motor upgrade help

[jp79er]

I want to upgrade the motor in my truggy but want to ask if this is the way to do it:

 

 

My current motors all I know about it is that is a 3065KV brushless/sensorless, so to work out its current performance as a bench mark:

 

3065KV x 11.1V = 34,021.5 is its top RPM

 

I now know in my truggy with all the ratio of gearing that approx.

 

34,021.5 will get me to 39.1mph (So 870.11RPM will get me 1mph)

 

So that as a rough guide is my starting point......

 

 

 

 

So if I shove in a 3600KV and run the same math:

 

3600KV x 11.1v should top out at 39,960RPM

 

So 36,960RPM / 870.11RPM = Should get me up to 45.9mph

 

 

or a

 

 

4000KV x 11.1v should see 44,400RPM

 

and 44,440PRM / 870.11RPM + Should see me at 51MPH (which is pretty much a firestorm Flux at full chat)

 

 

I know this will depend very much on the battery and the `C' Rating and the I guess the ESC?...but as a guide I reckon it probably not a million miles away...

 

I have also worked out percentage speed increases for changing pinions and spurs but that's something else....

Edited September 18, 2014 by jp79er

[jayuk022002]

Have a look here

 

http://scriptasylum.com/rc_speed/top_speed.html

[jp79er]

I have seen that before but that's a lot of inputting of values I don't know of my vehicle...

 

I calculated mine on known values as from what I understand a `volts x motor KV' is max RPM (not under load)...but the speed is taken from real time data, the only flaw is that the fact the RPM will be down from its top rate, but this difference would be mitaged to a degree from the telemetry taken as the top speed is based on GPS reading, this should capture the gearing ratio, weight, rolling resistance (on grass), difference in RPM reduction etc.

 

So hopefully now that across grass...I know with in a little 3600kv motor will get me around the 45mph, but if I want to get to 50mph I need to look at 4000kv motors...

Edited September 18, 2014 by jp79er

[jp79er]

Also looking a bit further my ESC is probably good for around 3500KV motors but no higher...SO looks like a combo is in order oh what a shame that will be....NOT

[jp79er]

Have a look here

 

http://scriptasylum.com/rc_speed/top_speed.html

 

Ok....now I have had a change to google and count teeth on things and measure...I think I have it.

 

Diff ratio - 3.090

Spur - 62t

Pinion - 22t

Motor 3065kv

Wheel 4.1" (No ballooning)

 

with

 

6cell NiMH - result is 30.91....my GPS thing says 28mph (running on hard surface)

 

3c Lipo 3.4v - results 43.7mph,,,my GPS thing says 39.1 (running on short grass), plus the run was after 6mins of pounding the battery

 

3c Lipo 3.7v - results 47.65......my GPS thing is to be tested....will be intrested in what I yield in the first 5mins of full charge....????? on a hard surface

 

Interesting, will have to play around some more.....also the new tyres I want to put on have a larger dia. just slightly.....

 

 

 

Chewers as you made me look at that chart a lot more closely...