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-   -   Gearing VS timming question (https://www.rctech.net/forum/electric-road/1029769-gearing-vs-timming-question.html)

b3master 11-09-2018 03:16 PM

Gearing VS timming question
 
I have non spec esc, with my current gearing and max timming im precisely same speed as my race mates (that are running spec elec), however im experiencing less runtime and more heat.

if i decrease my timming and increase gearing ratio and aim for the same speed will that cool things down and increase my runtime? Or do both actions cancel out? And hence i shouldnt bother?
i dont wana go through the trouble and hassle of experimenting till i reach the current same exact speed, if both actions cancel out or if there will hardly be any difference...

Knowing that:
Higher timming= more motor rpm, less runtime, and more heat
Higher gearing= faster car, less runtime, and more heat

my main goal is more runtime, and hopfuly less heat, (I read that lower timming runs the motor more efficiently)


tbrymer 11-09-2018 03:47 PM

Personally I would try reducing the timing just slightly (.5 to 1 degree) until you get the desired temperature and your lap times don't decrease dramatically at the end of the race. Then I would up my gearing if I'm out of sync with others lap times. All of this of course assumes you are driving exactly the same as your peers and everything else is equal, like car efficiency, starting battery voltage, etc. Good luck.

bertrandsv87 11-09-2018 06:13 PM

Share your motor setup, but it is best to set your timing according to no load amp draw(4A to 6A) on an analyzer first, then gear to the track(gear for infield punch)....Higher gearing does not necessarily make your car faster around the track......

b3master 11-09-2018 08:15 PM

Im not realy concerned with having it best suited for track or improving laptimes, i just want to remain same high speed on the straightaway...

its a tamiya tt01 which i have to take the rear end off if i want to swap spur gears which im not fond of
I guess ill zero out the timming first and see where that leaves me...


im using the ezrun B1 combo which has 13T motor that isnt even a true 3650 motor. Spec is justock 13.5T

b3master 11-09-2018 09:51 PM


Originally Posted by b3master (Post 15332743)
if i decrease my timming and increase gearing ratio and aim for the same speed will that cool things down and increase my runtime? Or do both actions cancel out? And hence i shouldnt bother?i dont wana go through the trouble and hassle of experimenting till i reach the current same exact speed, if both actions cancel out or if there will hardly be any difference...

thanks for the help guys, but my reason for starting this thread is to avoid the hassle of changing gears and avoid experimenting with timming if all Im doing is cancelling out at the end.... im after 30-40 practice as runtime

Does lower gear with higher timming cancel out the change in runtime with respect to higher gearing with a lower timming (acheiving same top speed)

bertrandsv87 11-09-2018 10:23 PM

If you do not want to complicate things, then, after setting up the car with the least amount of rear toe in(0.5* if possible)+ no front toe out, go down on timing first(2* down at a time) with the same gearing:
#1) If you gain speed down the straight, then check temps to see if you get down to 120* or under. Keep taking 2* of timing off until you either stop gaining speed on the straight or your temps get to around 120*. That should be max performance for the weight of the car, and the only way to be faster is to lose vehicle/drivetrain weight...
#2) If you lose speed down the straight, then I would put the timing back to the initial max setting and gear lower, one tooth smaller on the pinion at a time, until I find the gearing where the temps fall down to 120* without losing much straightaway speed, but if you get the correct temps at a gear that makes you lose too much straight speed, then you will need to change the timing per step #1...
​​​​​​

gigaplex 11-10-2018 12:45 AM


Originally Posted by bertrandsv87 (Post 15332821)
Share your motor setup, but it is best to set your timing according to no load amp draw(4A to 6A) on an analyzer first, then gear to the track(gear for infield punch)....Higher gearing does not necessarily make your car faster around the track......

Whatever you do, don't follow this advice.

gigaplex 11-10-2018 12:49 AM


Originally Posted by b3master (Post 15332878)
Im not realy concerned with having it best suited for track or improving laptimes, i just want to remain same high speed on the straightaway...

its a tamiya tt01 which i have to take the rear end off if i want to swap spur gears which im not fond of
I guess ill zero out the timming first and see where that leaves me...


im using the ezrun B1 combo which has 13T motor that isnt even a true 3650 motor. Spec is justock 13.5T

The ezrun combo you run is a sensorless system, and only supports around 26 degrees timing. You're not using too much timing even with it maxed out. The bigger issue is that you're using a completely different system to everyone else, so the temps aren't comparable.

What cars are the others using? The TT01 is not known for its efficiency.

b3master 11-10-2018 05:14 AM

Forget the temps, its not much of an issue. Its not an issue at all.
I just wana see yalls thoughts if the above cancel out so that i dont waste time changing gearing and experimenting timmings.....

