Joosh M

iTrader: (1)

Hey guys, I am working on trying to get a little more speed out of my motors, usually I gear around what everyone else at the track is gearing towards, then adjust the timing based on temperature. I was reading that there is a "sweet spot" to set the timing to get the max efficiency out of the motor and that this "sweet spot" is typically around 5-6 amps and if I understand correctly, it is the point where a very small adjustment of the timing will result in a big jump in amps. So I hooked up my motors to an amp meter and for the most part, this seemed true, somewhere roughly after 6 amps, the motor would jump up suddenly to 9-10 amps and so I set each of them to exactly 6 amps and I now plan to adjust the gearing based on heat. My concern is that I feel that the timing is set too high, some people claimed that their motors are set to only pull 2-3 amps, but then wouldn't that mean that their motors aren't running at peak performance? Using a contact tachometer, was able to record the RPMs at the wheels, and I noticed an increase in RPMs as the timing and amp draw was increased, something like 800+ RPM from 4.5amps to 6 amps. Any info would be greatly appreciated. Thanks!

urnotevenwrg2

iTrader: (1)

Setting timing based off an unloaded amp draw is (in my opinion) a stupid way to do it. The ultimate goal is to have a car capable of the fastest lap time without getting the motor too hot.

There are so many other variables that dictate the actual best motor timing and gearing. You would be much better off putting everything back to where it was and run the car to get a baseline lap time for that day. Then make a small change to gearing or timing, run the car again and see if you went faster or slower. Although, if you crash a bunch (more than one or twice per race), these small adjustments are not going to mean anything more than your car is going a tiny bit faster when you crash.

Can you run an entire race without crashing?

Also the 6 amp vs. 3 amp thing is because newer generation motors are more efficient, so they will draw less current at their optimal setting.

It doesn't matter what anyone else is doing. They don't have your motor or car, and they don't drive like you. Make small adjustments and see how the car performance changes for you.

Finally, this really should be posted in the Radio & Electronics section, not Electric Off-Road.

billdelong

iTrader: (33)

I would contact the manufacturer directly for your brand of motor, I've heard Tekin Spec-R likes to set their motors at 3A.

I run a Trinity MonsterMax and they recommend 5.6A and that's been doing really well for me. I actually have 2 of these motors, each set to 5.6A and 1 motor has an average timing of 45° where the other has an average timing of 47°, the motor reading 47° is the faster motor so that leads me to believe 1 of 2 things...
1) Higher timing = faster motor to a point of diminishing return and 5.6A is the point for Trinity
2) Every motor is different, so it's luck of the draw on getting a faster than average motor

Joosh M

iTrader: (1)

Thanks for the info guys, this really helps a lot. One more question is, if I wanted to compare each motor to see which one is the quickest, would I set them all to pull the same number of amps and then test the RPM? I know heat would also play a role in determining this as well. I have too many motors and want to get rid of the slower ones. Thanks

Antimullet

iTrader: (65)

Short of a dyno the best thing you can do is test each individually for best lap times over time and least fade over time. This requires adjusting timing and gearing on each motor specifically and uniquely to each motor even if they are the same brand and same exact mode. Where you end up at timing and amp draw may correlate somewhat between exact models but between brands pretty much not correlated.

And this magic 6 amp draw method is bogus. Most newer motors doing this only generates excess heat, inefficiency, and fade. In example, trinity like mentioned before they like higher amps 5.6-5.8 motive like lower amps. Same with R1s around 2.9-3.0 for instance in 1s racing slightly higher in 2s.

billdelong

iTrader: (33)

I agree that a dyno is about the only way to know for sure unless you've got a 95%+ consistency on the track, then you can make a reasonable estimate between motors on the track based on fast lap times.

