More Speed!
 

Ok, i have been pondering on a few things. I love my 10xl motor. I really like it with a 20T pinion. The problem though, geared that way, it's way hot and starts stuttering. So i run the 18 and it seems fine, but not enough speed for me i guess. I really want a motor / controller that can fly but stay cool on 16 cells. Any suggestions would be great. Or, if i change my controller, can i gear it up to get more speed, or would it be too much for the motor then? I want a good combo for speeds that won't get too hot! thanks!:032:

Yours gets hot with a 20T!?!? I run 20/51 with stock diffs! Thats pretty odd. I would stick with a XL motor unless you are gonna get a 1950.

Well, I know my controller does foresure, I haven't taken a temp gun to the motor yet. But my capacitors on the controller damn near pop with the 20T. It gets reall jerky with the 20T after about 5 min! Let it sit, then it goes like a batt out of XXXX, then gets stuttery (fine line to thermaling i think). But i also run UE diffs. So the 10xl can go FAST, just need a better controller to handle the temps better?

I don't think your controller is the issue, I think it's fine along with the cell count your running....the 19 series motors will work for you, i think you need to keep your rpm per volt around 2500 or less for the amount of cells your running, this will put you in the 40,000-50,000 rpm range on the motor. the big question is how to gear it for the speed you want without thermaling your system.

And that's the problem sjcrss, when i gear it to the speed i want, my 9920 gets too hot. when i gear it down a few teeth, my temps are good, but i have too much torque and not the speed i want....so my thinking was, if i got a btter controller, i could use the 10xl for the speed i want and gear the way i want, just need to watch the motor temps. the motor on the 20T was a tad hot, but the controller was woohoo hot...even with a fan on it!
Any other ideas guys how i can obtain my speeds?

I to would like to have more speed, but at what cost...bringing your controller to the brink of thermaling or thermaling or even a controller failure, you need to find a happy medium, I know it's hard, Well I've ran my system for 4 years and never had a issue with thermaling or anything, even after i switched to the UE diffs last August....the 9920 isn't much differant than the 2095 micro I'm running, other than the micro is programmable and the # of amps it can handle..the cell counts are the same....so the controller isn't the issue, it's the low rpm per volt on your motor...

Well, I'm currently running around 28,000 rpms (i believe) maybe 30,000 right now with the 16 cells, and my controller is getting hot. If i go with a higher rpm motor, will that keep my controller happier? Is this right? It just seems that i can't gear this thing the way i want without frying my 9920!

Ok. So with all my calcs, i can't seem to break the 40 MPH. I guess I will need LIPO to do that, the 16 cells just won't punch it. 1930/10T 16 cells: 16/51
40128 RPM
34.49 MPH

20/51
40128 RPM
43.12 MPH
But i think the 20 will be a tad hot....you'd think with 16 cells you could really push it faster, but guess not. Any ideas besides Lipo? Put a sail on it perhaps?

What is the gear ratio of those diffs, or are they like a normal emaxx? I assume you are locked into 2nd gear on the tranny? How much does your truck weigh?

My truck weighs(with the cells) about 12lbs. I run a single speed tranny(2nd only). My diffs are the UE buggy's, not sure the ratio....

I would NEVER run a motor over about 40k rpms. Thats getting out of the efficient range. Stick with somewhere around 35 to 40k....I think there might be a few FET's on your controller went bad...

Guys, Just curious, what would happen if he uses a 7xl motor instead of his 10xl, and with a 20T pinion...!!!

Is there an easy way to tell about the fet's?
Hustler: It would run way tooo hot!

I agree with you for the Feigao and wanderer motors. They are rated at 50K max. But you should be able to get way with more rpm from the Lehner motors, They are rated for 65K rpm max. I would think you could run it up to 45K easy without loosing much effiency. I could be wrong, but just my thoughts.

Ok. I have a thread on presales about a quark....can someone check it out, i'm gonna run that with the Lehner motor.

What if you used a 8xl with like 14 cells in your setup..!!! Would it still run too hot..!!

I hope, you dont feel I am threadjacking, just trying to get a feel and some knowledge of different combinations and their output speed etc.

An 8xl on 14 should be fine...

But would it reach the speed you are aiming for..??

That I'm not sure. Someone with more experience with those motors could probably spin in and give accurate info on that one. LOL

Here are the diff ratio's for you...
Diff ratio’s
Stock- 2.85:1
UE 1/8th - 3.31:1

and squee I've been running my 1920/8 ot the rpm range of 56433.6 RPM for over 4 years and I've never had a issue with it overheating or anything....for me to run it at 40,000 rpm I would only be able to run 8 cells and that's it...

Now now children, no fighting on the forums...I give you both 5 warning points! LOL, j/k! Thanks for the ratio's. What do you guys think of the 1930/10t with the quark set up on 16 cells?

Thanks for the ratios. Can you tell me the pinion and spur tooth count on those UE's? I want to add it to my speed calculator. To keep the precision as high as possible I don't round answers at all until the final output.

not with out having to take my diffs apart, these ratios are what was posted on the UE forum

You could ask Robin on the UE forums???

That's OK, I'll just use a 3.31T spur with a 1T pinion. :)

thats funny....i like that one...

Well, i'll hold my comments as well, but yeah good stuff! I'm still curious though. i wonder what the tooth count difference from stock and UE is?

The ue has 43 on the spur with 13 on the pinion.
The hb pro gears are 43 on spur 10 on pinion.

Would the hb work well with a 7xl or 8xl motor..!!! and what kinda speed..??

So basically if you change the pinions, would almost be like stock? What does stock pinions run?

That may be...But the Feigao's and Wanderers aren't as high quality and aren't rated for so many rpm's. The bearings will fail easily. And yes, jhautz is right. 45K would be good for something like a Lehner, but I would perfer to keep it around 40k. It would run cooler, draw less amps, ect.

Thanks CHC. I've added those diff ratios to my speed calculator and uploaded it.

I just realized that if you use the HB Pro diff along with a typical spur/pinion, you almost don't need a tranny, especially if you set the spur/pinion up right...

Brian, are you talking about if you choose to run a center diff?

Squee: No, just the HB diff.

Example:

A stock Emaxx: diff = ~2.85:1, tranny (2nd gear) = 1.72:1, spur/pinion (66/18) = 3.67:1. That's a total ratio of ~18:1.

If you use the HP Pro diff (4.3:1), you only need a pinion of 16T to achieve about the same final ratio of 18:1. Or, if using a 51T spur, use a 12T pinion.

Squee is saying that is what they are made for. They are designed for a truggy. It gears it down low enough for a center diff or slipper in a truck. Which eleminates the tranny. :D

How would one use a center diff in an emaxx? And what center diff would one use?

I used a ofna from a buggy. It just takes some modding. some fabrication. But nothing to serious.

Hey chc, do you have a link for that center diff?

Oh, I thought he was questioning how to get the same ratio without a tranny. :dft001:

Does anyone know about a center diff and if it's possible with an emaxx?