In my experience (which is all road course racing; no oval racing), I would definitely say that peak power is totally meaningless. In fact, peak power seems to have absolutely no bearing what so ever with on track performance. What I look at is each AMP step from 20 to 28. I tune so all the steps look good and so peak effeciency lands close to 23 amps, since my average AMP draw during a race is usually close to 23 AMPs.

I've done enough stock motors with my Robi to know what numbers I want to see at each AMP step. For example, any stocker with at least 90 watts at 20 AMPs and 110 watts at 28 AMPs is going to run strong. My best motors are around 96 watts at 20 AMPs and 120 watts at 28 AMPs. Keep in mind these numbers only apply to my dyno, since you cannot compare dyno results from one to another. For example, one friend's Robi shows totally different numbers when dynoing the same stock motors. Anyway, the key is to dyno a lot of motors using your dyno and the track to get an idea what numbers are good or bad.

If you just tuned for peak power, there is a chance that some motors with good peak power will also have a great powerband from 20-28 AMPs. However, you will not know for sure by only looking at the peak numbers. In fact, some of my best peak power numbers came from motors that stunk on the track. Those motors stunk on the track because their numbers between 20 and 28 AMPs were poor, even though the peak power number was very high.

First off... The web page I promised Goodwrench... I compare 5 of the motors he provided data for. First I compare his best dyno run 'MOTOR TEST' to what he has named 'Team 1 GM3'. Next I compare his friend's motor 'Jims Best GM3' to 'MOTOR TEST'.

Then mostly as a illustration of how gearing for two simmilarly powered motors that have RPM that would warrent at least a one tooth gear change... In this case I used 'Jims Fresh GM3' to 'MPH 003'.

The web page is located at...

http://www.wiltse.net/gwrench.htm

Next...

I fully admit I don't have enough experiance with the Fantom to know if it does ever show good low RPM motors to be as good as good high RPM motors... The only data I've really examined closely is Snuffy's and Goodwrench's. From what I have seen of these two data sets, I rarely see a motor with good Power that also has low RPM. There are a few specific cases in their data that i can find this type of behavior in their data. My data set is far to small to say anything conclusive on this matter.

I still would like to see data for a really good EX-Spec motor comapared to a really good 'Stock' motor... my perosnal experiance with testing this two differnt types of motors on a Fantom leaves me scrtching my head.


As for Peak power having no value at all... a month ago, I would have agreed whole heartedly... but I am changing my tune. I'm not saying it's the only thing to tune for... but I'm saying it's much more important then I had previously given credit to.

I've not tototaly given up on looking at data in relation to amps... but I no longer look at it as my sole means of evaluating a motor...


Shiloh... Do you have some data I could look at of a motor or two that shows one with exclent numbers from 20 to 28 amps, but doesn't also have exclent peak power? Also, do you have some data that shows exclent peak power but really crappy power between 20 and 28 amps?

I have some data that shows the second point, so I know it happens... I'm not saying it doesnt... however I'd like to see some of your data and examin it in the way I currently am... I suspect your method and my newest method come to the same conclusions about what makes a good motor.

Actually... I've got some data that shows pretty much how peak power alone doesn't make a good motor... however peak power with excelent effciency will show ALOT about what makes a good motor.

Back to Popsracers question... I didn't include this in my last response about what I think makes a good TC motor, as compared to a good Oval motor...

Oval races are shorter, effciency is less important then TC. TC races last one minute longer and effciency is more important as a result. TC racers can likely not average more then about 27 amps in a race without a meltdown... 6 cell Oval guys can likely average 30 without problems. To me, this basicly means that TC motors need slightly better effciency to be good throught the entire race.

Also... after reviewing some Robi data for 6 cell... I think a motor should have a peak effciency of at least 67% to be good for TC. Previously I had said 60% is as low as I'd play with... I'm thining now that 60% on a Robi is way too low for any decent motor I've seen on my dyno.

Here is a work in progress... attempting to illustrate a few things... mainly the fact that Peak power without effciency is not good... at least not if you can find a motor that has both...

It also illustrates how veiewing data with relation to amp input is also somewhat limiting, especialy if you should zoom in and only look at power between 20 and 30 amps...

In the end, the idea of viewing things with a big picture in mind is best I think... That is never over look one thing while focusing on another.

... Ok ok... so looking at amp input data makes the effciency thing really obvious... but how are you to make a gearing choice based on that info??


Anyway... the work in progress is here.

http://www.wiltse.net/king_and_queen.htm

Glenn:

I am not sure I have a good data file that shows excellent peak numbers and poor 20-28 AMP numbers. I used to have several, but they were on my old Win98 laptop, which I reformatted and gave to my wife. All of my more recent dyno data has been collected onto a new WinXP workstation, and I do not think there are any good examples in that collection of dyno results. One brush combo that consistently causes great peak numbers and pathetic track performance is the Trinity 4391 combo. That combo usually provides 10-15 watts more at peak power, but loses about 10 watts at each AMP step. If I can find a pack of those, I will try to build a good example motor and then gather dyno data from it.

I am not sure what you mean by good effeciency. I look at effeciency at each AMP step, because peak effeceiency will not always be in the AMP draw range where I race. For example, a motor with 73% effeciency at 12 AMPs will not be any good to me. I need good effeciency at or near my average AMP draw. I want to see 70% eff at 23 AMPs, because fast TC guys at our track will usually average about that much AMP draw.

