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View Full Version : Shawn, how about a 400 size "mamba" 8000kv



m18racer2003
05-04-2005, 04:56 PM
Hey Shawn,

How possible is it to make a 400 size mamba-like motor for the H8? or maybe mod an already existing motor, like the 400 sized brushless Eflite (spelling?). Maybe just rewire the Eflite with thicker wire or less "turns" or both. And maybe have it ready before the May 9th US release date. :D

That would be SOOO awesome!

Thank You.

TNB
05-04-2005, 07:41 PM
Don't you simply mean that you want more kv in the already larger brushless motors?

m18racer2003
05-05-2005, 02:06 AM
yup, exactly!

TNB
05-05-2005, 04:42 AM
There may be some one the way by at least one company. Are you using the eFlight 400 4200KV motor now? What is your set up? 3-cell LiPo?

m18racer2003
05-05-2005, 05:58 AM
Well, I don't have a H8 right now,(I currently drive a M18 w/ a mamba 8000) but I'm was seriously considering getting one. BUT... I've read in forums that it's very slow stock, and still slow with an x-speed! I want fast a brushless set-up WITHOUT having to go li-po.

I was considering a mamba 8000 but it's a 300 size motor, if the H8 is designed for a 400, why put a smaller motor in it? I guess it's just my flawed theory that a bigger motor is always faster than a smaller one. Also, many people have had problems with the mamba getting really hot.

In the prefect world, they would come out with a BL motor with the torque of a 400 motor and the rpm's of a mamba 8k.... and for CHEAP! lol

TNB
05-05-2005, 06:06 AM
I'm also running an Xray M18 with the CM2080 8000 (3-cell LiPo). I had a CM2080 in my Mini-Inferno, but I am currently running a larger but lower KV AON motor in the Mini-Inferno now (3-cell LiPo).

Hawk
05-05-2005, 07:59 PM
TNB, which do you like better and why? I have a CM2080 that I haven't put in yet, 3s2p lipo(s) and am waiting for the rest of the parts to make it all work. I am not familiar with electrics so the bigger motor w/lower Kv rating is a mystery to me. What is the effect?
Thanks
HAWK

mOOsE
05-05-2005, 08:44 PM
the larger the motor, the more torque you will have. the KV rating is a just a no-load rating stating you will get "x" rpm per volt. So your 2080 = 8000kv or 8000 rpm per volt.
The mambas are a little shy on torque for this buggy so thats why you run a larger can motor.

TNB
05-05-2005, 08:51 PM
If you review the charts at Castle, you will notice the recommendations made regarding their 4200Kv, 5400Kv, 6800Kv, and 8000Kv brushless motors. The same theory probably applies to the AON motors; however, I'm not a motor expert and don't claim to be. I just want to reiterate that point before the motor gurus jump on my post.

Brushless motors are rated three ways: Power, Kv, and Kt . . . kV is the motor voltage constant expressed in RPM/Volt. This indicates how fast the motor will turn for a given voltage (given there is no internal resistance).
http://www.balakracing.com/novakss.htm

The Castle CM2080 is rated at 8000 Kv and the AON T2415 I am currently using in the Kyosho Mini-Inferno is rated at 4900 Kv, so there is quite a difference in Kv.
http://www.castlecreations.com
http://www.aonelectric.com

The AON motor is physically larger in diameter and is closer to the physical size of the stock Kyosho motor. I may be wrong, but this reminds me of a big block automobile engine versus a small block automobile engine, meaning that although the small block automobile engine can be made to perform almost like a big block automobile engine, the smaller engine has to work harder (and probably more efficiently) than the larger engine to achieve that type of performance.

To me, less work means less heat and less heat means longer life, especially in a somewhat larger and heavier Kyosho Mini-Inferno when the ambient temperatures reach over 115F in the summer. Of course, the motor casings probably help dissipate heat as well as lower gearing but I would never consider running the CM2080 without a motor heat sink like I did with the T2415.

Here is a photo comparing the physical size of the Kysoho Stock Half 8, AON T2815-3002, AON T2415-4900, and Castle CM2080 motors.

http://www2.mini-zracer.com/albums/album649/MotorCompare3.jpg

Hawk
05-05-2005, 09:47 PM
:D No jumping here. I am an idiot about this stuff. I have see references to the mamba CM2054 being a 'better torque' motor setup than the CM2080. I think the esc is the same but the motor itself is different. Is this true or is somebody speaking out of their wishes.
So, if a big block and an small block makes the same horsepower, they probably don't make it with the same hp curve and certainly the small block has a lower peak torque and lower overall torque curve. In that analogy, you can gear for it and make up with less weight in the motor and overall in the platform(car,boat). If I use gearing close to stock and not jump to a high count pinion, would I be o.k. or maybe should I go to few teeth than stock?
I have the heat sink for the 8000kv cc motor and have a alu. motor mount on the way. I think the cooling may be doable if I am not running for top speed nor max accelleration but a longer term quick, fast buggy type environment that runs for 15-30 minuets.

