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Old 10-04-2003, 11:41 PM   #1
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Default Motor RPM ???

I dont get it, how do you get the specs for a motor when there not even on the manufacturers website????

trinity, orion, reedy

none of them seem to feel that rpm or power are figures that people want to know.

to me winds and turns are useless, I need to know rpm to calculate the proper pinion gear for my car, since gear calculating mathmatics do not allow winds and turn into the eqaution.

and you really cant compair 1 set of specs to another from another motor because I have seen 1 15turn double rated @ 22,000 rpm and another @ 33,000 rpm

You would think in all the years they have been making r/c motors that there would be a standard by now.

who buys a chevy 350 or ford 302 crate motor and they only want to make sure its a 302 with say a holley carb???????

No one thats who, they wanna know the horsepower

Is there some secret mathmaticle formula that I'm missing out on here?


Well that ends my rant, any help is apreciated as always
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Old 10-05-2003, 12:07 AM   #2
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Nobody really gears their car according to RPM, you gear by the motor turn and wind, it's just become a standard basically. There used to be a dyno printout on just about every motor you could buy, but because every one was tested at different voltage, it was useless.

Maybe I just feel like that because I dont buy chevy or ford crate motors though...
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Old 10-05-2003, 01:12 PM   #3
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You should really gear the car by how it feels on the track, how hot it is and your laptimes rather than mathmatically.
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Old 10-05-2003, 05:27 PM   #4
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Default Re: Motor RPM ???

Quote:
Originally posted by seriousre
I dont get it, how do you get the specs for a motor when there not even on the manufacturers website????

trinity, orion, reedy

none of them seem to feel that rpm or power are figures that people want to know.

to me winds and turns are useless, I need to know rpm to calculate the proper pinion gear for my car, since gear calculating mathmatics do not allow winds and turn into the eqaution.

and you really cant compair 1 set of specs to another from another motor because I have seen 1 15turn double rated @ 22,000 rpm and another @ 33,000 rpm

You would think in all the years they have been making r/c motors that there would be a standard by now.

who buys a chevy 350 or ford 302 crate motor and they only want to make sure its a 302 with say a holley carb???????

No one thats who, they wanna know the horsepower

Is there some secret mathmaticle formula that I'm missing out on here?


Well that ends my rant, any help is apreciated as always
i agree with you 110% i want know the facts as well. as afr as gearing a motor by the turns and winds-some one please tell me that they would gear say.. a Speed Gem 9turn and a KR or TI 9turn. now i am aware that no one would use a Speed Gem to race, but i made my point. and the only reason we dont use Speed Gems for racing is because it is common knowledge that they suck. but thats my other point if we didnt know that, then all we would have to go by would be "9 turn double". now if they just came right out and told you the "real" specs it would be alot nicer,would it not?
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Old 10-05-2003, 05:42 PM   #5
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Yer but the fact is that no motor is the same, that means they would have to run every motor before they kick it out the door. Which in turn means that to get decient nunbers they would have to do a hell of alot of work. Aligning the hoods, truing the comms, polish bushings blah..blah..... a crap load more prep work then what they do right now. What are the chances of the big companies doing this? Also, who would buy a motor that was less powerful, if the company market's a motor for the same price and one has better specs which will be left sitting on the shelf? It would be bad for buisness.
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Old 10-05-2003, 05:46 PM   #6
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It'd be nice if it were that cut & dried, sean & seriousre, but it's not. EVERY motor is different, even of the same type & wind. Honestly, the only way to have motors of the same wind that are that close to each other is when you have the same guy winding the arms & tuning them(which we usually only see by the big names in motors setting them up for their factory drivers at big events), & that simply doesn't happen in mass-produced motors. Winding arms is still as much an art as it is a science, which is why handwounds are almost always better performers than machine-wound motors. And in addition to that, every track is different, which means that using the same gearing for a particular wind at every track will just not work. That's why the manufacturers don't give a specific rpm number for one wind or another, there's just nonpoint(& if they did, they'd just end up getting a lot of complaints from customers saying that their motor isn't performing like it was advertised).....
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Old 10-05-2003, 06:03 PM   #7
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i dont know guys-yes every motor is different,but not that different. do you think that SEARS/CRAFTSMAN puts all their Dremel tool motors on a dyno to know that they spin at 30,00 rpms? how about when Rhule makes bilge pumps- are some 1100gallons per minute the next 1105 or 1098 gpm, no, it does not work that way. the big motor companies know when they build a motor how its going to perform-ESPECIALLY if its mass produced. and if they are that inconsistant maybe we should get Bob Villa to start winding our motors.
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Old 10-05-2003, 08:13 PM   #8
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i agree with "ian s", gear by how it feels and how hot it gets, not by rpm. If you gear by rpm, your being just a little to into it. Keep gearing till your lap times go down, or you motor is too hot.
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Old 10-06-2003, 12:58 AM   #9
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Sean, you're just gonna have to trust us on this, many of us have been messing with motors for many years(I've been racing over 14 1/2 years myself), & some of us have been doing a LOT of testing with motor dynos, & I can tell you from my experience that NO TWO MOTORS ARE EXACTLY ALIKE. Even when two of the same wind seem to show the same power, torque & rpm numbers, I still see one will do it in less time then the other(which is the REAL key to how the factory guys' motors are SO bloody fast, I know because I've tested a few of them on my Robitronics dyno, like ones used by Paul Lemieux & Barry Baker). The ONLY motors that seem to be that consistent from one to another are the ones that guys like Jim Dieter & Mike Reedy build & tune personally for their factory drivers(& frankly, they've probably forgotten more about motors than most of us will EVER know).....
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Old 10-06-2003, 11:38 AM   #10
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Quote:
Originally posted by Ian S
You should really gear the car by how it feels on the track, how hot it is and your laptimes rather than mathmatically.
Well the whole deal that got me started was because I just bought a
Rush 15t double "yeah they suck"

