RRTech...The SOURCE for Extreme Liquid Cooling
Sidewinders Bitspower Jab-Tech

Go Back   RRTech...The SOURCE for Extreme Liquid Cooling > R/C + Hobby Forum > R/C Talk

R/C Talk For general r/c discussion. Look to post in one of the vehicle specific sub forums first.

Reply
 
Thread Tools Display Modes
Old 05-07-2012, 01:53 PM   #1
nuclear
Semi-Liquid
 
nuclear's Avatar
 
Join Date: Apr 2009
Posts: 102
Default Brushless motor recommendation

Hello GenX or anyone else who knows better than me, I had 2 questions
first one is: i was wondering if anyone had experience with viper vtx10r ESC ?
how good or bad are they ? they seem nice, i have seen a few racer with them and they don't need a computer like tekin. it's more for a friend because i already have my needs covered with tekin.
second one is: I want to get a 13.5t motor and was wondering if there are any differences between the different companies. i currently have a 17.5t and 6.5t tekin and 8.5t, 10.5t LRP with 2 tuning rotors (12.23 1s and 13mm rotor).
So should i go with LRP since i already have a few spare parts and rotors. or is it better with another brand ?

Thanks
nuclear is offline   Reply With Quote
Old 05-07-2012, 07:53 PM   #2
1stGenCRXer
Where the RC's at?
 
1stGenCRXer's Avatar
 
Join Date: Jan 2010
Location: Hampton, VA, USA
Posts: 1,086
Send a message via AIM to 1stGenCRXer
Default

The Viper VTX10r is pretty nice, compact, and looks good. I've also seen a couple go up in smoke for unknown reasons and they're not quite as good as a Tekin when running boosted. They're very smooth and seem to do really well with Mod motors though, when they hold up. To be fair, the ones I saw in action were pre-production units being run by a team driver trying to find the limits.

As for a 13.5T, If you're not running any timing, LRP is fine, and so is the Trinity/EPIC RevTech. If you want to play with boosted profiles, the Trinity/EPIC Duo3 gets my nod.
__________________
-Harry
aka: 1stGen
I race and paint lots of stuff.
1stGenCRXer is offline   Reply With Quote
Old 05-08-2012, 08:31 AM   #3
nuclear
Semi-Liquid
 
nuclear's Avatar
 
Join Date: Apr 2009
Posts: 102
Default

yes i want to run boosted profiles, that the main idea of running tekin esc
what would be the difference between the revtech and the duo3 that makes the duo3 more likely to work with timing ? also, how does the tekin motors stacks up ?

Thanks
nuclear is offline   Reply With Quote
Old 05-08-2012, 12:22 PM   #4
1stGenCRXer
Where the RC's at?
 
1stGenCRXer's Avatar
 
Join Date: Jan 2010
Location: Hampton, VA, USA
Posts: 1,086
Send a message via AIM to 1stGenCRXer
Default

Tekin motors also take boost very well, but they tend to have a strong top end power band, whereas the D3 has, IMO, the best mid-range power band, which is where you should be spending the most of your time.

The RevTech was designed for the blinky classes, and the jury is still out on exactly why they don't seem to cope with boost very well. They're fast as snot, and stay cool, but for some reason, they let the magic smoke out. I've seen it with 3 RevTechs that were brand new at the start of a race day, and didn't last through the main running boosted. In Blinky classes, I can't recall a single RevTech failure all season.

Some people think the endbell timing range is different between the RT and D3, some think the magnet wire is coated differently, others think the endbell is made differently and localized heat causes the windings to short against the endbell, and some think the air gap between the rotor and stator is just different enough to cause issues.

Everyone agrees that the D3 is better suited for boost, however.
__________________
-Harry
aka: 1stGen
I race and paint lots of stuff.
1stGenCRXer is offline   Reply With Quote
Old 05-08-2012, 12:24 PM   #5
nuclear
Semi-Liquid
 
nuclear's Avatar
 
Join Date: Apr 2009
Posts: 102
Default

good thanks
nuclear is offline   Reply With Quote
Old 05-14-2012, 09:43 AM   #6
nuclear
Semi-Liquid
 
nuclear's Avatar
 
Join Date: Apr 2009
Posts: 102
Default

Hello Harry
i would need some help working with the rs pro
i'm now racing off-road (b44.1, losi scte and now 22t)
this week-end, i was racing with my b44.1 and tried to set the esc and motor to work correctly. I'm running an LRP 8.5 octo-wind (with -10 degree insert) with a tekin RS-pro esc.
motor temp was around 125-140 and esc got up to 150. i'm running a boost profile of 40 degree over the rpm range of 8500-22000. i played with the pinion to change the top speed and acceleration (17,18,19). with 18, top speed was perfect for the straight but was topping a bit early so i tried 19, found that temp was higher on motor (around 140) and esc (around 150), tried 17 thinking that it would be better but the temp were nearly the same. currently, there is no space in the body for airflow inside.
i tried a second profile that was 25 degree timing over 8500-22000 and 15 degree of turbo. but it seems the esc overheated during the race because i was loosing the turbo. When i got out of the track, the esc was at 150
Are the temp too high, or are they ok ?
also, what motor do you recommend for:
22t
b44.1
i currently have these options: tekin 6.5, lrp 8.5 octo, lrp 10.5, should have my d3 13.5 Friday and a tekin 17.5 . if you think i would be better of buying another motor, it could also be an option.

