Can the Robi and the Fantom handle MOD motors, or do yo just not want to put the stress on them? I understand completely if you just don't want to push your equipment, I wouldn't either. :)
Jake

Theroreticly my Robitronic can handle at least a 10 turn... I've been told that you can also do sub 10 turns with it, if your careful.

The newer Robitronic dynos are suposed to be able to handle sub 10 turn motors with no problems... My dyno is not new howerver...

I also just basicly don't want to take a chance on doing wild mod motors on mine. I don't run these types of motors myself, and really have very little desire to ever run them... So I personaly don't care that my dyno has a 10 turn limit. I also figure those guys running wild motors can and do have dynos they can use for themselves...

I'm not sure about the Fantom.

I've got one of those newer Robi's. I've spun up a 8 turn double P94 on it, and it had no problems handling the load. I would not try that with one of the older Robi's, though.

I read some where that the Fantom can handle any motor. In fact it was stated that you could connect the two leads together and it would handle the max amps from the supply source. To date neither I nor anyone I know has tried this (disclaimer). I have spun up 7x2 D5's with no problem.

i've had my fantom upgraded by al at wizard to what he calls the drag dyno mods.... i've run 6's, 7's, 8's... you name it wothout any problems. bring your ear protection though:cool:

Has anyone noticed over the years of Dyno testing Stock Motors if an Armature that lacks any balancing holes in the laminations will tend to have a stronger field and therefore a higher power output? This would explain the reason for epoxy balancing on Mod Motors. Anyone ever look at this?

Thanks, Popsracer

I've only had 1 out of hundreds with NO drill balance holes, so its hard to say. Personally, I dont think a few milligrams of iron is going to effect the motor either way. I know if I were balancing hundreds of motors I would rather epoxy balance. Its much easier, faster, cheaper,and if you make a mistake you can easily re-do it. And if there is anything to the mass thing your covered anyway. Those bits used for drill balancing arent exactly cheap either...

I too have had very few arms with no holes.

My personal feeling is that reducing the weight of the arm does very little if anything to increase power. It may very well make the arm have more RPM, but it most surely looses torque.

Basicly it's the same idea/argument... is there any advantage to today's high RPM motors. Is there any advantage to making them even lighter?

At this time, I don't see the advantage... but I'm still looking.


Well one minor advantage... I can use a smaller pinion, and it may save me $5 from having to go buy another to gear up further with my low RPM motors. :)

Actualy... there probably is some therotecical advantage because the pinion is smaller and lighter when you use a high RPM motor... it's probably a extreemly small advantage... Probably less then you would get by reducing the length of your wiring by an inch... and that's a very small help too.

FYI... I have just beat my previous best dyno run for a stock motor.... I did it with a P2K. I used my recent hood alignment techniques, and some Putnam brushes. I had to re-tweak one of the hoods after my initial alignment procedure, because on brush was wearing really funky. This motor looked like a real DOG when I started, in the end I reach 63 watts at the 5 volt setting on my Robitronic. My previous best was 62 watts. At 7.5 volts, it put out about 131 watts... my personal best before that was my Monster at somehting like 129 watts.

I'm trying to get ready for the Snowbirds warm up race this weekend at the Hobby Hub raceway in Lansing Michigan... Watch out Jake... I've got a 61 watt Monster, a 63 watt P2K, and I'm fully capbably of builing a Paradox that's in that same ball park... :) I'm speicificly going to run 4 cell stock this weekend, just to get some track time with all these stock motors I've been building lately. I'd get blown away in 19 turn class anyway...

Put away the dyno... lets go racing... :)

Originally posted by popsracer
Has anyone noticed over the years of Dyno testing Stock Motors if an Armature that lacks any balancing holes in the laminations will tend to have a stronger field and therefore a higher power output?

Good question...

I have seen maybe a half dozen or more "no hole" Stock armatures in rebuildables... The ones I've seen DID tend to be above average in performance -- one or two were outstanding!

To be honest, nothing in my physics or engineering background really convinces me it is because of the amount of IRON in the armature poles... I believe the answer is much simpler and subtle (but perhaps "obvious" once you think about it)... A rebuildable stock motor armature that (in theory) went through a balancing process, but has no holes has a secret "hidden" advantage -- such an armature was WOUND very evenly on all 3 poles... Think about that -- a heavily drilled balanced armature MUST have had a very uneven winding job (where else would the out of balance condition come from?)...

So (if I'm right) -- an armature with what we'll call "minimal" balancing (no holes or one or two SMALL holes) may be nearly "perfectly wound". It should have a minimal amount of wire on each pole, and each pole will have virtually the same electrical characteristics as the next. Such a motor SHOULD(?) be a very good performer...

