opinion time / debate! Pro4 / 4x4 SC 2s vs 3s vs 4s.
11-22-2014, 12:13 PM
#1
opinion time / debate! Pro4 / 4x4 SC 2s vs 3s vs 4s.
So im starting this thread to see who thinks the 2s lipo rule for 4x4 sc should be changed. What it should be changed to or why it shouldn't be changed and just be 2s.
Ill start with the facts.
Short course 4x4 is the heavy weight of 1/10th scale vehicles. now there more of a super light 1/8th buggy with a big bulky body. The reason 1/8th use lower kv motors and higher volt batties is simple. Heat. Kv is the amout of rpm per 1 volt of power. So a 4000kv sc motor at one volt makes 4000rpm. A 2000kv motor at 1v makes 2000rpm, Half of the 4000kv. Lets double the volt of the 2000kv to 2v. it will now makes 4000rpm but half the amperage is used to do this. Why is simple. as you multiply your volts you devide your amps but get the same amout of watts of output.
More weight needs more energy to move, more energy makes more heat more heat takes more money out of your pocket when it burns somthing up.
In 4x4 sc most of the competitive drivers are forced to run high c rated batteries that cost much more then is necessary and they still go bad quick, especially when used at such a high demanding amout of energy draw.
Why i think it should and should not be changed. I no this sounds a bit contradicting but hear me out. I feel it would be better suited for the 4x4 sc to be ran as a middle man it makes more sense to run a 3s lipo with a 2800-3000kv motor. This would keep the class in its curent state. It wouldnt be much faster, but would alow you to not have to run a massive heat sink and jet fan on your motor to keep it cool. Motors would last longer and you would have more gear options available. You wouldn't need as redicules wire gauge going from your batteries to your esc (some manufactures are even running four 12ga wires 2 positive 2 negative)
As a club racer i feel 3s with a lower kv motor makes alot of since. but here is the problem. Its easier for a track to just run a big sanctions rule book and it dose make since to do so. Some of your racers might race at sanctioned events.
I feel its time for a new class thats a true pro 4 class not just 4x4sc. Make 4x4sc a class that limits you to 2s and limits the kv as well. this would be for the slash and team associated pro lite basicaly a stock 4x4 class limit the kv and force 2s lipo. Then for pro 4 allow 3-4s lipo. This would be the true mod 4x4sc class.
These are just my opinion and i would like to here othere thoughts and ideas on the class.
Ill start with the facts.
Short course 4x4 is the heavy weight of 1/10th scale vehicles. now there more of a super light 1/8th buggy with a big bulky body. The reason 1/8th use lower kv motors and higher volt batties is simple. Heat. Kv is the amout of rpm per 1 volt of power. So a 4000kv sc motor at one volt makes 4000rpm. A 2000kv motor at 1v makes 2000rpm, Half of the 4000kv. Lets double the volt of the 2000kv to 2v. it will now makes 4000rpm but half the amperage is used to do this. Why is simple. as you multiply your volts you devide your amps but get the same amout of watts of output.
More weight needs more energy to move, more energy makes more heat more heat takes more money out of your pocket when it burns somthing up.
In 4x4 sc most of the competitive drivers are forced to run high c rated batteries that cost much more then is necessary and they still go bad quick, especially when used at such a high demanding amout of energy draw.
Why i think it should and should not be changed. I no this sounds a bit contradicting but hear me out. I feel it would be better suited for the 4x4 sc to be ran as a middle man it makes more sense to run a 3s lipo with a 2800-3000kv motor. This would keep the class in its curent state. It wouldnt be much faster, but would alow you to not have to run a massive heat sink and jet fan on your motor to keep it cool. Motors would last longer and you would have more gear options available. You wouldn't need as redicules wire gauge going from your batteries to your esc (some manufactures are even running four 12ga wires 2 positive 2 negative)
As a club racer i feel 3s with a lower kv motor makes alot of since. but here is the problem. Its easier for a track to just run a big sanctions rule book and it dose make since to do so. Some of your racers might race at sanctioned events.
