How much more run time from dropping 1 pinion size?
 

Roughly how much longer run time do you get from dropping 1 pinion size? At the moment I am geared for about 50mph but things are getting too hot and only getting 6-7 mins.

what motor you using etc car drop 2 teeth . i run a 15t pinion gear on my losi8t with a tekin rx8sytem with 2250kv. you will not get much more out of them what battery you using 4s ? or 6s . need to know the size of the spur gear etc and motor . as i get 20mins if not more out of my 4s packs

Losi madness is right it really depends on your battery and other set up.

But if i had to tell you something general i'd put it like this. According to my pinion testing (and i do organized timed testing on spreadsheets), I tend to get 4-5% more run time per tooth down, until i reach such a high torque that I am getting such excessive wheelspin then it actually gets worse.

On my Mugen with my 1900kv 4s, diminishing returns or reversal of time happens around 12 or 13T. That can be different for your car, track condition and driving style, so take that with a grain of salt.

Its called a Wasp 36-56 1800kv on a tired old 6s 2650 pack. Currently 13T with 46 spur (I think), its a Caster ZX-1, Mugan MBX5 copy so im told?

It is very fast! Ive ordered a 12T pinion and made a very large heat sink for the motor on a lathe. If that doesn't cool things down I think ill switch to 5s 3300mah, although a good 5s pack probably wont drop much voltage lower than the old 6s pack under load.

Ive also since put the servo disc break back on and programmed out the motor break, I presume this will put less stain on the motor and keep it cooler?

what sytem you running esc and motor ? you need bigger mha 5000mha plus and a good c rating about 35c to 50c . that why your batterys only lasting 7mins . my 3000mha 35c last 20 mins i dont know why your get so sort of a running time etc . and try turn your esc down etc if you can . i got 4s lipos forsale that like new

The main problem I have is gearing, the 1800kv motor is a bit high for 6s li-po and its hard to find a small enough pinion. Where can I get an 11T Mod 1 5mm bore pinion?

try modelsport uk there not cheap lol there in shock . go to the search and type pinion

Ihave a brand new losi one £5 posted

Rich is right that motor is too high for that 6s. The cheap solution would actually limit your travel in your controller to 60-70% of full. This will effectively limit the Volts that is feed to that 1800 making it feel and behave like a 4s. It should bring you back down to about 30mph speeds, cool things off and increase run time. Keep the rest the same man and try this first if you dont want to buy alot of 4s packs at the moment.

While that method might keep the motor temps down the ESC temps would increase as the ESC has to bleed off the excess voltage that isn't being used.

Na, my ESC's never increased when I do that, infact they go down too. That sorta of logic also would say an ESC would get burning hot if I ran my car at only 5mph since there is SOOO much unused voltage. I mean sure its got to go some where but time and time agian this technique cools all systems down when I do it.