Keep in mind that effeciency is simply the percent of input power that is converted to kinetic power. The rest of the input is converted to heat. IMHO, effeciency has no bearing on runtime, since I run 3000 and 3300 cells. With an average AMP draw of 23 AMPs, I have no worry about dumping during a 5 minute race. Effeciency is only a concern to me because a lack of effeciency will lead to a surplus of heat and hot motors run slow. A motor with only 60% effeciency will get hot during the race and the magnets will feel weaker, and the performance will fall off. A motor with 70% effeciency will feel consistent throughout the race, because there is less heat building up in the motor.

In my experience, if you have good numbers at 20 AMPs and 28 AMPs, and your effeciency is good at 23 AMPs, then your motor will be strong on the track. This rule of thumb seems to work regardless of what the peak numbers are. But keep in mind that I run touring car on a road course, and your method of interpretting the dyno results may be better for oval than my method. I've never raced oval, so I cannot say how my awesome TC motors would fare in oval racing.

Shiloh

I was just telling Mike in private email... If I had to use a TurboDyno I would look first at power at 28 amps (Actually I'd probably change it to 30 or 35 amps), then I'd look at power at 20 amps. The power at 28 amps would basicly tell you how strong the motor was, and the power at 20 amps would tell you how effcient the motor was...

On a Dyno with constant voltage, the output power is essentialy the same thing as effciency, when viewing data in relation to AMP input.

Now I know that Shiloh is talking about his Robitronic data... however I beleive the same basic technique could be used... However I see no real need to limit one's self to this... after all with the Robi we can view the data any way we choose...

Personaly I've never seen a stock motor have peak effciency located any higher then about 26 amps.and often effcincy peak around 20 amps... From what I have seen, when peak effciency occurs at above 20 amps, the actual peak is lower then it would be if it peaked at a lower amp location.

Again from what I have observed... If you have a motor that has peak effciency of 75% at 20 amps, it's likely to be even more effciency at 25 amps then another motor that has peak effciency at 25 amps...

Notice the peak effcicincy curves of the these two motors... this low effcincy on Motor 1, is very typical of what I see when I find a motor that has peak effciency that occurs above 20 amps.

http://www.wiltse.net/images/ppa.gif

Anyway... sure effciency is important... just how important and how much is nessasary is still open for debate. Basicly... in my opion... if the motor doesn't fall off before the end of the run, then it's effcient enough... If it falls off, or goes up in smoke then it wasn't effcienct enough... Or you need some ice on it before the start of the race... :)

Dyno....Actually there is no other form of racing more runtime dependent than oval. With 4 cells we have been forced to run 7 turn flat wires to duplicate 6 cell times, avarage amp draw has actually increased so we are back to square 1. There is still a very fine line between dumping in 4 min race with big 3300's at the top levels of oval racing anywhere right now! A setup even a little off can dump a pack in 3:45. I just race for fun with my sedan, and admittedly nowhere near the top levels but so far dumping isnt a problem in mod sedan for me. I'm not sure if the cleveland guys were dumping or not in mod sedan. Also very track dependant though. In my opinion Peak wattage is THE most important factor in a motor, at least you will be fast for most of the run, maybe finishing a little slow, but still allowing a pretty decent run. Without peak watts youll never get up to speed. Power AND efficiency is what we are all after. I tune to get my peak power where i want it in the powerband, then try to gain efficiency throughout losing a minimum of power at those points. The GP3300's make life a lot easier in the efficiency dept though..now throw motor power/efficiency drops into the equation and it really gets fun.

I have a question about Mike's Dynoviewer.

What is being done to the fantom data when you use the paste fantom data and correct option?

I should have qualified my statments by saying they are intended to apply to 'stock' racing only. I'll include 19 Turn spec as well, but I have veritualy no experiance in modified racing. 19 turn spec motors are much more powerfull and effcienct at high amp draw, and will not dump a 3000 pack no matter how you drive. 4 cell and 6 cell are also two totaly differnt ball games, and only some of the basic priciples I've been advocating apply to both. (actualy most do apply to both 4 cell and 6 cell, but there are addtional factors I havne't really spoke of too much that relate to each of these individualy)

Now that you mention it... Effiency in 6 cell oval may very well be as important if not possibly more important, then it is in Sedan... I really have very little experiance in either of these clases.

One thing I am sure of... power is very important. in all forms... you only need as much effciency as is needed to finish the race without proformance decline. Power is what makes you go fast, efficeincy is how much power gets to the tranmission/wheels compared to how much your putting into the motor

Snuffy,

The paste and correct Fantom from clipboard, does the DynoMoHum fudge factor to the Fantom data. Basicly it re-calculates Torque by using the RPM given by Fantom for the current interval. Fantom seems to be using the RPM change for the next interval to calculate torque. We went round and round about this a few weeks ago. In the end John Stranahan did some calculus on the Fantom data, and he says fantom is not doing anything wrong.... However my fudge factor makes the data look alot more like what you'd get if you had a Robitroinc Dyno... not exactly the same, but power and the efficeincy numbers come up alot and are far more beleivable to me in the 'corrected' form.

It doesn't really seem to change much in terms of which motors are good, and which are not, unless you would try to compare one that doesn't do the correction, to one that does... So if you start to play around with that feature, make sure you don't start compareing the corrected version to the non corrected data...

I got me some Putnam green and blue shunt brushes... some time off work, and dyno ready to go... I even got some track time lined up for this weekend... This should be a good holiday...

Maybe I should have got some red shunt burshes to go with the Christmas theem... :)

I'd be happy with some time off work right now. If I had a functional dyno that would be even better.:lol:

Well I tried the Putnam brushes this weekend... They worked well, but didn't proform magic or anything like that... I had tried some of the new Trinity 4503 brushes the week before, and they also worked very well.

