LST on 6s, What motor size?

[Crazy L]

As per title, I'm working on a brushless conversion of my old Champion/Wong bothering LST, I had planned on either 4 or 6s, so am after a guide as to what motors to use for these cell counts respectively. I have only one 6s pack but have two 4s packs and another 4 sets of 2s I can use for 4s duties. But would like to use the 6s too.

Any recommendations and /or advice would be apprec'd.

Ta muchly

[Crazy L]

Cheers folks, I guess no one on here has the slightest then

[dodgydiy]

1900 to 2200 kv on 4 cell, around 1400kv on 6 cell seems about right in an 1/8 buggy so would guess similar in anything else, geared correctly of course. thats about all i can offer

[Pulse]

If the weight is more than 3kg600, get a long can 1350kv T8. It will give you more torque. If the weight is under, go for a 1400kv.

I've tested about all motor kv ratings from 2S to 6S on a 1/8 buggy and a 1350/1400kv 6S setup will give you everything you need: torque, low temps, long runtimes and less stress for your ESC. Higher voltage setups are really better overall.

[jasonwipf]

Nice to see people are using my motor selection guide. I averaged that data from forums around the world and near 100 drivers submitting their stats. Randy Pike, lead service manager for Tekin said it was an accurate guide, even though he didn't like seeing references to Castle motors, lol. 2 months ago I switched to 6s from 4s in my buggy and bam, the mileage estimates were right on target.

[Pulse]

I'm running high voltage setups since a long time but this guide is a very good basis, good work

In racing I'm running 5S 1400kv on small to medium tracks, and 6S 1400kv on bigger tracks. I like the 1350kv on astro because it has more torque which is great when the grip is here.

I asked Randy Pike for a lower kv for 6S application many times but in his opinion the demand is too low, sadly. A 1200 or 1250kv T8 motor in 6S would be awesome and equivalent to a 1900kv in 4S but with less heat, better runtimes, and smoother motor response.

[jasonwipf]

true, the 1400kv 6s is faster than my 1900kv 4s, maybe a tad too fast, feels like i'm running a 2050kv 4s. Bright side is I have tones of speed and cooler temps still. On smaller tracks I'll turn down my EPA and calm things down.

[Pulse]

Originally Posted by jasonwipf

true, the 1400kv 6s is faster than my 1900kv 4s, maybe a tad too fast, feels like i'm running a 2050kv 4s. Bright side is I have tones of speed and cooler temps still. On smaller tracks I'll turn down my EPA and calm things down.

You should try a 5S lipo on smaller tracks, motor response is smooth as silk (similar to 1700kv in 4S) and you'll have more than enough top end. You might just get a bit higher temps from your system because of the taller motor pinion. I run no fan on my RX8 and on a very hot day I'm close to the limit in 1400kv 5S. The annoying thing going from a 6S setup to a 5S is that you'll have to change everything (brake power, current limiter, pinion etc..) to obtain the same feel as in 6S.

[dodgydiy]

I have a 1400kv outrunner in my car. The wattage is a bit lower than most of the inrunners at 1600 watts but it is only slightly bigger than a standard 540 can motor, torque is immense though. Have only run 6 cell on it, iff i want less grunt i can just set throttle end point and loosen slipperential slightly

[jasonwipf]

Thats sounds like it would work: running 5s for smaller tracks and 6s for larger tracks. But my Serpent has a saddle pack setup so that might be hard.

Interesting note. At a recent race, on what Europeans might consider a medium/large track i was running my buggy on 1400kv 6s and my best time was 29.45sec. On my truggy I had 1350kv 19.8v LiFe pack (which in my boats felt like a 5s LiPO) set up which felt much slower and was mathematically at least 10% lower rpm. Yet, I was still able to pull off 29.43 with that truggy. That truggy was so slow that on the straights people were passing me something bad, it was my 2nd class and I just ran it that way as my "for fun" class. But as you know truggies are big and very easy to handle so even though I was much slower I was able to get virtually the same lap times as my very fast buggy because on the infield i was smooth as ice and ubber stable. Sometimes we need to remind ourselves that too much speed results in excess wheel spin, excess brain power directed towards keeping the car in check/stable and not on making turns and jumps smooth. This was on a track in America so those kv numbers may not apply but you get the idea.

Side note: LiFe packs, run at 3.3v instead of the 3.7 volts you see with lipo (3.6 at full charge/cell for LiFe batteries). The Iron Fe in LiFe packs are heavier than lipo per MAH of capacity but you have more usable MAH since you can run them down to below 3.0v safely. Since you can use all of the available mah you do not have to run as large of a mah pack as you would with a lipo. In some tests I ran the cells down to 2.2 volts and no puffing. But vehicles were slower and selection is bad vs. lipo. Might be an option for people who want to get a noobie a basher car and do not trust them to manage lipos safely. Keeps the speed in check and the fires away. Set Lipo cut off on ESC at about 2.8-3.0 volts/cell. Setting at 3.2v/cell will trigger Lipo cut-off prematurely as current spikes will touch that frequently with a battery that has an average voltage of only 3.3v/cell. Voltage curve is very flat, when it dumps it dumps FAST. Just an FYI guys in case any of you were wondering about LiFE packs.

[Crazy L]

Ok guys, sudden change of plan, the LST (monster truck) will now be run on 4s. This is due mainly to the hobbywing speedo letting go today in my MGTe. I went out, the steering stopped working all the time I was using the throttle. When I let go of the throttle, the steering came back. Anyway, it went pop, and subsequently took out the 6s brick sitting 2 inches away, melting my shell and billowing acrid smoke down the street (yes, I said street, the truck was on the pavement outside the house when it happened)

So 4s, in a monster truck. Will a 2000kv be ok? All I have now in my stable, and the other money is now going to have to fork out for a new esc and battery tray

P.s, pics are on my facebook for those who know me.

[jasonwipf]

ya, 4s with 2000kv should be fine as long as your ESC can handle it.

[Crazy L]

Well, the hobbywing was rated at 150 amps, so I don't know why that went pop

My other dilemma now is, Do I go or another Hobbywing? the one in my 1/10th buggy has been diamond, So I figured maybe I was unfortunate with the 1/8th esc.