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Can a dyno find the good motors?


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#51 Butters37

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Posted 08 March 2016 - 01:28 AM

That is correct, Cap.
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#52 Brinkley47

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Posted 08 March 2016 - 02:37 AM

Are you looking for higher amp draw or lower amp draw on the power supply? To determine a "good" motor.
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#53 Samiam

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Posted 08 March 2016 - 03:13 AM

Off the subject... the motor issues would not be an issue if you design a class where the motor is so much better the the chassis... but then everyone would be flying off track.


It is called Eurosport. Expensive motors but you only buy two or three and you're done. But they can use the money they save on front wheels. :)
 
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#54 Noose

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Posted 08 March 2016 - 06:54 AM

I will say it once again. I saw 33 racers this past weekend. I was the 34th.  HP was not a problem out there. I saw (in tech and on the track) some of the sloppiest set-ups and of course these people had lots of issues out on the track.
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#55 tonyp

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Posted 08 March 2016 - 07:05 AM

Another thing that doesn't get mentioned is how much practice time you have on that RH along with the four or five races before they are worn out. Cheapest laps for the $$.
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#56 JerseyJohn

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Posted 08 March 2016 - 10:01 AM

the most effective way I've found (in the real world) was to break in a motor under a lite load. Most 1/1 motor shops put engines on test stands (dyno) and place a load against it while they set the rings and bearings.

I'm working on a propeller based test stand using a modified in-line motor bracket that sits atop the power supply and by using a prop as the load, it additionally cools the motor during testing and break-in.

just my $.03

 

With that in mind, Jeff, why can't you just mount the motor in a chassis with gear and tires and load it that way?


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#57 Butters37

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Posted 08 March 2016 - 10:18 AM

Would you put that on rollers, John? Like the old Tamiya break-in stand I believe? Have the rear tires actually run on painted wood rollers to simulate the track I mean.
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#58 MSwiss

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Posted 08 March 2016 - 10:31 AM

With that in mind, Jeff, why can't you just mount the motor in a chassis with gear and tires and load it that way?


That's not much of a load, with the tires not touching a sticky track and propelling the car.

Stu had a dyno with a big solid aluminum freewheel on it, maybe 9"-12" in diameter. All it did was confuse him.

What looked like it would run good on the track, didn't, and what didn't, did.

The only true dyno is the track. You'll never be sure you have a stud or a dud, unless you try it.
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#59 Steve Deiters

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Posted 08 March 2016 - 11:10 AM

I've wondered over the years if we used watts instead of amps to determine when a motor is being broken-in if that would be a better measure of it.
 
1) Being "broken in" meaning the brushes are now "seated".
 
2) Being at its maximum potential and is defined by an empirical number of some sort.
 
Thoughts?

#60 Butters37

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Posted 08 March 2016 - 11:35 AM

I've been recording ohms lately. The theory is that the meter will read the tab going in... through the brush... into the comm... through the windings... back out the comm... through the other brush to the tab.

A lower value should depict less flaws in the motor assembly thus giving a more efficient motor. All my values have been recorded.... I'm breaking them in now. Going through them at the track

I have a Fluke meter, not a cheap five-dollar Harbor Frieght unit. The values I've seen are 1.5 ohms (my best currently)... to 55 ohms.
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#61 Cheater

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Posted 08 March 2016 - 11:41 AM

Stu had a dyno with a big solid aluminum freewheel on it, maybe 9"-12" in diameter. All it did was confuse him.


Some years ago I had a brass flywheel made to fit on the motor shaft, sized (via guessimate) to simulate the load a motor sees pushing a car down the track. Got a photo tach with RS-232 output to graphing software. The idea was to see graphically how quickly the motor would spin up the flywheel, i.e. generate an RPM vs time curve. Give it 12v and see how steep the RPM curve that was generated, thinking the motor with the quickest RPM rise under the same voltage and load would be the "best" motor.

