Electric vehicles are the most popular form of racing and Spec classes like the 17.5T Stock 2WD buggy class have a huge number of participants at RC tracks everywhere. It combines skill and set-up knowledge along with a level of speed that’s fast enough to test most racers in a fun and competitive atmosphere. And just like any form of racing where there are limits on power (F1, NASCAR, Supercross, etc.), racers try and find an edge to give them a slight advantage. An area that isn’t often discussed is cooling of electronics and the use of small fans to improve efficiency and power. Art Sanfratello is the owner of RC Speed Secrets (rcspeedsecrets.com) and specializes in selling tuning options for racers. He has his own line of fans and knows a few things about their application and benefits. We got a chance to sit down with Art and have him shed some light on the topic. 

RC Car Action: You’re kind of the guy known for selling tuning options like small fans from WTF. We’ve seen them used for years with touring cars, but lately there seems to be a big push among racers to use them in buggies. Why do you think this is?
Art Sanfratello: For the same reasons we see the on-road guys using them to bring down their motor temps and operating temps for the speed controls. I was doing both on-road and off-road racing and figured it would be a good idea to bring the fans in to the Stock Buggy Class “Scene.” I thought it would be better to see our electric systems coming off the track at 100F instead of 170F. With a little bit of testing, I was able to find a bit more punch toward the end of the mains in five to seven-minute races. We are seeing a big jump in efficiency toward the end of races since the entire electric system stays cool. By cooling the motor, you’re also cooling the battery and the operating temps of the speed control. When you just cool the speed control, you don’t see the same benefits of also cooling the battery and motor. Not only are you getting a punchier car toward the middle to end of a race, but you are helping to extent the overall life of your electronics. In theory, your entire electrical system will have longer life and see an improvement in durability since you aren’t subjecting them to the high harmful temps. 

What kind of drops are most racers expected to see in their 2WD buggy versus not using anything at all?
Art Sanfratello: Obviously there are some other factors there including timing of the motor, gearing, traction, ambient temperature and things of that nature, but speaking on an average, I’m seeing guys running in the 160-170F range running without a fan on the motor after five to six minutes, are now usually getting around 100F or just below 100F. So in a lot of cases, you can see upwards of 70 degrees cooling difference- that’s a lot of performance gain. 
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And as apposed to popular opinion, a fan doesn’t really draw that much power does it?
Art Sanfratello: Well specifically, the RC Speed Secrets fans are designed to be in an RC car. The 30mm fan at 8.4 volts is operating at about 28,000 rpm and is only drawing about .43 amps. It does have a ball bearing in it as opposed to plastic male and female spinning parts- it’s normally what you’d find in your average 6.0 volts fan. A RCSS fan can be run at 8.4 volts, meaning you can wire it direct to the speed control or battery posts instead of just plugging it in to the receiver that limits the voltage to 6.0 volts. By going direct at 8.4 volts, you boost the rpm another 5 to 10,000. This really maximizes the output of the fan and having the ball bearing inside adds a lot of efficiency and keeps the amperage down. So the battery draw is minimal, and for instance, isn’t going to make a difference if you’re on the starting line with the fan running.

Article Credit: Radio Control CarAction www.rccaraction.com/

I get many customers that always want a brushless motor for crawling and scaling,  I'm posting this article from BigSquidRC.com to help explain the basics between choosing a brushed or brushless motor for your scalers.   I personally have run both types of motors, but because I'm mainly are rock and trail guy with my scaler, I want maximum torque and power on the bottom-end without huge RPMs.  Thus I choose to go with a quality "Hand-Wound" Brushed motor from either Team Brood or Holmes Hobbies and Tekin also has a hand-wound brushless motor.

First for those of you who have had experiance with brushed motors in the past, you know when you race you always had to put your comm on a lathe to shave the comm down to get the performance needed.  That because of the high-RPMs (21000rpms), when you crawl the average comm turn less than 1500 RPMs for a 27turn to 35turn brushed motor.  And to be realistic, your comm spins more like 500 RPMs when crawling.  So really you only need to replace brushes every year or more and you can pickup the old comm lathes on eBay for $50 and shave the comm yourself if you really need to.  So why do I prefer to run a brushed motor, simple, the hand-wound motors from the companies I listed, have more low-end torque and power at a cheaper price $60 to $90 for a motor. And you can get a great brushed ESC for about $45 for a Hobbywing 1080 brushed/waterproof ESC....  You cannot beat this price and the power these little gems put out on the low-end is incredible without cogging.

The main difference between a cheap $15 to $30 brushed Machine-Wound Motor and Hand-Wound Motor is torque and power.  A good quality hand-Wound motor will always perform way better than a machine-wound motor.  That winds on a hand-wound motor and neat and tight and usually dipped insulated vs sprayed like a machine-wound.  Plus the high-end custom brushed motor usually includes better shimming and components and most builders break in the motor before shipping.  With that said, if you are on a real tight budget, a machine wound motor that is included in most RTR kits or cheap replacement brushed motor will get you on the trail for loads of fun, you just wont have the ultimate torque and power like a custom hand-wound motor offers.  

