In this multipart feature we will go step-by-step through the tuning process of a P2K based motor. We will start with a slightly used, completely stock P2K motor and use all the tuning tricks to get the most out of it that we can. We will keep track of the costs involved in tuning the motor and compare the end results with a "tuned" motor that you would purchase at your local hobby store.

All dyno readings are done with a Competition Engineering TurboDyno 45. The TurboDyno is run off of a car battery with a 50 amps charger to keep the battery voltage up during testing. The motor leads are soldered onto the motor for consistent results. The results are printed out on a HP thermo-printer for a permanent record.

We start out with in lowest form of stock motor we can find. This motor started life as a handout motor for the 1999 MARS off-road series. It is P2K based with a Fantom label on it.

To start off with, this motor has about 3 runs on it, still has the stock brushes equipped with the eyelets, and the stock springs. The motor has not been taken apart for cleaning, comm truing or shimming. This is the type of base stock motor you would buy in your local hobby store.

Below are the results for the first dyno readings. As you can see, it is nothing special pulling 95 watts & 17,031 RPM at a 20 amp load and 102 watts with 16,182 at a 22 amp load.

The second part of our test covers zapping. Zapping a motor means that it was put into a motor magnetizer and the strength of the magnets of the motor were altered. In the case of this P2K motor, the motor was packed up and sent off to Phil Stuard at Superior R/C Supplies, the manufacturer of The Magnetizer, one of the most powerful zappers made. Phil was instructed to zap the motor for maximum power for use in a 6 cell vehicle.

You may wonder why I had the motor zapped now instead of later in the tuning process. I wanted to see if zapping a motor had any affect on a motor that was pretty much new. This way we would kill two birds with one stone, get max power with a zapped motor and see if it was worthwhile having a new motor zapped.

Nothing else was done to the motor between Part 1 and Part 2 except for the zapping. The motor was not cleaned or touched in any way.

Below are the results for the second dyno readings after zapping. With the zapping, the RPM increased about 13% to 19,554 with a 20 amp load (about 15% to 18681 @ 22 amps). The wattage didn't suffer with the RPM increase as it also increased a couple points at a 20 amp load with even bigger increases at higher load settings. This baby ought to have a noticeable increase in "punch".

I've included the readings from Part 1 below Part 2 so you can easily compare the results from the two tests.


The Magnetizer costs about $1200.00 but you can normally get your motor zapped for less then $5.00

Total Costs:
$25.00 - Motor
$ 5.00 - Zapping
$30.00 - Total so far

Since the motor we are tuning does have a few runs on it plus a number of dyno tests, we figured it's time to clean it and make sure the brushes were fully seated. I fully seated in the brushes as I had noticed that even with 3 runs and numerous dyno tests the full face of the brush was not making contact with the comm. I set the motor in my motor stand, attached the cooling/load fan and hooked up a 4 cell pack. Since the stock brushes were so hard, it took over 10 minutes to fully seat in the brushes.

For this test we cleaned the motor like the vast majority of us do at the track. I took a Parma Commutator Cleaning Stick and cleaned the comm of the motor and also worked over the brushes to take any glazing off the face of them. I like the Parma comm stick is made of fiberglass strands, it cleans the comm nicely without being abrasive and can also be used on brushes.

I take a piece of heat shrink tubing, shrink it around the Parma Comm Stick and then cut off about 1/4" of the shrink from the end exposing the bristles. This keeps the fiberglass bristles in place and makes the stick slightly stiffer.

All you need to do is remove the springs and brushes, insert the Comm Stick into the brush hood and spin the motor over by hand a few times. I put a gear on the motor shaft to help turn the motor over. Once that is done, just swipe the comm stick across the brush face a few times and you are ready to go.

Take some motor spray and clean out the motor well. In this case I used Trinity Buggy Blast but most any good quality motor cleaner will do. Let the motor dry out, put the brushes and springs back into the motor and oil the bushings.