I never completed the project, because I came to realize that each track's unique power and wiring could not be simulated.

As I've mentioned before, I've experienced situations numerous times where a motor that was the worst I tested at one track was a world-beater at another track.

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#62 Phil Hackett

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Posted 08 March 2016 - 11:56 AM

Testing is an area where you need to correlate the data with actual performance. Just because a dyno says a particular motor is better than another doesn't mean it is. You must create baselines and this is where the real work is. "Better" needs to be defined by parameters set out by the tester. Not all people (racers) define better the same way. Therefore "numbers" are relative only to the requirements of the user giving them.


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#63 Phil Hackett

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Posted 08 March 2016 - 11:59 AM

Off the subject... the motor issues would not be an issue if you design a class where the motor is so much better the the chassis... but then everyone would be flying off track.   :laugh2:

 

Not the better drivers… they wouldn't be flying anywhere.


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#64 John Streisguth

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Posted 08 March 2016 - 12:32 PM

Which is why there has to be a rule to limit how long any one racer can hog a lane. I just want to get a few minutes on an inside lane and the gutters.
 
But it's impossible when guys are testing five cars at a time.


I may have five cars, but I know within five minutes what's what with each. Then it's back to the pits to work on a few things.
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#65 Arne Saknussem

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Posted 08 March 2016 - 01:11 PM

Greg hit the nail on the old crumpet. Drag your dyno to the track and use the track's power supply or (IMO) you're wasting your time.

 

Logical thought (and my own experience) yields the following which should be fairly obvious to all concerned (disclaimer: I haven't won a race in a dog's age).

 

RH draw @ 4V <1.0A = may or may not be fast but will run cool.

RH draw @ 4V 1.0A to 1.4A = MOMNBF, runs about average temp.

RH draw @ 4V >1.4A = MOMNBF, will lay over late in the race in direct proportion to the heat generated.

 

Your numbers may vary.


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#66 James Grandi

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Posted 08 March 2016 - 01:17 PM

Most of the guys trying multiple cars at once seem to be running the middle lanes (usually), in particular orange courtesy of that being the qualifying lane.

It certainly is a good idea that instead of waiting for one of the center lanes, tune the car to maximize the gutters if you can. I followed Matt Bruce when I was in Purple and he in black during Can-Am, I was pushing hard to run the same pace as him. And we weren't slow, we were clocking mid-5.4 second laps. You have to be kind and give yourself a car that works generally well in as many lanes as you can - but if I had to pick, a race is won or lost in the upper and lower gutters.

As to sorting motors - it's pretty clear at this point that the power supply, or a dyno, isn't going to be the tool to make the call although it is useful to a degree. Track testing and a notebook is about all there is. For those who unfortunately lack a local track or a track within reasonable distance, of which I know there are quite a few with that problem, the only real solution would be planning for the travel and cost of going to the next event a day early and practicing/testing then.


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#67 Marty N

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Posted 08 March 2016 - 01:19 PM

Can a dynamometer find the good numbers?
 
That’s the question is it not? What’s it do? It measures and reports motor performance against a known load. If well designed that load will exceed the maximum capability the motor has to offer. It reports watts produced against watts drawn and gives and electrical efficiency number. It measures torque and reports. Amps and reports. It reports the rate of acceleration in tenths of a second. It plots all this on a nifty little scatter graph that allows comparisons on the same chart to several motors. In a nut shell 100 watts is ‘better’ than 80 watts and 60,000 rpm in 5 seconds is ‘better’ than 60, 000 rpm in 7 seconds. It draws amp traces that allow you to look at both raw and smoothed data that shows you how stable the current draw is  up to the test voltage (RPM). Better is just better.
 