I feel its time for a new class thats a true pro 4 class not just 4x4sc. Make 4x4sc a class that limits you to 2s and limits the kv as well. this would be for the slash and team associated pro lite basicaly a stock 4x4 class limit the kv and force 2s lipo. Then for pro 4 allow 3-4s lipo. This would be the true mod 4x4sc class.
These are just my opinion and i would like to here othere thoughts and ideas on the class.
11-22-2014, 12:29 PM
#2
Honestly I am not felling safe marshaling some people at our local track on 2S with their mod SC 4x4. I do not even want to think about them on 4S with ebuggy/truggy combo...
Last edited by fredmotokx; 11-22-2014 at 01:14 PM.
11-22-2014, 12:33 PM
#3
They wouldn't be any fastester then they are now you wouldnt be running a 4000kv with 3-4s also it wouldnt be the biger can motors its still a 540 limit on can size. Like the tekin pro4 3000kv at 3s. Its basicaly the same as a pro4 4600 at 2s
11-22-2014, 01:49 PM
#4
only way i'd be in favor of higher voltages would be if the mah of the batteries were limited. this would keep the speeds close to what they are now.
11-22-2014, 01:51 PM
#5
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There's a lengthy thread on the whole voltage debate in 4x4 SCT in here somewhere..
11-22-2014, 01:52 PM
#6
11-22-2014, 01:53 PM
#7
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I suspect this thread will end up the same way this one did...CLOSED
http://www.rctech.net/forum/electric...t-roar-27.html
http://www.rctech.net/forum/electric...t-roar-27.html
11-22-2014, 02:22 PM
#8
Here is an example using current off the self parts.
A tekin pro 4 4600kv on a fully charged 2s lipo (8.4v) would spin at 38,640rpm
4600x8.4=38,640
A tekin pro 4 2600kv which is one of the 2 motors that are 4s motors they are a 540 can size which is much smaller then the 1/8th buggy motor (canister is smaller diamiter and shorter length so less torque)
This would spin at 43,680rpm
2600x16.8=43,680
This is 8,040 rpm faster then the 4600kv pro 4
The pro4 1900kv would spin at
31,920
1900x16.8=31,920
6,720 rpm slower then your 2s powered 4600kv pro 4
Now this is just the free run rpm of these motors theres alot of ppl running the hobbywing 4000kv thatkeep up with the 4600 pro 4 no problem so gearing plays a big roll in all of this but so dose heat.
4s on a 540 size can in the 4s size motors 1900kv to 2600kv wont be much if any faster then 2s but will run a little cooler on the motor allowing longer run time.
A tekin pro 4 4600kv on a fully charged 2s lipo (8.4v) would spin at 38,640rpm
4600x8.4=38,640
A tekin pro 4 2600kv which is one of the 2 motors that are 4s motors they are a 540 can size which is much smaller then the 1/8th buggy motor (canister is smaller diamiter and shorter length so less torque)
This would spin at 43,680rpm
2600x16.8=43,680
This is 8,040 rpm faster then the 4600kv pro 4
The pro4 1900kv would spin at
31,920
1900x16.8=31,920
6,720 rpm slower then your 2s powered 4600kv pro 4
Now this is just the free run rpm of these motors theres alot of ppl running the hobbywing 4000kv thatkeep up with the 4600 pro 4 no problem so gearing plays a big roll in all of this but so dose heat.
4s on a 540 size can in the 4s size motors 1900kv to 2600kv wont be much if any faster then 2s but will run a little cooler on the motor allowing longer run time.
11-22-2014, 02:30 PM
#9
not true. this is where this argument always falls apart. say you're running your 2S setup tapped out. after an 8 minute main, your motor is 185. your top speed is 40mph. now let's say you goto a 4S setup. if you gear your 4s setup for 40mph, your electronics will come off much cooler and it will run more efficient (will use less mah). most people will not do this. they will see the 4s as an opportunity to go faster. they'll gear it for more speed, pushing the 4s setup and burning more mah's. if you limit 4s to say 3000mah, it will force people to gear the 4s setup to run similar speeds to the 2s systems.