I didn't have any other 19 turn motors to compare my results to... and being my driving and car setup is not as good as it should be... I didn't win any races with either of the brushes I tried in the past couple weeks... :)

On the Dyno the 4503s and the Putnams profromed quite simmilarly... Same with on the track... but I had no way to do any side by side comparisons.or anythign close to that. I do know that my motors came off the track dynoing as good or better then when they went on the track with both sets of brushes.


Speaking of dynos.... I finnaly got my Paradox and EX-Spec data off of my friends's Fantom dyno... All I can say is... Either my friends dyno has a problem... or all Fantoms do... I am trying to figure out a way to determin which... I only know of one other person local with a Fantom, and he never brings his to the track... So my options are limited in how I can persue this.

What I have observed is this... On the Fantom dyno I used, there almost seemed like a current lmiter of about 50 amps or so... That is, with both the Paradox and the EX-Spec motors they both pulled very close max current. When I test these two motors on the Robi, or the Trubo dyno, the EX-Spec will pull 25% or more then the Paradox. Not so on this Fantom...

Looking back at Goodwrench's data... I see his Monsters were pulling around 70 amps at start up. So, I know that at least some Fantoms are capable of pulling more then 50 amps...

Anyway... I'm kinda stuck right now in trying to figure out what's going on with this Fantom I have accesss too ocasionaly... About all I know is that this Fantom is using a lawn tractor battery as a power source... I don't know if it is somehow limiting the current or what. When I've used my Robitronic with a lawn tractor battery, I've not seen this happen, so I don't think it's directly related to the type of battery...

Any ideas on how to persue this? My next step was going to get some 19 turn data off my friend's Dyno and see if a 19 turn motor pulls more then 50 amps....

there's a problem with your friends dyno/power source. i regularly run 7 and 8 turn motors on my fantom and they all pull well over 100 amps at startup. i'm using a car battery for power with a small 10 amp charger attached to it. fyi, my monster stocks pull 55-60 amps at the start....

I agree with pancartom, there's something wrong with his battery.
A quick check is to try using your battery with his dyno.

I see a lot of people using alligator clips and 14 Guage wire to connect to thier battery, not the hot setup to pass 100 amp through. The length of the wire is also critical, even 1 inch difference off spec produces different numbers.
Also check the setup menu. There is a setting to limit current used for the "speed control" choice, which attempts to simulate your speed controller if you are using the current limiter on your speedo. The numbers you are seeing could be the dyno current limiter set to 50 amps......this is the DOS version. Pull up a screen summary of 2 compared motors and hit "s"

there is a setting on fantom dyno software to turn off the current limiter...

I've sent a message to the owner of this dyno, telling him about this... I won't get a chance to see him or this dyno for a couple weeks from now. So I won't be able to do much more myself with it for the time being.

I know the Robitronic has the ablity to limit the current as well... This type of feature may have some use, but I haven't made any attempts to use it myself. However recently I did notice that the Street Spec batteries may very be incapable of putting out much more then about 50 amps anyway...
I'm still investigating this phenomina...

Either way... next time I get a chance I'm going to look closer at the output of this Fantom... THe first thing I intend to do is to dyno a 19 turn, and see how much current it pulls at startup... I figure that surely a 19 turn will pull more then 50 amps.

almost double...

I didn't even know there was a way to limit current on the fantom.
I know there's a amp setting to use for comparing two motors at but, I don't think that has anything to do with what is supplied to the motor being tested.

exactly....

I'm confused now...

Almost double I assume is a refferacne to a 19 turn motor pulling almost double the amount of current as compared to a stock motor?

Or is almost double a referance to hos much power a motor would put out if it was really geting 5 volts as compared to about 3 volts at say 40 amps.???

I'm also confused about the current limter feature of the Fantom... Does it really limit the current? or does it just effect the way the data is viewed?

Dyno,

did you receive my email?

Pizza

Yes I did get your email... I haven't had a chance to look at the data yet. I still haven't even taken a shower yet this morning... and then... well... with any luck I'll take a look later today...

Did you buy a Robitronic? I thought you had a Fantom or something like that... or is this data from a friends Robi? (just currious)

Dyno- almost double as in ampdraw compared to a stock motor.My stockers draw 60+ amps, my 19T's around 100amps, you do the math.
Not sure on the current limiter question, but what does it really matter, if its on, it will affect your readings accordingly. I was trying to answer someones question on why he was seeing the results he was seeing...

Damn! it got awfully quiet in here.

Well... after this weekend I may have some more Fantom data to work with... I'm pretty confident I'm going to have access to two differnt Fantoms this weekend...

Also I'm going to be playing around with my Monster...

Another thing I'm working on is my revision to Snuffy's hood alignment ideas... I think it's going to work out well... my preliminary testing was very encuraging. I really would love to have a better more consistant way to align hoods... I think Snuffy's helped me come up with something good.

I just wondered if some of you guys with Robitronic Dynos have made some progress in eliminating spikes in the data and if so how did you do it?

In a word... NO.

In multiple words... I don't buy the argument that this is somehow related to bushings... It happens on Chemeleon 2, 19 turn motors with bearings as well...

I've tried increasing the mass of the motor stand by holding on very tightly with my hands when I make dyno runs, and this seems to have no effect at all on the spikes...

Basicly I just live with it...

Originally posted by DynoMoHum
Another thing I'm working on is my revision to Snuffy's hood alignment ideas... I think it's going to work out well... my preliminary testing was very encuraging. I really would love to have a better more consistant way to align hoods... I think Snuffy's helped me come up with something good.

Hmmm... I've gone back through this whole thread... ??? Where are "Snuffy's hood alignment ideas" ???

