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Old 07-09-2007, 08:37 PM   #31
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Im with Eddie on this. No dyno is great. The CE Turbo dyno is the best that's out to buy but requires a lot of maintenance....Its also the most consistent from dyno to dyno. The fantom is the absolute worst out there. Ive seen them that can vary as much as 10 watts on a motor. Most CE's are within 3-4 watts as long as they are taken care of and havent been abused.

Testing motors are 5 volts is pretty much useless to if you are racing in a 6 cell class. I have seen awesome motors at 5 volts just plain suck at 7 volts....BUT I have NEVER seen a motor tested at 7 volts be bad at 5 volts (Or 4 cell).

I have also seen motors come straight out of the case that are up to 10 Degree's advanced! It usually happens when a motor is first released to get everyone to buy them. Then they tend to get back to where they should be after people get hooked on them. Lately most have been pretty close to 24 degrees.

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Old 07-09-2007, 09:53 PM   #32
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Originally Posted by howard1 View Post
What numbers must one take not of when buying or tuning a stock motor? When looking at dyno results does e.g. efficiency play an important role? What readings constitute a good motor? Help a confused racer!
Howard. The CE TurboDyno and other owners will have to weigh in on those machines but for the Fantom dyno I would look at 3 numbers in order of importance:

Watts - This is the max power that a motor can make and it will be listed at a certain RPM. It's the first thing I look at but maybe not for others. I like to see at least 66 watts but generally somewhat higher numbers can be obtained - 70 watts is rare in my opinion and more than that I am suspect of foul play.

RPM - Well, this is RPM at 5 volts. I generally like to see 20,000 or more at 5 volts.

Torque - This is the torque value and with an electric motor will always be highest at the lowest RPM since Torque = 5252 x hp/RPM. As a general rule, this is your get outta the hole power and high torque will get you going faster but not help top speed.

Think of RPM as more speed oriented and torque as more acceleration oriented.

I personally don't factor in efficiency but maybe some people care abou it.


Here's the thing though... As much as we need to have some dyno data the reality is that sometime a good motor will show bad numbers but be good on the track and vice versa. The dyno numbers are at least SOMETHING to go by.

Personally - I look at all the data (full sheet of numbers showing power, RPM, torque, amp draw, effeciency, etc) to REALLY tell if a motor is strong. The little dyno sticker just doesn't have all the data that you REALLY need but at least it is something to get an IDEA of one motor vs another.

Finally...... for the most part if a motor of a certain type/brand/model is built with care, broken in properly, etc, etc they should all perform pretty closely. Granted there those few duds and few extra good onse but the vast majority seem to fall within a pretty close range and on the track they generally are indistinguishable from one another.
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Old 07-09-2007, 11:25 PM   #33
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Unless you are buying a motor with a TurboDyno print out the numbers are pretty worthless as they don't show the amp draw at max power and max efficiency. Max RPM is also completely worthless. So two motors might both show Max power of 64 Watts ... one might be doing it at 32 amps and the other at 35 amps. The one doing it at 32 amps would be the faster motor. The efficiency number is the same ... it could be 54% at 12 amps or 20 amps. I believe TeamB00d and EA both send motors with the TurboDyno printout. Look for high efficiency numbers in the 20-35 amp range. Don't worry about RPM or Torque - you can always change the gear ratio to get what you need. Now, I'm not saying tuners that use other dyno's don't sell good motors or spend a lot of time and effort on them. You can get some information from the Fantom dyno in the time-base mode ... I don't think it is as repeatable as the TurboDyno but it is better than nothing.

I have seen direct correlation with TurboDyno numbers and performance ... especially at the velodrome tracks.
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Old 07-09-2007, 11:53 PM   #34
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This might have been posted, if so, I apologize.

Will any motor tuners be selling dyno'ed or tuned brushless motors, like the 10.5 or 13.5? Seems more and more is being learned about these motors everyday? Thanks!
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Old 07-10-2007, 03:09 AM   #35
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Quote:
Originally Posted by peter_robinson View Post
where this is a great idea... i just does not work. as a joke one time eddies brother asked use to build him a stock motor to use. we had a motor that no matter what we tried would not pull anything remotely good numbers wise on the dyno.

we gave it to him and he used it in his car. later at the race he asked me to drive his car to see if the setup was good... and to my surprise the car a tons of horsepower. i asked him what motor he had in there and he said it was the one that we gave him. it was hands down the fastest stock motor i have driven to date, and had hands down the worst numbers i have seen from any motor on the dyno to date.

eddie and garrett will back me up on the story.
funniest thing ever! i couldnt get that thing to go over 100w on a CE, no matter what we tried....i gave up on it and put it on a shelf....then gave it to eddies brother, at the race peter yelled out "dude look at how fast this motor is!" we were all shocked..lol

and for that reason i never take a dyno to a race......

I can dyno 13.5's....would there be any takers if i had some good ones?
i have some in the hobby shop inventory.....ive got time...lol
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Old 07-10-2007, 07:04 AM   #36
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Thanks for the info QuickRC, it is appreciated. The main reason why I was asking is so that I can prioritse the motors according to the readings, and then do track testing.

Regarding efficiency, that is the current lost due to resistance etc. if I understand correctly. If you could improve the efficiency would that not impact on the watts the motor puts out? The question is how do you improve efficiency??? Some pointers anyone! OK not all the trade secrets just one or two will do!
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Old 07-10-2007, 09:23 AM   #37
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I have purchased a couple of cobalts from known tuners, yes they were good, but nothing special. so I thought it was me, my set up, or gearing.

then recently I purchase a cobalt from a friend of mine, Larry Ruby.
the motor scared me on the first run. I was setting up my car so I made 3 runs off the motor. I should have bought two because by race time it had slowed down to everone elses.