Billy Kelly 11-10-2018 05:53 AM


Originally Posted by b3master (Post 15332963)
Forget the temps, its not much of an issue. Its not an issue at all.
I just wana see yalls thoughts if the above cancel out so that i dont waste time changing gearing and experimenting timmings.....

ah, but so many post about how they enjoy working and testing almost more then like actual driving.

gigaplex 11-10-2018 06:21 AM


Originally Posted by b3master (Post 15332963)
Forget the temps, its not much of an issue. Its not an issue at all.
I just wana see yalls thoughts if the above cancel out so that i dont waste time changing gearing and experimenting timmings.....

With the ezrun system you're wasting your time experimenting with timing. Just set it to max. Like I said before, it only goes up to 26 degrees. Most people run their sensored systems at around 40+ degrees.

b3master 11-10-2018 06:42 AM

Wow, either im not clear enough or ppl dont read what the question is and only the title

ill try to clarify

i dont want to reach optimum speed
i dont want to reach optimum temp

i dont care for either speed or temp

my concern is i dont want other racers nagging and complaining that im faster since im not running limited spec electrics, im running 13t they running 13.5t they run zero fixed timming, i can play with my timming

lower temp would seem to be a benifited byproduct of running less timming but it is NOT my concern

i want practice runtime, i want batts to last longer...

so, ill try again, and repeat the question, if i lower timming BUT lower the gear ratio (higher gearing, more top end), will they CANCEL OUT????

Marcos.J 11-10-2018 06:52 AM

https://cimg3.ibsrv.net/gimg/www.rct...badb50b61.jpeg

Literally my monster energy drink just shot out of my nose

Originally Posted by bertrandsv87 (Post 15332904)
If you do not want to complicate things, then, after setting up the car with the least amount of rear toe in(0.5* if possible)+ no front toe out, go down on timing first(2* down at a time) with the same gearing:
#1) If you gain speed down the straight, then check temps to see if you get down to 120* or under. Keep taking 2* of timing off until you either stop gaining speed on the straight or your temps get to around 120*. That should be max performance for the weight of the car, and the only way to be faster is to lose vehicle/drivetrain weight...
#2) If you lose speed down the straight, then I would put the timing back to the initial max setting and gear lower, one tooth smaller on the pinion at a time, until I find the gearing where the temps fall down to 120* without losing much straightaway speed, but if you get the correct temps at a gear that makes you lose too much straight speed, then you will need to change the timing per step #1...
​​​​​​


trilerian 11-10-2018 09:44 AM


Originally Posted by b3master (Post 15332995)
Wow, either im not clear enough or ppl dont read what the question is and only the title

ill try to clarify

i dont want to reach optimum speed
i dont want to reach optimum temp

i dont care for either speed or temp

my concern is i dont want other racers nagging and complaining that im faster since im not running limited spec electrics, im running 13t they running 13.5t they run zero fixed timming, i can play with my timming

lower temp would seem to be a benifited byproduct of running less timming but it is NOT my concern

i want practice runtime, i want batts to last longer...

so, ill try again, and repeat the question, if i lower timming BUT lower the gear ratio (higher gearing, more top end), will they CANCEL OUT????

To answer your question. Yes and no...
For any given timing there is an rpm range that the motor operates at optimal efficiency. They higher the timing, the higher that rpm range is. Generally the more load you put on a motor (lower fdr) will decrease the maximum rpm that the motor is capable of for a constant voltage. So at first glass they (timing and gearing) look inversely proportional. However, you need to find the "sweet spot" first. It could be you need more timing and more gear.

b3master 11-10-2018 09:59 AM


Originally Posted by trilerian (Post 15333078)
To answer your question. Yes and no...
For any given timing there is an rpm range that the motor operates at optimal efficiency. They higher the timing, the higher that rpm range is. Generally the more load you put on a motor (lower fdr) will decrease the maximum rpm that the motor is capable of for a constant voltage. So at first glass they (timing and gearing) look inversely proportional. However, you need to find the "sweet spot" first. It could be you need more timing and more gear.