In fact -- my BEST motors almost always have no more than 2 SMALL balancing holes, and preferably only one or none... Now this could be coincidence, but....????

What do you think?

I've heard Tfram's theory before from some locals... I basicly buy into this theory... when I go look for a new motor, what else can I look at? Surely not the dyno lable on the side... :)

Actualy I found a Paradox recently with a very small ballance hole, others I had to choose from had bigger holes... I put brushes in the motor, allingend the hoods, etc... it was a dog.

I think I re-tuned that motor last week and built one of my best Pardox motors ever.

I've also recently taken severa other motors and/or arms I previously though were junk, and re-tuned them a bit and made them run quite well...

I'm begining to think that if you put enough time and effort into a motor, nearly any motor can be made to run well.

I did just look though my stock arms... I found a Pardox arm with no holes... maybe that'll be my next project arm... I need to build another to make up for the good one I let a local guy borrow...

Originally posted by DynoMoHum
Watch out Jake... I've got a 61 watt Monster, a 63 watt P2K, and I'm fully capbably of builing a Paradox that's in that same ball park... I'm not to worried, with a 60+ watt GM3 and a 62+ watt ROM, I just need to drive a little better than you. :)

What happened to letting me run some of your motors to see if some of your theories are true? I'd rather get beaten by you with your motor rather than mine. :D Maybe this weekend I will just have to out drive you. :p
Jake

Originally posted by DynoMoHum
I've also recently taken severa other motors and/or arms I previously though were junk, and re-tuned them a bit and made them run quite well...
I'm begining to think that if you put enough time and effort into a motor, nearly any motor can be made to run well.

Actually, some of my "best" motors used to be my "worst" ones... For me, it works like this... If a motor is strong right "out of the box", then I tend to leave it alone and run it as-is (with nothing more than minor "tweaks" if anything) -- but this means I may be leaving part of it's potential "on the table"...

On the other hand, sometimes I'll get a motor that's a real pig... On a motor like that, I'm not afraid of messing up a "good" one, so I'll really tear it down... I'll tear it all the way down, re-shim the armature, check all the SMD capacitors to make sure none are shorted, check how the caps are installed (sometimes they short on the small "tabs" in EPIC endbells), do a very detailed brush hood alignment procedure (maybe even take 3-4 shots at it before I'm happy with it), try different brushes, different springs, different brush cuts... etc., etc. ... 9 times out of 10, I end up with a very strong motor. Heck -- one of my best is a blue endbell handout I re-did half a dozen times before I was happy with it...

I think the secret is what you have already described... Keep tuning until you can't get anything more out of it and don't be afraid to try different things... Of course, this also explains why 99.9% of the "dyno tuned" motors you buy at the LHS are nothing special...

About the drill holes in the comm. Most of the magnetic flux is built up at the tips of the crown on each "pole". Hardly any of it is where we drill holes for balancing, so drilling holes does not affect the strength of the magnetic field generated.
Also, most stock arms over saturate the steel armature with their magnetic field. Removing a little material will just reduce the over saturation.

Dyno, you said, "Is there any advantage to making them even lighter?"

When I look for Mod motors, I want the lightest wound arm possible. The lighter the arm is wound, the faster it accelerates. Trust me, there is a HUGE difference between a 10 turn that is fully pack with wire, all the way to the tip of the crown, and a 10 turn with the arm only half filled with wire. Yes the fully packed one does produce more power, but to fix that, we just get an 8 turn that is half packed.

Here is an example. Lets compare the 10 turn Fully Packed motor to the 8 turn Half Packed motor. For demonstration purposes, lets say that the 10 turn and the 8 turn make exactly the same power and have exactly the same resistance in their windings. (to explain the resistance, 10 turns of large wire can equal 8 turns of small wire in terms of resistance) Now if we install these 2 motors and watch how fast they exit a slow corner, the 8 turn will out accelerate the 10 turn by almost 5 car lengths. Remember that these two motors have the same power. How can this be? Its all due to the fact that the 8 turn has a much lighter arm.

I think we can see how this can be applied to stock motors, right?

I should note, I run Road Courses with Touring Cars.

For Ovals, you want the Fully Packed arm, especially if your on a huge track where your geared to the moon.

Very interesting... I have virtualy no experiance with mod motors... I'm not sure comparing differnt wind mod motors has a whole lot of bearing on stock motors with all the 'same' windingd.... It probably does have some educational value. I'll have to give this some more thought. I do highly value the information.

Next ...

