Motor size 40mm--56mm

[Namba328]

If the amps and kv and max cells are rated the same, why go with the bigger can ?

[longballlumber]

My understanding is more mass to dissipate the heat created from the lack of efficiency.

Later,
Ball

[HTVboats]

The larger can will have a larger rotor with more mass. This will limit rpm range but yield more torque and turn larger diameter props. Kind of like a small block, big block, or short stroke vs long stroke. Either will work but depending on the hull size, weight and design one will be more efficient. A large mono or cat might work better with a 56mm can where a light weight rigger might work better with the 40mm motor. Being electric motors torque curve is more straight up and flat doesn't mean one motor doesn't produce more torque with similar watts or HP.
Mic

[Namba328]

Mostly asking for my dad who is converting his scales to FE, So it sounds like the smaller can woud be fine?

Tom.

[jkr]

Scales with what kv?
Why not an outrunner?

[Namba328]

Haven't looked at outrunners , he's shooting around 900-1000 KV on 8s. Any info would be grate.
Tom.

[jkr]

Hull?
Size?
Weight?
8s1p or 8s2p?

[Namba328]

1/8
42"
4 lbs empty
2x4S 5000mha

[RayR]

The watt rating of the motor will tell you how much heat the motor is capable of absorbing/dissipating per unit of time. The larger the can, the larger the watt rating, the longer the life span of the motor.

This assume the manufacturer tells the truth. Attached is a chart of the Neu 15xx and BAM series motors. as the can length gets longer, or diameter increases (more mass/metal), the motors are capable of absorbing/dissipating more heat.

Watts = Volts x Amps

As an example, the 1527 1.5Y on 10S is a common motor used for 1/8th scale boats. The average lipo puts out 3.4 volts per cell under load. The average 1/8th scale boat draws an average of about 120 amps continuous on 10S. Therefore, 3.4 X 10 X 120 = 3960 watts. On the upper end of the rating of the 1527 motor can size.

[jkr]

If you go outrunner then a scorpion hk4025 1100kv will work.

[785boats]

I run a 1527/1y (1250kv) on 8s in my 1/8 scale. I was going to put a 56 size motor in it, but it's just not needed.
But my next one will be around the 1100KV on 8s I think.

[iridebikes247]

I would stay away from outrunners, take a look at the size, dimensions and weight of a 4025 scorpion, they're quite small. Outrunners are cool but inrunners have proved superior in boats no question. I have run scorpion and also hobbyking outrunners, power is good but an inrunner will just stay cooler.

I think something like a neu 1530 would be a good choice. I've owned a few of them and they're very powerful for their size/weight.

[Agitator]

I run Scorpion 4035/800's in 2 of my 1/8 scales and have plenty of power on 8s. I also have one running a Neu 1527 1.5y 850kv on 10s. If you plan on any racing, these are the legal motors. And you can still get 4035/800's either directly from Scorpion or from Innovative Designs. The 4025 is way to small and will not last long on 8s-it is rated for 6s max. What ever you run, get a 8mm shaft and your bearings will last much longer. 1527 1.5y is pretty much the standard motor for those of us running 1/8 scale.

[jkr]

Agi
Have you run the 4035 on 10s?
The 4025 can run 8s with no problem 50-52mm prop.

[Ub Hauled]

I used to spin 48+ props on my 1/8th scale on 10s with a scorpion 4035/800, it was popping wheelies... 8s would be enough.
It's a beast of a motor with LOTS of torque.