Thanks
nuclear is offline   Reply With Quote
Old 05-14-2012, 03:48 PM   #7
1stGenCRXer
Where the RC's at?
 
1stGenCRXer's Avatar
 
Join Date: Jan 2010
Location: Hampton, VA, USA
Posts: 1,086
Send a message via AIM to 1stGenCRXer
Default

For motors lower than 10.5 winds, I wouldn't use Turbo, it really shouldn't be necessary unless you have a LOOOONG straight to get down with the hustle.

That said, where on the straight was the motor topping out at, and what kind of Turbo delay were you running on the second profile?

Overall, the second profile should have been more conservative unless you're trying to bring the turbo in too quickly. It's also helpful to know how [by reviewing video or something similar] how long you're at full throttle on the longest straight [in seconds, from the time you pick up the throttle on the corner entering the straight until you lift for the next corner], where [physically on the straight] you top out without turbo, and the maximum time [in seconds] you spend at full throttle at any other point on the track [intermediate straights, etc]. Knowing this info allows us to set up the boost level, RPM range, and turbo amount with the proper turbo delay so that you're ONLY hitting turbo in areas that you would otherwise top out in speed on, saving some heat from the motor and ESC.

If you're running Mod, I'd strap the Tekin 6.5 in the b44.1 running dual mode and call it a day. Shouldn't really need to run sensored only mode with a motor that stout, but you will want to figure out some way to get a fan blowing on the ESC. Dual mode will keep the temp on the ESC down as well, but it'll still be a workout.

For the 22t, the LRP 10.5 should be easier to drive, and probably overall faster with your first profile as a result.

As a general rule, if the ESC is hotter than the motor, you're probably under-geared, over-timed, or both. In mod, the ESC and motor can end up close to the same temp, but the motor is the more robust item, so if one can run warmer than the other, it's the motor. Also, lots of wheel spin can give indications of being under geared as well, so try to be smooth on the trigger always.
__________________
-Harry
aka: 1stGen
I race and paint lots of stuff.
1stGenCRXer is offline   Reply With Quote
Old 05-14-2012, 05:57 PM   #8
nuclear
Semi-Liquid
 
nuclear's Avatar
 
Join Date: Apr 2009
Posts: 102
Default

well i was testing turbo so both profile had the same amount of timing at the end
profile1: 40 degrees in a range of 8k to 22k
profile2: 25 degrees in a range of 8k to 22k +15 degrees of turbo
the thing is, after a few lap, turbo seemed to disappear so i was missing the top end
i'll try a more conservative timing in dual mode with the 6.5 to see if it's better
thanks
nuclear is offline   Reply With Quote
Old 05-14-2012, 07:30 PM   #9
1stGenCRXer
Where the RC's at?
 
1stGenCRXer's Avatar
 
Join Date: Jan 2010
Location: Hampton, VA, USA
Posts: 1,086
Send a message via AIM to 1stGenCRXer
Default

Yeah, but my point is if your turbo delay is set wrong for your track, you'll see more heat, and the whole power band will feel flat.

A quick check is to bump 10 up on the EPA for throttle, to make sure you're not getting WOT signal wobble, but I suspect you're seeing the result of heat soak, not turbo falling out.

For example, if, at race pace, it takes 1.4 seconds of WOT time on the main straight, and the second longest straight has you at WOT for .4 seconds, but the car doesn't top out there, you're not using turbo effectively if your delay is set at .2 seconds. In this scenario, if your car tops out at or a little after half straight, a turbo delay of .5 or .6 would be about perfect.
__________________
-Harry
aka: 1stGen
I race and paint lots of stuff.
1stGenCRXer is offline   Reply With Quote
Old 05-14-2012, 09:26 PM   #10
nuclear
Semi-Liquid
 
nuclear's Avatar
 
Join Date: Apr 2009
Posts: 102
Default

well the turbo delay is at 0.5 (default)
i'll try a few thing next race
there is only 1 long straight, i'll try to get a pic of the racetrack next time

http://www.youtube.com/watch?v=SKx_byNDZa0
here's a vid of the track
i will get more info about the track and add it as soon as i can

Last edited by nuclear; 05-14-2012 at 10:19 PM. Reason: added youtube link for track
nuclear is offline   Reply With Quote
Old 05-15-2012, 09:45 AM   #11
1stGenCRXer
Where the RC's at?
 
1stGenCRXer's Avatar
 
Join Date: Jan 2010
Location: Hampton, VA, USA
Posts: 1,086
Send a message via AIM to 1stGenCRXer
Default

Alright, are you using the canned profiles, or are you tweaking them on the C1 and C2 profiles with the hotwire?

