Difference between gearing up and adding timing?

[Dan Pickard]

Will there be any net difference between the two? Will one have more of an adverse effect on the motor over the other? Thanks

[sosidge]

Very different.

Timing changes the motor's performance (within limits, more power at the expense of efficiency), gearing just changes the way the car uses the motor's power. Both can kill a motor if you aren't careful.

[Welshy40]

Sosidge,

So as an example if i were using a 6.5 and had a factory recomended ratio what would you do to make it have more top end? Alter the timing, gear up or both?

[12-nitroman]

adjusting the timing on the motor or the esc will have make your motor temperatures higher if you adjust the percentage to max.
usually motor timing makes a difference upto a certain percentage depending on motor and after that all you'll be doing is overheating the motor.

i would recommend using a bigger pinion (depending on how big the race track is) you could also adjust the timing, but if you think the motor .temps are too high then you should decrease it.

Sosidge,

So as an example if i were using a 6.5 and had a factory recomended ratio what would you do to make it have more top end? Alter the timing, gear up or both?

[SlowOne]

Power = torque x revs. You need power through the whole track so whatever you do to one side of the equation hurts the other side.

At low timing levels the motor has more torque. Torque, or turning force, is what you need to get weight on the move. That means that you can have higher gearing so you get speed on the straight, and it will pull the car out of the corner faster.

At high timing levels the motor will get to a higher rpm at the expense of the torque. In these situations the gearing is lower so that the car will pull out of the corners and then use its higher revs to get speed on the straight.

In both cases, give or take, you are putting the same energy in, so you will get the same power out. It just comes out in different ways. The 'give-or-take' bit is that there is a 'sweet spot' in there where the motor is at its most efficient so giving you the best lapt time for the lowest energy used. Less energy used means higher cell voltage through the run and therefore better performance towards the end of the race. But...

A dc electric motor retards under load. The interaction of the permanent magnet (rotor) and electromagnet (coils, or stator) fields is such that as the load on the motor increases, the effect is to reduce the timing. So, if you want more total power, then you have to start throwing some dynamic timing at it - boost.

When the static timing is low, the motor is suited to low revs and producing good torque. AS the revs rise the motor retards and so it tops out at a lower rpm. When the static timing is high, the motor is over-advanced at low revs so can't spin up so easily, but then tops out at a higher rpm.

Dynamic timing is in effect adding timing in as the revs rise to cancel out the effect of the retarding caused by the interaction of the magnetic fields. That's why these speedos are so devastatingly effective, because they work to cancel out the natural restraints on a motor enforced by the Laws of Physics.

Having said all that, if you gear wrongly you will toast the motor whatever the timing, boost or turbo you use. If you want more straightline speed then the best answer is to put in a faster motor, or dial in some boost. If you go the boosted route there is no need to add static timing or change gearing, just bring the boost in late in the rev range so you get more revs without upsetting the torque low down. Make sure static timing is at zero and then work with the boost settings. HTH :)