​Brushed vs. Brushless is a non argument pretty much everywhere in the hobby. Everyone knows brushless technology offers the most speed, reliability, ease of use, etc at this point so why even bring it up? Because scaling/crawling is one of the last stands for brushed motors, a place where the discussion still takes place with merit to both sides, that’s why. Click the “Read More” to see both points of view (and for a guest appearance by a famous talking rock).

Let’s start with the basics. Crawling is unique in that it demands low throttle performance as the defacto “thing”. That’s completely different from nearly everything else in R/C where the end goal is usually top speed. While you may be saying “Well, duh”, I bring it up because that means non-sensored brushless systems are eliminated from the equation due to glitching/cogging at low throttle. That means the real argument at hand is brushed vs. sensored brushless (sensored systems allow for smooth throttle response across the full spektrum). That’s a very important distinction to make. Let’s go with brushed first.

The most popular brushed setups are either 27 or 35 turn. This range is nice and torquey when crawling and putting it on 3S will allow for plenty of wheel speed should you need it. As long as your ESC is waterproof you can also run around in the muck relatively worry free as brushed motors operate just fine in the drink (clean them off afterwards, you don’t want mud inside of them). The best part about all this is the cost. You can score a nice waterproof system for around $50-75 (like the new Axial AE-5 ESC/27t motor as an example). If a motor goes bad a new one can be had for around $15-$25 bucks. It’s about as low cost as it gets in the r/c world.

Now for the flipside. A good sensored brushless crawling system is no slouch and in many ways is totally better than its brushed brethren. The top of the line systems have fantastic drag brake hold, smooth throttle response and gobs of wheel speed on tap. So what’s the catch then? Why isn’t everyone flocking to brushless? It’s the combination of cost and being unable to perform in certain conditions without modification.

Sensored systems DO NOT like water or mud. Waterproofing steps must be taken to insure liquid doesn’t get inside the sensor ports on the ESC or motor. Even then, if you are running in deep water or mud bogging (not out of the question for this style of truck) you are playing with fire. A soggy port can leave you standing still until it dries out or even just fry the system completely.

Cost is also a major factor. A good brushless crawling system starts at around a $200 ballpark, substantially more than a brushed system. There isn’t that big of a performance difference on the rocks in many hobbyists eyes to warrant the higher price. It’s also a piece of mind thing; you can go bash your cheaper brushed system really hard and worst case you’ll most likely be out less than $100 bucks. The guy running a $300+ top of the line Tekin Roc 412 with RX8 speedo (an amazing combination FYI) may not want to tackle the nastiest parts of the trail for fear of ruining his system…or worse, he DID run that section of the trail and DID smoke his fancy top end system (possibly inventing new curse words in the process).

So that’s the conundrum in a nutshell. If you plan on staying relatively dry or don’t mind waterproofing and want to go fast as well as crawl (i.e. you Yeti folk) then pony up for a good sensored brushless system and sleep well at night. If you are primarily just wanting to crawl obstacles, get into the nasty stuff and/or don’t want to break the bank then you are just fine staying with a high torque brushed motor.

Understanding Gearing: By Tony Phalen on Apr 24, 2017 Axial Blog

Moving your rig is a pretty simple process; when you apply throttle from your radio, the ESC draws juice from the battery and directs it to the motor. As the motor spins, it rotates a series of gears that ultimately drives your vehicle forward.

CHANGING THE GEARING
Let’s say you want to increase the speed or torque of the vehicle; this can be done by simply changing the gearing. There are two gears that we work with to modify this; the pinion gear and the spur gear. The pinion gear is attached to the motor’s output shaft while the spur gear is attached to an output shaft on the transmission.
Changing these gears alters the ‘gear ratio’; a higher ratio equals more torque and acceleration but less top speed while a lower ratio equals less torque and a higher top speed. It is also good to note that a lower ratio can also build more heat, so it’s a good idea to monitor after changing the gearing.

GEAR PITCH
Pitch denotes the size of the teeth on a gear; the lower the number, the bigger the teeth. For example, most Axial rigs come with 32P (32 Pitch) gears. These gears have large, strong teeth on them, perfect for high-torque applications. Then there’s 48P, a slightly smaller tooth that is a good combination of efficiency and strength. Finally, there’s 64P. These gears find their way into extremely fast onroad cars that are made for speed instead of torque. It’s safe to say you’ll never find these delicate gears in a crawing rig!

