What kV BL motor for Truggy conversion??? - need help!

What kV BL motor for Truggy conversion??? - need help!
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What kV BL motor for Truggy conversion??? - need help! - 6/29/2008 11:40:50 PM

bhcvc

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From: Los Angeles, CA, USA
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The standard seems to use inrunner BL motors for conversions...for trucks, typically in the range of 2000kV to 5700kV. Most people seem to use enough voltage to operate the motor in the 30k to 50k rpm range.

However, I've seen quite a few people use low kV (i.e. 500-600kV) outrunner motors for truggy and buggy conversions. They seem quite fast also, but with the same battery setup, the kV is MUCH lower, but the people that have done the conversion said it's ok because it's direct drive (no tranny) in truggies/buggies.

So, here's an example...assume a 1/8 truggy of any sort, no tranny, center diff only:

2200kV BL INrunner motor running 2s2p 14.8V = 32560rpm
600kV BL OUTrunner motor running 2s2p 14.8V = 8880rpm

Just doesn't seem like the Outrunner motor would be fast enough relative to the Inrunner setup, but people with Outrunners claim the same speeds (about 45mph). How is this possible? Which setup is correct or better?

I'm looking to do an electric truggy conversion and would really like to know which setup to get.

Thanks.

Post #: 1

RE: What kV BL motor for Truggy conversion??? - need h... - 6/30/2008 12:09:51 AM

HandyRacing

Posts: 293
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From: Jackson, MI, USA
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I'm gathering tech resources for Nitro to Electric conversions. You can find the list of links on the "Resources" tab here:

www.HandyRacing.com

I suggest you start with the www.RCProductDesigns.com link - they have experience with the NEU motors (and sizes) that work best with buggies and truggies. Thay have also provided us with very good techno advice along the way on our project(s).

< Message edited by HandyRacing -- 6/30/2008 12:10:51 AM >

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RE: What kV BL motor for Truggy conversion??? - need help! - 6/30/2008 1:39:19 AM

nitrosportsandrunner

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From: skowhegan, ME, USA
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2200kV BL INrunner motor running 2s2p 14.8V = 32560rpm
600kV BL OUTrunner motor running 2s2p 14.8V = 8880rpm

if the inrunner spins at 32560, but has to spin 3 times to turn the tire once(becuase the tranny gears it down), and the 8880 outrunner turns the tire once for every rotation of the motor...doesnt that account for the same relative speeds?

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Post #: 3

RE: What kV BL motor for Truggy conversion??? - need h... - 6/30/2008 1:43:56 AM

bhcvc

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From: Los Angeles, CA, USA
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Handy - thanks! I'll check out your site!

nitro - the point is that the setups the motors are going into are identical, so there is NO tranny in either setup...both are direct driven via a center diff ONLY. So, I've seen people use inrunners with much higher rpms and people use outrunners with much lower rpms, both in diff only truggies and both group of people say they're fast (40-45mph). Doesn't make sense to me.

(in reply to nitrosportsandrunner)

Post #: 4

RE: What kV BL motor for Truggy conversion??? - need h... - 6/30/2008 1:51:23 AM

HandyRacing

Posts: 293
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From: Jackson, MI, USA
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bhcvc,

Thanks - Right now, some 1/8 scale buggy outdoor race footage is at www.YouTube.com/HandyRacing

(click the "view at higher quality" option)

There is also some indoor Truggy action from last winter, albeit with a poorer quality video camera.

I hope to have some Truggy (exhibition) footage up by tommorow evening.

I'm not sure about the specifics, but something to consider..... From what I've seen, the plane / helicopter motors are "open can" designs, on a track the dirt will tear them up, some "protection" is needed while also still need to keep things cool.

(not much dirt to worry about in the air)

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RE: What kV BL motor for Truggy conversion??? - need h... - 6/30/2008 1:51:48 AM

nitrosportsandrunner

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ok, i misunderstood before.
well, if when you say direct drive to the center diff, you mean the motor has a pinion gear meshed to the spur on the center diff, then the size of the pinion make the difference.
a lower kv motor will have much more torque, and can be geared far higher than the inrunner.

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Post #: 6

RE: What kV BL motor for Truggy conversion??? - need h... - 6/30/2008 1:55:53 AM

HandyRacing

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From: Jackson, MI, USA
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quote:

ORIGINAL: nitrosportsandrunner

well, if when you say direct drive to the center diff, you mean the motor has a pinion gear meshed to the spur on the center diff, then the size of the pinion make the difference.

Yes, this is how the folks racing 1/8 buggies do it. No tranny and assciated gear reduction. 1/8 scale conversion rigs typically use a Kyosho 48 tooth plastic spur, with a pinion choice to be made (typicaly a Mod1 12 tooth for starters).

Pay attention to motor shaft size to avoid the need for a "reducer" bushing.

