Im planning on keeping the traxxas/mamba motor, probly shoulda said that. also, because im getting the e-revo with bl standard, and i wand to run a 700HO 4 the winter. If there are any brushed ESCs that can take 6s... well thats not an option. I could pick up another nimh pack cheap enough, but i dont wana have to condition them. Looks like if I can gear for 40-45 and keep temps low enough 4s is the way to go

arg, ppl say 6s is deadly, but BrianG's calc only gets me to 37 geared kinda high. Comments???

If its geared to go 37 mph on 6s then that isn't high gearing (unless your vehicle weighs more than 12lb).

my maxx is right about 12 lbs.
i finally got a chance to run it a bit with 1515/1Y on 6s.
first off, i'll say this:
6s geared for 40mph seems WAY faster than 4s geared for 40mph!
motor did run a little hot that way and system is much more balanced geared for 50mph.
geared it for 55mph and haven't been able to hold full throttle yet. even after two 15 minute runs. need more room.

...considering the costs and vehicles i run i may go for 5s if i can find some identical packs. otherwise its 2x 3s1p 5000mah packs

Not sure how our scenarios would compare, but I just went from 4S to 6S and my E-Revo is quite a different animal now.

I've been running a Hobbycity KB45-08XL 1600kv motor geared 24/58 with a pair of 2s2p TRC 8000mah lipos and the thing is plenty fast and has plenty of power, but the motor still gets hot after 10-15 minutes and I have to stop to let it chill out. Batteries and ESC are always cool, though. Thinking I may need to go to a 25t pinion to keep the RPMs down or something.

Just got some new 3s1p TRC 5000mah 15/20C lipos and the thing takes off like a rocket now. Insane speed and power, but the motor and ESC got pretty hot rather quickly. Fan was on after maybe 5 or 10 runs up to around 75% throttle down the block and back.

I haven't even bothered to test it out in the E-Maxx yet which has the CC 2200kv monster combo geared 22/62.

Time to hit up Brian's speed calc, re-gear and start carrying the temp gun, I guess.
After reading this thread, I'm wondering if these batteries are going to be a problem.

So yeah, if you wanna show off, I'd still start off with 4S and maybe go 6S later on with a battery that would also work in a 5S config so you have some flexibility. 6S can be overkill, but I am looking for efficiency and heat reduction more than the power and speed. I want a system I can run a whole battery through without it overheating on me.