:confused:

TNB
05-05-2005, 10:22 PM
I was using a 16T with the 8000Kv and a 1900 mAH 3-cell LiPo in my Mini-Inferno. I also vented the body and upper deck to cool the motor and LiPo even with the motor heat sink. Although very fast, the run time wasn't all that great and no where close to 30 minutes. In my opinion, it simply seems like there is a reason to have and to own more than one different Kv rated motor--one to bash around the track and another to go as fast as you can. In simple terms, I would not only change the gearing for the situation but the motor as well though I also believe that a faster motor can be slowed down by using different batteries, yet the slower motor can't really be made to go as fast as a higher Kv rated motor. The downside is that a faster motor may need a "larger fuel cell" or higher mAH rated battery to run longer--fuel efficiency v. performance. After all, even my SUV can pass a lot of other vehicles driving up the large hills but it also has a larger fuel tank than numerous other motor vehicles.

m18racer2003
05-06-2005, 01:51 AM
Hello, this maybe a bit off topic but i've come to a conclusion (by reading many forums) that the Eflight 4900kv almost at fast at the Mamba 8k because if can put out better rpm's per volt UNDELOAD because it's 400 size (more torque) than the mamba can underload. I hope i don't sound too dumb right now.

I know TNB is lucky enough to have both motors. Could you possible put together a side by side comparison of both motors, the mamba and the Eflight. Maybe compare like runtime, speed, heat?

I really want to get an H8 but I don't want to have to spend a lot of money making if go fast. I calculated it to be almost $500.00 total to get a H8 going fast:

H8 =$185.00
F&R shocks = $60
Mamba Comp X = $140.00
Jr Receiver = $45.00
GPs 1100 3 9.6vpacks = $65.00

Grand total: $495.00

And that's NOT including the bling! :(

I could get a 1/8 scale buggy for that price! (already have fuel and starter box from my 1/10)

Sorry, my motor comparision post has become me whinning about how expensive this hobby is. :(

You can start flaming me now. Thank You

Hawk
05-06-2005, 02:55 AM
If you really want to whine, do the 1/8 MP777SP1 ($630) and do the upgrades and you will get to the amount you posted X10.
3pk $300
Spektrum DSM $160
OSengine $300
Tires/wheels $75
receiver batteries $65 (two sets)
Upgrades to the upgrade kit, Fioroni, King Headz, or Racers Edge $900
Servos $250
Upgrade Screws $40
I could go on but I might start crying too. :eek:

It is only a hobby, right?

TNB
05-06-2005, 04:33 AM
I know TNB is lucky enough to have both motors. Could you possible put together a side by side comparison of both motors, the mamba and the Eflight. Maybe compare like runtime, speed, heat
I actually have the CM2080 and a couple of AON brushless motors, not the eFlight motor. I did post some temp readings with one of the AONs around here somewhere and will probably do more this weekend at the track. Later I may increase the pinion gear size on the AON since I actually ran the CM2080 with a 16T instead of a 14T.

Regarding expense, this hobby isn't cheap especially if someone wants a fast R/C that performs well and actually wants to race it. The last I knew one of the Futaba radios was over $2,000.00 and I've seen R/C cars at the track that sold for over $3,000.00. I also know there are ARTRs that are $3,000.00 too and some that are even more.

mpetrich
05-06-2005, 05:08 PM
Just to add something here (and I am by no means an electric motor expert) but can size (300, 400, 540, etc) has nothing to do with torque or motor performance. You can put the same internals into a bigger can with no performance improvement. A bigger can definitely gives the "illusion" of more "power" but in reality it's all about what is inside the motor.
Matt

m18racer2003
05-06-2005, 09:19 PM
you are correct matt, but a bigger can will give you more room to put bigger magnets and more wire and thicker wire, and the saying goes: "there's no replacement for displacement" ;)

mpetrich
05-06-2005, 09:25 PM
That is exactly right! That's what I was "trying" :D to say................
Thanks,
Matt

milknbutter
06-04-2005, 07:53 AM
Here is a photo comparing the physical size of the Kysoho Stock Half 8, AON T2815-3002, AON T2415-4900, and Castle CM2080 motors.

http://www2.mini-zracer.com/albums/album649/MotorCompare3.jpg

From your exp, which motor is really better suited in speed and torque to the Mini Inferno chassis.

MnB