MGM compro + feigao 6s + TC4
 

Hey guys, even though this is my first post, i've been lurking around for some time now.

I purchased an MGM Compro 8012 and feigao 6s from mike a month or so ago. I put this setup in a 1/12th scale pan car The thing was definitly a freakin rocket. 65+ MPH on 6 cells. i used a 20 tooth 48p pinion and a 75 tooth spur. Overall final ratio was 3.75:1.

I reprogramed the ESC so it would accelerate over 1 second, otherwise it would just spin out under hard acceleration. Well, after going through 2 sets of tires in only 4 or 5 battery packs, i decided the car isn't for me. Moving on......

I purchased and just assembled a brand new RC10TC4. Using the same 20 tooth pinion, and the stock 72 tooth spur gives a 3.6:1 ratio. The differentials, front and rear, are 2.5:1, for an over all ratio of 9:1. Now, given the much higher ratio, i figured it would obviously not reach the same speeds as the 1/12th car, but should rev fast with lots of torque. I reprogrammed it to accelerate quicker (now having the advantage of four wheel drive as well). Still using 6 cells. Well, it takes 100 feet or more for the car to reach top speed. the thing is an absolute dog out of the hole. It takes forever to come up to speed. I tried several different programming settings. After about 5 minutes, the motor was only luke warm, the controller wasn't much warmer then that, and the battery pack was quite cool. Shouldn't this thing be ripping up some asphualt? any idea's?

My rc10t with the novak 4300 brushless system has close to the same ratio, and wheelies off the line and ROOSTS like mad in dirt!

Sorry for the long post :o

Thanks guys!
Mikey

The 6s is not really a good motor. I really don't recommend that motor for anything but say drag racing. That motor works well if it's got a pretty big pinion, batteries that LIKE to give over 100 amps etc.

The TC4 is much better off with a "380" size rotor. So, motors such as the Lehner 1520, 1525, Hacker C40 S, Kontronik Twist are probably the ultimate motors for a 1/10 TC. The Basic series and Plettenberg are a bit larger and need more power to get them going and so I don't think those are the ideal motors either.

That motor has a really heavy rotor too. BTW, are you sure you got the MGM programmed right?

by why did it propel the 12l3 so well, and why does the novak push (still 540 motor) the rc10 so freakin hard? the 4300kv novak should be about the equivalant of the 7s feigao, no?

You say the 6s is a drag motor, well, drag racing calls for SERIOUS acceleration..... this thing just takes its sweet time spooling up.

Yeah, drag racing with like 12 cells and TALL gearing and with batteries that can deliver 200 amp spikes and a controller that won't smoke with 200 amp peaks.

Anything propels the 12L3 well. That thing is so freaking light.

I didn't have the Feigao 6s, but the Hacker B50 6s. I've also had the Hacker B508s, C40 6s, C4012s, Lehner Basic 5300, 4200, 3600, 3100, 2700, 2100, XL5000, XL3100, XL2400, XL1600, XL1200, Lehner 1515, 1520, 1920, Feigao 10L, Plettenberg Shadow, Indoor II, Twist 42, Novak SS5800. I've tried big motors in small cars, and small motors in big cars, and from 6 cells to 29.6 volt lithium polymers and I gotta tell you, there are DEFINITELY motors that work MUCH better in certain applications and motors that just plain SUCK. The 6s motor just SUCKS for 99% of applications. Sorry, but that's my experience and plain truth. It can really be a BEAST on 6 cells IF you have the massive amp capabilities and a controller that can deliver it, but otherwise, it's a no go.

If you thought the 6s propelled hte 12L3 well, you should try a Lehner 1515 5 turn or 6 turn in that little vehicle. It's a 90 gram motor (3 ounce) and it'll turn about 70,000 rpm in your car with 6 cells. It'll take it to over 80-90 mph in 2 seconds - but you'll never find the traction!!

Check out the 1520 5 or 6 turn or C40 6s with 6 cells in your TC. You'll be doing oer 50 easily.

If you truly want to go FAST, you should try a combination of Lithium Polymer with a mild brushless but with higher voltage. That's what I'm doing in my TC4 - a 4200 KV motor with 14.8 volts runs insanely fasssst. The 14.8 volt 3500 mah weighs 11 ounces so it's much lighter than even a standard 6 cell pack.

Good stuff! thanks lipomax. Definitely educational. I suppose its safe to say you have a lot of BL experience.

On a better note, it turns out what i thought was a good battery pack, must of had a few crappy cells in them (that pack has overheated a few times) and just wasn't putting out. I tried my eight cell piggy back from the 12l3 car with a fresh charge..... with the 24 tooth pinion, it just LIGHTS the tires up. Soooo..... time to throw out that one pack, and make some more.

