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Losi 1/10 TEN-SCTE ARR 4x4 Short Course Truck Thread

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Losi 1/10 TEN-SCTE ARR 4x4 Short Course Truck Thread

Old 01-06-2012, 07:45 AM
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Originally Posted by namewasdallas View Post
Im trying to understand this, I run the pro 4 4600. I was told to run 10degrees of timing. Idk if the motor comes advanced but under hotwire on the rx8 I added 10 to timing. So would that be 10degrees + whatever timing the motor has?

Im confused by you saying this "The timing advance slider in hotwire is based on absolute 0 timing. 0 on the slider is absolute 0 while 100 is 30 degrees of timing. "
The Pro4 motors don't like a lot of timing. With 10 on the timing advance slider you are all set.

Clearing up the 0 is 0, 100 is 30:

Sensorless esc's determine timing by looking at the voltage of the un-used coil.

Sensored esc's determine timing by rotating the sensors relative to the coils.

When you start from 0 or low rpm the RX8 strictly looks at the sensors and the timing is based off of them. Then it switches to sensorless mode once it can clearly read the timing off the un-used coil and the timing it applies is only what you select in the hotwire interface. There is no adding.

The timing marks on brushless motor cans are arbitrary. One manufacturers 20 degrees of timing rarely is the same as another manufacturers 20 degrees of timing. 0 on the timing advance slider is true, absolute zero. The slider goes up to 100, not in degrees, but % of max timing. Maximum timing in sensorless/dual mode is 30 degrees, so 100% on the timing advance slider is 30 degrees. 50 on the timing advance slider is 15 degrees. 10 on the timing advance slider is 3 degrees.

Does that help at all? Or am I typing too much?
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Old 01-06-2012, 07:51 AM
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Originally Posted by Casper View Post
I would recommend the upgrade spring kits. The springs help a lot. For more turn in try moving the bottom of the front shocks in a hole on the arm.
Casper.. just wondering.. do you have any idea on the shock pistons? the losi 22 shock pistons compared to the ones for the truck? would you reccommend either over the other.. or bout the same?
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Old 01-06-2012, 07:55 AM
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To finish my extrapolation from the last couple posts:

550 2 pole motors like the Novak Ballistic, Tekin sc4x, etc like timing. 540 and 550 4 pole motors do not.

If you are running the rx8 on a 2 pole motor, set the timing advance to at least 50. If you are running the rx8 on a 4 pole motor, don't set your timing higher than 20 on the timing slider. If you need more speed just gear up. Also, I would like to copy/paste something I posted elsewhere here:

Motor torque and gearing:

Motors make peak torque at 0 rpm. Motors make 0 torque at peak RPM. Without dynamic timing, this is usually a pretty linear slope from max torque to no torque.

Time for another math problem:
Assume a car with a 10:1 transmission ratio. The transmission divides rpm and multiplies torque.

Assume a motor with 100 torque units at 0 rpm and 0 torque units at 20,000 rpm in the previously assumed car.

Assume at full throttle (20,000rpm) the car goes 20 mph.

At 0 rpm (and 0 mph) you have 1,000 torque units at the wheels. Nice. That's a lot of torque. At 20,000 rpm (20 mph) you have no torque. Nice. You've topped out and are flying down the straight. It's safe to say at 10,000 rpm (10 mph) you have 500 torque units. Half rpm, half the available torque.

Now lets gear down for "more torque". Lets go 15:1. Your car now tops out at 13.3 mph and has 1,500 torque units at 0 rpm. LOADS of toque. However, how much torque will you have at 10 mph? 10 mph is 75% rpm, so you have 25% torque. That gives you 25 torque units multiplied by the 15:1 gear ratio which gives you: 375 torque units. We used to have 500 torque units at 10 mph.

"What the heck" you might say? "I thought we geared down for more torque" you might say? We did, but not at 10 mph. You have more torque down at 0 to 5 mph than you did at 10:1, but at 10 mph you have less. Our cars are rarely going less than 5 mph, so gearing up from 15:1 to 10:1 would give you MORE overall torque on the track than gearing down. I think it's safe to say most longer jumps are hit at 10+ mph, so if you wanted more pop off the face of a certain jump you hit at 10 mph, gearing at 10:1 will send you further than 15:1 would.

Again, this is still a balancing act with heat as gearing up for more torque at 10 mph can put you in a lower rpm range most of the time where current draw is high.
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Old 01-06-2012, 08:15 AM
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Originally Posted by namewasdallas View Post
Im trying to understand this, I run the pro 4 4600. I was told to run 10degrees of timing. Idk if the motor comes advanced but under hotwire on the rx8 I added 10 to timing. So would that be 10degrees + whatever timing the motor has?