By the way -- I have a P2K that has me puzzled right now... Looks good on the TD45 (very high torque, rather low RPM's, but solid power), but it heats up QUICK! One or two dyno pulls get it hotter than I like, and in my offroad truck, it runs STRONG! for 3 minutes, then starts to fall off and it finishes the last minute at about 3/4 speed... This thing is a killer for those first 3 minutes (geared properly of course)... Brushes are aligned, comm's been trued (and shows no signs of excess wear), bushings feel "free" enough... Possible cause(?): When I center an arm, I normally have left them a bit "sloppy" because that was "safe". On this motor, I got to thinking that "sloppy" shimming of the arm could lead to problems (Big Jim always said the arm moved toward the can under power and toward the endbell under braking) -- so I shimmed this one with much less "play" in the arm. It is "free" on the workbench, but is it possible that thermal expansion under load causes it to get "tight" at that 3 minute mark? Any ideas are welcome... (I really want to get this motor sorted out -- it was so strong for the first 3 minutes that I still managed to win the A-main, but only by 0.5 seconds, because second place was really charging hard as I was falling off...)

FWIW: (sort of a change in subject) I ran an Integy V10R with my own "tuneup" in my XXX buggy and won the A-main. My V10 is high RPM, sort of low on torque, but the power is HIGH. Again, I had to gear it right, but this thing impressed me!

tfrahm: It sounds like the P2k has low effeciency, and is simply getting too got during the run. Tune it to get the effeciency up at the amp draw you average. I'm not sure what all you have tried with it so far. Here are some things to look at:

1) Is there too much side to side play in the bushings? In other words, are the bushing worn out, and allowing the shaft to move around. If yes, then the brushes are bouncing, and that is causing some sparks. The sparks cause input energy to be wasted as heat instead of converted into kinetic.
2) Is the comm surface rough? A worn comm will cause from friction when the brushes glide over it. Recutting the comm may be the solution.
3) Spring tension may be wrong. Too little and the brushes bounce. Too much and they become brakes. Either way, effeciency tanks. Try using a pair of red springs as a baseline setup with a P2k.
4) Try putting a vertical slot in the positive brush. That will usually increase effeciency.
5) Clean the motor really well.
6) Oil the bushings with Tribo.
7) Recheck hood alignment.

So what are the Dyno numbers?

Snuffy has never posted his alignment idea... he sent a email to me, asking me what I thought about a idea he has. I am somewhat hesitatant to say exactly what his idea is... only because it is his idea, and I wouldn't want to make it public without his consent... I am actualy farily sure he wouldn't mind, I mean it's not like he's trying to keep it a secret.

Oh, what the heck...

Basicly Snuffy sent me a drawing of a hood alignment bar he had dimensions for, it's alot like many typical alignment bars, such as the Racer's Edge centerline alingment tool. Dimensions of the bar are basicly very simmilar, the height and width being basicly the same as a brush. The lenght of the bar would be the lenght of two brushes, plus the diameter of a commutator. Essentialy when you put it in the hoods, and stick the shaft through the bushings and the alignment bar, the ends would wind up eaxctly where the end of the brushes would be in a working motor. The idea was then to align the hoods with this bar in place... bushing the hoods in such a way that they would be posistioned exacly like would be needed to do proper hood alignment using the 'wear mark' method... Only you don't really use the wear mark... you use the tool to make sure it's physicaly centered...

If I missed anything I'm sure Snuffy can and will correct it...

My idea was that I didn't think it mattered too much if the ends of the tool were at the exact same location as the ends of the brushes... that you could just use a longer tool, and the differance would be insignificant, as long as both hoods were aligned the same (realtively speaking)

I modified my Racer's edge bar, just a tiny bit and started working with Snuffy's idea... I got a peice of 1/8" music wire, sanded it down to .124", so it woudl fit very snugly through the motor bushings... I enlarged the holes on my Racer's Edge bar to .125", and set out to align some hoods...

My procedure is this... loosen the spring post, and the other screw that holds down the brush hoods... (losen both sides) Put the bar through both hoods, then put the modified music wire though the bushings, and the hole in the alignment bar. Next push the bar, and the hoods in the advanced posistion, hold it there and tighten down the brush hoods. I don't stop there... I take my L shaped needle nose pliers, and tweak each hood a litttle more, I use a clock wise twisting motion to do this final tweak of te hoods. This cocks the hood slightly, however the bar is still in place, so it's virtualy impossible to bend too far... At this point your hoods should be REALLY close to perfect... take the music wire, and the alignment bar out of the motor, and then test fit a brush in each hood. If it's a little too tight, use the alingment bar to open up the hood a little. Not too much, because you don't want alot of slop in there...

When I did this myself, I put a new set of 766s in the motor I did, ran it for a few seconds, and checked the wear marks... They were about as close to centered as I've ever seen, I don't think I could get them any closer with any other method. Dyno results were darn good on this motor as well. I beleive I coudl repeat this methold consistantly without any trouble. After I get more confidence in the methold, I beleive I could stop checking the wear marks, and basicly just start to assume I've got the alignment good enough. I've only done two motors this way so far, but both turned out very well.

The main reasons I like this type of aproach is, that it that it should be very easy too do for just about anyone. I also beleive it will be very consistant, and that I can actualy save time by doing it this way, and not have to worry about doing more harm then good. Based on limited testing of this method, I beleive it will work quite well. Also... if it really does work out as well as I think it will, I can stop buying all these new brushes, with the sole intent of using them strictly for hood alignment procedures...

I beleive the wear mark method requires too much skill, and can be somewhat inconsistant, mostly do to lack of skill and patiience. I also beleive there has to be a way, some way that is realtively fool proof. I thnk my modified version of Snuffy's idea is a good one.