I dynoed somewhere between 10 and 20 differnt motors for competitors and myself this weekend. We were running in Lansing Michigan at a 'snowbirds warm up' race... I didn't dyno too many Monsters, maybe 3 or 4, can't remember for sure. I dynoed some GM3s, some Paradoxs, a P2K2, and a couple P2Ks... My best motor was a P2K, at about 63 watts... I saw at least one GM3 at this same point... and I also saw a blue endbell Paradox that I tuned for fellow hobbytalk patron (Jake) that put out something like 64 watts (a new 5 volt setting dyno record for my dyno).

Most of these guys were basicly intending to run 4 cell stock, so I didn't dyno anything above 5 volts. I dynoed a few 19 turn motors, but just a couple other then my own.

I still have never seen a Monster that puts out any more power then any ohter EPIC stock motor. On the EPIC stock motors, RPM and Torque change from one to the next, but generaly speaking once gears are applied, there is little differance in them from everything I have seen on the track or on the dyno. At least in terms of 4 cell oval racing and dynoing... Oh... actually there is one interesting notworthy item about Monsters vs. P2Ks.... The Monster seems to run cooler, I can't realy explain why, but that is my observation, and it's not because of efficiency.

My Monster is within a watt or two of my best looking motor on my dyno. On the track, I'd have to say that both motors in my car with 4 cell stock setup, run within a 10th of a second on a 5 second/lap type run... (snowbirds sized track). Basicly in all honesty, I can not tell the differance between my Monster and my P2K on the track in 4 cell stock oval racing. On the dyno, the motors only vary in Torque and RPM, however the power is not all that much differnt. I have no reason to beleive that any of the other motors I dynoed would work any better then my two motors I used on the track... (the Monster and the P2K)

I came in 3rd place in the A-main on Friday, and 1st place in the B-main on Saturday. My car was probably a 2nd place car on Saturday, but the leader got in a wreck near the end of the race, and he wound up 3rd. If my car would have been better on Saturday, I could have easly won the B-main even if the wreck had not occured. I had the P2K in the car for the mains on both days, geared at about 2.50" rollout.

Monsters used about a 2.18 roll out, GM3s between 2.2 and 2.3" rollout. This all jives very well with what I get when I compare typical motors of these types on Golden's DynoViewer using my methd of matching up the torque curves...

Chris Ulbrik (13 year old brother to Frank and Mike Ulbrik) won the A-main in 4 cell stock oval both Friday and Saturday. I did not get a chance to dyno any of the Ulbrik motors... maybe someday I'll ask them too let me dyno some of their motors, more then likely they would agree to. I wouldn't be at all surprized if some day Chris will be a national champ... He is one heck of a driver, I was very impressed with Chris. (Frank and Mike were competing in other classes, and I don't know for sure how well they did, I know one of them had problems in their main) I think the Ulbriks told me they had Chris' GM3 at a 2.32" rollout... All the Ulbriks are very fast, and also very nice people...

I did get a chance to dyno a couple Big John Zubak GM3 motors... they were right up there with my best EPIC motors... I never saw any of these on the track... Zubak ran 19 turn I think... I didn't dyno any of his 19 trun motors.... John's fast... and is reasonably nice... :)

Oh, and by the way.... Thanks to EVERYONE who let me dyno their motors... I really do love to get a chance to see what other peoples motors look like, espeicaly if I get to compete agaist them on the track as well... makes me fully realise just how little motors have to do with going fast on the track. Jake owes me $5 for the tune up job I did on his Paradox... :)

FYI... I'm thinking of ziping up all my dyno runs from this past weekend and making them available to everyone... There are very few notes on them however... I'm trying to decide if I should go back through them and add comments in the Roibtroinc fields... Maybe later I'll zip them and tell you were you can get them.

I wasn't really trying to compare 2 different winds, I was trying to show how a lighter armature will spin up a ton quicker. I only used the winds and resistance to show how the two arms can be made to have the same power. In stock motors we cannot change the wind (obviously), so we need to remove material from the arm to get the same effect. If you look at a monster, you'll see that it has the least amount of material as any other stock arm out there.

Yes, I understand what you intended to be showing with your example of the Mod motors... I'm still not sure it directly applies to stock motors... but at this point I'll take your word for it...

My observation that the Monster motors stay cooler.... I wonder if the redcution in armature mass also somehow increases the heat disapation? Perhaps more air gets to the wires and such, and the whole motor ends up staying cooler as a result? Either that or, perhaps the can of the Monster somehow also disapates the heat better? I don't know for sure, but I'm pretty sure the motors were alot cooler, and I don't think it was because they were geared incorectly...

Seperate rant I have...