It was back to the dyno to see if cleaning and brush break-in made much of a difference. The big affect here is the now fully seated brushes. The wattage is almost the same but the RPM dropped from the added friction of the fully seated brushes. This is not all bad as you see the Torque and Efficiency increased. The wattage at the critical 20 to 22 amp load range is almost exactly the same and the power curve is now much flatter throughout the range.

Total Costs:
$25.00 - Motor
$ 5.00 - Zapping
$ 0.00 - Cleaning
$30.00 - Total so far

In this part we replace the brushes. This is one of the basic steps that most racers do and we will attempt to show what the improvements are by just replacing the stocks brushes with new higher grade brushes. For this test we chose BRP's #7148 XP Serrated Hollow Brushes. I picked these because I have used them in the past and have found them to give good power and have pretty good durability.

I installed the brushes soldering the brush lead to the brush hood and then fully broke in the brushes using 2.5 volts for about 5 minutes.

I then did 3 dyno runs to make sure the brushes were seated on the comm and to make sure the runs were consistent. The test show that we have picked up a lot of RPMs while the Watts have stayed the same at 20 a amp draw. I note that this motor now likes higher amp draws as at 20 amp and high ranges the wattage and efficiency is much better then before we changed the brushes.

Total Costs:
$25.00 - Motor
$ 5.00 - Zapping
$ 4.50 - Brushes
$34.50 - Total so far

We next come to the brush springs. After brushes this is the second most often changed item to get more performance. In this case I used a red spring on the positive side and a green spring on the negative side. This is the most common performance setup. I know that this combination of springs will not work in all cases but it has been known to be the best all around setup for 6 cell racing and is always a good place to start.

The springs being used were Trinity springs. Because the P2K has polarized springs, you most likely will be using Trinity springs no matter what the name is on the package.

Before changing the springs to the new combination, I cleaned the comm with a Parma fiberglass comm stick. I also used the comm stick on the face of the brush installed in Part 4 to get off any contamination that might be there from previous tests. The motor was then run for about 30 seconds at 2.5 volts. This short run-in makes sure the brush is properly seated in the brush hood and comm.

I made 3 runs on the dyno to make sure the results were consistent. Almost across the board the numbers are the same. The wattage, torque and efficiency are all up slightly with a small loss of RPM.

We do notice a trend of a flatter power curve towards the higher amp draws. In this case the RPM only drops 3000 RPM between 18 and 25 amps compared to 3500 RPM before the spring changed. Also, the efficiency curve is flatter. Of course these numbers could be different depending on what springs comes on a motor when you purchase it.

In our final installment we will cut and center the comm plus align the brush hoods to try and get the last little bit out of our test motor. Stay tuned for the wrap-up of the Motor Tuning for Performance feature article.

Total Costs:
$25.00 - Motor
$ 5.00 - Zapping
$ 4.50 - Brushes
$ 4.00 - Springs
$38.50 - Total so far

After all this testing, it was time to cut the comm. While I was at it I figured I'd center the armature in the can. Once I pulled out the arm I could see some nice grooves in the comm from the brush serrations. Surprisingly, the comm was not burnt at the edges of the comm segments which leads me to believe that it was fairly true from the factory.

I chucked up the armature in my trusty Cobra lathe and set out to clean it up. I ended up taking off .004" to completely get rid of the grooves from the serrations.


When reassembling that motor I also found that the armature was very close to already being centered. I just had to move one thin washer to get it right.

After reseating the brushes at 2.4 for about 3 minutes it was time to stick it back on the dyno and see what improvement cutting the comm had. Below are the results.

I was surprised to see really no difference when the comm was cut. All I can guess is that the comm was already fairly true from the beginning since no real "burn" marks showed on the comm, just some grooves from the brush serrations.

Our last step in the P2K tune-up is aligning the brush hoods. I have found that very few people do this and if they do it, they do it incorrectly. Here is how I have learned to align the brush hoods. I took a new set of brushes, ones that were some original brushes that came with a stock motor, and put them in the motor. I then ran the motor at 2.4 volts for about 10 seconds.

