15mm)
kV Rating: 1800 rpm/V
Weight: 10oz (283g)
Input Voltage: 14.8-22.2V
Max. Constant Current: 50A
Max. Surge Current: 90A
Max. Constant Watts: 1110W
No Load Current: 1.9A

ammo 36-56-2600 motor
SPECS: Motor Diameter: 1.42" (36mm)
Motor Length: 2.2" (56mm)
Shaft Diameter: .197" (5mm)
Shaft Length: .591" (15mm)
kV Rating: 2600 rpm/V
Weight: 10oz (283g)
Input Voltage: 11.1-14.8V
Max. Constant Current: 55A
Max. Surge Current: 90A
Max. Constant Watts: 815W
No Load Current: 3.9A

I'm going to put one of these in a E-WideMaxx but I might get a new E-Maxx 3905, they would both be about same wieght or close to a E-Savage.
If the 1800 has a 50amp rating w/1110watts and the 2600 is 55amps w/815watts, wouldn't I be better with the 1800 with 14-cells?
I'm running a pair of Johnson DCM-267: http://www.allelectronics.com/cgi-bi...3-24_VDC_.html and They are good but I want more power.
My concern is I use these with 66t spur and 22t pinion already and I don't want it to be slower. I think these Johnsons are rated at about 1541kv.

Will I see a significant improvement in the 1800 motor or do I need to go with the 2600?

_paralyzed_ · 01.03.2008, 03:40 AM

it depends on the batteries and speed control you plan on using, in general a slower kv motor with more volts is better

notnodak · 01.03.2008, 04:04 AM

I'll be using a MM esc w/ UBEC and either 12 or 14 cells.

My unbderstanding is that the 2600 in a E-Savage witha 18t ponion on 14 cells will go about 40 and not get to warm but I also thought that a lower kv withould handle more gear better also. I'm not sure if I have the setting on the speed calculater in correct could some one try these motors on it so I'll have a better idea. Actually if I just knew the size and balloning factor to fill in for Stock Revo wheel/tires I could probibly do it myself.

Thanks for the help.

_paralyzed_ · 01.03.2008, 04:29 AM

since you are running the mm i'd go with the 2600kv. you are limited to 4s or 12 cells with the mm, (some have run 14 cells or 5s, be careful!) so the motor is closer to the sweet spot (35,000rpm) with the 2600kv, an overall matched system where you would be under volted with the 1800kv. on the speed calculator balooning doesn't really matter and 6 is a good number for a revo diameter

lincpimp · 01.03.2008, 11:09 AM

Keep in mind that both of those motors have 5mm shafts, so you will have to buy a 5mm bore 32p pinion. I would suggest the 2600 on 12 cells, the MM can definately run that.

Check this out, I figured a 18t pinion would be your best bet, as it would keep the system cool and give decent speed.

Differential Ratio: 2.8461538461538462
Transmission Ratio: 1.7222222222222223 Emaxx 2nd gear
Spur Tooth Count: 66
Pinion Tooth Count: 18
Total Voltage: 14.4
Motor KV: 2600
Tire Diameter (inches): 5.75
Tire Ballooning (inches): .1
Spur/Pinion Ratio: 3.67 : 1
Total Ratio: 17.97293 : 1
Tire Circumference (inches): 18.69 inches (474.79mm)
Total Motor Speed: 37440 RPM
Vehicle Speed: 36.87 MPH (59.23km/h)
Effective Speed Rate: 2.56mph/V (4.11kmh/V)
Effective KV Value: 2600

DrKnow65 · 01.03.2008, 07:29 PM

I use the 36-50-2300, it's rated at 60A constant and 1100watts. It is shorter than the 56mm cans but so far I am very happy with it. I am only running it in a 4wd 1/10 buggy on 3S but it's never more than warm to the touch... where my cs36,5700kv used to get WAY hot. I know it's not apples to apples, but I'm liking the motor alot anyhow.