I hate spinup time as any kind of indicator of proformance... To me, spinup time on the dyno is useless. I say this because the flywheel doesn't exactly dupliacte the load a motor will see in a car. If we used multiple flywheels, on for high RPM mtors, one for Low RPM motors, another for Medium RPM motors, then maybe spinup time would tell us something.... or maybe dynos should have a gear box built in them... gear differnt motors differntly, and then collect the data after the gearing... I think if there is any flaw in dynos, this is what it's related to... each motor needs a differnt flywheel...

In response to armature mass...

Although in theory a lighter armature spins up faster than a heavier one, it is somewhat incorrect. That theory is based identical materials and parallel physics, which do not exist. Take this example:

1.Motor Cans Identical (tested in-depth for mass, resistance, field effect, etc.)
2.Identical and matched magnets
3.Identical endbells and brush hoods
4.Armatures shimmed identical to each other
5.Wire on armatures wound EXACTLY the same
6.Brush Hoods aligned exactly the same

There are other items as well, but that would get you started. I'm pretty sure you would find that if you took (whether you drilled or cut) material out of one armature and left the other one stock, you MIGHT see an increase in both spinup and rpm on a dyno. However, as DynoMoHum said, this does replicate real-world performance. The Mass of the armature (usually three different coeffecients of inertia, which is why you have to balance an armature) is indirectly related to the output of the magnetic field generated by the current through the wire. In other words, removing material will most likely decrease torq, in proportional amounts to the RPM and spinup.

You can watch the same principle in racing real cars. An 800bhp 4-Cylinder Honda has problems taking a 600bhp V8 in the quarter mile. The difference in that case is that, more than not, the V8 is a BUNCH heavier than the Honda. Horsepower (usually higher in high-RPM engines) does not always equal fast.

It isn't really fair to compare an RC electric motor to a drag motor. There are other differences in full size drag racing that make up for the horsepower differance you mentioned.

One of the major differences is powerband. Fact is, given the same weight and layout (FWD or RWD) the higher power 4 cylinder will be faster in the 1/4 provided it has enough gear ratio's to keep it in it's powerband. Peak power means nothing unless the powerband is wide enough for the available gearing.

In RC, a lighter armature may or may not accelerate faster on the track. Droppong a few grams off the armature is just a drop in the bucket when you consider the entire drivetrain of an offroad truck for instance.

When all is said and done, most of the new motors make the same peak power and have similar powerbands (for me this is the slope of the torque curve). The only differance is what RPM the motors peak out at. In the end, given the correct gearing they produce the same force at the tire and thus perform the same.

Some of the older motors do have different powerbands and can not run the same even if gearing is corrected. Once the slope of the torque curve changes all bets are off.

Well... my 'expert' test driver has given me the results....

My Paradox I gave him to try rand 10.2 second laps, his Monster ran 10.0 second laps, and his GM3 ran 9.8 second laps... This is in stock Touring Car... I don't know exactly what the track looked like.

The motors he used were in my robi_data I put up last week. GPDX7V was my paradox, KGM37V is his GM3, and KFROM7V is the Monster he ran.


I think those are the correct motor names, I'll correct it later if I find out otherwise.

Glenn, Are you gonna zip all my motor files and send them to me? Pretty please? :D

Yeah... I'll zip all the motors I did on Friday and Saturday...


FYI... with the help of a Techtalk participant, known as Gee-dub, it's becomeing somewhat more clear, that there may be a flaw in the way I was figuring gear relationships to the torque and RPM data... Mike's working on a feature or two that should prove to be even more helpfull then what is currently available in the DynoViewer... Stay tuned...

(oh, and he already corrected the 'geared motor rollout' bug that I found on Saturday)

Look for the data from this weekend at...

http://www.wiltse.net/zips/warm_snow_data.zip

Give me at least a half an hour to get it put up...

Cool, Thanks Glenn. :)

Here is something that I emailed to Dyno earlier today. It may enlighten a few. It is in reference to Gee Dub's data that he sent us.

He is correct. I never looked at the data from a % increase before. Just load 2 motors and do a gear that lines up the torque. Now if you compare % difference at the low RPM range and the High RPM range, you will see a huge difference in Torque. I will use an elementary example of how the numbers trick us.

Low RPM:

Motor 1 - Torque is 130
Motor 2 - Torque is 125

Torque diff is 5. Percentage diff is (130 - 125) / 125 = 4% more Torque for Motor 1.

High RPM:

Motor 1 - Torque is 10
Motor 2 - Torque is 15

Torque diff is 5. Percentage diff is (15 - 10) / 10 = 50% more Torque for Motor 2.


