4s vs 5s and gearing

OK so i,ve a big question. I,ve sell my RC8 to my brother but i,ve keep my brushless system and i,ve put it back in my Mugen truggy yesterday night, and the setup is, flightpower 5000mAh, 4s, Neu 1515 1Y and MGM16018.
I,am geared 15/46 on 4s, but i,am plan to buy a 5s or 6s this week.
I want to know, if i run my truggy on 5s or 6s, can i leave the same gearing (15/46) or i must absolutly go down on the pinion

I,ve keep the mechanical brake on my mugen, and i,am limit to a 15T on the pinion, i can,t go down. If i want to go down on the pinion, i must remove the mechanical brake and use the controller for braking, and i realy don,t want to do this.

I know if i go 5s or 6s with the same gearing, the top speed will be realy to fast, but my goal is not to be realy faster but it,s to go down on the current.
So if i keep the same gearing, is my current and the temperature will go down and the efficiancy will be about the same or i will reduce the runtime, raise the current and temperature

Thank you!

[othello]

>or i will reduce the runtime, raise the current and temperature

This is exactly what will happen when you increase voltage without changing gearing. So yes, if you increase voltage and you don't want to go faster and want to benefit from lower currents you have to change gearing. Why do want to go down on current? Do you have heat issues with your ESC, motor, battery?

I would like to have harder acceleration. For sure, little more top end would be nice too
My friend have a Jammin CRT truggy with the new OS .28XZ and i want smoke it on the track.

so if i well understand, if i go 5s or 6s, i must to gear it down to stay in the 40mph range, like on 4s setup???
But if i keep the same gearing, i'll pull more curent??

[othello]

First thing i would try at your place:
If your electric components do well on 15/46 and you see some headroom temperature wise, try 16/46. With good batteries (flightpower for sure are) you will see an increase in top speed and acceleration won't really be any worse. But check your temperatures.

A friend of mine runs his Mugen MBX5T like you do with a 1515/1y and MGM 16018, but he uses 6s2p A123 which can be compared to 5s lipo. This translates to good top speed and more acceleration then the car/tires can handle. But the motor does reach 70°C at the end of a 7-9 minute run with 25 degrees outside temperature. Still on the safe side but this tells me, that 6s Lipo would simply be too much -> too much power and every component would run at its limit.

With 5s your voltage increases by 25%. With a good 5s battery your top speed could increase by 15-20% (when you do not change gearing) as your new 5s battery will most likely be heavier then the one you are using now, air drag increases ....

You will definitively use more current, as going faster and getting to higher top speed requires more energy. So runtime will decrease when you choose a flightpower 5s 5000mah (compared to your 4s 5000mah) without changing gearing.

OK i,ve look for the Flightpower 4350mAh, 5s. The weight is about the same, and i,ve try a 14T pinion and i,am to the limit but i can use it. On BrianG speed calculator, with my actual setup i,ve a top speed of 40mph, and if i go with 5s and 14T pinion, i have 46mph.
Do you think that i,ll see a big difference with this gearing and a 5s, and for the runtime and temps, i think it should be about the same

What do you think

[othello]

Theoreticaly with 5s 4350 (78300mWh) you will have 8% more energy on board when compared to your 4s 5000mAh (72000mWh) battery pack. But on the other side your car will need more energy (higher top speed ...), therefore i would expect the temperatures to rise somewhat. Runtime will go down somewhat too. But as you said not by far.