I have a few ideas that may make this slightly better, but I'm not very confident in them at this time, so I won't elaberate on them.

Originally posted by Shiloh
tfrahm: It sounds like the P2k has low effeciency, and is simply getting too got during the run. Tune it to get the effeciency up at the amp draw you average. I'm not sure what all you have tried with it so far.

Thanks for the ideas. Most have been covered in my tuning... New motor, comm was cut right before going racing (after initial breakin), Springs are Red+(7.75 FS)/Green-(7.5 FS) (yes, the green does seem a bit "firm"), I use TRIBO on the bushings, motor is smoooooth on a 4cell test pack and on the dyno, hoods are aligned (Big Jim style), Brushes are 4499's (full face, with a 1/32" off the trailing edge).

Efficiency is good (on my TD45, at 7.00 volts the best I've ever gotten was a Paradox that put out 20,733 RPM, with 6.4 torque for 98 watts at 20 amps, with 70% eff.) -- this motor puts out 94 watts at 67% efficiency. (17,873 RPM with 7.1 torque)... Please note that my TD45 seems to be "conservative" and produces lower power numbers than most others, but trust me, my best motor RIPS and the motor I'm talking about here really hauls with the right gearing -- I just have to keep it cool for 5 minutes...

I'll consider going slightly softer on the springs (at least get a more typical Green on the - side). I'll also be re cutting the comm as a part of normal maintenance... I also want to recheck the bushings to make sure they are as free as I think they are...

NOTE: I recently got a P2K2 with bushings so "tight" that I may have to go back to some sort of break in sauce to get it freed up -- it dyno's strong on the first pull, then heats up and falls off -- very much like the symptons of this P2K, but I'd swear the P2K bushings are OK...?

What are you getting for 28 amp numbers? what is your best?

Your occurance sound quite strange...

How much curent does this motor draw at say 3 volts with no load? is it more then with other P2Ks you have?

I know you said your hood alignment is fine... however one thing I've seen is that if hood alignment is off, it does make efficency go down... and amp draw go up... Have you tried useing a differnt endbell? one that you've used before, and have not had problems with?

I'm not sure I have any answers for you, I'm just thinking out loud about things I'd check or look at.

Dyno

I had an idea very similar to the one you posted above (I posted it on BJ’s forum but he never responded) – Ref below which includes a sketch of my idea

http://rccars.com/forums/showthread.php?threadid=2&perpage=15&pagenumber=2

After thinking about it some more I let the idea drop. The problem that I envisioned was that if the hoods were cocked too much, you wouldn’t be able to remove the tool after you got them aligned without messing up the alignment.

Dyno...

The best I've seen at 28 amps and 7.00 volts is 126 watts, with 120-122 watts being more typical for GOOD motors. This "hot" motor puts out 117-119 watts at 28 amps.

During brush break in (on a 5v power supply with a small fan on the shaft) the motor drew a peak of 9.7 amps -- most of my good motors will draw between 8-10 amps under the same conditions...

(the good thing for me is that everyone else seems as puzzled as I am... somehow that is oddly reassuring...)

Tom,

you cut 1/32 of the trailing edge.
So actually you're running timed brushes right?!

That's also something which could seriously contribute to your problem with your motor.

Why don't you horizontally cut these brushes or slightly narrow them, (in combo with lighter springs f.i.)

Good luck.

Pizza

No offense Tfram... but based on your numbers... I can't help but wonder why your thinking the motor should run very well on the track... From what your saying, it seems that every number you've got with this motor is a bit lower then your good motors...

I guess what your trying to figure out is how to make it better... did you check the capacitors??? I personaly have never experianced this, but I keep hearing people tell me about how the caps can cause strange motor problems...

The only other thing I can think of is... some arms just plain don't work very well. Not sure if it's because of the windings, or if the comm slots are cut strange, or what.... but maybe it's just a bad armature. One of my common procedures is to swap arms and such in a known good can. This can be time consuming if the comms aren't exactly the same size on two differnt motors, but if you really want to sort out some funky problems, swaping peices one at a time is the only way to go.


Calvin... One of the first suggestions to Snuffy, was to modify the alignment bar exacly like your idea... Soon after that I decided that it probably wasn't even nessarary and may cause more harm then good. I think you are correct in your thinkng that you may not get the tool out once you've aligned the brushes that way...

One of my thoughts on a mod that might help a tiny bit... a too that is a couple thousandths of an inch more narrow then a real brush. This would possibly allow even slightly advanced brush alignment... although I also beleive it would tend to cause the hoods to get pinched too much if you use pliers like I do...

I plan to take some photos, and make some drawings of my methods... I think that it can work pretty well... and I also think I could put together some step by step procedures that would make it pretty easy for most anyone to do this pretty well.

For what it's worth... I think that it should be possible to have slightly advanced timing with some creative hood alignment. I also think that if both hoods aren't concentric with one another, it doesn't matter if one side is perfect... if they both aren't perfect you've got problems. You'd be better having both sides slighly retarded then having one side dead on, and the other off a bit.

And I think the same goes for cut burshes... I think if you don't get your 'timed' brushes trimed pretty closely on both sides, your going to have problems related to mis-matched timing. This could be Tfram's problem... I don't know for sure, it's hard to say what's going on with his motor.

Originally posted by DynoMoHum
No offense Tfram... but based on your numbers... I can't help but wonder why your thinking the motor should run very well on the track... From what your saying, it seems that every number you've got with this motor is a bit lower then your good motors...
...
And I think the same goes for cut burshes... I think if you don't get your 'timed' brushes trimed pretty closely on both sides, your going to have problems related to mis-matched timing. This could be Tfram's problem... I don't know for sure, it's hard to say what's going on with his motor.