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RE: What kV BL motor for Truggy conversion??? - need h... - 6/30/2008 2:07:36 AM

nitrosportsandrunner

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handy, you mention reducer bushing...will a reducer bushing make a mod 1 pinion gear for 5mm shaft fit on a 2mm 540 motor shaft?
i have a cheapo no-name truck that uses a mod1 gear. the pinion is too big for the vxl motor to run its best. but the only pinions i can find for 2mm/ 1/8 shaft are mod 0.4-0.6

and, you are saying im right, it is the gearing that make the inrunner and outrunner run the same, right?

< Message edited by nitrosportsandrunner -- 6/30/2008 2:08:45 AM >

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RE: What kV BL motor for Truggy conversion??? - need h... - 6/30/2008 2:18:47 AM

HandyRacing

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quote:

ORIGINAL: nitrosportsandrunner

handy, you mention reducer bushing...will a reducer bushing make a mod 1 pinion gear for 5mm shaft fit on a 2mm 540 motor shaft?
i have a cheapo no-name truck that uses a mod1 gear. the pinion is too big for the vxl motor to run its best. but the only pinions i can find for 2mm/ 1/8 shaft are mod 0.4-0.6

and, you are saying im right, it is the gearing that make the inrunner and outrunner run the same, right?

I try to not get too deep with specifics, my partner is the brain trust of our operation.

But, yes with the reducer bushing / 5mm shaft / motor selection, I think. I'm not good at running the numbers on the gear reductions for an outrunner / transmission detailed analysis but think of it this way - why have all the extra load (drag) from a tranny / gear box on a race rig if you dont need it?

Somewhere I (we) have a link to a nifty web based gear reduction / motor rating / battery spec - speed estimator. Will post a link on my page in the "Resources" tab one of these days....

That being said, we are (slowly) building a LOSI LST Nitro to Electric conversion - so we will have to factor in the tranny for our choices.... that project is on the back burner, trying to keep our race rig on the track for the time being.

Looking for deep pocket sponsers.....

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RE: What kV BL motor for Truggy conversion??? - need h... - 6/30/2008 5:21:12 AM

bhcvc

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From: Los Angeles, CA, USA
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Thanks for the info and continued idea sharing Handy and nitro!

So instead of a tranny, the Final Drive ratio and resultant rpm of the wheels is determined by the spur to pinion ratio. So in my example of 33k rpm vs. 9k rpm, a factor of 3.7 difference, the spur:pinion ratio would just need to be adjusted accordingly to attain the same wheel rpm.

Anyone know what rpm the wheels should be at? That would help determine what kV motor I should pick and what pinion to match either the stock spur or a Kyosho 48T spur.

Thanks.

(in reply to HandyRacing)

Post #: 10

RE: What kV BL motor for Truggy conversion??? - need h... - 6/30/2008 5:36:38 AM

HandyRacing

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From: Jackson, MI, USA
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quote:

ORIGINAL: bhcvc

So instead of a tranny, the Final Drive ratio and resultant rpm of the wheels is determined by the spur to pinion ratio. So in my example of 33k rpm vs. 9k rpm, a factor of 3.7 difference, the spur:pinion ratio would just need to be adjusted accordingly to attain the same wheel rpm.

Anyone know what rpm the wheels should be at? That would help determine what kV motor I should pick and what pinion to match either the stock spur or a Kyosho 48T spur.

Thanks.

And tire size.

I would consider motor / ESC heat as the "driving consideration" for selecting the gear(s). Wrong gear and you could toast expensive stuff in a hurry. And pay close attention to cooling fan selection and use. Send an email to Dan @ RCProductDesigns, the NEU with spur / pinion selection for both a LOSI 8eight(T) and Mugen Truggy is well proven on the track from last winter.

(Mention I sent ya)

If I recall, I discuss the gear choices we made and what we learned in my "Resources" project thread.

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RE: What kV BL motor for Truggy conversion??? - need h... - 6/30/2008 5:38:38 AM

HandyRacing

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If you haven't yet, you might go visit the (electric) threads on the 1/8 scale list.....

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RE: What kV BL motor for Truggy conversion??? - need h... - 6/30/2008 12:00:53 PM

happywing

Posts: 1713
Joined: 11/9/2005
From: Canton, MI, USA
Status: online

These 1/8 conversion can be very difficult...but only if you go cheap.
Just get a Neu and be done with it. It's a proven motor. It will not let you down. It will not overheat. It will be plenty fast enough. The Neu 1515 1.5d/f or Neu 1515 1y are great choices for running on 4s.

< Message edited by happywing -- 6/30/2008 12:01:29 PM >

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RE: What kV BL motor for Truggy conversion??? - need h... - 6/30/2008 12:06:00 PM

HandyRacing

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From: Jackson, MI, USA
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quote:

ORIGINAL: happywing

These 1/8 conversion can be very difficult...but only if you go cheap.
Just get a