but I got it for $15.00 new

and it was the only sub $15 motor that had
bearings, rebuildable, timmming adjustment

This is going into a blackfoot with aftermarket gearing

3.05:1 gearbox
48t spur
10t pinion
My tires are stock 4.5" or maybe I will upgrade to 4.75"

So what turn motor should I use?
you cant tell me can you, and thats all the specs you need besides rpm.
With the above specs you can find a good rollout for torque but you need to know rpm to figure in max speed "mph".
Once you know that then the obvious comes into play, such as a 27t motor should not exceed 21mph etc.....

So I ripped into the blackfoot motor and counted the winds, 27t single stock mabouchi "or whatever" motor.

But my countergear is aftermarket, so I counted the teeth on a stock one and if memory serves me correctly its closer to 2.5:1

With those specs and going by how most manufactures recommend dropping 1 tooth per 1 wind after 19t
between 16t and 27t you only drop 2 teeth on your pinon.

which would give me something needed like a 7 tooth pinion "just for example, but taken into consideration my aftermarket gearbox gears I should be back up around a 10 tooth pinion, my rollout is there but I really dont know without knowing the rpm and being able to see my max speed.
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Old 10-06-2003, 11:39 AM   #11
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Quote:
Originally posted by Ian S
You should really gear the car by how it feels on the track, how hot it is and your laptimes rather than mathmatically.
My cars are all parking lot racers, its more about fun factor then run times, a slow car off the line is no fun, as is a slow car at top end.
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Old 10-06-2003, 11:42 AM   #12
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Quote:
Originally posted by fatdoggy
Yer but the fact is that no motor is the same, that means they would have to run every motor before they kick it out the door. Which in turn means that to get decient nunbers they would have to do a hell of alot of work. Aligning the hoods, truing the comms, polish bushings blah..blah..... a crap load more prep work then what they do right now. What are the chances of the big companies doing this? Also, who would buy a motor that was less powerful, if the company market's a motor for the same price and one has better specs which will be left sitting on the shelf? It would be bad for buisness.
All they would have to do is test one random motor of a specific brand/model and turn/wind and allow +/- "x"% difference

I am also talking true rpm without brush alignment and such and such.
Because the rpm should be the same right out of the package, not after you spend a day prepping it.
Thats why there are $60 motors and $13 motors
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Old 10-06-2003, 11:57 AM   #13
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Quote:
Originally posted by Grizzbob
It'd be nice if it were that cut & dried, sean & seriousre, but it's not. EVERY motor is different, even of the same type & wind. Honestly, the only way to have motors of the same wind that are that close to each other is when you have the same guy winding the arms & tuning them(which we usually only see by the big names in motors setting them up for their factory drivers at big events), & that simply doesn't happen in mass-produced motors. Winding arms is still as much an art as it is a science, which is why handwounds are almost always better performers than machine-wound motors. And in addition to that, every track is different, which means that using the same gearing for a particular wind at every track will just not work. That's why the manufacturers don't give a specific rpm number for one wind or another, there's just nonpoint(& if they did, they'd just end up getting a lot of complaints from customers saying that their motor isn't performing like it was advertised).....
But the motor can be off by up to 1000rpm

If a p94 15t double is 20,000 and the next is 22,000 then I think there are some serious manufatcuring problems going on.

if the motor specs are off by 1000rpm or less it will only throw off common speed calculations by 1mph or less with most trucks
it will thorw it off my less then that with most cars

and we wont even talk about direct drive "pan cars"

not that big of a deal

If a motor varies more then 1000 rpm then there has to be a problem somewhere.