No offense taken. Keep in mind the numbers for this motor are close to my "good" motors (it actually starts out stronger, but by the second pull it has heated up enough to fade a bit). For local "club" racing, I don't use my "best" or the better "good" motors -- I save the cream of the crop for bigger races...

I also have learned over the years that it is the motors like this that can teach me new tricks as I try to figure out why it acts "funny". After all, even "as is" it won the A-main! I figure that if I can "cure" it, I will probably pick up a new trick...

As to the "bad capacitors" thing -- I have worked on a hundred or so new style EPICS (I tune motors for a lot of people locally), and I have seen 3 that absolutely nothing would "fix" until I took the caps out and installed external ones. Big Jim always said that maybe I just installed the brush hoods with a better alignment after taking them off (and he might be right), but the difference on them was like night and day (from total pig to race motor -- as much as 15 watts improvement)!

As to the "timed cut" (someday I'll start a furball thread on that issue, since my Physics and Engineering background tells me the timing doesn't change, it's the DURATION the pole is energized that changes)... Anyway -- I have built a rig to do a precise, repeatable shaving of the trailing edge of the brush (cutting both sides with my rig produces a perfect "Big Jim" 0.14" MVP brush). So both brushes are the same, and both hoods showed identical wear patterns when originally tuned.

The cut I use is designed to be the optimum to eliminate a flaw in the design of laydown brush motors. A full face laydown brush produces a DEAD SHORT 6 times per rotation, as a comm segment momentarily overlaps the trailing edge of one brush and the leading edge of the other. The cut I use is the minimum to just barely eliminate that short. My experience has been that this improves efficiency (by eliminating the wasted energy from the short), keeps virtually all the RPM's of a full face brush, and brings torque up noticably (as you'd expect on a TD45 -- less amp draw and greater efficiency always shows as more torque at a given amp load)...

On the subject of hood alignment -- your alignment bar mod shows a lot of promise. As you point out, the WORST thing is mis-matched hoods. Better to have consistent, repeatable alignment results that mismatched hoods...

Anyway -- I'm enjoying this thread a ton! Always nice to discuss and debate without flames and bashing...

Originally posted by tfrahm
As to the "timed cut" (someday I'll start a furball thread on that issue, since my Physics and Engineering background tells me the timing doesn't change, it's the DURATION the pole is energized that changes)... Anyway -- I have built a rig to do a precise, repeatable shaving of the trailing edge of the brush (cutting both sides with my rig produces a perfect "Big Jim" 0.14" MVP brush). So both brushes are the same, and both hoods showed identical wear patterns when originally tuned.



Tfram,

Think about this some more.
Trimming the trailing edge of the brush changes both the timing and duration. You can visualize it by drawing a straight line through the center of the contact area of the brushes. The difference won't be a lot but the centerline of the contact area will shift slightly in relation of the magnets.


On second thought, I see your point. Trimming the trailing edge of the brush doesn't change the position of the leading edge, so each segment should energize at the same point of rotation. they'll just turn off sooner.

With that in mind wouldn't laydown style itself increase the timing to a little as apposed to standup brushes? That would actually energize the segment sooner, wouldn't it?


Originally posted by tfrahm
The cut I use is designed to be the optimum to eliminate a flaw in the design of laydown brush motors. A full face laydown brush produces a DEAD SHORT 6 times per rotation, as a comm segment momentarily overlaps the trailing edge of one brush and the leading edge of the other. The cut I use is the minimum to just barely eliminate that short. My experience has been that this improves efficiency (by eliminating the wasted energy from the short), keeps virtually all the RPM's of a full face brush, and brings torque up noticably (as you'd expect on a TD45 -- less amp draw and greater efficiency always shows as more torque at a given amp load)...



I'm curious about this. Could you give more details about it?

I wish I could win the A-main with a motor that's down on power about 2 or 3 watts over a good motor... Lately when I go to the track there are at least 6 or 7 guys that are Natiional caliber racers... Anohter 5 or 6 that are just a couple tenths off of the fastest six... and me... well I struggle... That's probably why I enjoy my dyno so much... :)

Next weekend it's going to be even worse were going to have guys from other states come in and race... ahh...

Anyway... I'd find another P2K with the exact same comm size... start swaping parts till I figured out which compoenent was causing the biggest decline in proformance, then start looking much closer at that compoentent to see if you can figure out what is differnt about it... I'd say if you can't get the dyno numbers up to what the good motors are, it's never going to be a top conenter on the track.

I'm just starting to play with timed/trimed brushes.. what I've seen so far is very promising. Quite frankly I've never felt much need to improve the effciency of a P2K... but perhaps it would help... I'll try it today.

Snuffy -- You seem to have picked up on what I was talking about. And, yes, Laydown brushes have a big advantage over standup brushes -- the leading edge is several degrees further around the comm than a standup, and thus give significantly more RPM's. The downside is the overlap/short that happens 6 times a rotation. Most racers aren't aware of this short situation, and that's too bad. Read what Trinity says about the P94 brush design and think about what that means for laydown brushes.. That dead short 6 times a revolution burns the comm, wastes battery and creates significant amounts of harmful heat.

The thin cut I make on the trailing edge just barely elimintes the short -- I want to keep as much of the duration that pole is energised as possible (the pole "pulls" longer, producing more power), but I don't want the waste... Please note that Todd Putnam has posted on the "Monster" thread that he does the same sort of thing to the LEADING edge on high RPM motors to intentionally retard the timing to get more torque. Clearly this idea is worth some experimentation, but so far I haven't done much on RPM motors other than the MVP.