Now if you look closely, you'll see that at High RPM and Low RPM the difference we see on the graph is 5. Our minds trick us into thinking that it is the same on the High end as it is on the Low end, but when we are only producing 10 Torque on the High RPM end, 5 more is a Huge increase.


I'm going to add a Percentage Difference in Torque to the DynoViewer. It should really open our eyes. Also, there is nothing wrong with the DynoViewer's calculations. Its just our minds playing tricks on us.

As evidence of Glenn's tuning ability, the red is my Paradox that he tuned! Green is my Green Machine 3, blue is my P2k and the purpleish/girlish color is my Monster.

I think Glenn is as good as anyone out there at building motors, because he is ALWAYS fast. It is not uncommon for him to have the fastest car on the track....... :)

Keep in mind, this is zoomed in.
http://www.helmsfuneralhome.com/Jake/motors.jpg

Well... Mike's got a new version of the DynoViewer ready...

http://www.wiltse.net/zips/NewDynoViewer.zip

He corrected a bug in the rollout of the geared motor... he also added a feature to display the "percent differance in torque" when you are compareing two motors.

You don't need to re-instal the whole thing, just copy this new DynoViewer.exe file and use it, insted of the older one. If you don't have the full instal done first, you'll need to go get that and instal the older version first.

This newest feature is not as significant as I once thought it may be. It is helpfull, but in my own way, I pretty much took this into account when I did my thing with gearing anyway.

It seems to me, that if you look more at POWER insted of Torque, the whole issue becomes a non issue.

I'm still strugling to understand how some people, including my test driver, seem to go faster with high RPM motors then they do with low RPM motors... Nothing in the dyno data that I can see gives any indication of how this could be. Quite frankly, I also don't see it, in my own on track testing... but then my on track testing was limited to oval racing.

In refferance to Jake's praise of my motor tuning skills...

My cars may be fast down the stratights... but I have trouble in the corners... so my lap times are often not all that good. I should probably put my dyno away and start working on my car, and getting more hours behind the wheel...

We'd probably make a good team Dyno. I can drive better than I can tune a motor.
When I build a motor it comes with a gaurentee.

I gaurentee it to be 5 watts lower than what it was before I messed with it. I wish I could figure out what I'm doing wrong.

The only advantage a high RPM motor has is that it feels like it has a broader power band. At least that what guys who like high RPM motors always tell me. Personally, I always prefer motors like the P2k on the track. For some reason, certain people love high RPM motors, even if they look bad on the track. I loaned a buggy of mine a Monster Stock I had tuned that was 5 watts less powerful than my blue endbell motors at every amp step. He won the A main with it, and commented that he loved the power band. Other than having a lot of RPM, I could not see anything impressive about the motor. Power and effeciency were clearly lower at every amp step.

Maybe it's the fact that the high RPM motors with less torque make the car a little slower and a little smoother making it a little easier to drive.

Just a guess

Mike/Glenn: Thanks for the update and data. I do my own gearing calc based on performance so this was not an issue. Dyno, like you I need more time behind the wheel. I also build good motor, gave one to a bud who was behind in all 3 qualifiers. It was a tuned GM3, he won the "C" main and beat all 3 that were ahead of him all day. :) On the RPM/Torque thing. I am more comfortable with a P2K/P2K2 that with a GM3. My style fits a torque motor vice a RPM motor. But I do drive touring not oval. Even in my 1/12 I like the hellfire with narrowed brushes or a P2K.
Dyno, here the oval dudes run either a GM3 ot the monster. 1 out of 12 runs a P2K2. Wish I had time to go in depth like you guys are, but working part time at the track and runnng the website is eating most of my spare time!

So... then we wind up back at the question of power band... and where and what it is. I think Fred B. had the most reasonable decription of the power band, that being the 'slope' of the torque curve. Clearly a motor like P2K, has big torque up front, and it slopes down, to near zero, just like every other motor. A motor like the GM3 or Monster has much less torque at 1 RPM, but it's torque doesn't seem to taper off as quickly, because the torque stays longer, the RPM continues to climb.

Still... based on everything I see on the dyno (and for me even on the track) what I see is that once you put a couple gears between the motor and the rear axle, you wind up with a torque curve that has nearly identical shape and slope... so then I'm back to square one, where I don't understand how there can be any differance.

I wonder if it's a little like fishing... If you've ever fished, you probably have a favorite lure, one that you catch most of your fish with. It's likely the first one you put on, and the last one you take off at the end of the day. The question becomes, do you catch more fish because of some magical quality of that perticular lure? or do you catch more fish because you have more confidence in it? Or simply because you give it more of a chance to catch fish?

Dyno,

I really think you're confusing the powerband issue by throwing gearing into it. The powerband is a charicteristic of the motor itself. Gearing doesn't have anything to do with it.