My main problem is im not suposed to go faster, if my top speed is 40mph i need to stay 40mph, before justock spec racers complain about my speed! Im after more runtime...
however i can deduce from your post that i need to find out at the currect setting how efficient my current setup is, and to find this out i need to do as per somone's previous post and test my temps, if they too hot it means im running inefficiently, ill have to reduce timming till their stabelized then change gearing to get back to 40mph. however if the temps are good then i should just leave evrything the way it is , since its running effeciently wrt itself, nothing else i do will add runtime....


tbrymer 11-10-2018 02:26 PM

Yeah, no one understands, just delete this thread. LOL

Marcos.J 11-10-2018 02:31 PM


Originally Posted by tbrymer (Post 15333202)
Yeah, no one understands, just delete this thread. LOL

really ? I think Bert explained it perfectly ;)

tbrymer 11-10-2018 02:49 PM

LOL

Bry195 11-10-2018 10:07 PM

Your motor has a sweet spot. Think of a bell curve in the middle of an x-y plot. Up the left is torque and across the bottom 0-30000 rpm. It converts current to torque the best right int he middle of the curve. So if the car spends most of its time or it averages in the middle of this curve the car will be most efficient. but you have gearing that makes a mess of things.

so you have to calculate the average speed and current required for a specific track with telemetry. Add up all the currents and speeds for a lap and divide by the number of samples and it will tell you your average speed requirement and current requirement. Then calculate the FDR you need to keep the motor average speed in the middle of the curve most of the time.

you can then set your throttle end point to control the max speed so that you dont creep into the bad side of the curve that generates too much heat.

porsche928gs 11-10-2018 10:11 PM


Originally Posted by tbrymer (Post 15333202)
Yeah, no one understands, just delete this thread. LOL

:smile:It's simple. I'm cheating by not using the required equipment in a spec class but i don't want to be to obvious about it. how can I tone things down? decreasing the timing or changing gearing which I don't want to.:smile:

b3master 11-10-2018 10:31 PM


Originally Posted by porsche928gs (Post 15333353)
:smile:It's simple. I'm cheating by not using the required equipment in a spec class but i don't want to be to obvious about it. how can I tone things down? decreasing the timing or changing gearing which I don't want to.:smile:

its simple indeed, i dont have the budget to change elect, im trying to make do with what i have laying around for the time being... we r just having fun and not racing for medals or anything... if there was a proper organized race id either have to get proper gear or not race... for meanwhile its just practice....

anyways, indeed great information gathered here and made me look at things differently, and I havent checked the temp but i have a good feeling im already pushing it with current timming setup on current gearing and I indeed have to test as advised to get proper temps FIRST then sync with other racers...


porsche928gs 11-10-2018 11:26 PM


Originally Posted by b3master (Post 15333358)
its simple indeed, i dont have the budget to change elect, im trying to make do with what i have laying around for the time being... we r just having fun and not racing for medals or anything... if there was a proper organized race id either have to get proper gear or not race... for meanwhile its just practice....

anyways, indeed great information gathered here and made me look at things differently, and I havent checked the temp but i have a good feeling im already pushing it with current timming setup on current gearing and I indeed have to test as advised to get proper temps FIRST then sync with other racers...

I understand your point but no matter what you do if you are winning, people will always complain. I had run a class before that did 80amp trackstar esc blinky with 21.5 trackstar motor. Like you I did not want it to spend money on a new esc and was running a HW2.1 120 amp with a 21.5 trackstar motor and people didn't like it that I was winning and said it was because a .0001ohm diference in the esc resistance. I bought the cheap esc later and it was the same outcome.

tbrymer 11-11-2018 09:37 AM

The problem is if you can't really drive and so you try to compensate by increasing the timing in your ESC. You end up being to fast in straights and end up screwing everyone else in the race.

b3master 11-11-2018 10:08 AM


Originally Posted by tbrymer (Post 15333512)
The problem is if you can't really drive and so you try to compensate by increasing the timing in your ESC. You end up being to fast in straights and end up screwing everyone else in the race.

Actualy i had already previously mentioned im at perfect speed with all in the straight (hence same top speed) i started this thread to see if at all possible to gain runtime without having cancelation occuring of higher gear and lower timming...

just because im a new comer they wanted an easy meal, they cant get over me running with them without proper tires, body or wing, and wanted to blame the electrics like porsche said ppl will complain using any excuses when your a threat to them...

massenb203 11-11-2018 12:33 PM


Originally Posted by b3master (Post 15333528)
Actualy i had already previously mentioned im at perfect speed with all in the straight (hence same top speed) i started this thread to see if at all possible to gain runtime without having cancelation occuring of higher gear and lower timming...

just because im a new comer they wanted an easy meal, they cant get over me running with them without proper tires, body or wing, and wanted to blame the electrics like porsche said ppl will complain using any excuses when your a threat to them...

IMO is that you already have the motor and gearing where you need it to maintain your straight away speed and just looking for more run time. I would use a higher milliamp battery to increase the car runtime.


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