I so want the 80mm 1600kv for my savage. Really can't afford it at the moment especially with the really bad exchange rate. I wonder if this would solve my temp issues with out gearing down.

Does anyone know if the 80mm is too long to fit in the new e-revo? I remember reading somewhere of a person using a KB45 XL and having to do some trimming to fit it in and those are 77x45mm. I would measure it if I had an e-revo but I don't have one yet.

The Medusa is 36mm in diameter so it'll fit. People had to trim stuff to make the KB45 fit mainly due to its 45mm diameter.

Thanks, going to pre-order just as soon as I'm done typi...

Ahh, the art of paying attention...:whistle: I would go with the 2000kv as well.

:lol: That's ok. We'll let it slide...THIS time! But you just used up your weekly allotment of 1 mistake...

I guess that I cannot post again till this time next week...

We'll see how far it would go :rofl::rofl:.

This is exactly my feeling too. Although the speedcalculator and these forums are a great help, it seems impossible to chose 1 motor and getting it right from the start, especially if your setup is different than common setups.

If I understand correctly:
- larger can motors with the same kv rating produce more torque than smaller can motors.
- lower kv motors produce more torque than higher kv motors with the same can length?

So if a have a setup geared for 40mph and I need more torque (and don't want to sacrifice speed) I could:
- get a larger can motor with the same kv rating;
- or go for a higher voltage setup with a lower kv rating/ same can length...

The larger can will provide more torque because there is essentially just more surface area. You get longer coils and thus a longer magnet (rotor) so even though it may be spinning at the same RPM, it will be able to provide more torque. Hopefully someone else can clear this up a little better.

A brushless motor's torque is largely dependant on amps. The KV rating tells you how many RPMs it will spin per volt applied, but the faster it spins per volt the more amps it needs to maintain that RPM. Theoretically, these Medusa motors are all capable of the same output (wattage) as long as they're the same size. A higher KV motor will require more amps and will drain the batteries faster while a lower KV motor will require fewer amps but more voltage.

If you're aiming for 40 MPH (very reasonable goal, according to BrianG's calculator my Muggy was doing around 45 on 5s with 40 series tires and a 2700KV Neu) and you already have your motor, it is cheaper to just get a smaller pinion gear. The smaller pinion gear will reduce the load you put on the motor, ESC, and batteries (reduce amp draw) which gives you more torque in 2 ways. The first way is you now have a shorter overall gear ratio, which is easier for the motor to turn, and the second is you are requiring fewer amps out of your batteries so if you really get it bogged down you have those extra amps to pull. If you aren't happy about the drop in speed, add more voltage. It's a good idea to aim your KV/voltage around 30-40k RPM though these motors can do 50k without coming apart (the bearings are rated to 60k, but you shouldn't need to push it that far).

This is where I get all confused. I spend a lot of time before buying a motor trying to balance out the weight of higher voltage packs with the amp output of the batteries I'll be using while trying to keep temps down. Technically the lower KV you run the better as long as you can feed it enough volts, but adding cells for voltage gets heavy and takes a lot of room. For a 1/8th Buggy or Truggy anything between 1500 and 2300 KV and 4-6s lipo (5-7s A123) should be fine though.

Sorry if I completely lost you, I just spent almost 8.5 hours at work so I'm a little out of it. Hopefully someone else can jump in and correct errors I've probably made :whip:

As I understand, if you go for higher voltage and lower kv, you can get lower capacity amp packs. With 5s5000mah packs you should get about the same runtime as with 10s2500mah packs (both setups geared for the same speed). So the weight of the batterys should be about the same.

what controller
 

What controller are you using with the 9S a123 setup. I am at 6s and really would like to move up to 9s.

Highflier

In theory that sounds about right, but I think the 10s 2500 mAH pack would still be bigger. The weight should be really close though. The problem with running 10s is there aren't a whole lot of ESCs on the market to run that unless you get an air ESC and go through the trouble to make it work. MGM has some ESCs that'll handle it but you're looking at $500+ to get one. Lutach has a 10s ESC though, it seems to be pretty good so far. Not sure what price but they seem to be great ESCs for the price.

Im looking for a few opinions, i just want to make sure i dont get the wrong motor. As some of you may or may not know i pre ordered a MEDUSA 70mm 2300kv motor to run on 4s in my GTP . Is this the right choice or should i get the 2000kv motor instead ?. I have recived a few opinions via pm's, & im looking for a few more . Thank's

The 2300Kv is good for 4S lipos as 300Kv isn't much when using such low voltage :tongue:. I would have gone higher voltage, but if you insist on 4S then it's a good motor. It'll be spinning at around 34000rpm so it won't be running too hot, but that will also depend on your gearing.