Motor A outperforms motor B on the dyno at X inertia load. Which by the way has a wheel with several times more inertia load than your car. Bur even if the cars load is twice that of the dyno load motor A will still outperform motor B in terms a dyno measures. What a dyno can’t do is measure your skills as a driver, as a chassis tuner, what the track conditions are or your chosen setups efficiency in delivering that improvement in real world results of quicker lap times. So yes, a dyno is more than capable of sorting a good motor from a bad one. It just can’t tell you how good you will be with the results it reports. That’s not it’s fault. It isn’t it’s job.
 
Blaming a dyno for ones inability to understand or use it effectively is like blaming a hammer for a bad meal. IMHO.
 
My 2 cents worth and a dime in change.


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#68 Cheater

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Posted 08 March 2016 - 01:52 PM

Most of the guys trying multiple cars at once seem to be running the middle lanes (usually), in particular orange courtesy of that being the qualifying lane...


If I was short on time, I always just tuned on the gutters. If I could run them, the middle of the track should be OK.

And as an even further aside, if it was possible, I always found it very instructive to do at least one session across the track, red to black or vice versa, say 5-15 mins on each lane. It teaches you a lot about a track.
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#69 Phil Hackett

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Posted 08 March 2016 - 02:29 PM

Nothing beats trigger time. Even $800 of special tools for working on motors... :D

 

Who ever "owns" black at BPR will always be up front because if you're not fast in the middle it won't matter.


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#70 Noose

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Posted 08 March 2016 - 03:22 PM

I run the gutters. If the car is fast there it is going to be great in the middle. Races are won and lost in the gutters. I have set many fast race lap times on the red lane. Usually that is the one that is the trickiest in the deadman on all tracks. 

So yeah, as John Streisguth said, with a couple of minutes with multiple cars I know exactly what works and what doesn't. 
 
BTW, I have never had a Hawk Retro motor read anything above .9 amps 6 volts and that as one that had many races on it. The norm for these is typically .48-.52 amps after a light break in.
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#71 tonyp

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Posted 08 March 2016 - 04:05 PM

Ditto.

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#72 Tim Neja

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Posted 08 March 2016 - 05:16 PM

I have read all the post on this and it looks like a lot of time is being taken trying to find a good motor but nobody wants to build a motor because it takes up to much time and money to buy motor building equipment.  

 

But yet you will spend $80 on a break-In motor stand and God only knows how much money is spent on these motors.

Just saying!!!

Why is it in slot racing--some find the need to slam something that has proven to work?  The Retro Can Am class IS one of the best racing class's slot racing has seen in 40 years!  But all you're doing is bitching about it?  WHY?? It's been a great revival for slot racing, yet you find the need to force a change?  In another thread clearly %95 of the racers posted they love NOT having to build motors. But that didn't satisfy you, so now you're bagging on that idea here as well? WHY?  Retro racing is successful because we don't build motors. It's become a proven fact.  Why not enjoy  that and attempt to continue to GROW the class?  As was pointed out--there ARE motor building class's even in retro. Why is that not good for the motor builders?   Just enjoy the racing we have -- if it's slot racing--it's all good! :)


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#73 CoastalAngler1

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Posted 08 March 2016 - 05:56 PM

I'm the new guy.  I can get in the A Main with these RH motors.  Why?

I learned to test car(s) at the track and tune them at the track with multiple motors.  This is not easy, others are much faster in the pits.  

I've been trained 5 motors for each class for each big race.  Locally you should be able to find enough HP with what is leftover.

3 chassis per class means one race car, one backup car, one practice car. The 3 bodies hopefully interchange and you test those too.  

Take testing notes, change one thing at a time, you can always go back.  

Drive better to get first place.

I can find a bullet right now in my 30 motors from 2015, the new batch of 10 are pretty darn good too.

There is not a big difference in these motors - mine happen to like swimming lessons before they learn to crawl.  :ph34r:

All races are big to me.  I do not save 'bullets' for out of town.  

RH motors do not like excessive heat.

I never, never spin them above 6v unless in a car.

