R/C Tech Forums

Go Back   R/C Tech Forums > General Forums > Electric On-Road

Reply
 
Thread Tools Search this Thread
Old 07-14-2017, 09:18 AM   #1
LJH
Tech Adept
 
Join Date: Nov 2009
Posts: 154
Default Performance difference between a 17.5 and a 13.5

Hello All,
While pretty well versed in brushless motors for E flight I am a newbie when it comes to BL motors in cars so looking for some guidance.

I have a TT02 that I am running with a old Novak Sport 17.5T motor and a Justock ESC. I have it geared with a FDR of 4.33:1 and it goes alright but being a motor head I wonder if it would be more fun if it was a bit faster. I do like the torque that I get with the 17.5 and I get an easy 15 minutes of duration out of a 4000mah pack.

If I was to switch to a 13.5T motor and gear it appropriately how much of a difference would there be in torque (acceleration) and top end over the 17.5? Any guesses on how much of a hit I would take in duration?

I am not racing, I drive the car 90% of the time on two tennis courts (70' straight?) and set up a little course with field markers. These tennis courts are not all that well used or maintained so the surface is not that sticky.

Thoughts?

Thanks.

Cheers,
Jim
LJH is offline   Reply With Quote
Old 07-14-2017, 09:27 AM   #2
Tech Elite
 
EbbTide's Avatar
 
Join Date: Nov 2012
Location: Bay Area, Ca
Posts: 2,641
Trader Rating: 34 (100%+)
Default

Quote:
Originally Posted by LJH View Post
Hello All,
While pretty well versed in brushless motors for E flight I am a newbie when it comes to BL motors in cars so looking for some guidance.

I have a TT02 that I am running with a old Novak Sport 17.5T motor and a Justock ESC. I have it geared with a FDR of 4.33:1 and it goes alright but being a motor head I wonder if it would be more fun if it was a bit faster. I do like the torque that I get with the 17.5 and I get an easy 15 minutes of duration out of a 4000mah pack.

If I was to switch to a 13.5T motor and gear it appropriately how much of a difference would there be in torque (acceleration) and top end over the 17.5? Any guesses on how much of a hit I would take in duration?

I am not racing, I drive the car 90% of the time on two tennis courts (70' straight?) and set up a little course with field markers. These tennis courts are not all that well used or maintained so the surface is not that sticky.

Thoughts?

Thanks.

Cheers,
Jim
For that car the difference between 13.5 and 17.5 is a pretty good jump in power. But it is by no means "too much" power. I actually felt like I could have used more power out of my TB03 when I was running 13.5, but then you have to consider driveline components too. Going too big in these cheaper on road cars can munch gears if you're not careful. I would stay above 10.5t with that being said.

As far as torque goes, it should be roughly the same between the two, but of course you'll notice far more top end with the 13.5. I can't speak of the runtime you'd get with 13.5, but I would guess maybe a 3 minute decrease? But that's just speculation.
__________________
::: Tekno EB48SL ::: HPI Blitz ::: Kyosho RB5 SP2 WC :::Team Durango DEX210 v2 ::: Team Durango ExoDex210 :::Tamiya TB03r/TRF418-ish :::
EbbTide is online now   Reply With Quote
Old 07-14-2017, 01:31 PM   #3
LJH
Tech Adept
 
Join Date: Nov 2009
Posts: 154
Default

Quote:
Originally Posted by EbbTide View Post
For that car the difference between 13.5 and 17.5 is a pretty good jump in power. But it is by no means "too much" power. I actually felt like I could have used more power out of my TB03 when I was running 13.5, but then you have to consider driveline components too. Going too big in these cheaper on road cars can munch gears if you're not careful. I would stay above 10.5t with that being said.

As far as torque goes, it should be roughly the same between the two, but of course you'll notice far more top end with the 13.5. I can't speak of the runtime you'd get with 13.5, but I would guess maybe a 3 minute decrease? But that's just speculation.
That is good to hear.

I went down "to much power" road with a 1:18 scale truck and while it is stupid fast it is not very driveable and a maintenance nightmare.

I may have to keep my eyes open for a decent used motor to try out.

Thanks.