By the way -- the reason the Big Jim MVP brush cut (shaving both the leading and trailing edge) works, and the reason others (I think DynoMoHum has posted about this) recommend cutting the same brush to the same width as the Big Jim cut (0.14"), but doing all the cutting on the LEADING edge (about 1/16" cut) has to do with the design of the MVP (and the Core and the V10) armature laminations. These motors have holes (they call them "power tunnels", etc.) drilled into the center web and the top of the pole. These holes affect the limit to the ability of the pole to be "magnetized" when the coil of wire is energised. These motors normally get super hot because the iron in the pole is "over-saturated" (meaning the coil produces a stronger magnetic field than the iron in the laminations is designed for. By reducing the duration the pole is energised, this over-saturation is reduced or eliminated. Since anything more than the iron can handle is a waste, the motor now runs cooler and actually produces more power.

A further note on the "short" situation I describe above... On a modern EPIC motor, the big window in the endbell top/bottom is really handy for observing this. Take a motor, put a pinion on the shaft and SLOWLY rotate it while looking in the "window" -- you will clearly see that each time a segment comes to the window, it will gradually rotate out from under one brush, cross the window and then it will touch the other brush while STILL contacting the first brush. There can be no mistake about it once you see this -- that is solid copper touching BOTH brushes at the same time ZAP! a dead short! And this happens 6 times per revolution (3 copper comm segments, and the short happens once for each at the top and bottom of the rotation -- that's 6 dead shorts per revolution)... Think about how much energy that wastes and how much that hurts your performance!...:rolleyes:

Lots of things to report... First a comment in response to Tfram's last posts...

My MVP playing, has not been very controled in terms of brush width... I know for sure I didn't narrow the brush quite as much as is recomened by Big Jim. In fact I probably took slightly less then Big Jim does off of only one side... I took it off the leading edge, but also tried it once with taking it off the trailing edge. It didn't seem to make that much differnace if I took it off the trailing or the leading edge... the basic effect was that Efficiency improved, and peak power either went up, or was not effected. I stil am working on the MVPs... Basicly I think Big Jim's narrowing technique is taking off about twice as much as is really needed. (you loose too much peak power by taking off that much).

I tend to think that taking it off the leading edge on the HIGH RPM motors is best... but still have very little testing on this...

Basicly I'm agreeing with Tfram on this... a slightly narrowed laydown brush is often a good thing... taking too much off is a bad thing.

Other stuff... I had a very productive weekend... cut about 15 comms on old stock arms I have... Tested 4 motors of a friend (two GM3s and two Monsters) on the dyno... I built me a killer Paradox out of a average Paradox I had laying around... and I further verified my theorys on gear selection given dyno runs for two differnt motors and a referance gearing for one. (Using Golden's DynoViewer). I also backed up my dyno data for my Monster and this new Paradox setup with on track testing...


I tested two GM3s and two Revenge of the Monster motors for a friend. His motors were all pretty decent motors, I'd call them above average. One of his Monsters looked quite good, and one of his GM3s looked slightly better then his best Monster. Both of these look very simmilar to my Monster's proformance level on the dyno. Basicly I didn't see anything to indicate that his Monsters were any better then any really good EPIC motor.

I went through all of my stock armatures and cut the ones that needed cutting, and measured and sorted them all in terms of comm size. My intention was to start doing lots of tesing... The first motor I actualy put together was a Paradox. I used my newly improved hood alignment technique. I didn't even look at the wear marks, I just completed the alignment procedure stated late last week here, and put the motor together and broke it in. The first thing I noticed was this... this was the first time I ever had a Paradox motor pull too much current for my Turbo35... this was at 2.4 volts, and it was pulling more then 12 amps. I think this had alot to do with the brushes... they were warn in the shape of a much smaller comm... and the brushes were only touching on the tips of the brushes... Eventualy after I got them fully broken in, it went down to about 7.5 amps at 2.4volts with no load (not even a fan)... The motor looked very promising on the dyno... 127 watts peak with the 7.5 volt Robitronic setting. My personal best motor was 128 watts... So this is about as good as I've ever gotten from a motor myself.


I tested the Paradox and my Monster on the track... I was running 4 cell Sanyo 2000 packs with pretty good numbers. On the Robitronic with 5 volt setting, both these motors look pretty good, within 2% I think... On the track... same thing... both motors ran within 1/10th once proper gearing was applied... I forget exacthly how much differnt the gearing was... I'll have to go back and check my notes... but it was in the neighborhood of 4 teeth differnt. In the end I felt the Paradox was the better motor.

So... To me the two most exciting things (besides my race in 19 turn 4 cell oval) was that I verified my gear selection technique using Golden's DynoViewer... and I verifyied that my hood alignment procedure is capable of producing very good results...

My race... Well I lead the A-Main (there were only 3 of us racing 4 cell 19 turn) for at least 30% of the race... I qualified 2nd, it took me about 5 laps to gain the lead, I held the lead for about 10 or 12 laps... I hit a inside corner, lost 1.6 seconds and the lead, I fought back, was gaining about .05 seconds per lap on the leader... wound up loosing by .6 seconds... My wreck caused me to loose... boy was it fun though... best race I've had in a long time.

DynoMoHum (I still like 'TMFU'... LOL!) -- I agree on the "Big Jim" cut -- at least to the point that I am experimenting to see if the double cut is too much...

Since the V10 and the Core use the same type of laminations as the MVP, I've been doing some experimentation on them too...

On MVP's with the Big Jim double cut (cut both leading and trailing edge, making the brush face "centered" and 0.14" wide), the MVP will look strong on the TD45, with high torque and lower RPMs. In fact, they look almost identical to a typical P2K. On the track, they perform well, but the "feel" is very different. My testing has been in sedan and offroad, and the BJ cut MVP turns quick laps, but in spite of the dyno numbers, it never seems to have the raw "rip" I'd expect from those numbers. It's sort of a subjective, subtle thing, but I find I like a Paradox, P2K, or P2K2 better for the raw punch I get from them...