I still want a Trinity Dyno  :shout:


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#74 JerseyJohn

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Posted 08 March 2016 - 06:37 PM

You mean thrashing like maniacs and ending up being one of the first five cars to go out for qualifying? That's me, every race LOL.

 

Another  issue is when A Mainer guys go up there with five cars. Practice and checking cars is out the door for a lot of us... Just saying...


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#75 James Grandi

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Posted 08 March 2016 - 06:42 PM

I don't bring up 5 cars to practice. I bring 2 cars per class, and I tend to only test those 2 cars at a time. At one point I did test a 3rd car for another racer, but even then I try to make sure I only run a minute or two per car at most.

I know there are some guys that do run 4-5 cars at once, and I've certainly experienced waiting in the rotation for longer than I think it should take sometimes, but I have no more or less opportunity at track time than any other racer
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#76 Cap Henry

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Posted 08 March 2016 - 06:44 PM

You don't have to practice on the qualifying lane to compare the cars. Sure it's not ideal but you work with what you have. I'm one of those guys that can I start off with 5-6 cars but quickly cut it down to 2 to work on.


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#77 Nate Graham

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Posted 08 March 2016 - 08:00 PM

Back on orig idea:

 

Cheater, I think you had the right plan - find a way to quantify performance. I think Marty N laid out a nice discussion. A dyno is a tool but interpretation is key. The top racers who have chimed in on the other side of the argument have already figured out how to test and get results without it - they are obviously very consistent drivers who can also analyze a car on the track and know if the issue is their driving, track conditions, set-up, or the motor. They are much better than me. 

 

Years ago, I raced R/C carpet and asphalt. I did not have money to buy a dyno but had the skills to build one based on the top one of the time. I think it was called the SnS dyno. You linked the test motor to a slave motor - at the time a Mabuchi 540 - and then varied the load like the brake on a slot car controller: open circuit, large resistor, small value resistor, and shorted for "full electromotive brake." Voltage produced by that motor was used to determine RPM - today we have readily available RPM counters. Calibrating these voltage numbers for real world torque is a more challenging physics problem but may be unnecessary as relative numbers will probably suffice. It does make it impossible for me to compare my homemade device results with yours.

 

Analyzing the slope of the curve with varying resistance as well as the top-end changes can tell loads - pun intended. Short tracks - motors with a higher slope of acceleration under heavy load, long straights = higher top end under moderate load, etc. 

 

In summary, I think the dyno has merit for this hobby. nobody makes a unit for slot car motors at present, right? 

 

Re: the flywheel, I would be concerned that it gives too much load at start-up with too light a proportion load at top speed while the slave motor that increases load as RPM increases might be a better model. 


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#78 Cheater

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Posted 08 March 2016 - 08:26 PM

There's still the problem of the varying power delivery systems at the tracks...


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#79 MSwiss

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Posted 08 March 2016 - 09:01 PM

If you paid your $13, you should give that motor a spin on the track.

 

One is better off spending that home dyno time, sitting and watching Downton Abbey, with the wife, or whatever it takes that she'll let one go to the races early, to test the motor where it matters.


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#80 smokie

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Posted 08 March 2016 - 09:17 PM

John,

 

I did try doing it that way but noticed a variation in the RPM without changing the voltage on the power supply. I did notice that the amp draw didn't stay consistent. I attribute it to that once the drivetrain get to its RPM, the load disappears as does the resistance. The propeller is always under a more substantial load with the side benefit of the air blowing across the motor helping cool it.


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#81 A. J. Hoyt

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Posted 09 March 2016 - 02:07 AM

Marty N and Nate Graham are on the right track, trying to apply some level of science to the task at hand. It comes down to using whatever measurable quantities you can accumulate, then correlating that with the on-track performance, keeping meticulous notes. After a time (with rules stability), one can accumulate some data that you can use to predict which motors are worth trying at the track. I think that is what you are looking for, JJ; to believe you have separated the wheat from the chaff at home so you only take the good motors to the track. It takes a bit of time to learn and a lot of controlled parameters to arrive at that point - I just don't think there is any easy short cut. It also helps to track a motor to know when it is time to take it out of service.
 
