Test run with 80mm Medusa today
 

So I did some runs today with the new 1600kv 80mm. Good fun. It has a little more power then the feigao 11xl but not that much, it is very drivable power. The motor seems to run a lot cooler too.

Anyway after some runs we could smell a very strong burning smell. Every time we have run this car especially while doing speed runs we have smelt this smell. To me it really smelt like an electrical burning smell. It was always a bit of a concern.

Anyway with a bit of investigation with our noses we worked out what the smell was. Turns out the big heavy savage works the mechanical brakes really hard. The brakes seam to be holding up OK even with the load. I'm glad I'm not running electrical brakes, not sure if everything would cope.

You replaced a 11XL Feigao with a 1600kv 80mm Medusa and it only seems a little up on power? I was under the impression that the Medusa was a significantly better motor than the feigao. Did you adjust timeing for the motor change one being 2 pole and the other being 4?

I just got my 36-80-1600 medusa last week but have yet to run it. I am hoping for insane power out of this thing.

What were you running for voltage? 6S lipo? Thanks for your mini rewiew of the motor.

-Brian

I think this shows several things.

Cooler operation means better effeciency and longer runtimes.

If you didn't change gearing, spool up time is about the same.

If you want to see a big difference, gear it up some. The 4 pole will easily outpull the feigao.

What kind of temps were you getting?

I would think electrical brakes would work just fine with your setup.

I have a feeling Sike is right...

I was concerned about using motor brakes on my lst but the MMM and hacker c50 xl do fine. I plan to put the 1521 1y in it and see how the 4pole motor compares to the 2 pole hacker.

I am currently looking for a smooth can 1521 1y for my flm savvy. I was thinking about trying the 80mm 1600kv medusa as it was considerably cheaper, than a used neu, and the smaller diameter will help with gearing and battery placement. I will wait till they come back in stock.

I've played around in my basement with my 80mm 2000kv Medusa on 5s in an XT8 and it has a LOT of power and stays cool. Of course, it's not very hot down there and I can't get near full speed, but usually motors and ESCs get warm running a lot of partial throttle.

I know my 50mm medusa was way more powerful than my fiegao it replaced in my .5. It was a bit disappointing on the first run as the gearing was low, but once I geared up the motor really woke up. Nearly as powerful as a LMT I had before all that.

I was definitely surprised not to see a big difference in power output. I am running 6s and I just did a direct swap of the motors. I didn't change gearing or any esc settings.

I almost think the spool up time is possibly slower. It's hard to judge as I didn't run the motors back to back. the medusa does not seem like it as working as hard, the 1st to 2nd gear change is less noticeable. Something that may be making this motor look so similar to the feigao though is the slipper. It is possible that the added torque of the 4 pole is causing the slipper to slip.

I am running the Cen diffs in mine and the gearing issue is why I went for the medusa over castles 1521. It would probably require a 22 or 24 tooth pinion with 52t spur to make enough clearance for the neu in my car. That would mean being geared for some serious speed.

I really need to run my car for longer and with my eagle tree attached to get a good idea of what is going on power wise. If I had a hall effects sensor on the drive train I would be able to see if the slipper was slipping which would be nice.


I took the savage to the track today to give it a real test. The plan was to race my mate with his nitro LST2. Acceleration wise we seemed very similar but I definitely had more top end. My acceleration was probably not as good as it could have been due to the tires I was running.


We did a lap or two just slow warm up and then he had a frequency clash with another guy:whip: who turned up. So we marshalled for a bit. Then we went to have another go and I decided to jump onto the track from beside the pits after being told that's what one of the other guys does. So I gave it a go and just as the car left the lip of the jump it hit a piece of 2x4 :diablo: sticking out from the pits. I hadn't even seen the stupid piece of 2x4 it blended in well with the background.

The 2x4 hit the shock and snapped the shock shaft and that was the end of that. If it had hit anything else the car would have been fine but it hit the shock and that was the end of testing for today.

I may have to tighten the slipper and have another run during the week and possibly even swap motors to do back to back comparison.

Ok I replaced the shock shaft and tightened the slipper. The slipper was definitely the problem. The medusa has a heap more power now. Wheelies when it hits second which is just scary and the brakes stink really fast. The medusa gets warm now too.

I will have to get some video, it's amazing how well this thing handles considering it's a monster truck.

Yeah, def get a vid.

On the slipper, I found using a temp gauge works pretty well to figure out if its slipping or not. If its warm/hot, you know you got an issue. This applies to a lot of things one the car. Once I found a cvd that was 170F! Little binding in the cup was causing excessive wear, but not something you would necc check for.

What gearing do you use?

Greetz,
Joram

That is a good idea and that is kind of how I knew it was slipping. I could actually hear it slip at times. What I did notice was it is better to check temp of the input shaft or the plate not the slipper its self. I was checking the spur and it was a little warm, then I touched the input shaft and ouch. I will keep that in mind though and check the dog bones and CVDs next time too.

That's a good question. I worked this out in standard form the other day which i'll have to find. I am running the 2 speed with Cen diffs and a 52/18t spur pinion which comes out to 45mph or 72km/h.

I'm going to run on a Savöx 4570 , 2000kv motor, cen diff's and savage flux tranny.

My gearing would be 16/48, think that would be a nice start.

Greetz,
Joram

Another question, how does the 2 speed hold on?

I have here three titanium gears, and an titanium idler shaft, but the 2 big gears are still plastic, how do they perform?

Greetz,
Joram