11-22-2014, 02:38 PM
#10
not true. this is where this argument always falls apart. say you're running your 2S setup tapped out. after an 8 minute main, your motor is 185. your top speed is 40mph. now let's say you goto a 4S setup. if you gear your 4s setup for 40mph, your electronics will come off much cooler and it will run more efficient (will use less mah). most people will not do this. they will see the 4s as an opportunity to go faster. they'll gear it for more speed, pushing the 4s setup and burning more mah's. if you limit 4s to say 3000mah, it will force people to gear the 4s setup to run similar speeds to the 2s systems.
11-22-2014, 02:45 PM
#11
not true. this is where this argument always falls apart. say you're running your 2S setup tapped out. after an 8 minute main, your motor is 185. your top speed is 40mph. now let's say you goto a 4S setup. if you gear your 4s setup for 40mph, your electronics will come off much cooler and it will run more efficient (will use less mah). most people will not do this. they will see the 4s as an opportunity to go faster. they'll gear it for more speed, pushing the 4s setup and burning more mah's. if you limit 4s to say 3000mah, it will force people to gear the 4s setup to run similar speeds to the 2s systems.
Also the main pojnt is to reduce strain on the battery and wiring. When your wide open your basicaly coneting the battry to the motor directly full voltage. At 2s you would need a 80c 5000mah batery to do the same thing a 40c 5000mah 4s would do.
Its simple volts x resistance = watts.
Lower turn motor or highr kv have lower resistance. So this being said. watts are what make heat.
If you double the votage but divided the resistance by 2 your wattage is the same but your amps drop by 2x as well. so less heat on the battery but same heat on the motor you would get the same speed your motor would get just as warm, but your lipo would be cheeper to buy and last longer.
11-22-2014, 02:59 PM
#12
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Drifter73, read..actually READ the 27 pages in the thread I linked and see if you can come back with a post that contains info and an argument that HASN'T been covered in that thread..if you can't this thread is a pointless rehash.
Last edited by racer1812; 11-22-2014 at 03:05 PM. Reason: 27..not 23
11-22-2014, 03:33 PM
#13
Wattage is really what makes heat and power. All 4s vs 2s will do is add some weight to the car more tire grip and greatly decrese the price of lipos. 4s doesn't make more power then 2s unless you were using a bigger motor. When i say bigger i dont mean highr kv i mean longer and bigger diamiter can.
An example is this if a 1500w heater heats a 12ft room from 60deg to 80deg in ten min
It wouldnt mater if the heater was ran in 12v or 120v or 220v its still a 1500w heater.
If your motor is the same dementions it will generate an x amout of heat at a x amout of power dosnt mater if its at 2s or 4. You could gear 2s to be 80mph fast but it would get hot quick.
4s with a 4600 pro 4 would be stuipid fast but over heat in less then a minute of running it. You coldnt even gear it to not over heat and if you did the speed of the pinion would melt a nylon spur.
I have seen a pro4 3300kv on 3s and my pro4 4300 was just as fast on the track and came off cooler as well but he had more lowend from the added weight and traction but top speed was the same if not less.
Most of you are comparing a 2s 540 can motor to what you see in ebuggy which is a much bigger motor that pulls more watts but is bigger in size so it displace more heat.
I guees it will take a turn marshal having a lipo blow up on them from someone running a cheep 90c battery. Befor people get the idea that its actualy dangerous and backword thinking to not consider 3s or 4s.
Also 3s would be a great idea but there's few motors in that kv range that would work compaired to 4s if tekin and hobbywing ect make more 3000-3400kv range motors 3s would be the best alternative.
An example is this if a 1500w heater heats a 12ft room from 60deg to 80deg in ten min
It wouldnt mater if the heater was ran in 12v or 120v or 220v its still a 1500w heater.
If your motor is the same dementions it will generate an x amout of heat at a x amout of power dosnt mater if its at 2s or 4. You could gear 2s to be 80mph fast but it would get hot quick.
4s with a 4600 pro 4 would be stuipid fast but over heat in less then a minute of running it. You coldnt even gear it to not over heat and if you did the speed of the pinion would melt a nylon spur.
