Because motor rpm isnt the only thing that determines the systems power output.
From what I understand, and there are much more knowledgeable people than me on this board, amps are what cause heat buildup in most ESCs. Also, the amp load capability of the battery can be a major limiting factor in the total power output. So keeping the amp load low is important for efficiency and longevity of everything in the system. Since power is determined by amps and volts, the only way to lower the amp requirement without losing power is to also increase the voltage. It also works the other way, the only way to increase power without increasing the amp load is to increase voltage.

BP revo beat me.

So does voltage directly effect motor efficiency? Ive seen people calculate power output by multiplying the motor efficiency by the watts drawn from the battery. Then its assumed that the extra 10-25% is turned into heat. If less amps also means less heat, is that any different from using a better motor?

ok so i was kinda right.

keeps heat down and improves efficiency

i just bought this.
http://i1.ebayimg.com/01/i/000/bf/49/c918_3.JPG

its the onroad car yusa 1/8th scale. i may have to buy a single speed center diff for the conversion, but i always wanted a 1/8th buggy converted rally car, and couldn't pass up $79.

btw, he has another buggy for sale.

P = V * I

V = I * R

Hence Power = Amp * Amp * Resistance

Motors have fixed resistance (Ignoring heat changing the resistance of the coper wire ).

Therefore Power loss (aka heat generated) increases with the square of the increased amp draw...

This is why people go for increasing the voltage and decreasing the current to maintain a fixed power

Hey, let me know how you like it, im always looking for a rally chassis, its what got me into the hobby, but i have a hard time finding anything

...and then there were THREE
 

OK guys Yusa Buggy #3 is on it's way.

The ultimate head to head testing:

1 - Nitro Buggy
1 - Direct NTB (Nitro to Brushless) Conversion that retains disk brakes
1 - Plate (RC-Monster style) NTB conversion that has the motor handle breaking.

So far here is the propulsion I have to test.
Brushless
Neumotor 1515/1Y
Neumotor 1512/2.5D
Hacker C50S Maxx
Hacker C50S 11L
Medusa Research 2200Kv 10th scale motor with heat sink
Novak HV4.5R System
Castle Mamba Max ESC
I am sure a Tekin will end up there somewhere.

Nitro - We'll see if they all fit
Nitro Star F4.1
Nitro .26 Hotbodies
Traxxas 3.3R

Should be a fun but very long test.

Under penalty of death and divorce my wife assured me that this would be the last and final Yusa buggy I purchased. :(

new guy here. I bought the last Yusa buggy
 

and his .27 Infinity motor to go with it. Ill get it together and post pics.. :)

hey B15.. you ever get the parts from larrys for yours? How were they??
Frank

for you guys who converted your to electric.. Ya want to get rid of your parts you ripped out?? I can use spares:)

I can't speak for B15, but I've ordered spare parts for my Yusa 1/8 rally conversion from Larrys.I got my stuff in about a weeks time.

thanks..

I did also, read near the bottom of the third page.

ok missed it.. Thanks..

Just received the Thunder Tiger EB4 S2 "PRO" RTR from RC Car as payment on an article. This looks pretty much part for part a Yusa. The bad news and very sad part is that the Yusa is a much higher quality build. The EB4 doesn't even have sway bars, or adjustment nuts on the links. It's like Thunder Tiger took a decent cheap roller chassis and then stripped it of everything good.

Feel I got a better deal on the Yusa's by the moment.