Confused about pinions

[Aussie newbie]

Can anyone help me understand the effect of using different sized pinions. I am flying an X400 eCCPM conversion with standard Ark 2750kv motor and 13Tooth pinion.

What would be the effect of using a pinion with more or less teeth?

I am currently getting about 6.5 minutes flight time with an 11.1V 1800mah Lipo. Have no idea what my head spped is as I don't have a tacho.

Any help would be appreciated.

Thanks.

[L0stS0ul]

using a pinion with less teeth will give you a lower head speed and lower amp draw. Using a pinion with higher teeth will give you higher head speed and higher amp draw.

You generally have to find the perfect balance of both so that the motor runs in it's efficient range. unless you enjoy popping pinions on and off it's best to read up on the motors and see what other people are using.

Here is an easy formula that you can use to guestimate headspeed

((Motor KV * Battery Voltage) / (Main Gear Teeth / Pinion Teeth) ) * motor efficency

So you have a 2750kv motor with a 13 tooth pinion on an 11.1v battery. The MX-400 has a main gear of 138 teeth and the motor is probably in the 80% efficient range so...

(( 2750 * 11.1 ) / ( 138 / 13 )) * .8 = 2300 rpm of the main rotor.

[Steeltoes]

Smaller the pinion slower the head speed, larger the pinion the faster the head speed. If you want a higher headspeed you may want to look into a higher kv motor. (ex. 3550kv) You could use a 11t pinion and be around the 2700rpm mark.