Im confused by you saying this "The timing advance slider in hotwire is based on absolute 0 timing. 0 on the slider is absolute 0 while 100 is 30 degrees of timing. "

I was thinking in timing on the hotwire the 0-100 was meaning each move was a totoal of 1 degree's of timing are you saying if I bump it to 100 that is only 30degrees and not 100degree's if that makes sense?
The Rx8 runs dual mode 100% of the time. Timing advance is a scale from 0 to 100, 100 being 30 real degrees of timing. Motor timing does NOTHING when using the Rx8 since we don't utilize this input for timing calculations.

SO if you set Timing Advance at 50, that is 15 degrees of real timing.

With the Pro 4 motors you really don't need timing and often it will just zap your run time. If you need more speed, gear up and just keep an eye on temps.
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Old 01-06-2012, 08:18 AM
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I thought the torque in a brushless motor was only limited by your ESC and lipos capacity to provide the amps to the motor.
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Old 01-06-2012, 08:23 AM
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It has always felt to me like gearing up a bl motor gives more power everywhere. Acceleration and top speed. Like the more you load them the more power they make, as long as you keep an eye on temps.
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Old 01-06-2012, 08:29 AM
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Originally Posted by cwilkinson View Post
I've got a quick question I've been running a 12.3mm rotor in my novak 4.5 and thinking about putting my 14mm rotor in there and running low pinion and higher timing I don't mind the drag from the 14mm with the push control in my rx8.. Track I run at is pretty tight with one long straight away is this worth a shot I got better run times and lower heat with my 14mm but had it geared so high it just felt like a slug in some tight areas
I had to gear up 3-4 teeth when I went from stock to 14mm rotor on my novak ballistic back when I ran that motor. The bigger rotor drops the KV rating like Edumakated stated so you have to gear up to get speed out of it. The good news is when geared right it still had more torque, similar or maybe slightly better top end and ran cooler.

Originally Posted by lowroad View Post
Just a follow up for those interested.I ran my SCTE with the BCE chassis again yesterday for a bit...

I can honestly say, that this chassis makes a world of difference. I was skeptical when everyone first started getting them, writing it off as bling, mainly because no one would say WHAT is better, just "it's better" or "it has less flex". I mean, that tells me nothing.

I will now say, after a few good sessions with it, that it rotates better, jumps flatter, responded better, and clearly acceleration was better due to the reduction in weight. I'm not even going 4 pole now, don't need it.

As for the battery location change, i.e. bump, not needed in my opinion. Options are nice, for sure, but I run mine all the way back, like most, and the balance is so perfect it's actually little weird to get used to coming off the stocker. It is VERY responsive in mid-air. It doesn't take but a little nudge of the throttle (or brake) to correct in flight. Best money I have spent on the truck, by far.
As you said you noticed better acceleration from the lighter chassis you can save that same amount of wight by going to a 540 4 pole motor. My TLR chassis is about 2.5 oz lighter then stock and my pro4 motor is about 2.3 oz lighter then the SC4X it replaced. The Pro-4 is a little stronger motor to boot. So you save wieght and get better performance. A rare true win-win!

Originally Posted by dgrobe2112 View Post
Casper.. just wondering.. do you have any idea on the shock pistons? the losi 22 shock pistons compared to the ones for the truck? would you reccommend either over the other.. or bout the same?
I have not tried 22 pistons in my SCTE shocks so I don't have any experience to compare them. I have stuck with the SCTE pistons and they are working great for me.

Originally Posted by Krio View Post
To finish my extrapolation from the last couple posts:

550 2 pole motors like the Novak Ballistic, Tekin sc4x, etc like timing. 540 and 550 4 pole motors do not.

If you are running the rx8 on a 2 pole motor, set the timing advance to at least 50. If you are running the rx8 on a 4 pole motor, don't set your timing higher than 20 on the timing slider. If you need more speed just gear up. Also, I would like to copy/paste something I posted elsewhere here:

Motor torque and gearing:

Motors make peak torque at 0 rpm. Motors make 0 torque at peak RPM. Without dynamic timing, this is usually a pretty linear slope from max torque to no torque.

Time for another math problem:
Assume a car with a 10:1 transmission ratio. The transmission divides rpm and multiplies torque.

Assume a motor with 100 torque units at 0 rpm and 0 torque units at 20,000 rpm in the previously assumed car.

Assume at full throttle (20,000rpm) the car goes 20 mph.

At 0 rpm (and 0 mph) you have 1,000 torque units at the wheels. Nice. That's a lot of torque. At 20,000 rpm (20 mph) you have no torque. Nice. You've topped out and are flying down the straight. It's safe to say at 10,000 rpm (10 mph) you have 500 torque units. Half rpm, half the available torque.

Now lets gear down for "more torque". Lets go 15:1. Your car now tops out at 13.3 mph and has 1,500 torque units at 0 rpm. LOADS of toque. However, how much torque will you have at 10 mph? 10 mph is 75% rpm, so you have 25% torque. That gives you 25 torque units multiplied by the 15:1 gear ratio which gives you: 375 torque units. We used to have 500 torque units at 10 mph.