I do however plan on running lipo's in this car more then nimh. I will run both, but the lipos will be for performance, and the nimh will be for play.

lipomaxx, i'm pretty new to lipo batteries. i know 3.7v per cell, very sensative to heat and low voltage. I have no idea what else to look for when looking at lipo's. I don't think i want to make my own packs, i'd rather just buy them. Of course i'd need something with substantial amperage. I think 14.8v on a 5915 motor with 28-30 tooth pinion is over doing it, but its going to be fun trying :-)

looks like you found the solution before I found the post(batteries). While I don't agree that the 6s "sucks" in most applications, there are certainly motors that will be better matched to this application. I run a similar setup in my tc3 (11.1 volt lipo with 4200Kv motor). I like the basic motors (most smaller motors work extremely well in these applications, as Lipomaxx said). For the record, I wouldn't run the 6s on 14.8 LiPos and tall gearing unless you have a lot of room and a serious controller. Also, be prepared to rebuild/replace some parts!

Yeah, i'm picturing the diff gears flexing everytime i nail the throttle and hear the 4 tires break loose. Does anybody make steel gears for this? i know the TC3 TC4 and i think NTC3 all share the same diff setup.

Yeah i was more or less kidding with the 4s lipo's I'm sure it would certianly exceed this controllers amp draw (depending on the quality of the lipo). I think this 6S motor is awsome. The whole point was i wanted a higher KV motor so i can achieve a higher RPM on less cells.

Mike, can you send me a PM or e-mail when you get the expert series MGM controllers. the 120amp you have in stock, is that expert(computer programmable?)

The 120 amp controllers in stock are not computer programmable. The next time the 80 amp controllers come in stock, they will be computer programmable. Hopefully in a week or so.

ok, whats the ETA on the computer compatible 120 dawgs?

Should be later this month, along with the 80 amp "dawgs" ;)

Sorry to jack your tread but since were on the subject of "computer programmable" ESC's..what are the pros and cons of this..I ordered an 80 MGM last Monday and it is not "computer programmable"....does this means its not programmable at all?

ME no understand...:o

The controllers are the same. Your controller can be programmed using your transmitter. The computer programmable controllers can also be programmed via a cable hooked to the computer. The computer progarmming is a bit easier. Otherwise, the controllers are the same.

I believe the computer programmable one stores data too such as peak current, or peak RPM or something.

Ah...a little brain use doesn't hurt..thanks Mike

Mike, and anybody else with experience with this controller...

Is anybody having a problem running this controller on 12 cells? I get the current over load beep 90% of the times i punch the throttle. i even programmed it to accelerate over the course of a second and a half, and it would still do it. 6S just too much motor for this controller? its really discouraging when you come around a corner, nail the throttle and it just dies.

I haven't used mine on more than a 3 cell Lipo. Are the cells good quality? 12 cells is a bit much for the 6s motor, so I am sure it is drawing some serious current. The 6s on 12 cells will definately draw more than 80 amps on hard acceleration (motor isn't meant for this high cell count- 6-8 cells is a better place to be on this motor).

:mad: thats no fun..... so less batteries or a higher wind motor?

You got it! I run 11.1 lipo on the basic 4200 in my tc3. The 4200 could take 12 cells as well, but I would probably go with a basic 3600 or 3100 even on 12 cells. The 6s on 12 cells would be over 80000 rpms! Yikes! On 8 cells, the 6s is still pushing in the mid 50k rpm range, which is pretty fast.

pretty fast? since when is pretty fast, fast enough?! i figured that 80K+ too, but lets face it, all the resistance on the drive train at 60+ MPH i think would restrict it to less then its 60K recomendation

Well, the batteries would drop in voltage as well, so it likely won't hit the 80k rpm mark. I would assume it will probably exceed 60k rpms if you have good cells. The bigger issue is the amp draw, though. Are you using full size cells? How about gearing? Also, let me rephrase - the 6s on 8 cells will be VERY fast!

6s on 8 cells = not fast enough ;-) i cut the pack down and made it 8 cells (they are just generic 3300mah cells), i changed acceleration to .26 seconds, and it seems to be pretty happy with that. i have the gearing pretty tall too. 26/72, i think i'm gonna pick up a 30 tooth pinion just for ha-ha's.

BTW, if i can still control it, its not fast enough :-)

A simple upgrade in cells will provide more performance as well.

What would you recommend mike? How about in the lipo field? i'm interested in owning a pack or two. can i get them through you? how bout NIMH?