Take a gasoline engine for example.
The powerband of a fuel engine it the rang of RPM where the engine produces the most power.

The same is true for an electric motor. Yes, an electric motor produces max torque at 0 rpm, but HP is RPM x torque so it's also producing 0 HP. As the RPM increaces the torque decreases. At some point RPM x Torque will peak. This would be the middle of the powerband.

Gearing is used to keep the motor running in it's powerband so maximum HP is delivered to the wheels. A higher RPM motor will have Peak HP at a higher RPM. We use a smaller pinion gear so the motor will have higher RPM at the same speed thus operate in it's powerband.

When proper gearing is applied to two motors that produce the same HP at different RPM's, there should no difference in power at the wheeles.

Well... I think we are spliting hairs about it Snuffy. I fully understand power band in terms of combustion engines, and especialy how it relates to a vehicle with a multi speed transmission.

I also understand that a Monster motor will have it's peak power at a higher RPM then does a P2K.

However the typical electric RC vehicle has but one gear to use at any given time. So, for this reason I think it's totaly legitimate to view things in terms of what happens when you actualy put a gear in line with the motor and the wheels of a electric RC car.

Near as I can tell, when you do this, all stock motors have peak power at the same point. THat is, at 50% of maximum RPM. I've never seen any differnt. One interesting point is... we only spend a small portion of our race at this point were peak power occurs. Normaly we are either above or bellow this point, and only breifly spend time at the point of peak power.

With normal cars with combustion engines, it's a whole differnt thing... and power bands do change significantly depending on many factors. In the end I beleive it's very confusing to try and apply these same principles to 'stock' electric RC racing with single speed gearing. Near as I can tell, the only way to get a 'wider' power band with an 'stock' electric RC motor is to increase overal power, this in effect widens the power band. I see no other way to widen the power band of these electric motors, so they are differnt then combustion engines in this regard. I don't beleive we should attempt to compare the two as if they were the same.

I think Snuffy is getting confused by looking at the Power at the Rear Wheels. No mater what gear you throw into your car, you will always have the same Power that the Rear Wheels. But Power at the Rear Wheels does NOT Accelerate our cars. Torque at the Rear Wheels Accelerates our car. The equation is F=MA, or Force = Mass times Acceleration. If you want me to turn it around, A = F/M. Force here is Torque. We all know that gear ratios drastically change Torque at the rear wheels, and the only way to describe how our cars will accelerate is to look at the Torque Curve produced at the rear wheels. This is the whole reason I wrote the DynoViewer. Originally it was to show DynoMoHum what I was talking about.

I too have been bitten by the highRPM bug and noticed a real beating in the corners. All of my understand ing of rollout was near useless but one thing I did note, the package says do to the high RPM gear down more than you are use to. The more I dropped the pinion the faster my corners times were without suffering on the straights. RPMs are nice but tourque is the ability of the motor to reach RPM. If you need to run high RPM motors you have to make up for the fact that they take awhile to reach high RPM's. I attribute this to the lower torque. Gearing down makes up for this, I now run a much lower rollout but go faster.

Actualy, near as I can tell, Snuffy understand the relation ship of Torque, RPM, and Power. I think for the most part all of us do. However I think it's because we often use the terms loosely, and somewhat inconsistantly then we all get confused.

If we assume that my Robitronic data is accurate, and that Golden's DynoViewer correctly calculates torque and RPM once gearing is applied, it becomes farily obvious to me that the torque and power of these elecric motor is nearly identical once you get the motor in the car with reasonably correct gearing.

High RPM motors require high gear ratios, this lowers the RPM and the wheels, and increases the torque at the wheels. Low RPM motors require Lower gear ratios, makes the RPM at the wheels very simmilar to a correctly geared High RPM motor, and the torque also ends up very simmilar.

My real question revolves around the following concept... It's fairly hard for me to explain. But basicly a flywheel dyno represents a fixed load, with it's single flyweel. A low RPM motor initialy has a easier time acclerating the flywheel, because it has more torque. A high RPM motor has a realtively hard time acclerating the flywheel early on in the dyno run. Spin up time from 0 to 20% RPM will basicly always be slower with a high RPM motor, it all has to do with physics. What happens as the flywheel picks up in speed, is not as clear, or easy for me to understand. I know that the Low RPM motor reachs it's max RPM faster then does a High RPM motor... Anyway... at some point I'm wondering if it becomes a un-fair test for one or the other of these two differnt motors, simply because of the way everything works. Maybe the high RPM motor would show better power with a lighter flywheel, then a Low RPM motor would... and maybe just the oposit would be true if you had a heavier flywheel... I can't say for sure, becasuse I only have one flywheel and I'm not a physics guru. So... at the heart of my remaining questions is... are we handicaping one motor with the way the dyno run is done...