Also, what firmware version are you currently running?
__________________
-Harry
aka: 1stGen
I race and paint lots of stuff.
1stGenCRXer is offline   Reply With Quote
Old 05-15-2012, 09:54 AM   #12
nuclear
Semi-Liquid
 
nuclear's Avatar
 
Join Date: Apr 2009
Posts: 102
Default

firmware is 223 (latest iirc)
i'm using c1 and c2 profile
nuclear is offline   Reply With Quote
Old 05-15-2012, 10:10 AM   #13
1stGenCRXer
Where the RC's at?
 
1stGenCRXer's Avatar
 
Join Date: Jan 2010
Location: Hampton, VA, USA
Posts: 1,086
Send a message via AIM to 1stGenCRXer
Default

That's good, 223 does help everything run a bit cooler.

Watching enough of the video to see some clean laps, you're probably going to be best off without turbo. You're spending around 2 seconds WOT on the main straight, and almost 1 full second accelerating in other sections without major jumps to worry about. That's just trying to use turbo too often without enough room to gain anything from it other than heat.

The same layout on an on-road track would be turbo heavy, but we also wouldn't be worrying about the drive line getting unloaded and then spiked like you see in off-road.

If you really want to run turbo, I would put the delay up around 1 second.
__________________
-Harry
aka: 1stGen
I race and paint lots of stuff.
1stGenCRXer is offline   Reply With Quote
Old 05-15-2012, 10:33 AM   #14
nuclear
Semi-Liquid
 
nuclear's Avatar
 
Join Date: Apr 2009
Posts: 102
Default

it's not really that i want to run turbo, i was simply seeking more info
the profile without turbo seemed to be running better and with less heat, and i was wondering why.
i need to get a netbook so i can set my rs pro at the track and i'll try with a 1 second delay
i'll also try to up a bit the minimum and maximum for the timing boost to see if i can get it a little bit cooler

Also, what's the max normal temp that i should see on the motor and esc?
should i shoot for lower than 200 and be done,or it should be lower than 150 ??
Thanks
nuclear is offline   Reply With Quote
Old 05-15-2012, 01:43 PM   #15
1stGenCRXer
Where the RC's at?
 
1stGenCRXer's Avatar
 
Join Date: Jan 2010
Location: Hampton, VA, USA
Posts: 1,086
Send a message via AIM to 1stGenCRXer
Default

Boost only profiles usually run with less heat because they're more predictable.

When I start a profile from scratch, I take the KV of the motor, multiply by the peaked voltage [8.4 for a 2S battery], and set my start and end RPMs as percentages of that max unboosted number, usually 20-30% for start RPM and 70-80% for End RPM.

For example, a 17.5 should be in the 2400kv ballpark [with motor timing at zero], so:
2400kv * 8.4v = 20160 RPM

For End RPM: 20160*.8 = 16128 RPM
For Start RPM: 20160*.3 = 6048 RPM

Which is very close to the round number 6-16k range I actually do run.

For an 8.5 motor [~5000kv] the numbers are [for 2s, with motor timing at zero]:
Unboosted Max RPM: 42000 RPM
End RPM: 33600 RPM
Start RPM: 12600 RPM

These are just to get started. If you want more lower end punch, you can add some endbell timing, or try lowering the Start RPM. If you want more mid range rip, you can try tightening up the RPM range either by raising the start or lowering the end RPM. For more top end, adjust gearing and total boost level.

I've found that my starting RPM ranges I don't adjust too much because the setups tend to be fast, and pretty smooth, making it easier to drive fast. You really don't want a car that feels like it's got 2-3 gears, because it makes timing speed for jumps and corner entry much harder if you get a sudden boost of acceleration right before a speed critical element.


For temperatures, I always try to keep my motors under 165*F, 180*F is my absolute max. If my motors start hitting 180 and nothing seems to be able to bring down the temp, I start shopping for a replacement motor, because chances are the rotor and/or windings are starting to get weak.

For the ESC, I go by the RS's onboard temp LEDs, and prefer to see 3 lights or less.
__________________
-Harry
aka: 1stGen
I race and paint lots of stuff.
1stGenCRXer is offline   Reply With Quote
Old 05-15-2012, 02:15 PM   #16
nuclear
Semi-Liquid
 
nuclear's Avatar
 
Join Date: Apr 2009
Posts: 102
Default

woot thanks for the maths
it will help because there's not really that much info about timing on the tekin site, and the profile i saw from the drivers were the default ones
nuclear is offline   Reply With Quote
Old 05-15-2012, 02:23 PM   #17
1stGenCRXer
Where the RC's at?
 
1stGenCRXer's Avatar
 
Join Date: Jan 2010
Location: Hampton, VA, USA
Posts: 1,086
Send a message via AIM to 1stGenCRXer
Default

There's lots of ways to skin the timing cat, but my method has yet to fail me

When you get it right with the correct gearing, it's great to have guys scratching their head with "WTF" expressions trying to figure out how you're so fast with a motor running so much cooler than theirs.
__________________
-Harry
aka: 1stGen
I race and paint lots of stuff.
1stGenCRXer is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -5. The time now is 11:10 PM.


Powered by vBulletin® Version 3.7.6
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Ad Management by RedTyger