Brushless B4
 

Hey guys, im gonna go BL in my B4, but was wondering what setup to take for it? I was thinking a 1920/1930 with a quark 80B but was wondering what turn/size of lehner? Thanks guys, BTW im running 6 cell packs.

I assume by "6 cell", you mean 6 NiMH?? If so, why not use the MM ESC? It's smaller, more powerful, computer programmable, and cheaper.

Yes, 6 Nimh. I was thinking of using the MM esc, but what motor? I would love to run a lehner in it for the greatest efficiency. Thanks.

Well, how many RPMS are you planing to get?

get the mamba maxx.. it's cheap, and reliable....
if you want high rpms.. it's difficult to get high efficiency with 7.2 volts...
for example, say if you got the 1930-4 HiAmp(5225 kv) version.. you would only reach 90% efficiency at 90+ Amps...

Im not sure what RPM i want, id want somthing equivilant to a 15 T brushed motor, just dont want it to run too hot. Thanks. MM esc it is.

Not sure the kinds of rpms brushed 15T motors gets....

I was thinking of the MM combo, the 4600 pack, think this would run for a 5min main on GP3700 packs? Or would you reccomend a higher kv? Or maybe a better motor? thanks. The brushed motor gets 31,750 RPM. This is the motor i was supposed to use. http://www2.towerhobbies.com/cgi-bin...?&I=LXJAJ4&P=7

you should last 5mins without a problem...

So what you think, 4600, 5700 or 7700? I was thinking 4600 for longest run time, but the 5700 will give me a nice balance between both. So its either the 4600 or 5700.

Well, you could try the new version of the R/C Calculator to see what motor it suggests. Just go to the Motor Selector page. Besides, I'm curious to see what it says for real-world applications...

The 4600 and 5700 will run for over 5 minutes easily. The 5700 is a really nice speed on 6 cells.

5 min on 3700 in a light little B4 should be easy.

I would def go w/ the MMax over the Q80. If you really want a high eff motor you could look at the Neu's as well. I have a 380C-6L in my heavy rustler and I really like it as well, this could be an alternative to the 5700. Loads of Tq, fast spool and should easily do 40 mph in the B4 and give ~10 min run on 3700s.

You don't hear about these as much now the MMax systems have come out, but its not bc they are not great motors. The mamba have just kinda taken over everything since they are sold as a system.

Ive decided on the MM 5700. Hope its not too much power on the track. What would be a good place to start with gearing? Ive got an 81T spur.

use the speed calculator dude... trial and error is the best way....

I had a b4 in the past and I can give you some help.
With the 5700 motor, which is almost equivalent to a 10-11T brushed motor, I recommend you to start from 19t pinion and go up from there.

Thanks captain, Ill try that out.

Hey Syl, are you racing with this set up? If so, someone here suggested the 4600?

Yes i will be racing. Who suggested the 4600? Im still thinking of the two systems because the 4600 would have the best spool up and plenty of runtime (more than i need) . My track isnt that big, yet isnt that small. Probably gonna get the 5700 for in-between performance- besides i can always just get the 4600 as a seperate motor.

Very true. Man, I can't remember, but they were comparing the two for racing aspects in another thread. both have pros and cons. Just from what Mike says, on the track, speed is not everything and sometimes more of a hinderance than it's worth. But you can dial down the mm i think too.

I have the 5700, on cheap 3000mAh Nimhs it lasted over 5 minutes, closing in on 10. I can't see a problem. It's a really nice speed to, will be perfect for racing.

Don't forget, if you get the 5700 you can always tone it down with the settings the ESC software features. Such as the throttle curve, power input and so on. ;) I think I used 20/81 gearing in my T4. 20t seems to be the sweet spot.

Just some input, in a post on the first page you mentioned something about a 15t brushed motor. The 4600 should be equivalent to about a 12t brushed motor, so you might want to factor that into your decision.

Yea, thanks MM. Ok, the Mamba maxx is for sure, but now its either the 4600/5700 motor or the lehner 1920 ? Turn..... I LOVED my 1950, thats why i want the 1920 so bad, think it would be a good investment?

I think i would go with the 4600 or 5700. Just my opinion.

In talking with Castle, they said that the 5700Kv will work like the best hand-wound 10T ever built. I run mine on 3300 Radio shack 6 cell packs and easily get 25 minutes runtime out of it. The experience I've had with the 5700 has been great. Tons of power/torque and if you put a 3S LiPo on it, it's flat smack insane. As with any BL system, power delivery is where it's at, so it will perform better on a 2S than a 6 cell NiMH, mainly because the LiPo can deliver the current and not have the voltage dip. If you had 1 2S 3800 mAh LiPo pack, that's all you'd need for a full day of racing. LiPos maintain their power longer, so even a small mAh such as 2500 will give you plenty of tire shredding power for 20 minutes. I'd guess the 3800 would be good for 30+ minutes. I've brought two 3300 mAh packs to the track and I don't believe that I've ever run down two totally yet, hah!

As for gearing, with my B4 I was running 17/81 and I could blast the bowties senseless with 6 cell pack. Tuning the slipper made it behave. You get a whole bunch of tunability in the ESC software, so you'll be able to get it where you like it. Checking with a radar gun, I saw right around 32 mph with that gearing and the bowties on it with 6 cells.

The package that castle offers works very well together and the price is pretty tough to beat. You won't be dissapointed.

Oh, might want to take a peek at the thread here: http://www.rc-monster.com/forum/showthread.php?t=4476

That's my B4 with the above setup in it in the video. There's a T4 in there running 17/87 I think also, with the 5700/6 cell on it too.

Sleebus

I've got the 5700 in my B4 and on 6 cells, it'd be too much on a track IMO. I didn't run it with the GPS on 6 cells, but on 9 - IB3800 cells (unmatched and unzapped), I GPS'ed it at 52.2mph. Here's a couple of fun pics we took today while we had it out running:

http://onelouds10.com/rc_pics/IMG_2306.JPG
http://onelouds10.com/rc_pics/IMG_2307.JPG
http://onelouds10.com/rc_pics/IMG_2308.JPG

Nice! Incidentally, what tires/gearing are you running? I might get brave and strap a GPS on mine one day...I just shudder to think of flipping the thing over and grinding my GPS 70' on the concrete!

Sleebus

I'm actually running tires and wheels from an Evader Pro BX, which are Pro-Line Wide Front on dish wheels in front and Pro-Line Bowties on dish wheels in the rear. I'm running 21:84 gearing right now. After running for a while with a 6cell pack, my motor temp was ~110F and the ESC was ~135F.

FWIW, I probably could have gone faster if I'd had picked a spot with more running room. I was driving it on about a 6' wide strip of sidewalk that runs around a park in our neighborhood. I only drove it about 200-250', gradually rolling on the throttle until the last second or two. With rolling on the throttle very gently and it never picked up the front wheels.

I was going to say.. 52 mph seems kinda low for that setup in a B4 and 9 cells. I drive 8 cells in my heavy (5lb rtr) rustler and it does 48..