The brushes were then pulled and by looking at the wear spot on the brushes, you can tell the brush hoods are off-center and need to be moved. Just loosen the screw and spring post that holds the brush hood in place and move it in the direction needed.

Tighten down the screw and post that holds the hood in place. Clean the face of the brush to get rid of the shiny wear area and run the motor again for about 10 seconds.

Once you have the hoods aligned correctly, you will see the wear spot from the comm in the middle of brush. Aligning the brush hoods this way not only saves you money (you don't need to buy some fancy alignment tool) but is really the only right way to do it.

It was now time to put in the "race" brushes, give them a quick break-in (about 3 minutes at 2.4 volts) and crank up the dyno and see if it made a difference.

And what a difference it made! We were able to hit the magic 100+ watt mark at a 20 amp draw, ant the torque and efficiency increased to boot. Below are the results.

That is the end of our P2K motor tuning. We took a bone stock P2K motor and applied most of the tuning that is available to the majority of racers. In the end we turned a so-so 95 watt - 17,000 RPM motor into a 101 watt -19,500 PRM monster. All the while efficiency rose 5 percent.

The two big items that made the most difference was changing the springs (red on the positive and green on the negative) and aligning the brush hoods. Those two inexpensive and easy to do items accounted for 2/3 of the power increase that we seen.

Total Costs:
$25.00 - Motor
$ 5.00 - Zapping
$ 4.50 - Brushes
$ 4.00 - Springs
$38.50 - Total

We hope you have found this article useful and that you can see what the steps (and costs) are involved in tuning a motor.

End of article. Your comments are welcome.

Thank you for the info.This is my 2nd winter running electric (12 scale) AndMy son and I are going to get better batteries 1.95-1.99 Ib 3800 and we have bought 2 tuned motors from Hyperform and the motors are 30.00 already tuned.And the info you gave me will help keep these motors running at their best.thanks
mike

Glad you have found the info useful. Good luck this winter!

Thanks Hank, I will definitely be using the hood alignment info. Can you recommend a manufacture that still makes/sells that wrench that turns the spring post? Sockets I have do not fit that tight space. How often does one need to change brush springs anyway? I've noticed that spring testers are available but never gave them much consideration.

Thanks in advance

The only good spring post wrench that I have tried is from Integy. I personally don't check spring rates but I know of a few guys that do... they do vary some. If your motor doesn't heat up too much your springs should be good for a few months (maybe a dozen race days). If you really overheat the motor once it's a good idea to change them... the brush hoods can get over 500 deg. if you overheat the motor.

I am not sure anyone sells just the brush hood alignment bar by itself. You can buy ones that have a rod that goes through motor bushings and just use the bar part to tweak the brush hoods.

Good stuff Hankster! What are your thoughts on polishing bushings as far as performance? Any techniques you'd like to share ?

Cut a slot in the end of the spring post with a Dremel and a cutoff wheel. Then a screwdriver works. Takes about 30 seconds........

How about Polishing Your Shaft for More RPM (http://www.hobbytalk.com/bbs1/showthread.php?t=102984)?

I use a sharpie marker on the face of a brush to show me were the comm in making contact. I use some old very hard brushes and they don't wear very quickly. I check one side at a time, running it in a dremel, (make sure it rotating the motor the correct direction). Then adjust the brush hood so that the commutator contacts the center of the brush.

Good stuff Hankster! What are your thoughts on polishing bushings as far as performance? Any techniques you'd like to share ?

Try this:
http://www.hobbytalk.com/bbs1/showthread.php?t=127508

Brandon

Hank....is their any hope for a Spec Motor?. You have any secrets for those?....thanks KF

Hank....is their any hope for a Spec Motor?. You have any secrets for those?....thanks KF
hmmmm...just as I suspected...their are no tricks for these junkers...KF

Here's the thing with the spec motors,yes they are pretty much all junk,but everybody is racing with junk,so it's all even steven.

Can you tell me how to get intouch with some one to zap my motors for me