"What the heck" you might say? "I thought we geared down for more torque" you might say? We did, but not at 10 mph. You have more torque down at 0 to 5 mph than you did at 10:1, but at 10 mph you have less. Our cars are rarely going less than 5 mph, so gearing up from 15:1 to 10:1 would give you MORE overall torque on the track than gearing down. I think it's safe to say most longer jumps are hit at 10+ mph, so if you wanted more pop off the face of a certain jump you hit at 10 mph, gearing at 10:1 will send you further than 15:1 would.

Again, this is still a balancing act with heat as gearing up for more torque at 10 mph can put you in a lower rpm range most of the time where current draw is high.
Another reason you can time the 2 pole much higher then the 4 pole is there is room to time. The angular gap between the poles is twice that of the 4 pole (I know most will say duh!) but this is the major reason lots of timing in the 4 pole just does not work well. The software for timing advance was all setup for 2 pole which allows for much greater timing but for those of use using 4 pole we need to be cautous of not overtiming a 4 pole motor. They produce tons of power without it though so this is not a big deal.

Last edited by Casper; 01-06-2012 at 10:33 AM.
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Old 01-06-2012, 08:30 AM
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Originally Posted by ToxicBanana View Post
I thought the torque in a brushless motor was only limited by your ESC and lipos capacity to provide the amps to the motor.
This statement is partially true only at 0 rpm. Amps = Voltage over Resistance. At 0 rpm the only resistance comes from the copper in the windings, so it is very low. That is why you get 100+ amp spikes at 0 to low rpm full throttle launches. Once the rotor is spinning there are 2 phenomenons dictating how much current can flow: Back EMF and Impedance.

If you move a magnet next to a wire, a voltage difference across that wire is created. Back EMF is the voltage generated by the magnet moving next to the coil and this is subtracted from the voltage coming from the battery. You know how we rate motors with KV, meaning at this voltage it will spin this fast? Well, it works in reverse too; if you spin the motor this fast, it will generate this voltage. Just like a generator. Concluding this mess of a paragraph, as the rpm goes up the voltage difference drops so less current can flow.

Part two is Impedance. I like to vaguely describe it as electricity's unwillingness to change direction. As the motor spins faster the magnetic field created by the coils has less and less time to form and collapse. This introduces more resistance into the system which also limits how much current will flow through.
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Old 01-06-2012, 08:32 AM
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Nerd alert!
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Old 01-06-2012, 08:52 AM
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my brain is killing me right now.. lol
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Old 01-06-2012, 08:56 AM
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Originally Posted by dgrobe2112 View Post
my brain is killing me right now.. lol
Mission accomplished.

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Old 01-06-2012, 08:56 AM
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Originally Posted by Casper View Post
As you said you noticed better acceleration from the lighter chassis you can save that same amount of wight by going to a 540 4 pole motor. My TLR chassis is about 2.5 oz lighter then stock and my pro4 motor is about 2.3 oz lighter then the SC4X it replaced. The Pro-4 is a little stronger motor to boot. So you save wieght and get better performance. A rare true win-win!
well, maybe, but if you can't get it to the ground, it's no good. If it's faster than your track allows for, it's no good. If you are buying it because that's what the big boys say to buy or because it's the "latest and greatest", it's no good. If you are turning down your motor 25 or 50%, no good.

I also like the ability to play with timing and punch with a 550, which is a basic nogo with a 4 pole. Additionally, I think the SCTE was designed with a 550 in mind and the little bit of extra weight transferred towards the rear end, really helps with traction and especially in-flight stability.

That said... the tekin sc4x, well, no one really raved about them. These trinity monster 550's are insane.
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Old 01-06-2012, 08:57 AM
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Originally Posted by Krio View Post
Mission accomplished.

might just be the hangover.. hahah.. jk..
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Old 01-06-2012, 08:59 AM
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Originally Posted by dgrobe2112 View Post
might just be the hangover.. hahah.. jk..
lol! Sorry, I'll turn the lights down.
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Old 01-06-2012, 09:40 AM
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Originally Posted by lowroad View Post
well, maybe, but if you can't get it to the ground, it's no good. If it's faster than your track allows for, it's no good. If you are buying it because that's what the big boys say to buy or because it's the "latest and greatest", it's no good. If you are turning down your motor 25 or 50%, no good.

I also like the ability to play with timing and punch with a 550, which is a basic nogo with a 4 pole. Additionally, I think the SCTE was designed with a 550 in mind and the little bit of extra weight transferred towards the rear end, really helps with traction and especially in-flight stability.

That said... the tekin sc4x, well, no one really raved about them. These trinity monster 550's are insane.
I loved my SC4X. It was a great strong motor. I was never down on power with that thing in my truck. I agree with getting the power down to the track. I run my ESC with CL at 80% but I did the same with my SC4X. Other then that I have the brakes turned way down. The 4poles have increadilble low end control. At full punch I can easily over power the traction avaible but I could do the same again with the 550 motor.

To each there own. I do seen benefits to both setups but you will have a hard time getting the pro4 motor out of my truck!
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