Comparing unloaded RPM on a motor is no different than doing voltage readings on a LiPo without a load, yeah my identical motor comparison with the same 5.6A draw showed the faster motor was both higher in timing and higher in RPM, but I'm not convinced these numbers correlate. Not even sure I would set different brands of motors to the same amp draw either because that's basically comparing apples to oranges

Troubles Dad

iTrader: (204)

As I tend to agree with some of these guys, their is questionable variables as not all motors are the same, as I went thru my 17.5 motors a while back as had some tekins and figured they where good, as kept turning up the timing till it maxed out and still where duds, as tried a Novak stock spec motor with no timing adjustment and had over a 1,000 more RPM's, so going from one manufacturer to another is like comparing apples to oranges, but if you find their "sweet spot" it will show you what motors are good and the ordinary motors, and we all have had them motors and nothing you ever did would make them faster, but on track will give you the best options, provided you can get to one on a regular basis, but like myself I am 125 miles away from my favorite track, so I cannot afford to spend race day playing with motors, so I need to have my stuff ready and have set many motors to the way the OP has described as I have a motor analyzing tool, as it gives me numbers and I can make my best judgement on what they can and cannot do, as I gotta ask what the heck does driving cleanly around a track have to do with having a faster motor, just asking as that makes no sense to me, as the way I see it as I can get around the track without problems and a lot of the time it's others or lap traffic that causes the biggest issues

urnotevenwrg2

iTrader: (1)

If you can drive clean and consistent, you can use lap times as a metric for performance gains. If you can't drive clean, the performance gains from the perfect timing and gearing will not mean much if you spend a lot of time waiting to be turn marshalled. Ultimately though if OP is wanting to try some adjustments to see what they do that is a good thing.

The progression of brushless motor designs over the years is pretty incredible. I have an old Speed Passion 10.5. It is so old the timing is fixed. On track it is almost indistinguishable from a modern 13.5

That's unfortunate that you are so far from that track.

Troubles Dad

iTrader: (204)

Lap times could be measured on single fast laps or consistent laps as rarely do you ever get a full race in without traffic, even during practice as I struggle with finding the best gearing choices, and rarely get to practice as I have tons of time to work on the cars to have them good, as when we run VTA class, the cars get everything done, cleaned and fresh oil in the bearings and as of late I have been doing all the same tricks to free up the off-road cars, and yet I still struggle with gearing.

big ted

iTrader: (2)

Setting by trial & error at the track is all well & good, but throw in the variable timing capabilities of modern ESCs & I can't imagine how one would start to get dialled in without having something of a good baseline.

My 13.5 Motiv was previously dyno'd and had the end bell timing set accordingly (to about 35 degrees iirc). However, this is only the right setting if the ESC is used in blinky mode. I'm still playing with other aspects of my car for now, but at some point I imagine I'm going to be in the same boat as the OP when I move the timing from the end bell to the turbo & boost settings of my ESC.

billdelong

iTrader: (33)

nevermind

Joosh M

iTrader: (1)

Alright, so most of you seem to be saying that there is no "magic number" to set the motors to and that it is hard to compare motors based on amp draw. As for my lap consistency, I usually run in the top 3 positions in the A-main in the stock class at my local track, always higher than a 90% consistency ( I think this last Friday's race was a 97%). I finished 3rd this last week as well and it was simply because 2nd place was faster down the straight and was able to overtake me, hence my question concerning a faster motor. I think that I will just take a weekend and go down to the track and setup each motor and play around with gearing, timing and temperature to determine which one feels the fastest on the track. Ideally I believe that it would be the one that can run the fastest with the smallest gearing/lowest amount of timing and the least amount of heat.

urnotevenwrg2

iTrader: (1)

That is the thing, your situation is not the norm. Most people have local tracks where they can test when they are the only car on the track.

Volksford

There are probably about 20 different variables that make a big difference in timing. First and most important is battery cell count. 1 cell racing requires a different strategy than 2 cell. To make it as simple as I can. 1 cell tune to 3 to 4 amps. 2 cell around 5 to 6. Actually timing will vary with different rated rotors (strength). I weaker rotor will require more actually timing where as a strong rotor needs less timing. Once you are getting the most out of motor then gear to track.

Volksford

The people that say don't use free amps either has someone tuning for them are more equip than the average joe. The average joe doesn't have an analyzer or dyno but he probably has a amp reading device. (DVOM). Also if doing an amp draw between battery and esc, the esc does draw a bit of power. On the order of half amp to 1amp.
As a guy that started with nothing and built up to dyno's, analyzes and stator equipment I can give you this info from an average guy point of view.