Gear ratios
 

Hi guys, I'm fairly new to the EP scene, and I was wondering how do you find out what gear ratio to use for a track?
Im running a Tekin RS/Redline 21.5 combo, and I was told to start around 5.5 FDR for this particular track, but I only had 5.28. I couldn't get the motor under 90 degrees that day and it was a cold day. The highest I came out with was a whopping 110!!
I tried changing the timing, boost and turbo, but after reducing the timing from 60 to 20 (212 software) the next race launched me to 110.
I had crappy acceleration and was outpacing the rest, even after all those changes, but still could not get the temps down! Did all I have to do is go a larger spur/smaller pinion? Or drop the current as well?

Take you spur divided by your pinion x's your drive ratio (2.167) for the hot bodies to figure out your FDR. Also you should be shooting for temps around 150....

Sorry, I should've been more clear with the temps, that 110 was 110 Celsius.
My FDR is 5.28, that's all I have that will fit atm. otherwise I have a spur that would make it 4.28

Oooooh my, that motor is likely a paperweight now....Sorry I misunderstood you.

what is your setup on your speedo?
do you use motor timing. if so lower it.
higher your start rpm.
as you set your start rpm higher and your rpm range wider, than you get also lower motor temps.
what is your turbo ramp and delay?

Heres my Speedy specs:
Current Limiter: Off
Throttle Minimum: 0

Timing Advance: 20
Boost: 50
-Start @ 2850
-End @ 12000
Turbo: 13
-Delay: 0.15
-Ramp: 2

Motor timing: looking at the motor with the pinion on top, the right side of the notch is a small part past the 2nd line.
I was told by a good racer, after i finished racing, that maybe I shouldve geared it higher for more acceleration less top speed, seems maybe I should do that for that track.
And no, the motor is still fine - no melted parts and it still runs fine.

Edit for next post...

look one post up!

We still need to know what pinion and spur gear you are running. (???)

Too much timing advance?? On 20?
OK, I'll try Ramp 1.

My S/P is 100/41.
Internal FDR is 2.1667 (18t pulley's)
This limits me because I don't have much room left towards the gear side, so if I was to go higher, i would need bigger spurs.
One thing I need to get also is a heatsink for the motor - that would dissipate some heat too.

as you use timing on the motor, gear than higher. you will lose some topspeed but as you change your setup. you can get some topspeed back.
I would start with setting the start rpm higher. tiss will give you more power for accelaring driving away and comming out of the corner. lower motor timin will do the same.
also set your turbo delay higher.

your setup has a lot of timing ad the moment that your motor must work harder to accelarate.try this.
turbo 15
boost 50
motor timing 0
turbo ramp 2
turbo delay 0,8
start rpm 5000~
end rpm 14000

as you drive away with 0 timing, than you will have the most power.
the motor can as it goes faste, work with more timing.

as you find that the motor stays cooler and you want some extra topspeed. ad than some extra motor timing. start with just a bit of timing.

With the motor timing, is that in the ESC or the motor itself? I have both adjustable, so which are you referring to?

First off, if you're running sensored only mode, timing advance would only come into play if the motor sensor wire was removed. The ESC then falls back to sensorless mode. If you're running dual mode, then the timing advance setting is used after the ESC switches to sensorless mode (after the car moves a few inches).

50 boost and 15 turbo are way too much. Turn off turbo, start with about 45 boost, and play with gearing first. After you get the gearing right, add a little turbo at a time. Try an FDR around 4.5 - 4.75. When we were running 21.5 in VTA last season (no turbo allowed, but boost was) that gave good motor temps and decent speed. I wouldn't go much above 45 boost and 10 turbo. The start / end RPM was 3500/5000, since a 21.5 doesn't turn that many RPMs.

So using dual-mode will let me be able to effectively use the timing advance in the ESC?

I've since changed the advance and turbo to 20 and 13. That was when the heat jumped to 110 C, it was usually around 89-90 in previous runs.

both.
as you use motortiming and a low start rpm and a low turbo delay, than you have a lot of timing ad once and you will lose a lot of torc.
you can gear higher to make it lighter for the motor.
the best way is to set the start rpm higher and a lower motor timing.
you can also chose for some motor timing, but set than the start rpm higher.
as you set a lower motor timin, than you can set the start rpm lower.
you can run with 0 turbo delay. this will make your motor fast to hot.
just use it to ad some top speed.

as you need more power set your start timing motor and speedo timing lower.

timing advanced is in dual mode? timing boost is in sensort mode.
do you run dual or sensord mode?
because the timing in dual mode will not change your speed or power as you run in sensord mode.