Feigao heat problems.

[Kyosho]

First thing i need to clear up. I know feigaos arent great, i know i should get a new motor, i know, i know, i know.
Now, In my CRT i run a feigao 10xl, MMM, 5s zippy, 11/46, and diffs 43/13. and my tires are 5.6in without ballooning.
temps within 7-10mins are:
Motor-140* 145* F
ESC- fan turns on at this point or it also hit 165* on me.
Batts at this time-86*F
So on Beat your truck i was informed that i may be under geared, so i had a 14t pinion laying around so i tryied it.
temps after 5-7mins:
every thing the same give or take a degree or two, but it heated up faster.
With 11/46 its geared for 38MPH
14/46- 48MPH
I cant gear any lower because the mounting slots stop and the motor cant move over any farther.
any sugestions?
and when i get a new motor i want around 38MPH on 5s, so i would get like a 1600kv motor. but i cant get a motor that is any wider than the feigao because it will hit the center diff out put, so i would have to get a medusa 80mm 1600kv motor, geared 12/46

[E-Revonut]

140-145 isn't hot!

[Metallover]

You should be good up to about 160f, then you have to worry. Get the medusa you mentioned. It will blow the fiegao away.

[Kyosho]

its not the motor im worried about, its the esc getting so hot, i have it mounted up high and it has lots of air flow. but i think its the motor making it hot, i now 140 is a good temp, but its gets there so fast, i only have to put about 300 to 400 millie amps into the battery to charge it because the esc just gets hot and i cant run it.

[nitrostarter]

What are your settings on the ESC. This may play a large part in the heat problems. Things like timing, start power, etc...

[Kyosho]

timing lowest for 2 pole motors.
start power is low. i never try to wheelie or do huge burn outs or any high power starts. im easy on the throtle and slowly get up to about 3/4 throtle before i run out of room and have to turn around.

[BrianG]

A couple more points

1: What is the ambient air temp? If it's ~100*F, that's actually not a bad temp

2: Temps that rise fast but do not get much higher is nothing to worry about, as long as the temps don't keep climbing higher and higher. For a given surface area, any material can dissipate so much heat. The hotter it gets, the faster it dissipates (up to a point of course). At some point, the rate at which the temperature increases will slow and stop as there will be a balance between the delta between ambient air temp/material temp, and the rate at which the motor case dissipates heat. Also, fast rising and falling temps simply means there is efficient transfer of heat.

3: High ESC temps usually means overgeared. I know you say you can't gear lower due to physical constraints, but is it possible to increase the spur size? Or maybe get a diff ring/pinion that is geared lower (not sure how the CRT is set up)?

4: Assuming you can do something to gear lower somehow, I personally would not get a 1600kv motor for 5s. Some may disagree. 1600kv on 5s is under 30k rpm, and when geared for ~40mph, may cause the ESC to stutter a bit at startup because the motor is spinning relatively slow per mph and the ESC may not be able to get rotor positioning feedback as easily at lower rpms.

[E-Revonut]

Originally Posted by BrianG

A couple more points

1: What is the ambient air temp? If it's ~100*F, that's actually not a bad temp

2: Temps that rise fast but do not get much higher is nothing to worry about, as long as the temps don't keep climbing higher and higher. For a given surface area, any material can dissipate so much heat. The hotter it gets, the faster it dissipates (up to a point of course). At some point, the rate at which the temperature increases will slow and stop as there will be a balance between the delta between ambient air temp/material temp, and the rate at which the motor case dissipates heat. Also, fast rising and falling temps simply means there is efficient transfer of heat.

3: High ESC temps usually means overgeared. I know you say you can't gear lower due to physical constraints, but is it possible to increase the spur size? Or maybe get a diff ring/pinion that is geared lower (not sure how the CRT is set up)?

4: Assuming you can do something to gear lower somehow, I personally would not get a 1600kv motor for 5s. Some may disagree. 1600kv on 5s is under 30k rpm, and when geared for ~40mph, may cause the ESC to stutter a bit at startup because the motor is spinning relatively slow per mph and the ESC may not be able to get rotor positioning feedback as easily at lower rpms.

Listen to Brian, he knows what he's talking about! Also I have a 36-70-1600 Medusa and a 1515 2.5D (1650kv) and run them both on 5s with great results. Low speed power is fine and top end is incredible! On my RC8T I can gear it down to at least 30MPH, I race with it geared 50/15 or about 35MPH, fast enough to pull on the nitros and slow speed cogging doesn't exist

[blueb8llz]

have you tried changing your motor timing to normal?

[Kyosho]

ok, so if i get a 2000kv medusa geared 11/46 it will be. 46mph this is alttile fast for me. and to go with a lower diff ratio i would be spending close to $150, the air temps here are about 86*F, I live in Canada.
if i get the 1600kv motor it will be geared under 40mph, about 36mph with 11/46 gearing.
I dont drive Wide open all the time, i barely even get up to full throtle.
here it is with the medusa 1600

Differential Ratio: 3.3076923076923075
Transmission Ratio: 1
Other Ratio: 1
Spur Tooth Count: 46
Pinion Tooth Count: 11
Total Voltage: 18.5
Motor KV: 1600
Tire Diameter (inches): 5.8
Tire Ballooning (inches): 0
Motor Current Draw: 0
Motor coil Ω: 0.006
Spur/Pinion Ratio: 4.18 : 1
Total Ratio: 13.83217 : 1
Tire Circumference (inches): 18.22 inches (462.82 mm)
Total Motor Speed: 29600 RPM
Vehicle Speed: 36.92 mph (59.31 km/h)
Effective KV Value: 1600
KT constant: 0.85 oz-in/A

[BrianG]

IF you are happy with ~36mph, the relatively low kv of 1600 should be fine. I wouldn't gear much higher though for the reasons I stated earlier.

$150 to change the diff ratio? Wow, that's a bit pricey! Have you checked the ebay chopshops, or is that the retail price? 3.3:1 diff ratio is typically used for buggies, so it makes sense now. Truggies typically use a 4.3:1 ratio which allows more flexibility with spur/pinion gearing. And since you didn't say, I assume there are no larger spurs available?

[Kyosho]

I am using the CR buggy mount and a larger spur probaly wont fit. and i cant find any 43/10 diffs for cheap, the only ones that i was informed worked were the LSP diffs wich are about $70 (canadian) each. the CRT uses 43/13 diffs, like buggies.
my track is pretty small so a low top speed is what i need.

[Kyosho]

will the medusa 80mm 1600kv motor on 5s geared for 36mph be good? i want an effecient setup that runs cool.
will the esc be cooler?

[nitrostarter]

Definitely! More efficient as well than the Feigao!

[What's_nitro?]

Originally Posted by Kyosho

will the medusa 80mm 1600kv motor on 5s geared for 36mph be good? i want an effecient setup that runs cool.
will the esc be cooler?

Yup, that'll work. And later on you can gear it for 72mph and not have to change anything!