Or... should I have kept my CE TurboDyno??? (I think the answer is no... but I'm not 100% sure)

My turbodyno data basicly always agreed with my Robitronic data... so I honestly don't feel there is a problem with flywheels... but then I still can't explain why my dyno data sometimes doesn't agree with other peoples on track proformances.

A while back, DynoMoHum posted:
Oh... actually there is one interesting notworthy item about Monsters vs. P2Ks.... The Monster seems to run cooler, I can't realy explain why, but that is my observation, and it's not because of efficiency.

I want to throw something out on this to see if it offers any clues...

At first glance, a less efficient motor should run hotter, but Dyno has not found that to be the case... Add in the fact that some racers are seeing great ontrack performance from the Monster and others see only average to poor performance...

Consider the fuzzy definition of "power curve", etc. and think of this... If you have a "torque" motor, you gear up to take advantage of the torque and if you have an "RPM" motor, you gear down to take advantage of the RPMs. You can't have both, so you trade either torque or RPM for speed through gearing changes. But -- how does this impact "heat" and/or performace on the track?

Normally, my high torque motors are more efficient, but when I run them in my touring car on the parking lots in the summer, the motors get smoking hot (240+ degrees!). I'm starting to think this is a side effect of the gearing -- when I gear up to get the speed (using the torque), I'm now "lugging" the motor almost constantly. A geared up torque motor doesn't get to "breathe", because I've geared up to keep it down in the strong torque part of the "power curve"...

Now -- a less efficient RPM motor will force us to gear down to gain torque through gearing... This motor may(?) actually run cooler because it gets the chance to rev out and "breathe" -- the gearing reduces the "lugging" of the motor and it runs more "free" in the upper ranges of the RPM part of the "power curve"...

Please note this is just an idea, but what do you think?

I know I'm rethinking things lately... I have never even tried a GM3 or a Monster in a sedan or an offroad vehicle because of the typical lower torque -- I always run P2K's or P2K2's... Well lately, I've tried specially tuned MVP's, V10's and a CORE and I'm finding that if I get the gearing right, they work!

Some of this is just another way of looking at the gearing adjustment comparisons DynoMoHum and others have posted, but I thought maybe it would be worth a shot...????

Dyno,

I think we’re talking about different things. I’m trying to answer the question you had about the powerband and how it can be moved. And how different motors have different powerbands.

If you have 2 motors, both producing the same total HP, one has a max RPM of 5000 the other has a max RPM of 10000, the two motors have different powerbands.

If you tune the 5000 RPM motor to achieve higher RPM with the same total HP what you’ve done is moved the powerband of that motor to a higher RPM.

Well Snuffy... I don't think you and I have any disagreement... I basicly understand what your saying... However when the power comes out at the wheels, there is virtualy no differnace that I can see. So... I guess I could say, by your deffinition of powerband, the only thing it really effects is gearing.

Many people seem to beleive that a Monster puts out more power near it's highest RPM, and that a P2K puts out more power near it's lowest RPM... but this just simply is not true.

Now, Tfram has a intersting idea... does the high RPM motor cool better, because it turns faster? Sort of like having a built in fan... If you couple this with the fact that on a motor like the MONSTER, you have little or no iron blocking the airflow to the wires. If you look at a Monster arm, you can actualy see air bellow the windings, between the shaft and the wire, thre is air... I've never seen this on any other motors. My best guess is that somehow, this helps the motor run cooler. If this is true, it may be possible to slightly over gear the motor (realtively speaking) and even though it's consuming more power, and wasting more power, it still stays cooler. If this is all true, this in itself may be a advantage, and may also explain most of what I'm seeing and hearing about with people who like high RPM motors.

Incedently... I'm racing mostly 4 cell oval... I beleive tha heat is much less of a problem with this class, then say a Touring car... Touring cars run for 5 minutes, and they use 6 cells... more power, more wasted power, more heat... My experiance in 4 cell oval, probably has very little correlation to someones experiance in Touring Car.

I still say that for a short period of time, regardless of cooling or effciency, a P2K should run just as fast as any Monster. What happens after 1 minute goes by, may be an entirely differnt story.

tfrahm,

I was thinking the exact same thing. Higher running RPM = motor moves more air and stays cooler. Now, with the 3300's avalible, I simply gear as high as motor temp will allow. If the Monster runs cooler, I can gear higher and go faster.