I thought I would give credit to where credit is due. I tried rebuilding it. but doing that during race day at the track, doesn't work for me. I will give it back for a rebuild and probably buy another one.

If your in the Southern California area, Look for Larry Ruby.

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Old 07-10-2007, 02:44 PM   #38
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I've ran alot of 27t monsters..

From alot different tuners, some they send are hooot others seem avg - luck of the draw it seems or maybe i'm just very unlucky!

Last edited by 8800; 07-10-2007 at 02:55 PM.
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Old 07-10-2007, 11:56 PM   #39
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I've ran alot of 27t monsters..

From alot different tuners, some they send are hooot others seem avg - luck of the draw it seems or maybe i'm just very unlucky!
if your buying blueprint motors then there should be no such thing as luck involved. these motor tuners that use that word on there web site should look up the meaning of blueprint. becuase some are using it very loosley, and leaving themselfs wide open.
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Old 07-11-2007, 12:15 AM   #40
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Funny ...
If a dyno is deem useless as a tool for judging power output , how do you account for most motor tuners featuring hand tune & dyno motor `s for sale ?
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Old 07-11-2007, 12:27 AM   #41
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Quote:
Originally Posted by Wild Cherry View Post
Funny ...
If a dyno is deem useless as a tool for judging power output , how do you account for most motor tuners featuring hand tune & dyno motor `s for sale ?
because you can still use it as a gearing tool...

that is what most use it for anyways
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Old 07-11-2007, 11:47 AM   #42
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I can't believe how much difference there can be between two motors of the same make and model tuned by the same person/place. I have had a c027 with an insane amount of RPM and had very little torque, I have had a c027 with lower RPM but an insane amount of torque that ripped through the bottom end, yet when you look at them, same brushes, same endbell, same can, and armatures "look" identical and yet totally different powerbands, its really weird
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Old 07-11-2007, 12:00 PM   #43
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Quote:
Originally Posted by howard1 View Post
Thanks for the info QuickRC, it is appreciated. The main reason why I was asking is so that I can prioritse the motors according to the readings, and then do track testing.

Regarding efficiency, that is the current lost due to resistance etc. if I understand correctly. If you could improve the efficiency would that not impact on the watts the motor puts out? The question is how do you improve efficiency??? Some pointers anyone! OK not all the trade secrets just one or two will do!
Hmm... Efficiency. that's a tough one but it is basically a measure of input power vs output power. Technically higher efficiency will equal more power output but the problem is that the motor will only put out so much power therefore it can only be so efficient - in other words the motr has a LOT of potential power available to it but it can only use so much of that because it will only draw so much current that it can convert into power.

I've honestly never tried to change effieciency but today I have to tune a couple motors for a race and I'll try a couple things and report back.

I've attached a printout from my Fantom Dyno (Please everyone, I know already, it's a piece of junk and worthless but it's what I use) from a Komodo 19T motor I had in my shop. Take a look at the numbers:

Basically the dyno KNOWS certain things and CALCULATES other things - just like any other electric motor dyon or Car dyno for that matter.

You can see that the dyno measures some things that it KNOWS: TIME, AMP DRAW, INPUT VOLTAGE (not displayed), RPM and ACCELERATION. The dyno uses those known quantities to CALCULATE efficiency, torque and watts of power. It does this by accellerating a known mass (the flywheel that you attach to the motor) and measuring the results. Despite what some may say this is a very repeatable process and varies very little from dyno to dyno (I once compared 3 Fantoms at once and they were very similiar). This process relies on physics to make the calculations.

Anyway... see how the numbers interact - remember some numbers are known/measured actual values and other numbers are derived values.

Back to effieiency, look at the amp drawnumbers and multiply them by 5 (volts) that will give you the amount of Watts put INTO the motor. Then look at the calculated Watts value the motor is puttin OUT and that will give your efficiency. For example 47 amps in x 5 volts = 235 watts of input power. Output power is about 103 watts. Therefore 103 watts out divided by 235 watts in = about 43% efficiency. A motor could be tunes for more efficiency if desired (I never tried) but this is at least is how efficiency is calculated.

Probably didn't really answer our question but hopefull efficiency in general makes more sense now.
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Old 07-11-2007, 01:39 PM   #44
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Howard1, I did a test on a motor with different spring combinations on a Cobalt motor. Here's what I found:

with Green/Green springs average efficiency as 27%
with Red/Green springs average efficiency as 26%
with Red/Red springs average efficiency as 26%
with Purple/Purple springs average efficiency as 24%

Max efficiency followed the average curve by about the same percentage - from a low of 46% max to a high of 49% max.

Basically, the lighter springs gave better efficinecy and lower overall amp draw and the heavier springs had the opposite effect.
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Old 07-11-2007, 04:21 PM   #45
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QuickRC thanks for the investigative work and the explanations.Now the science gets interesting! What factors limit a motor from putting out more power (higher efficiency). Is it the windings, brushes,comm or a combination of all of these? Did the lighter springs give better numbers all round? Is this a positive sign to obtaining a more efficient motor that can deliver good overall performance?

An interesting comparison would be to take a hand wound motor and a normal motor of the same windings,core, brushes etc. and see what efficiency/power is obtained. Surely with these given parameters one should be able to create the almost perfect motor! I do realise that it would mean going through hundreds of armature just to get the one with least resistance and good balance. Perhaps QuickRC you could experiment?

I do not yet have the working knowledge (or equipment) that you proffessional tuners have, but I want to learn hence the questions.

Thanks!
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