Would twin brushless setup with dual MMM's work withmy set up? - RC-Monster Forums

Rivermaxx

Some of you might allready know I want to build a high speed g-maxx. I am thinking about running twin brushless 2650 kv mmm combos with 2 6s 5000mah 30c batts. I know a OverrevO has done 91 mph in a revo with one of these motors on 6s but I personally think he was pushing it with the high gearing he was running. I think 2 combos will help each pull the high gear with out smoking and esc with amp overload. You guys think it is possible to make work.

scarletboa · 08.30.2009, 01:20 AM

if i were you, i would just go for one neu 1521 or 1527 imo. if the MMM isn't up to the task, a EZrun 150a might just do the trick. both escs have similar internals, but the EZrun has a bigger fan (that runs 100% of the time) and bigger heatsink.

so, a 1521 with a EZrun or a MMM if you already have one will provide better results than a duel motor setup.

Rivermaxx · 08.30.2009, 01:36 AM

Is there any proof to this? I just seems that 2 mmm 2650 combos will make way more power than 1 with a bigger motor too me. 2 6s batts running 22volts each, 2 esc's for double the amperage capability. Yes there will be a little more weight but I am sure it would be fairly minimal.I theory 1 2650kv on 6s is rated @ ~3hp 2 should be around 6hp together compared to the 4hp bigger motor. I might be wrong in my thinking though.

zeropointbug · 08.30.2009, 01:42 AM

Yah, stick with single motor setup, the truck will not even be able to handle twin CC/Neu's, especially when running twin 6s, 5000 packs... heavy.

You don't need that big of a pack, really, a 6s, 4200mah pack should provide you with the power that is needed, but, a 5000mah or larger will get you a point or two on the top speed.

Get a 1521 Neu, very powerful.

BTW, with a 1512/3D(1700kv.) on 6s, 4200mah G3 pack, Revo can hit 75+mph top speed, would be higher with proper setup as well. But, going from 75mph to 90+mph would take twice as much power, give or take. The setup was sucking just over 1000watts, IIRC.

zeropointbug · 08.30.2009, 01:44 AM

You won't need anymore more power than a 1521 can produce... like I said, I hardly ever push my 1512 to the limit, and I do a fair share of speed runs.

_paralyzed_ · 08.30.2009, 01:58 AM

If you want to do it, do it! It will work and will be awesome! I'd love to see it!

However- If your goal is top speed a single setup is better. Every gram counts in top speed runs, the additional weight would be substantial.

Also, high voltage is the way to put down power. 12s at 100 amps is 4400 watts, or 5.91 hp. To make that power on 6s takes 200 amps, which equals alot more heat and possibly fried components.

I know you plan to "split the load", but you'll be pushing things.

I say do it and see what happens. Do it your own way! (post video please!)

Rivermaxx · 02:20 AM

Heres what I come up with a 1521 1d question is with my high gearing will the esc handle the load. Notice I only used 3v as the voltage because nic case told me to use that figure. The the only reason I was going with 2 2650kv combos because I know they both together can handle the load splitting the load.A mmm can handle 100amps easy so 2 can handle 200 amps easy also right?
Differential Ratio: 3.3076923076923075
Transmission Ratio: 1.7222222222222223
Other Ratio: 1
Spur Tooth Count: 36
Pinion Tooth Count: 25
Total Voltage: 18
Motor KV: 2900
Tire Diameter (inches): 5.5
Tire Ballooning (inches): 0
Motor Current Draw: 0
Motor Coil Resistance: 0.003
Spur/Pinion Ratio: 1.44 : 1
Total Ratio: 8.20308 : 1
Tire Circumference (inches): 17.28 inches (438.88 mm)
Rollout: 2.11:1
Total Motor Speed: 52200 RPM
Vehicle Speed: 104.12 mph (167.26 km/h)
Effective KV Value: 2900
KT constant: 0.47 oz-in/A
Motor Torque: Amperage not specified...
Final Torque: Amperage not specified...
Final Power: Amperage not specified...

Understand this is not going to be a stock g-maxx chassis truck its going to be lowered,narrowed, lengthened and lightened with custom made tires for high speed.The drive lines are going to be titanium and steel. Still working on a good aerodynamic body though ,any sugestions?. I plan on running this at the ISC event here in california 15th of november. Hopfully break the current ~70mph record, I am shooting for a 100mph. we'll see

zeropointbug · 08.30.2009, 02:22 AM

Yah, well he didn't realize not all batteries are the same. If you have a G3 pack for example... it will do 20C discharge @ 3.7v/cell, so if it's a 5000mah, that's 100amps. I don't think you will be that much, so the voltage will be at least that value and higher.

_paralyzed_ · 08.30.2009, 02:31 AM

If you are stuck with 6s and the MMM your last setup seems to be the way to go. You may be near the limit of the MMM.

I'd go for a 1600/kv ish 1521 (or even 1527, go big!) and a 12s plane esc. They have drag brakes, your vehicle will stop! The CC HV110 is the boss, but a hobbycity "turnigy" unit has been proven to work well.

although the braking requirements of the ISC may not be met.

With 6s you'll really be pushing all of the components.

Rivermaxx · 08.30.2009, 02:35 AM

Trust me he knows that all batteries are not the same. He is very knowledgable and knows his $hit. 161 mph car proves it. Maybe he was telling me to do the 3volt figure because of the batts I plan on using or maybe it was a form of handicapping to get real world results like drag & wind resistance IDK.

_paralyzed_ · 08.30.2009, 02:36 AM

Quote:

Originally Posted by zeropointbug

Yah, well he didn't realize not all batteries are the same. If you have a G3 pack for example... it will do 20C discharge @ 3.7v/cell, so if it's a 5000mah, that's 100amps. I don't think you will be that much, so the voltage will be at least that value and higher.

-not arguing-

scales and graphs and numbers are cool and all, but Nic Case holds the world record for fastest r/c, and was backed by neu(yes neu batteries too), so if he says figure 3v/cell, I would figure 3v/cell

-still not arguing-

but it has been a while and battery tech has come a long way, better make it 3.35v/cell

Rivermaxx · 03:03 AM

Quote:

Originally Posted by _paralyzed_

If you are stuck with 6s and the MMM your last setup seems to be the way to go. You may be near the limit of the MMM.

I'd go for a 1600/kv ish 1521 (or even 1527, go big!) and a 12s plane esc. They have drag brakes, your vehicle will stop! The CC HV110 is the boss, but a hobbycity "turnigy" unit has been proven to work well.

although the braking requirements of the ISC may not be met.

With 6s you'll really be pushing all of the components.

Biggest problem is the gearing I am limited with the g1 maxx tranny.That why I an going with a higher kv motor. I really dont want tire spinning or wheely torque. I want a gradual ramp up to the 100 mph barrier. I wish mike would get those center diffs out so I could get one, it would solve alot of issues. Why dont you let me borrow yours harold so I can break some records. The car does have to have brakes I believe in the ISC event.