Oh, and I run Touring cars and not 4 cell oval. I have to deal with very tight corners, short straits, very sweeping corners and very long straits. Gearing taller does not seem to affect the tight corners or the short straits, but it does help a ton in the sweepers and the long strait.

If all this is true about the cooling effects of a higher RPM motor, then I would say that it is an advantage. Especialy in a class like TC... you could gear up much farther as long as the motor stays cooler. So even on motors with equal power, the motor that stays cooler longer, would have an advantage. This may solve the whole riddle...

Still... why do you rarely see a P2K go up in smoke, but you do see GM3s and Monsters going up in smoke? Is it because people just natruraly push them harder? or what?

DynoMoHum -- good points...

IF higher RPM is related to "air cooling", then why...

Well - first, it is easy to over do a good thing. If the RPM motor seems to encourage gearing up because it is cool, and IF the motor is happy in a narrow RPM band, then it would be easy to go a tooth too far and "poof" -- you release the factory smoke... A torque motor normally has so much torque that you can be off by 1-2 teeth and it will still not fry (it's "happy" range is over a broader/lower RPM range). The RPM motor might fry if you are only a tooth "over", but the Torque motor might not fry even if you are 2 teeth over...?

Back to performance... Factor in battery "IR" (don't worry about how you measure it, just include it in your thinking)...

The torque motor will be geared up, will draw more amps -- thus it gets less voltage from the cells because of the "IR". So even though on the dyno, it produces equal power, on the track it gets less voltage IN, so it puts less power out...?

The RPM motor will be geard down, will draw less amps at this lighter "load", and thus gets more voltage from the cells. So even though it produced equal power on the dyno, on the track it gets more voltage, so it puts out more power...?

Is this a clue or am I off track (pardon the pun)...?

Dyno, You hit on almost the same point. If a High RPM motor takes time to reach its peak on the dyno spinning a flywheel it also will take time spinning wheels up to top speed. The higher ratio (Smaller pinion) compinsates for this because one problably run out of track before attaining this desired RPM. A tourque motor, while not revving as high will reach this rev band quicker and propel the car fast.
Now if you run a large oval the High RPM motor might be fine, but a short course or a road course where bottom end and quick bursts of power are needed would benefit from tourque, not rpm's.

Unrelated to this: When looking at the #'s on say a Fantom what would be the catagory that would tell you which aspect would benefit you the best. Assuming your looking at only one motor but several different versions, like for example a stock with 3 different spring combos. Which set of #'s shows the most improvement RPM, AMPS, Power etc. I mean you change springs and RPM go up but amps do too or power goes down. How do you best determine which # has the most bearing on improvement?

Another "smoke factor" is "mechanical"... The more full the armature laminations are, the better the wire is held in place. A P2K lamination stack, combined with the aluminum keepers on the ends keeps the wire pretty firmly in place, so you don't get wires vibrating around (chafing on the stack and shorting out) or "throwing" a wind -- both reduce the chance of "smoke"...

The GM3, Monster, etc. have a very OPEN design -- not much supports the center part of the wire "wrap". If there is any slack in the wires (remember -- machine wound arms), then the wires can loosen, vibrate, chafe on each other and/or the stack or get "thrown" (greater centrifugal forces at higher RPM) -- all increase the chance of "smoke"...

I think your getting a little off track... but that's ok...

Actualy the lower the IR, the higher the voltage should be under heavy load. Basicly V = IR, so the more current you pull the higher the voltage drop of the battery (if it's pure resistance) the lower the IR, the lower the voltage drop of the battery at any given current amount...

The motors should be drawing the same mount of current, and also should be seeing the same voltage as near as I can figure.

I also don't like the idea of wider or narrower 'powerbands'. I see no evidence to support this.

Even the higher/lower torque thing doesn't make much sense to me in terms of motors smoking or not, but there may be some truth in it. Bascily, there surely is a point when you gear a low torque so far over, that it just simply doesn't have enough torque to push the car... but the same is true for a low RPM motor, it just takes even lower ratio to do it.

Think about this.... Just because a motor doesn't feel hot to the touch of the can, does not nessasarly mean the windings are also just as cool. It could be that the heat just doesn't travel from the windings to the can as much on a higher RPM motor. The temperature of the wire is likely to be just as hot at some point as the wire in the lower RPM motor. Under ideal condtions, the cooling effect keeps the insulation on the wire from melting... however if you push too far, the insulation melts and we have smoke... With a motor that doesn't cool as well, we may notice a drop in proformance due to the magnets getting hot, and we may avoid overgearing as a result, because we can see the negitive effects, long before the insulation on the wires melt... So.. this may be why you rarely see a low RPM motor smoke.
( I like my theroy much better , even if it is my own...)