My experience with the 6S on 7 gp3300 cells in a losi xxx4 geared 21/94 = not fast enough. My novak geared 23/94 is almost as fast and accelarates just as quickly. Maybe I'm doing something wrong. I've tried "automatic 5*, 10* and 15* timing and higher gearing. Nothing seemed to work. Very quiet and efficient motor though. And I still get 7-8min of runitime on 2600mah charge.

Speedy, 21/94 gearing is a pretty high ratio, 4.47:1. Maybe try 24 tooth pinion? I can't say i've had problems with this motor not having enough power, my problem seems to be GIVING this motor all the power it needs!

The 6s motor should very easily beat the Novak. It shouldn't even be close! Perhaps your batteries can't deliver the needed power to capitalize on what the motor can deliver.

For cells(mikey), a decent set of nice voltage gp cells will spice it up a bit. The 6s can draw some serious power, so if your cells can deliver the power, you will have a beast on your hands. I can supply the nimh, but I don't currently offer Lipos or Lipo chargers.

ok, but on the contrary, before when i had it on 12 cells, apparently i was applying all it needed, in fact, more then it needed because the controller was activating its protection (what a wonderful little circuit). so some spicier cells produce the same results? (figuring the voltage drop wouldn't be as severe)

The cells that I'm using are gp 3300s that were once matched. They are pretty old though. I know what I'll do, I'll put muy two 7 cell packs in parallel and see what happens. That should be able to supply twice as many amps.

...Ok I just tried my two 7 cell packs in a series. All I can say is W0W what a difference!!! I actually got to the point where my car was unstable at top speed. It looked as though the balloonaing of the tires raised the ride hight about an inch. Must have been 50mph. maybe more. And the motor was barely warm. For those of you that want to run higher voltage and a lower kv motor, you can acheive the same with a higher kv motor and more cells in parallel so you don't have to buy a new motor.

Sounds like fun! I had my old RC10T2 about 65mph with a 6s on 8 cells! Too fast, if you ask me, but it was fun for the time! Great for showing off as well!

I still don't think it's a great motor - especially for a touring car. A touring car has a very lightweight drivetrain and tires and the extra weight of that rotor really slows performance down. A Twist 42 with 4s lipo makes my TC4 uncontrollable. It'll go beyond 60 mph with only a 23 tooth pinion and 72 spur (the diff ratio is 2.5) and stock tires. It'll spin out all 4 tires all the way to 60 mph too. Oh, to give you an idea of how fast this thing accelerates - it literally peels rubber on the concrete and you can see it in the picture. After doing a few laps around my driveway, the tires get over 170 degrees hot!

I'm thinking that the reason I can't go much faster than mid 60 mph is because my batteries won't give me more power. I need bigger lipos.... Currently using 4s 3500 mah Polyquest 12C packs.

I agree that the smaller motor perform better in the touring cars. My basic 4200 rips in mine. The fact that there are other motors that accelerate quicker in this application doesn't make the 6s a bad motor, it jsut means that there are better motors for this application. The 6s still rips, but is a touch slower off the line. I run 11.1 volt Lipos in my tc3 and it is an animal! I can turn the wheels and pull the trigger and the car will spin in the same spot like a top.

both of you guys have pretty impressive setups. I'm not saying the 6s is king, nor am i saying my setup is perfect. But, Mike, i do the same thing with mine, spin her around in one spot, like the middle of the car is sitting on a nail.

lipomaxx, when it comes down to it, lighting up the tires is great.... but if your just spinning tires, your wasting horsepower and RPM, not to mention rubber. Maybe you should see about getting more of that power to the ground? if we sat side by side, and gunned them at the exact same time, if my tires broke loose and turned 1000 rpm, and your tires broke loose, and were turning 2000 rpm....... then who would be in the lead? LOL :L: kinda interesting when you think about it like that


incase anybody's interested

http://community.webshots.com/photo/...51258636DPfIGb

http://community.webshots.com/photo/...51258809robRFI

http://community.webshots.com/photo/...51259006fNzudm

my aluminum rims are on there way :-)

I did a comparison not too long ago.. Basic 3600 vs. C4012 s (3500) and using 3s and 4s, they had the same top speed. However, the smaller motor was noticeably quicker off the line and because of the lower rotating mass, didn't "coast" as long either so it was actually more raceable. I'm DEFINITELY NOT saying the basic aren't good motors, they're awesome motors. Mike, when you say the 6s is a touch slower off the line - are you comparing it to the Basic 4200? The 6s has a kV of 5900 so it should be WAY faster than the basic 4200. I bet the Basic 5300 is faster than the 6s though despite the big difference in kV.