MOTOR CHANGES
If you decide to upgrade your motor from stock to something a little faster, you’ll need to adjust your gearing as well. Gearing is usually calculated for a specific motor (especially in an RTR) for a good combination of speed and torque. If you put a faster motor in your rig and don’t change the gearing to match, you could overheat your motor and/or ESC, resulting in a failure. See our comprehensive Axial Transmission Guide complete with gearing charts for all of our current vehicles.

STOCK GEARING
Below is the factory gearing that comes in our vehicles:
SCX10: 32P 13T Pinion / 56T Spur Gear
SCX10 II RTR: 32P 13T Pinion / 56T Spur Gear
Wraith: 32P 12T Pinion / 56T Spur Gear
SMT10: 32P 16T Pinion / 56T Spur Gear
Yeti: 32P 16T Pinion / 64T Spur Gear
Yeti SCORE Trophy Truck: 32P 16T Pinion / 64T Spur Gear
RR10 Bomber: 32P 12T Pinion / 64T Spur Gear
SCX10 II: 32P 15T Pinion / 56T Spur Gear

RCcarStars strives to bring racers and bashers the most modern motor diagnostic tools, these tools will allow you to see what the true specs are for your brushless motors 540/550 size motors that run on 2 cell Lipos.
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I think everyone has agreed that brushless motors are one of the best things that have happened to the world of RC racing for some time. They have taken away lots of the maintenance issues of 'Brushed Motors" and also removed some of the "Mystery of Motor Tuning". Essentially if you see a guy with a fast car at the track, you can go buy the equivalent motor you should at least have parity in speed.. or will the RCcarStars Motor Analyzer Test, "prove that wrong"?

                         Motor Analyzer Test
          Only $5 per/motor (540/550 Motor Size)

The Motor Analyzer Test is great for the following reasons:

1. The "Motor Speed Test" will let you compare motors "side-by-side" to see what kind of RPMs the motors are generating with no-load on motor. (This is the same information that most manufactures provide in their specification on the box) (Note: RPMs are derived from taking the current voltage and multiplying it by the KV - So the higher the KV=Higher RPMs, Lower KV=Higher Torque) Usually 300kv difference is no big deal in overall performance or speed of a motor, but when you see variances of more than 300kv or more, that generates into speed and possible lap time savings or loss.
2. The "Motor Efficiency Test" portion of the analysis, will show what motor may be more efficient on power when you compare the AMP draw. AMPs ultimately equal "Motor Heat", so you alway like to see lower AMP draw numbers as that means that motor is more efficient at higher RPMs. 
3. The "Motor Timing Test" portion of the motor test will show you the true average of the motors endbell timing.  (we find that most of the time that the timing marks on the motor can endbell are just for reference and not usually that accurate as to the true endbell timing degree when measured.  This can play a huge part in knowing if you should increase your "ESC" timing.... Many people automatically just increase the ESC timing without knowing what the motor is already set at. This leads to poor performance and "Heat Issues")
4. The "Motor Sensor Timing Test" portion will allow you to see the A, B, and C pole timing degrees of each sensor.  Many times if you see large variations between these numbers it can mean one or two of the sensors may be out of alignment on the sensor board, or you may be able to fine tune the variances by shimming the motor closer to the sensors.
5. The "Hall Effect Test" will assure that all 3 sensors are actually working correctly and soldered in the right order.  
6. The "Noise Level Measurement Test" can be used as a benchmark if the motor is new or has fresh bearings.  We have found that when bearings start to fade you will see about a 15dB increase. This test lets you know when it may be time to replace your bearings. ​

The Motor Analyzer Tests Are Ideal For:

1. Used motors you may have purchased from someone else or online. This is a quick way to determine if you got what you paid for!
2. Use the Analyzer to compare motors of like "TURNs or KV".  You will find that different manufactures models and brands will test "Hotter or Colder" than you may have anticipated.
3. Stock Class Motors - What can we say but this class is so competitive, that it only makes sense to choose your best Stock Class Motor to race with.  Again even as much as 400 RPMs or a lower KV may make a difference over a 5 or 6 minute race depending on the track.  ( We also advise our racers to use our "Magnetic Rotor Strength Test".  Usually as long as the rotor is of the same diameter and length, you can swap rotors.  The higher the magnetic strength rating the more torque the motor will put out, with the weaker strength rating giving more RPMs.
4. Testing new or freshly rebuilt motor and "Benchmarking the Data", then at the end of the season recheck the motor and compare against "Benchmark Data" and identify any major changes that may affect performance.
5. For those of you who race to the edge and your battery is on the brink of "Cutoff", these tests will help you find the more efficient motor (less AMP Draw).
6. Ideal for testing a new motor or after you have adjusted the Motor Endbell Timing.  It will record the true motor timing so you can adjust the ESCs timing according without fear of overheating the motor.

Here's a sample of the Motor Analyzer Report you will receive after your brushless RC motor is tested:

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