And all of this for a motor that is likely going to lose its brakes (and become useless for anything but soldering into a steel chassis wing bodied class) after about 4 races.
 
I've said this before on this blog: I have watched a certain top Retro racer (whose motor rebuilding business has untold resources and testing equipment) run in the A Main at many races where he did not ever seem to have the dominant fast car on the straight - sometimes not even the top half of the A main. He knows that there is a lot more turn than straight in the course of a lap and that racecraft and set-up is what gets the most laps. A car that is not slowing down as much for the corners (better exit speed) is not as labored pulling itself out of the turn. Also, the best racers are like machines in turning consistent laps at 95%+ every lap and "recover" very quickly to resume that consistency after a de-slot or a crash.
 
If you need to be convinced, it is certainly available to you to watch the race monitor during an A Main.
 
If one does find the "magic numbers" to pre-determine if a motor is worthy of down-selecting to bring to the track, you are not likely to share it (sorry, JJ).
 
Also, all of this knowledge of what is relevant to test and the time to test it and validate it to on-track performance will be required of a purchased sealed motor set OR for a built-up motor. And all of it counts for nothing if you have only an hour to break-in a hand-out motor before tech-in.
 
Put your time into what counts - chassis tuning and racecraft. That is what the upper crust racers consistently do well and the rest of us aspire to.


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#82 Noose

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Posted 09 March 2016 - 06:58 AM

Way too much "Sheldon Cooper" going on over this. 

 

Fact one, if the motor vibrates, well it is probably a dog. If it revs smoothly put it in the car and go for it.


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#83 Marty N

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Posted 09 March 2016 - 08:16 AM

Jersey John's question was, once again, Can a dynamometer find the good numbers?  It's a simple question of ability.

 

It's no different than the question, Can a tape measure accurately find the length of an object? Not much "Sheldon Cooper" to it. He didn't ask if you find a tape measure useful or if you can read one or agree as to the definition of an inch.

 

The only part of his question that is possible to intelligently debatable is the word "good". It will find the numbers, It will find accurate numbers...Their being good or not is the question within a question. No different than coming to an agreement on the inch on a tape measure being a "good" or accurate number.

 

Not much point debating "good" until you've answered "can". Maybe after "can' and "good" are explored "useful" might be relevant. But as we've jump to the last page in the book and made a decision based on personalities, passions and opinions why on earth would we wish to digress to find the fact John asked for?

 

If ever there was a squirrel in the dog pound, this one is it.


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#84 tonyp

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Posted 09 March 2016 - 08:21 AM

Prop works pretty good.The R/C guys did that until dynos became more readily available. You can adjust the length to adjust the load.


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#85 Arne Saknussem

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Posted 09 March 2016 - 05:28 PM

Thank you Marty.  And Greg.  Now, about that squirrel...

 

Electric motors convert the electrical energy supplied to them into mechanical energy, imparting motion, right?   It seems to me that unless we can duplicate the energy supplied at a specific location (i.e. track) at a given time (i.e. race day), we will never get (in John's words) the "good" numbers... assuming we knew what they referred to, which I'm pretty sure we don't.


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#86 MarkH

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Posted 09 March 2016 - 05:35 PM

Having tested Kart Engines for around 10 years +, I can tell you those who proclaim a Dyno has never won a race are correct. I can also tell you finding the best setup for for any engine varied per engine. However, the package that produces the most power was the one we used on race day. Tweaking the other variables, (gear ratio - clutch slip - handling etc) at the track to give the engine the best chance to shine against the competition was as important.

