Is this really a 12's motor?

[BW won]

Leopard 4074, 1050kv, 2600 watt, max amp draw 65 with 45v (@3.7v per cell, 12 cells) as the max voltage, or "lipo cell" as Leopard's website classifies it.

http://www.leopardhobby.com/product/product_veiws.asp?id=1251&functionID=01020201

I suppose my questions should be:
In general, are smaller motors able to trun at higher rpm's (as apposed to larger ones)?
what allows one brushless motor to handle more rpm's than another? Quality of bearings and magnet glue?

[Make-a-Wake]

I'd say 8s for sport boating, 8-9s for racing...............10s for SAW's.

[keithbradley]

It's a 12s motor in a car...not as much in a boat.

[BW won]

I'd say 8s for sport boating, 8-9s for racing...............10s for SAW's.

I thought so,too. However, with a max draw of 65 amps, a voltage of 37 (3.7 volts per cell) would bring the amps to 70+ at 2600 watts (A x V = W or W / V = A). Is this simply not a boat motor?

[BW won]

It's a 12s motor in a car...not as much in a boat.

This would make a lot of sense- my buddy's 1/10th scale castle motor has "good to 100,000 rpm" engraved on it.

[keithbradley]

I thought so,too. However, with a max draw of 65 amps, a voltage of 37 (3.7 volts per cell) would bring the amps to 70+ at 2600 watts (A x V = W or W / V = A). Is this simply not a boat motor?

The motor will draw as many amps as you can supply, if you load it hard enough. There is no governer on brushless motors, that spec is to assess how hard you can load the motor. To get a 65A draw, you wont be able to spin it that fast with a decent prop. A road car is much lower load, so you could get away with it.

[Make-a-Wake]

Is this simply not a boat motor?

Depends on the hull as well. You could actually run it on 6s and use an LV ESC(2-6s) which are alot cheaper. Then you could swing a prop with more pitch to make up for the 'lowish' rpms. Will you just be sport boating??? If so, its plenty on 6s.

What hull and length?

[BW won]

Depends on the hull as well. You could actually run it on 6s and use an LV ESC(2-6s) which are alot cheaper. Then you could swing a prop with more pitch to make up for the 'lowish' rpms. Will you just be sport boating??? If so, its plenty on 6s.

What hull and length?

It was intend to be used in a twin set up for a 41" Apparition- mainly used for sport- really competitive sport . I had a choice of 1050kv or 2200kv for $50 each, so I chose the 1050's so I wouldnt have to buy more lipos ( already had 8s packs). But, after checking the specs of the motor, I started to think I made a poor choice.

[NativePaul]

It will be fine on 8s.

[BW won]

It will be fine on 8s.

Thanks for the info. I thought lowering the cell count ( lowering the voltage) would increase the amp draw, though.

[keithbradley]

Thanks for the info. I thought lowering the cell count ( lowering the voltage) would increase the amp draw, though.

No. That's backward.
It will draw more amps at a higher RPM vs. a lower RPM because the load increases.

A 1000kv motor will pull less current at 30k RPMs than a 2000kv motor at 30k RPM, but will require more voltage.
A 1000kv motor will still pull less at 30k than it will at 35k though.

When you go up in voltage on a given motor, the power increase is exponential and experienced on both the voltage and current sides of the equation.

[BW won]

No. That's backward.
It will draw more amps at a higher RPM vs. a lower RPM because the load increases.

A 1000kv motor will pull less current at 30k RPMs than a 2000kv motor at 30k RPM, but will require more voltage.
A 1000kv motor will still pull less at 30k than it will at 35k though.

When you go up in voltage on a given motor, the power increase is exponential and experienced on both the voltage and current sides of the equation.

Awesome, Kieth! Thank you for your knowledge and patients.