Cheers,
Jim
LJH is offline   Reply With Quote
Old 07-14-2017, 05:15 PM   #4
Tech Initiate
 
Join Date: Mar 2017
Posts: 43
Default

You will feel much of the difference between regular 17.5 (blinky) vs 13.5T (blinky).
In case of newest, outlaw with right timing 17.5T i.e. MM Fleta Sting would be very close to blinky 13.5 in terms of top speed.
Running time is pretty similar. In my case on large asphalt track 5min of race means 1800-2000 mAh
Macio4ever is offline   Reply With Quote
Old 07-14-2017, 10:58 PM   #5
Tech Regular
 
B3nno810's Avatar
 
Join Date: Apr 2015
Location: Kalgoorlie, Western Australia
Posts: 484
Trader Rating: 3 (100%+)
Default

13.5t is a quicker, less torquey motor. The 17.5t is slower but more torquey.
B3nno810 is offline   Reply With Quote
Old 07-14-2017, 11:52 PM   #6
Tech Elite
 
sosidge's Avatar
 
Join Date: Dec 2001
Location: Bristol, UK
Posts: 3,864
Default

I don't thnk there is that much difference between a 13.5 and 17.5, especially if bashing. Modern 17.5s are not slow. You would need to go to a modified motor to start to notice an obvious difference

A bigger factor for you is probably the age of the motor - the original Novaks had a weaker rotor than current motors, and the your gear ratio - there is probably scope to gear up a bit, although the TT-02 is quite limited.

You will probably find a faster brushless motor easier to gear in a TT-02. Bear in mind that a faster motor might start to push the mechanical limits of the car - Tamiya developed it for their sealed brushed motors which are a lot slower.
sosidge is offline   Reply With Quote
Old 07-15-2017, 09:28 AM   #7
LJH
Tech Adept
 
Join Date: Nov 2009
Posts: 154
Default

Quote:
Originally Posted by sosidge View Post
I don't thnk there is that much difference between a 13.5 and 17.5, especially if bashing. Modern 17.5s are not slow. You would need to go to a modified motor to start to notice an obvious difference

A bigger factor for you is probably the age of the motor - the original Novaks had a weaker rotor than current motors, and the your gear ratio - there is probably scope to gear up a bit, although the TT-02 is quite limited.

You will probably find a faster brushless motor easier to gear in a TT-02. Bear in mind that a faster motor might start to push the mechanical limits of the car - Tamiya developed it for their sealed brushed motors which are a lot slower.
I have the "High Speed Gear Set" and running 64P gears as well as an adjustable motor mount so I can hear as low as the low to mid 3's and on up to 8+ so gearing is not the issue.

I am aware the motor is 8 years old and probably not fast as the current generation motors.

Do you guys think I would be better off picking up a more modern 17.5 or a modern 13.5. How much effect does motor timing have on overall performance?

Thanks.

Last edited by LJH; 07-16-2017 at 07:59 AM.
LJH is offline   Reply With Quote
Old 07-16-2017, 01:10 AM   #8
Tech Initiate
 
Join Date: Mar 2017
Posts: 43
Default

All one's manufacturer engines cost about the same - windings does not matter. Buy 10.5, set timing and you would be happy ripping off gears out of your tt02
Macio4ever is offline   Reply With Quote
Reply

Similar Threads
Thread Thread Starter Forum Replies Last Post
Tekin RS ESC sensored Jeff Cuffs Electric On-Road 23359 10-02-2016 05:57 AM
R1 Brushless Motors (Roar approved) 17.5,21.5 & 13.5 BIBOY Electric On-Road 481 06-19-2016 04:45 AM
LRP SXX StockSpec ESC Stein Tumert Electric On-Road 1241 06-08-2012 08:52 AM
ALTOONA RACEWAY FORUM Ed237 Track Locator Forum 9108 06-28-2011 05:10 PM
Sydney Tamiya F201-103RM and GT's Thread Rubedude Australian Racing 317 08-11-2010 03:29 AM



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search

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
Trackbacks are On
Pingbacks are On
Refbacks are Off



All times are GMT -7. It is currently 01:16 PM.


Powered By: vBulletin v3.9.2.1
Privacy Policy | Terms of Use | Advertise Content © 2001-2011 RCTech.net