Thats something really neat about the MGM, although it takes a little getting used to. But backing off from full throttle, to say, half throttle, it actually applies the breaks until it reaches the designated thottle position, its great for speeding into a corner and being able to stay on the throttle, not have to flip from the brake, and meter the throttle to keep in control.

I suppose burning up tires on concrete is like nothing but wheelies for an off road car. Its an awsome show, great bragging rights, but its not very practical for racing. Not like i'm about to join a racing league. I've been playing in the dirt for a long time (t-maxx) and this is my second onroad car (just sold the L3) in like 10 years. These high performance touring cars weren't around when i was playing on the street, so i'm pretty new to them, but its is a pretty awsome experience....

Lipomaxx: have you had any drive train problems at all? diff problems? spur? outdrives? What are you using for tires?

Yes, on a dusty street, spinning the tires is no fun... but for indoor carpet racing with traction compound, it's absolutely amazing at how fast the thing will launch out of a turn. In 20 feet, this thing will go from 5 mph to 35 mph! I mean, the brushed guys are going the same speed through the turn, but then suddenly they look like they're standing still! Yes, I can still spin out the sticky tires on carpet (my eagletree was showing OVER 2 G's of acceleration) but that's why you gotta be smooth with the throttle control. You know, in Formula I racing, they can spin out their tires in first gear if they want, they have to power - they just control the power. That's how I like my RC vehicles.. I want them to have MORE than enough power and I have to control the power through throttle control and not due to limitations of HP. Now, admittedly, it's not going to give the best lap times and you won't be that consistent lap after lap, but it's a whole lot more fun to drive. Sometimes, when I catch a wide sweeping turn just right, I can powerdrift/accelerate with sticky traction compounded tires on carpet! It's NUTS to see it do that. It seems like TC on high traction surfaces are the vehicles that truly benefit from the instataneous acceleration that the smaller motors provide. On the street, it really doesn't make that much difference. Buggies and ST's really can't benefit from it either. Those vehicles don't have the traction to take advantage. Even if you did, you would only wheelie all the time.

The TC4 would loosen my diff after 5 minutes of high powered runs on carpet. The diff outdrives eventually all melted and failed so I went with steel outdrive and rebuild it occasionally (the spring needs to be nice and fresh). On the street, that never happens cuz the lack of traction limits the torque on the drivetrain.

I actually didn't like that feature of the MGM and that's the reason I sold it on ebay. It causes my 2wd vehicles to spin out in a turn. Some controllers actually have "drag brake". Also, slotted brushless motors have that "drag brake" also.

On the street, I only use rubber - I believe some company's 20 compound (premounted and glued). On the carpet, purple/plaid foams or those same rubber tires. Rubber seems to be more forgiving - if you crash with foam tires, they are harder on the suspension and liable to break more parts. On street, foam tires don't stick for me. My street is too dusty.

I don't peel out on the street for fun, nor do donuts... actually after watching DualBL's video where he smokes and destroys 2 rubber tires, I did the same thing - but with 4wd. After that, I figured it was a waste of rubber so I don't do that anymore. Now it's about maximum G's of acceleration. I'm thinking of possibly doing drag racing. A lot of "experts" are saying that it can't be done with BL due to the lag time but I think it can and I think it can be very competitive. BUT, nobody to drag against here.

lag? what is this lag of which you speak? with such instantaneous response to throttle, i don't see where there could be any lag! besides, wouldn't you have to do something to break the 60mph barrier first? i dunno if the TC4 would make a good drag car...... i suppose if you made some adapters to put much wider wheels in the back, and hike it up a little in the rear....

My TC4 already does faster than 60. With 4s lipo, 23 tooth pinion, and a Twist 42, it does 60 really quickly - actually traction limited. It blows the tires all the time though.

According to the brushed drag guys, we have some millisecond initial lag where the controller tries to locate the position of the rotor. I think they're BS and that's why I wanna go prove them wrong. Those guys are not using speedos - they're using plain microswitches so it's plain off and on switch to a DC motor so they claim they have no "lag". But, the servo takes a few milliseconds to switch the switch on!

My TC4 or Pro 4 doesn't make a good drag car cuz of the inline motor and shaft. I get massive torque steer when I gun it real hard. The XXX-S G+ was a much better performer for accelerating in a straight line. But either way, I want something with a bit longer chassis to keep it more stable.

BTW, I measure speed with GPS. Occasionally I pull out the old Bushnell radar gun too. That setup takes my car to 61.5 mph. BTW, using only 3s lipo, I ran my XXX-S G+ to 64.5 mph with a PUNY Lehner 1515 6 turn motor (that motor is ONLY 90 grams!!!!). The 1920 5 turn is the fastest - on 3s it was soooo fast - but I ended up busting the whole thing so I never actually got a number - but probably around 70.