motor heating up

[thrashmetal]

i ran my newly purchased 36" drifter cat for the first time today and was very impressed with the speed and handling of the boat.

im running a castle hydra 120 esc and a feigao 9xl motor with a pair of 3s lipos in series with an octura x642 prop . i have a trubo tranny in it as well with a 66 tooth spur gear on the motor and a 42 tooth on the secondary shaft.

the speed control was barely breaking a sweat with a temps of 94 degrees. my motor on the other hand was temped at 178 degrees. by the time i brought the boat out of the water, removed the tape from the hatch etc it had probably been even higher.

what should i do to bring my motor temps to a more acceptable level?

should i go with a different prop? or should i change my spur gears and go with more/less teeth?

[ED66677]

Does the motor have a watercooling jacket? stupid question but...
9XL/6S => 1853KVx3.7*6=41136rpm at motor shaft unloaded
66/42*41136=64636rpm at prop!!! that's way too much!
The aim of the turbo trans is to reduce rpm at the prop so you should swap the 66 and the 42 gears, 42 on motor shaft and 66 on the output shaft to get then 26177rpm at the prop... much more reasonnable!

[thrashmetal]

re motor heating up

yes id say thats way too much rpm for the motor. lol


thanks for the advice
im going to switch the spur gears around and then run it again.

[thrashmetal]

re motor heating issue

actually i went to switch the spur gears on my cat but i noticed that the 66 tooth is on the secondary shaft and the 42 tooth gear is already on the motor.

i do have a water cooling jacket on the motor as well.

[ED66677]

actually i went to switch the spur gears on my cat but i noticed that the 66 tooth is on the secondary shaft and the 42 tooth gear is already on the motor

that sounds much better then!
if you have a cooling jacket, you may have to increase or reduce the water flow in it, too much water flow does not help transfering the heat from motor to water, not enough flo and it deos not evacuate the heat fast enough! IMO too much is better than not enough, I always try to have the water outlet pointing to the sky so that I can see if the water comes out or not, just for controling!
also, don't forget to lubricate front and rear bearing of the 9XL every time you get back from the pond!... this might be a reason for overheating!

[Doby]

Just throwing this out for consideration (as I know nothing about gearing) but a 9XL in a 36" cat sounds to me like to much boat for the motor. I run a couple of 9XLs in a few 28" and less boats (direct drive) and the temps are always around ambient.

I've got a 2280/13T in my shop that would really move it without breaking a sweat!

[ReddyWatts]

How many amps/watts are you using with the Feigao motor? What is your run time?

The 9xl runs best around 74 amps.

Example: 6s and 90 amps is over 2000 watts. That would explain a hot motor.
6s and 74 amps = 1600 watts.

Look at lowering your voltage and keep it closer to 1600 watts or reducing your runtime?

[ED66677]

Doby a 9XL gear down at almost 1.6:1 certainly does not suffer from moving a 36" hull with a "small" X642! one of the reason of the extrem heat is that he uses a coil type cooler around the can instead of a proper jacket, that does not provide a sufficient heat exchange, no matter if it run at 50 or 90amp, just my 2 cents!

[ReddyWatts]

Thrash, be sure and use one of these motor water cooling jackets when running maximum wattage. (1600 watts)

http://www.offshoreelectrics.com/pro...mjacket&cat=42

http://www.offshoreelectrics.com/pro...k-540XL&cat=42

[egneg]

Could be that the X642 is a bit small and cavitation is the problem (not to different than if it was out of the water) - is the boat slow to get going?

[ED66677]

Could be that the X642 is a bit small and cavitation is the problem

no cavitation but not enought load on the motor... remember that a brushless motor/ESC does not "like" running unloaded, that's basically where he is as it is geared down, testing the motor "in the air" for an short period of time makes the motor to heat up very quickely, I'm wondering if this can also have an impact, back EMF? induced current?
IMHO a proper jacket will fix this!
Anybody successfully using coil on an inrunner?

[Rex R]

I'm using a coil* on a 380 12l but, I'm not loading the motor over much...hardly a proper test
*5/32 Al w/ thermal goop & heatshrink to keep things tidy.

[thrashmetal]

re motor heating up

thanks alot guys for all the input and help.

i removed the coil style cooling jacket that was on the motor and installed a proper water jacket made for the 540 xl size motors. i also lubricated the front and rear motor bearings


to answer the question about if i was getting cavitation i wasnt . the boat has a very quick acceleration from the start and really moves throughout the whole throttle range on my radio.

after removing the motor to take off the coil jacket i noticed that the motor isnt a feigao 9xl like i though it was .

the motor in my boat is a nemesis 9xl motor . not sure of the kv of the motor as it doesnt say anywhere on the motor.

i will run it again soon and see if the motor temps are still high.

thanks again guys for all your help. much appreciated.

[ED66677]

Nemesis = Feigao
As I said, get an Eagle Tree Micro Logger, that's the best tool for FE boaters, you'll know where you are, it'll tell you how many amp (peak and cumulate) your setup drain, you can add LCD for immediate readout, rpm sensor and temp sensor, adjust prop size according to what you read and what your batt/ESC/motor are capable!
keep us posted!