How much different do motors you guys test vary?
Of same model/brand new just opened from package?

btw sorry to open a can of worms, Im just the guy who always wants to know the specs.
I just like to know who has the bang for the buck
To me its not who's winning races "what races I dont go to any" its what motor is easy to get my hands on quick, cheap enough to have a spare, or even different winds on hand so I can easily swap out motors for more torque or more top end, and what motor I'm not going to fell like maybe I spent too much money on for packing lot fun.

I have my USA-1 truck, TC3, my g/f's Blackfoot, 1 Pancar, and 1 Stampede, all need new motors

So when I have to buy motors its usally more then 1, and If I want extras were talking 7 plus motors, I cant afford $420.00 in motors, lord knows it would be alot easier to grab a bunch of D5's since there rpm is actually stated.

thanks
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Old 10-06-2003, 12:06 PM   #14
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As several have stated, the industry standard has become to list the wind and turn of a given motor.

Some aftermarket tuners do include with their motors a dyno sheet on that particular motor's performance. Does this include top RPM?? Probably not - and here's why - there is no standard voltage at which to run the motors to find the top RPM.

Simplest advice for you? BUY A DYNO for your own use to figure out what the appropriate motor for your purpose is. Most people will change the gearing based upon the motor - in this case it would appear that you are stuck with a certain gearset, thus limiting your possibilities. If you buy too hot of a motor, you run the risk of burning it, or your ESC up.

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Old 10-06-2003, 04:17 PM   #15
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seriousre - There are lots of factors that can make one motor perform better then another.

1 - Hood alignment, if you happen to hit it lucky and get a motor with perfectely aligned hoods then you WILL see better performance as opposed to one that has hoods that are way off. But the motor needs to be aligned so that the bushes are aligned inside not just the hoods because the brushes cock to the side a little as the motor runs(this takes time to get right).

2 - Aligned bushings/bearings, if slightly misaligned they can cause excess vibration, wear and obviously performance suffers(excessive sparking/wear).

3 - Magnets in all motors arn't in exactely the same place, thus may not be directely across from each other casuing a less effective magnetic field.

4 - Arms, not all arms are perfectely balanced. If the arm isn't balanced then your motor will never reach it's peak(thus less performance)

5 - Comm's, the next motor you buy cut the comm after using a nikko to cover the surface, do one light cutt and you'll see that it isn't perfectely round.

6 - If your motor has internal caps they are sometimes defective which causes excessive resistance via sparking when the motor is running.

....................and more.................and more.......

These motors have parts parts that create lots of wear and tear, this is why we have to do quite a bit of crap (polishing bushings, comm cuts, brush changes, hod alignments......) to make our motors fast.

If you take 2 motors off the shelf (basic motors, not tuned my axiom or putnam or alike), dyno them and then race prep them and dyno them again you WILL see quite a jump in performance and neither will be exactely the same before or after preping them. This is why you can't just same test one out of a batch and clasify it as a 22,000 rpm line of motors. You are taking industrial motors that last a long time with little maintance, we are talking motors that need a new set of brushes each couple of runs and need comm cuts....blah...blah ..blah. If you want to know how your motor is going buy a dyno, integy has a reasonable inexpencive dyno, I think $100 which would do the trick. You may tune a motor using the rpm's but it's useless on the track since you tune so that your motor is fast in the corners not just in the straight, if you just bash, then sure it may work, but there is little point in paying $60 for a top of the range racing motor instead of $15 for a cheap machine mod that will still run ok. Masses produced motors(in most cases) arn't fast out of the packet(due to all the problems listed above), you need to make them fast and there is still a chance that your motor will have magnets that are a little off, an arm that's out of balance or other problems causing the motor to perform worse then your previous motor that was exactely the same type of motor.

Sorry for the long responce, just trying to help you understand...
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