I have a V10R (raw un-tuned when new), that I tuned by cutting 766's on the trailing edge (essentially 1/2 the BJ cut, making the brush face 0.18"). This motor RIPS! Won the Expert Buggy A-main at the local club last week... At 7.00v on the TD45, 20A numbers are very nice (22,423 RPM, 5.7 torq, 68% eff, 94 watts -- well above average on my dyno). Clearly and "RPM" motor, but when geared down a tooth or two, very good to drive -- strong punch out of turns and over the doubles, fast on the straights...

I have just started playing with a CORE "dyno tuned" (big joke) motor, and out of the package it was sad (smoking hot after a couple of pulls on the dyno, low torque -- "gutless")... On this motor I tried doing the 1/2 cut to the leading edge (brush is 0.18" like I used on the V10), but I wanted to see if this would trade off some RPM's for torque... No track testing yet, but the motor went from 85-88 watts at 20 A (very erratic results when new due to the heat problem) to now being a very solid motor with a solid 92 watts at 20A without recutting the comm... I've now cut the comm but didn't have time last night to dyno it (I wanted to let it cool after reseating the brushes)...

Right now, I'm thinking that the 1/2 BJ cut 0.18" brush may be the "optimum" trade off of efficiency, torque and RPM....

OH -- after recutting the comm, reshimming the arm, and a few minor brush hood recheck/retweak, that problem P2K I posted about a while back is looking better. 93 watts at 20A on the TD45, with 117-119 watts at 28 amps and less heat buildup. I'll run this Wednesday night (if we don't get snowed out) in my XXXT-MFE and see if it holds up for the full 5 minutes...

(edit) What I find interesting is that the P2K above now seems to run cooler after the tweaking and shimming and cutting of the comm (which had gone back out of round), but the NUMBERS are about the same... Not a total surprise, since the heat took 3 minutes or so before it would make the motor fade, but I still expected the numbers to come up or something...?

An observation about hood alighment... The Paradox brush hoods have alot more slop between the holes and the screws that hold them in place then the more Modern EPIC motors. I'm thinking this can be a good thing for a motor tuner. It sure seemed to me, that I was able to move the brush hoods around to where I wanted them to be, much easier then I can on a P2K, P2K2, GM3, or Monster... I'm thinking that maybe this is why I can often get a Paradox to proform as good or better then any other EPIC motor...

I wonder if the motor designers haven't out foxed themselves on brush hood/motor design. It seems that in a effort to make motor tollerances tighter, they've also elimated adjustablity in the motors. Theorteicly tighter tollerances would be a good thing... but not if the tollerances all line up in the wrong direction... Anway... some food for thought.

One further note on the "double cut" (Big Jim style) MVP brush setup... The slightly softer punch can be a real "speed secret" in offroad for some tracks or for intermediate drivers. I built one of these for a friend, and his performance has picked up for the same reasons I was unhappy with this type of motor. The reduced raw punch helps him run much more consistent laps, yet he still has the speed he needs for straights, etc.

This is an issue we cannot lose sight of when we discuss motor tuning... Pure raw punch isn't always an advantage, just as huge RPM with low torque isn't either... As I learn more about motor tuning, I think I am starting (only STARTING) to understand that there isn't ONE "best" way to tune motors -- you need a "bag of tricks" that you can draw from to tune a motor to match the type of racing it will be used for...

Yeah, I agree with tfram. I gave my MVP to my father, and he thought it was a rocket. I believe it was the lack of punch that actually made him drive better. I took his GM3 as a trade. Man that motor is fast (GM3). I wish I knew why this particular motor is so different than all my other motors that I've tested.

Yeah... you've hit on something I've suspected for a long time. That is, I beleive that sometimes people do indeed go faster with less power...

Just for example... I can go faster with 4 cell 19 turn on a Oval then I can with a 6 cell stock setup... Now there is more here then just power... but the fact is that with 4 cell 19 turn I have less power, and I can tell that it's easier to drive then it is in 6 cell stock. (at least for me). In 6 cell stock, I can actualy spin the tires comming off the corners and get loos as a result... I can never do this with 4 cell 19 turn, and my lap times are faster.

Even so... I personaly would never put up with less power... there are other ways to make a more powerfull motor drive better... for one, you could gear it up a extra tooth... This would give you better overall speed, but still keep the low end power/torque managable... Or simply improve driving or car setup to handle more power...

As for the MVP... I am getting really close to the point were I beleive I could go just as fast with a MVP as I can with a good EPIC motor... even in high traction situations... A month ago, I had given up all hope of ever making a MVP run well on a carpet track... I've never liked the MVP with narrow brushes... didn't like them on the Dyno, and didn't like them on carpet (which is all I do). I'd love to be able to run fast with a MVP... One of my problems now is that I don't run stock motors very often... and rarely use 6 cells either.

Glad to hear you finnaly got that GM3 from your dad... it should be put to good use... that's a awesome motor from what I can see of your dyno data...

So... Mike... have you been doing anything new with the DynoViewer? I like your 'perfect torque' feature... I've been putting it to good use... I'm begining to think it may be possible to use the point of peak power to calculate gearing as well... with very simmilar results. I haven't played with the numbers yet, but on the graph... what I often see is that if you line up the arch of the power output on two motors, the torque curve is basicly paralell at that point. I'm thinking that maybe it might be easier to find peak power then it is to find 'perfect torque'...