 

So with these little electric motors a Dyno with proper outputs would give you enough information to find a motor that produces the most power the most efficiently. It is up to the driver to tune the car with gearing, tires and driving to get the most out of setup. Putting in the same gear ratio you always have run might not be the best. Perhaps a few teeth less prove to be better. Create a matrix of important values for both the motor and track testing. You may find some group of motors can run strong if they are geared for top end while others not so much. We had Kart engines that were real good on the bottom and other that liked to be spun to the moon, so that is how we ran them.

 

It only makes sense to me to test at full power. Lower voltages in the 6-10volt range should only be tested if that is the max available at the track you will be racing. Your controller will let you overcome performance short falls at lower voltages by just squeezing the trigger more.

 

So John, "Can a Dyno find Good Motors", yes for sure. But it will be a program that requires much effort in the details. One must always be ready to change direction based on real world findings. Don't hang on to preconceived notions of what should be good.


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#87 Arne Saknussem

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Posted 09 March 2016 - 05:55 PM

Hi Mark.

 

I used to spend hours dyno running Kart engines myself back in the 60's.  The significant difference with slot cars is the energy input.  We played with compression, combustion chamber shape, pipe lengths, etc., and, as you say, each engine was a little different.  But the energy coming in was supplied by the fuel we selected ourselves and brought with us to the race.  It was a known quantity.  Slot track power isn't.

 

But I couldn't agree more with you on this bit:  It is up to the driver to tune the car with gearing, tires and driving to get the most out of setup. Putting in the same gear ratio you always have run might not be the best. Perhaps a few teeth less prove to be better. Create a matrix of important values for both the motor and track testing. You may find some group of motors can run strong if they are geared for top end while others not so much. We had Kart engines that were real good on the bottom and other that liked to be spun to the moon, so that is how we ran them.


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#88 JerseyJohn

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Posted 09 March 2016 - 08:01 PM

We have one component we are missing... watts.


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#89 Half Fast

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Posted 09 March 2016 - 08:09 PM

We have one component we are missing... watts.

 

Can't you simply multiply Amp draw times voltage applied to get watts?

 

Cheers


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#90 Butters37

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Posted 09 March 2016 - 09:23 PM

According to ohms law you can
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#91 Butters37

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Posted 09 March 2016 - 09:25 PM

But that number would just be used for reference along with amps and ohms. Find the numbers in your fastest motor. And find one that is close to each. Test it on track and if it's similar you have a guide on what to look for in a motor for your track....possibly. all hypothetical until the green flag drops
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#92 Marty N

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Posted 10 March 2016 - 01:06 AM

A road course is a variable dynamic load. An inertia dyno is a transient dynamic load. Seems there is no correlation. The Fantom dyno measures motor outputs based on 5 volt inputs. The drag track is 16+ volts, road course what 13.7V? . Seems there is no correlation. Here's your correlation.

 

More is always more. That is what a dyno does. It measures the difference of more. If it is more at 5 volts it is more at 20 volts. More is where you are getting hung up. More isn't magic. More is work. If you make more and your slower that isn't the motors fault and it isn't the dyno's fault. When you believe either is true that's your fault and your stuck having the same old arguments about what is better, five apples or ten. Ask how big the pie is.

 

Guys, If more doesn't matter then why you all wound up about someone with a 'cheated up motor'? Why? Because it's MORE!!  If more didn't matter Group 7 and FK's would run together. You think a dyno can't tell the difference because the test voltage is something different than the track?

 

Current draw of an unloaded but properly broken in motor at a fixed voltage is indeed a measurement of one of three motor parameters engineers use to make performance charts. One. What it measures is stray losses most of which are frictional losses. Bushing, brush tension and windage.  If the motor is sound to begin with and properly broken it is ALL it tells you. Nothing more, nothing less. 6 volts and .5 amps is 3 watts stray losses. Now having said that, to compare that motor with another motor whose production tolerance for timing is 5 degrees different or magnets were 5% stronger or gap was 5% closer would require you measure the motoring and generator constants as well and do the calculations. Or, put it on a dyno and directly measure it. Trailing amps and fixed voltages don't tell you anything even comparatively unless it is the EXACT same motor.

