Motor RPM Thread

[mclarenowner4]

I was wondering if anyone could tell me what is the fastest, brushed 7.2 volt motor in terms of RPM. I have a Team Orion 10T x 2W, and so far, it's about 44750, but my Team Orion Revolution V2 7x2 is 57500. I am just wondering because I am considering a really fast electric motor for drag racing purposes only. So, if you know any motors that are really fast in terms of RPM, please reply below.

Also, what are the RPM ranges on these:
Team Orion Revolution V2 6 x 2
Epic Shock 6 x 2 Round/Flat

[ryanD]

made just for drag racing, not in stock at tower yet, late april. http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXHPD2&P=7

[mclarenowner4]

Do you have any idea of the rpm on it?

[tadium54]

i think hacker made one that was about 60000 or so

[mclarenowner4]

Hacker, as I looked up, is a BRUSHLESS system. I don't want to run brushless systems because of the INSANE $ tag. Currently, with my Tamiya F103GT, I have maxxed it out with a 10T and a stock 5:1 gear ratio, at 67 mph. I am working on it, though, because I just installed a new 18T pinion gear (up from the stock 14T) into the 70T Spur, pushing my ratio to an INSANE 3.888:1. That is the lowest ratio I have ever had. As I used my rc calculator, I have discovered an amazing feat! With my 7x2 Revolution V2, I can push my rc car to an amazing 109 mph (hopefully). Although I have not tested it yet, that would be incredible! I would only need a few more rpm to increase my speed to the WORLD RECORD!

[loopy]

I'm wondering if a 7x2 will have enough torque at 3.88:1 :eek:

You might be better with a higher wind running a higher voltage for a speed attempt.

[tadium54]

ok first things first- youre assuming the car is 100% efficent, such as no loss due to heat, friction, etc. if that were the case, then youd be right, but things like drag and aerodynamics play a huge roll. also add more cells. thats a sure fire way to increase speed

[highroller]

Big misconception with motors is looking at one power level and assuming it's good. High rpm levels with low torque or watts don't always equal to the fastest motor or the ideal motor. What goes into selection of a particular motor is first surface conditions - amount of power you can put down without making vehicle unstable. Heard of guys setting records with a specially wound 13 turn motor, to some being able to use 5 turn when traction was ideal.
In tuning motors the ideal power number to look at is watts which equal to HP or speed motor is likely to reach - rpm and torque are used in the formula equation for gearing with efficiency used to determine how motor consumes power for the the power is produces. So for all the high rpms a motor produces it may not produce as good of other power that makes it a good motor. When the rpm or torque are higher it generally means the motor needs to be geared lower (smaller pinion) compared to a motor that make lower levels or rpm ran in the same area.
Almost each modified motor produces the same speeds but as you get lower in the turn range the motor generally gets up to speed faster in a shorter duration than one with more turns. Add winds from single to double and the added wire slows the on power output a little without dropping in overal speed.

[trailranger]

MY feelings are:

Motors should be rated by the Area Under the power curve! Yes...use some calculus to add up all the total watts produced under the rpm band. Calculus would give a more accurate measure over just simple math considering motor power curves can somewhat complex at the ends. Then give that number as an index number. Maybe it should be called Josh's Total RPM Wattage Produced.

Here is why, there is no point in running a motor that has a very narrow powerband. What is the point in having a stock motor with a peak of 100 watts if that peak 100watts last for 100rpm and drops off to 20 watts with in 1000 rpm. If you can gear car to use that very narrow but high power band, great! But in reality, racing is all about using the whole power range of the motor. So I would rather run a stock motor with mild peak watts that span most of the rpm range than a motor with extreme peak numbers that span only a short rpm band.

[mclarenowner4]

As of now, I have 3 kinds of motors, my stock 23T, a Team Orion 10T, and a Revolution V2 7T. I want to have my car capable of racing at my local track by at least being able to keep up with those kinds of cars. How can I tune it to keep up with the other cars if I put in the lower rpm stock motor? What do you recommend for tuning it if I have a stock 70T Spur Gear?

[highroller]

