The Feigo would be better cooling people say as it has the attached heat sink. but really, if you want a "cool" system, go with like the 7xl on 4s should be good. Throw a fan on the esc, heat sinked motor, and you should be fine. this would also depend on gearing, what pinion you use, the spur, the pitch of both, your weight, many things.

I am defiantly going 4s no matter what an my truck will weigh a little less than stock. i want to at least stay in the 40s consistently and reliably. that is my goal. also i want a pinion that will get me here without straining the motor and running cooler(than it would with a 20t). Also i want to know will the motor(7XL 540) run cooler with the smooth can and RC monster heat sink, or will the 7xl540c w/ built in heat sink run cooler. I want to use 36t spur and maybe 18t(if it runs noticeably cooler than 20t) pinion do you think this will be as much stress on the motor as the 20t or do you think stepping it down 2 teeth on the pinion helps it run cooler and more efficient.

Ok, here is what I ran to give you an idea. I ran the 10xl on 5s geared 18/51 mod 1. You can use the Feigo 540 7xl with the 4s. what slipper are you using?

revo slipper and slipperiential

someone would need tochime in here as I'm not familiar with the Revo slipper. But I would think you would want like a 44t and 16t pinion

The biggest spur for the Revo is a 40T. Also, why would you want a 44T? Thats to big...Your gonna need to go as small as possible on the spur and probably as big as possible on the pinion if you go with the Slipperential...Anywho, I would go with the buggy diffs, a 7XL, 4S LiPo, and somewhere around a 18T pinion. You should get around 39 mph without the tires ballooning (if the tires balloon slightly, you will gain a mph or two...). With a 20T, somewhere around 43...That should be about right...

Why? Because as I said, I do not know the Revo slipper and what it takes and would hope you would chime in! LOL, also, henever specified what this is going into? Anywho, I was thinking the 36 would be too small and the gearing would be too high....

take a look at this thread it will give you a better idea of my future set up and see if you can tell me if you think the motor will run cooler than it would with a 20t ad more efficient and reliable. Thanks

You should be good with an 18t

Well lets put it this way. You will need about 1200 watts of power to get to the
50 mph mark. If you run 4s with the drain on batts 3.5v per cell =14 volts.
You be drawing about 85 to 86 amps to get 50 mph.
If you go 5s. It will have less amp draw to go 50 mph at 1200 watts.
But even if the cells are still 3.5 volts. The amp draw will only be about
68 amps. For no matter how much gear you put on it. It will still take
a certain amount of wattage to get the speed you want to run.

i gave up the 50mph goal

i am just now trying to run the 7xl cool and efficently on an 18t pinion.

So you in the test mode now. Let us know.

You should be happy. 50 is nice, but not totally needed for most applications.

I'm aiming for about 55 mph with my BPP LSP. Thats with normal gearing as well :D.