 

Here's the one thing a Fantom dyno can't tell you due to the low test voltage. Will the brushes bounce at three times the test voltage? But we talked about that earlier. Anyone here want to hold on to a Cobalt 43 and spin it up to 16.2 volts without a load to see if the brushes bounce? BOOM!!! I thought not.


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#93 JerseyJohn

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Posted 10 March 2016 - 09:51 AM

OK, Martin,

 

One of the issues I have before is getting track time to break-in motors. It was discussed that running a RTR motor in chassis isn't enough load. What if instead of tires a balance weight could be attached to the axle, say in the 75 to 90 gram total. I aleady have them. Should get us closer to track conditions. I could set my Trinity to mimic voltage variations...

 

JJ


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#94 Marty N

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Posted 10 March 2016 - 11:55 AM

I know where that comes from, John, but we are not seating in a set of hard chrome rings in a small block Chevy where load matters. The springs provide all the load the brushes require to conform to the commutator. In fact running the motor under power with enough load or even enough RPM to create arcing is damaging the commutator, not breaking it in. Arc erosion. You've seen it in  your re-buildable motors on the commutator leaves. Leave that unavoidable wear for the track.
 
There are two forms of arcless break-in I know of. Wet, which is an iffy idea with these FKs (and my personal favorite)... or... a slave motor. Some of the drag guys break-in with their Dremel motors. A drill press works. A coupling between an FX and your FK. Right rotation of course. I made a small stand and drive one motor with the other with a drag bike belt drive and a sleeve. I've seen face to face gear driven. Anything that lets you get handsfree and you can regulate and measure or know the RPM is the same each time. It takes awhile.
 
So how do you know when the cake is baked? A voltmeter during steady state operation says I'm broke-in when the voltage peaks at your predetermined RPM. And how do I know what peaked is? Experience. But a good guide might be a known good motor that you're still racing and still running well driven to the same RPM and metered. One of the things I like about a belted AC motor drill press is the RPM is a given as long as line frequency for the AC drive motor stays constant... and it does.
 
You wanted a "number"? Pick a target motor voltage. The output of the one you're breaking-in. The broken-in motor that produces that voltage at the lowest RPM is your marker. That is the motor with the highest generator constant. If you have two that are identical then the second mark is trailing amps at a set voltage running. The lowest current draw for the same voltage is the one with the lowest losses. If you pick the lowest current for the same voltage among two motors with the same generator constant it will also be the motor with the highest voltage constant. That is produces the highest RPM per volt and now you have all three engineering variables. If you learn the math that lets you use these three to determine watts, RPM, and slope then you've just done the work of a Fantom Dyno in long hand. But at a fraction of the cost.
 
Then again just plain old low voltage operation below the arc point for enough time on the bench will do it to. Not ideal but the least worst of the bad. In which case you have to break a few eggs to make your omelet. Open a few and look at the brushes using your observation as a guide for time. Which takes you back to the original thread. That enough options?
 
The whole point to all of this in sealed motors is is perfecting commutation and controlling friction.
 
As far as your idea about weighted drive and your programmable Trinity. Excellent idea for breaking-in gears. Now I have tool envy.


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#95 JerseyJohn

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Posted 10 March 2016 - 12:05 PM

Dude, you are super funny. So spin it like a generator. You are the second guy that said that. I even have pics of his unit. Interesting...

 

Stay tuned.


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#96 A. J. Hoyt

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Posted 10 March 2016 - 01:17 PM

JJ, this might help if you have limited time at the track.

 

I have read that Ford used programmable dynos when preparing for the mid-'60s LeMans and Indy efforts. I have spoken to engineers who were there who said you could hear it down the hall when the engines were screaming down the Mulsanne and even simulated pits stops. More recently, some dyno rigs have been used that turn the engines for the corners so the oil flows to the proper centrifugal side.