I have seen a pro4 3300kv on 3s and my pro4 4300 was just as fast on the track and came off cooler as well but he had more lowend from the added weight and traction but top speed was the same if not less.
Most of you are comparing a 2s 540 can motor to what you see in ebuggy which is a much bigger motor that pulls more watts but is bigger in size so it displace more heat.
I guees it will take a turn marshal having a lipo blow up on them from someone running a cheep 90c battery. Befor people get the idea that its actualy dangerous and backword thinking to not consider 3s or 4s.
Also 3s would be a great idea but there's few motors in that kv range that would work compaired to 4s if tekin and hobbywing ect make more 3000-3400kv range motors 3s would be the best alternative.
11-22-2014, 04:19 PM
#14
Wattage is really what makes heat and power. All 4s vs 2s will do is add some weight to the car more tire grip and greatly decrese the price of lipos. 4s doesn't make more power then 2s unless you were using a bigger motor. When i say bigger i dont mean highr kv i mean longer and bigger diamiter can.
An example is this if a 1500w heater heats a 12ft room from 60deg to 80deg in ten min
It wouldnt mater if the heater was ran in 12v or 120v or 220v its still a 1500w heater.
If your motor is the same dementions it will generate an x amout of heat at a x amout of power dosnt mater if its at 2s or 4. You could gear 2s to be 80mph fast but it would get hot quick.
4s with a 4600 pro 4 would be stuipid fast but over heat in less then a minute of running it. You coldnt even gear it to not over heat and if you did the speed of the pinion would melt a nylon spur.
I have seen a pro4 3300kv on 3s and my pro4 4300 was just as fast on the track and came off cooler as well but he had more lowend from the added weight and traction but top speed was the same if not less.
Most of you are comparing a 2s 540 can motor to what you see in ebuggy which is a much bigger motor that pulls more watts but is bigger in size so it displace more heat.
I guees it will take a turn marshal having a lipo blow up on them from someone running a cheep 90c battery. Befor people get the idea that its actualy dangerous and backword thinking to not consider 3s or 4s.
Also 3s would be a great idea but there's few motors in that kv range that would work compaired to 4s if tekin and hobbywing ect make more 3000-3400kv range motors 3s would be the best alternative.
An example is this if a 1500w heater heats a 12ft room from 60deg to 80deg in ten min
It wouldnt mater if the heater was ran in 12v or 120v or 220v its still a 1500w heater.
If your motor is the same dementions it will generate an x amout of heat at a x amout of power dosnt mater if its at 2s or 4. You could gear 2s to be 80mph fast but it would get hot quick.
4s with a 4600 pro 4 would be stuipid fast but over heat in less then a minute of running it. You coldnt even gear it to not over heat and if you did the speed of the pinion would melt a nylon spur.
I have seen a pro4 3300kv on 3s and my pro4 4300 was just as fast on the track and came off cooler as well but he had more lowend from the added weight and traction but top speed was the same if not less.
Most of you are comparing a 2s 540 can motor to what you see in ebuggy which is a much bigger motor that pulls more watts but is bigger in size so it displace more heat.
I guees it will take a turn marshal having a lipo blow up on them from someone running a cheep 90c battery. Befor people get the idea that its actualy dangerous and backword thinking to not consider 3s or 4s.
Also 3s would be a great idea but there's few motors in that kv range that would work compaired to 4s if tekin and hobbywing ect make more 3000-3400kv range motors 3s would be the best alternative.
you're right. sorry. i missed the part where it would be the tekin pro-4 class. who else makes 540 4-pole motors in low kv's? or would you open it up to the "545" motors (trinity, hobbywing)? what about 2 pole 550's? 4 pole 550's? tekin T8i (550)?
11-22-2014, 04:26 PM
#15
I would love to run a lower kv with 3s lipos. I run a Losi SCTE with an rx8 gen2 with a pro4 HD 4300kv. I would like to run about 2400-2800kv with 3s. 4s is just too much. Cheaper batteries and easier on electronics would be my reasoning for this.