The watts is the only number that stays relatively unchanged, but different things can done be to alter the rpm or torque output and even efficiency.
Stock motors (27turn only) brush compounds and spring tension are about the only things used in tuning - besides polishing armature shaft/bushings and aligning brush hoods and finally truing comms.
Spec motor are generally those in the 19 - 23 turn they are too mild to be a true modified, but don't conform to stock rules. Most of these produce power that is similar to a stock motor in some areas and a mildly tuned modified. Sometimes these motors are geared like a high rpm stock or higher than a stock motor to achieve the desired affect. IN 4cell oval the 19turn spec motors use a pinion the 4 teeth higher than what is commonly used in 4cell MS2 and Epic Roar stocks.
In true modifieds (handwound) 5-14 turn not only can you use different brush compound, spring tensions but also timing to change the power a little.
Increasing timing- produces more rpm = acceleration but normally a slight drop in torque depending on degrees of timing is advanced. Motors builders generally set the timing at a point that produces what is considered the ideal amount of rpm and torque which could be anywhere from 6 - 24 degrees.
So when comparing the 10turn and 7 turn the ideal motor to use would depend on what traction is like and how good your batteries are. While both would be obtaining the same speeds, the 7 turn would be of benefit in that it reaches it speed faster than the 10turn. The downside - motor lowend - topend power may make vehilce a little hard to control when traction is not ideal, runtime may be another issue. Also because of the differences in rpm and torque, the 7 turn would be geared 2-3 teeth lower that the pinion used with the 10turn.
The 23turn spec mod it's not a legal stock motor, would be close to a stock motor or above depending on vehicle.
Motors even those of the same type may require a 1 tooth gearing difference, the spur size may also have a slight effect on how vehicle accelerates, rolls through the turns and gets back up to speed. Stock offroad I like either a 83 for P2K2 and rpmish motors 87 spur, for TC went to 64pitch 112 for 19turn and 95 for stock, 4cell oval 116 for stock and 114-124 for 19tmod and mod.
Find what the ideal pinion range is with each of your motors generally you have a 1-3 teeth range with some motors, while others have a limited range of 1 tooth where motors produces the best acceleration and gets up to speed. See if you can get suggestions from locale racers or look at motor's manufacturers gearing suggestions for type of vehicle you have. Start at a safe, low range adding one tooth at a time - vehicle should get crisply and smoothly up to speed, should run for duration of race at the speed and only slow for battery dumping. If motor seems to fade after 2 minutes, motor seems adnormally warm try dropping on tooth on pinion. For spur try using a friends spare that is in the 78, 80 tooth range to see if you can tell a difference in how vehicle reacts or feels to you - try to use the same numeric gear ratio spur divided by pinion.
Stock motors used either a Reedy 767 or Trinity 4499, Springs Trinity Red (pos) Green (neg), two reds or sometimes a Purple (pos), Red(neg) on MS2 and Epic Roar stock. Some use the Putnam Green shunt on pos, Blue shunt on negative. For a little less comm wear switch to a moderate brush like Reedy 766 or low content Reedy 760 or Trinity 4499.
For spec and modified motors
Brushes for laydown hood use the ones suggested for stock motors for standup standard size brushes Putnam X, Trinity xxx Lemans, Trinity 4383 or Reedy 738. Springs start with Trinity Red (pos/neg) to a Purple/Red setup.

[trailranger]

Big misconception with motors is looking at one power level and assuming it's good. High rpm levels with low torque or watts don't always equal to the fastest motor or the ideal motor. .

Once again....I think motors should have a power rating index equal to the area of wattage x rpm under the power curve....the higher the number.....the more power it can lay to the track...its your goal to gear it to make use of the power. The index will help "noobs" trying to pick a great stock motor, since most tuned motors come with peak rpm, wattage, and torque...I think an index number would be easier to compare with.

[rcguy2477]

Motors can't be given index number, even if you have the numbers from the dyno. A motor may act totally different on the track than on a dyno. You are also assuming that every dyno gives the same numbers, when some are off 10+ watts. The only way to figure out gearing is to try out the motor, simple as that.

[Maxxcrazy]

Back to the topic....

Both of those motors are no where near "the best". Not even the Trinity D6 drag motor can stand up to one of these neodymium magnet motors. http://www.randersonengineering.com/Motor%20Battery.htm

[trailranger]

During a manufacture run that uses dynos to rate motors...I would assume that all the dynos are calibrated to be the same... this is called quality control. So if I were to pick out a new trinity cobalt from lot of pro motors that were all indexed I would pick out the higher index number rather than looking at all the numbers currently listed on the labels now. This makes my life more simple, and I would assume motor indexing would make all hobbyist motor selection easier. Think of the hassle....peak watts @ rpm, max rpm @ "x" volts, peak torque @ rpm and then comparing the differences. One number...less confusion.

BTW...just because you might not have formal education in calculus or physics...don't be unwilling to learn a little more to help yourself or others.

[trailranger]

Here is the reason why two motors with the same peak numbers can be totally different. The power curve for the red line have more "area" than the power curve for the blue line. But they both have the same realitive peak numbers for RPM, Power (WATTS), Torque.

[scoob]

Here is the reason why two motors with the same peak numbers can be totally different. The power curve for the red line have more "area" than the power curve for the blue line. But they both have the same realitive peak numbers for RPM, Power (WATTS), Torque.

Makes sense to me. Peak power doesn't mean much if a motor is weak in other parts of the powerband.

[mclarenowner4]

Back to the topic....

Both of those motors are no where near "the best". Not even the Trinity D6 drag motor can stand up to one of these neodymium magnet motors. http://www.randersonengineering.com/Motor%20Battery.htm


Will I be able to use that kind of motor with a brushed system? All the motors I have seen with Neo Magnets have all been brushless systems.

On that page, the one I really like is the 6 Neomagnet, 7x2. Only problem- $231!!! I don't have that much money to blow on a motor that (knowing my luck), the armature will blow up at that speed. Anyone know how fast that would be in a 5:1 gear ratio? How 'bout a 3.8:1? I am guessing in the 100's!

[Maxxcrazy]

Its a regular brushed motor, it just has neo magnets instead of FB9 wet magnets.

You can try to email rae@randersonengineering.com for an rpm quote

[ElectricThunder]

In a neodymium magnet can, RPM is going to drop considerably because the magnets are WAAAAAAY more powerful than your standard wet magnets. So even with a 7x2, I wouldn't worry too much about RPM in a 6 magnet Neodymium can.

[Maxxcrazy]

True, but with more power and torque, you can gear them even lower

[ElectricThunder]

True, but with more power and torque, you can gear them even lower
This is true, but the motor RPM still won't be as high as a 7x2 with ferrite magnets or any other weaker-than-neo magnets. I can only imagine how brutally powerful neo canned brushed motors are... then I go back to playing with my brushless...:D:D:D:D :p