 

Recalling this, I have always thought it might be important to break-in the Falcon and Retro Hawk motors in real world conditions. I do an initial break-in that hangs the motor pinion end up so that oil on the comm end does not wick onto the brushes at this critical time, 5 volts for 15 minutes. I learned a really cool trick by accident, to hang the motor on a brass rod with a loop at the bottom end to use one of the screw holes (pinion end up, remember) and a simple "L" hook at the top. When I did this using the latch hole of a steel door, it really resonated and significantly amplified the sound in the door and you could hear the motor get smoother, quieter and faster for that 15 minutes.

 

Then, I put the motor in a car and run it never exceeding half throttle on the whole track for about three minutes (one heat) but try to maintain race pace in the turns. I think it may be important to do this break-in to simulate the not insignificant lateral loads from cornering as this is part of real-world conditions. I feel the motor to see if running a "heat" at half throttle causes the motor to run hot, then let it cool down completely. If the motor is hot from half throttle running, there is a good chance it will run hot when run in anger and will not keep its brakes for long.

 

Then I go ahead and race the car. Falcon motors would run the best they are ever going to run after a couple of heats of racing. Retro Hawks seem to come in at about four heats of racing. By then, you know if that drivetrain (motor, gears, and bearings) is a good one. I know this requires commitment. I have been known to loan cars to other racers to run that first race for me and they have podium'd and beaten me.

 

Then, never practice a motor for more than three minutes without two minutes of cooling when practicing or you are potentially giving that motor a death sentence. My experience is that running hard for eight minutes continuous (like an Enduro) just takes the edge right off of these motors. 

 

If we could make a dyno that could create these real racing conditions lateral forces (I have to believe that the motor brushes on those cheap cantilever arms are significantly influenced by cornering), that would be an essential part of predicting a good motor from home, in my opinion. You can see how many things a dyno has to do to be really up to the task. Then, how would one measure the ability to handle torque pulling out of a tight 180, the lead-on, or up the donut? I have to believe this can only be observed at the track.

 

If you can match the fastest guys down the straight and around the Bank, man, that seems like the best one can ever hope for.


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#97 Marty N

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Posted 10 March 2016 - 04:14 PM

Dude, you are super funny. So spin it like a generator. You are the second guy that said that. I even have pics of his unit. Interesting...

 

Stay tuned.

 

 

Does it look something like this one?

 

 

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#98 JerseyJohn

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Posted 10 March 2016 - 07:10 PM

 

 

Does it look something like this one?

 

 

Not quite so nice but the same theory is involved


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#99 John Streisguth

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Posted 10 March 2016 - 08:06 PM

You guys have way too much time on your hands.   :rolleyes:


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#100 Marty N

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Posted 10 March 2016 - 08:21 PM

On re-buildable motors I assemble the armature/bell assembly in an empty can spaced as it will be in the target motor. Take the black wire from the power supply and attach that to the target motors negative post. Place a jumper between the slave motors negative and the target motor positive. Gator clip the Ohm meter set to millivolts to the target motors positive and negative. Adjust the power supply to 3 volts and flip to amps. This is a four wire resistance check. Use ohms law using the power supply amps and the voltage drop over the target motor to find Terminal Resistance. Subtract armature resistance and you know the resistance of everything between the post minus the armature. That is brushes, interfaces, and hardware. Shunts if used as well. Terminal resistance is part of the power equation...not armature resistance.

 

If I've made this clear then you will understand WHY a good break in is so important to getting the best from your sealed motors and guess what...it's legal to properly break in your motor.

 

Anyway once I have the lowest resistance my brushes and commutator are broken in. I place that red thimble on the exposed shaft to remove it all, undisturbed, as a unit and use it to install it in the loaded can it will call home. Sealed motors are as in my last post. Resistance can't be four wire checked with magnets in can and the armature generating voltage.


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