RPM question

[floatn turd]

kv_voltage[1].pdf <------open for the KV volt, chart.


I gots me a question.

If a motors max RPM is 58K and I want to run up to 8s and not blow it up. According to the chart: I should buy a 1,200KV motor, but if it spins up to 58K then could'nt I go with a 1,610KV and still be fine?

What is the advantage of staying @1,200KV?
Will I get more power with the 1,610KV, or is it just a matter of how I prop it? (as far as power goes between the two "KV's")

PS the motors in talking about are the: TP Power Pro Competition Series 4050 1160kv
TP Power Pro Competition Series 4050 1610kv


thanks

[Boaterguy]

rpm isn't everything, you will draw tons of amps spinning 58k unoaded, most don't go over 40 or 42 (unloaded that is).
spinning a small prop at insanely high speeds isn't the only way for speed (sorry if i sound harsh), setting up is a huge factor
you could run the 1600kv motor on 6S and 7S for SAW (high speed, single or double pass runs) and have a good setup.

[floatn turd]

So then, the 1,160KV is probably the way to go for longevity of motor life? If they will make the same speed (more or less) then it sounds like the smaller KV (1,160) is the better route to take, running 6s-8s.

is my thinking right?

[LarrysDrifter]

1610kv on 8s would be blow up mode. This kv is better suited for a fast 6s set up.

[floatn turd]

I agree with you, but is that still true on a motor with a max 58K rpm, and according to the chart on "Fightercat" the 1610KV on 8s is @ 48,840RPM. Would I be drawing to many amps with the 1610KV on 8s? Is that why I should go with the 1,160KV?

I just want to buy the right motor the first time. So I have a lot of questions.

[jamespl]

I always thought between 30,000 and 40,000 rpm was the best place to be. And around 30k for sport then closer to 40k for racing. Or have I just made that up? Sure I read it somewhere.

[Rumdog]

The motors max rpm means nothing.

[floatn turd]

I always thought between 30,000 and 40,000 rpm was the best place to be. And around 30k for sport then closer to 40k for racing. Or have I just made that up? Sure I read it somewhere.

Thats right! thats what it says in the chart at the top of the page. But if a motor can take the RPM's why stay low with the KV's? is my question. (chart recommended 1,200 ish on 8s)

[floatn turd]

The motors max rpm means nothing.

why is that?

[Rumdog]

You are loading it. It doesn't matter what the bearings can handle. It wiil draw more amperage at a higher rpm, and you'll be forced to use a tiny prop which will likely push your boat inefficiently.

[floatn turd]

Got it, thats what I needed to know,

So I will order the 1,160KV motor instead.

thanks for the info.

[rcboatmanwithkids2880]

Hi Guy's

On another tact , couldn't you run a motor such as the Turnigy 56-74-1050 - with T180 . Then prop up to about x450ish & have good reliable results on 6s , just a set - up I have been advised about , that I am considering ??

Brad
Oz

[iamandrew]

Dood, forget about how fast a motor can actually spin, but the rest of the equipment!
you could hit a peice of weed and destroy your prop and flext shaft, and send that through your hull!

[martin]

As been stated the rpm a manufacturer states is meaning less in a boat, take the same motors we use they also use these motors in ducted fan airplanes on much higher voltages at unbelievable rpm. Safe for them but not for us in boats, all to do with loads & amp draw.

[Boaterguy]

big prop, high rpm, low amp draw, pick two.
goes well with the saying cheap, fast, reliable.