Limitless First time speed build.

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LegacyIV

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Hey all I just really need some help with my build. Limitless v2 dual 1721, x4 cnhl 6200 4s1p have been ordered. My main problem at the moment is figuring out what gearing I should be using. I've already watched all of Raz's videos 100 over seeing if he mentions what gears to use but he doesn't. Community may frown upon me for just wanting the hand out but the thought of going through all these different pinion and spur gears buying them $20 a pop just doesn't sound enjoyable to me. I saw that these cars are fast and just want to enjoy the speed. I just want to know what gearing is used for 150mph and 180mph with my setup and I guess a bashing gearing setup also for the days I just want to rip around without blowing my motors/esc. Sorry for the long post and I understand if im banished for wanting the handout I know some of you guys worked very hard to reach these high mph and I respect it but the gearing part of this hobby is where the joy bleeds out for me.
 
You can use a gear calculator to get an idea of what pinion spur to look for.
https://www.radiocontrolinfo.com/information/rc-calculators/rc-car-calculator/

However, this is the just math in ideal conditions, in a vacuum, no friction and everything works. Realistically figure on about 75-80% of the number given. Assuming you don't crash.

You might verify your batteries fit. The V2 battery compartment is
2.16in (51mm) wide
7.00in (150mm) long
2.16in (70mm) high
Many of the CNHLs are longer than 150mm. This was a huge limitation when I did my build.

I built mine and thought it's all about the gearing. But there is a lot to consider outside of the mechanics, specifically driving ,and NOT crashing. It's not simply pin the throttle. Also your talking about some pretty high speeds, do you have a road for that? I'm on 1600 feet of empty business park on a weekend and that is a bit small for the speed your looking at.

The advice that was given to me is start with some lower speeds and build up to it. Maybe 4S or 6S first, then work up to 8S. That was very solid advice. I limited the ESC Power to practice with. Now that I'm on 8S I'm looking at going back to 3 or 4S parallel.

You will need to make sure you radio works at the extended distances. Most of us seem to run RadioLink or Futaba, or modified versions of those.
 
You can use a gear calculator to get an idea of what pinion spur to look for.
https://www.radiocontrolinfo.com/information/rc-calculators/rc-car-calculator/

However, this is the just math in ideal conditions, in a vacuum, no friction and everything works. Realistically figure on about 75-80% of the number given. Assuming you don't crash.

You might verify your batteries fit. The V2 battery compartment is
2.16in (51mm) wide
7.00in (150mm) long
2.16in (70mm) high
Many of the CNHLs are longer than 150mm. This was a huge limitation when I did my build.

I built mine and thought it's all about the gearing. But there is a lot to consider outside of the mechanics, specifically driving ,and NOT crashing. It's not simply pin the throttle. Also your talking about some pretty high speeds, do you have a road for that? I'm on 1600 feet of empty business park on a weekend and that is a bit small for the speed your looking at.

The advice that was given to me is start with some lower speeds and build up to it. Maybe 4S or 6S first, then work up to 8S. That was very solid advice. I limited the ESC Power to practice with. Now that I'm on 8S I'm looking at going back to 3 or 4S parallel.

You will need to make sure you radio works at the extended distances. Most of us seem to run RadioLink or Futaba, or modified versions of those.
I've already modified my chassis and looks like Raz's dual motor build his just looks clean and perfect. I ordered 4 cnhl 9500 Mah 90c 4s (they are having a buy 2 get one free deal right now) not realizing those are gigantic and even putting them on top of each other won't work even for a deltaplatiks body. Just got my order changed for 4 cnhl 6200 Mah 90c 4s. I have a Radiolink RC6GS v3, GYC 441 gyro, Perfect Pass launch control, PP carbon fiber drive shaft, Spectrum s6290 servo, 2 xlx2, and dual motor mount from PPS.

The roads near me are nice and smooth I'm stationed in Japan they take very good care of everything here. As for going 8s straight out the gate its to minimize costs I already have it set in my head to go 8s and wasting my money on more batteries/gearing than necessary seems like a waste to me. I know I'll crash the car, blow both diffs etc so the money spent on these things are expected. But as for batteries/gearing I will never use the 3s/6s sets again once I work my way up to 8s. And the gearing like I explained in my original posts I have no interest in going through 100's of gearing combos spending $20 a pop.
 
Any recommendations on pinions/spur gear I should start off with? Will be buying from saga
 
What you're asking for is how to wreck your car in the shortest order. I would implore you to reconsider jumping into speed running at 150mph as I can all but guarantee that you'll total your car out on the first or second outing. But I'm not going to spend much time on trying to talk you out of your plan as you're obviously dead set on going down this path, come hell or high water.
What I can tell you is, those batteries won't get you to 180mph, but I don't think that's going to be your issue as I don't expect that you'll get anywhere near there. But I'll be happy if you prove me wrong.
This is my speed calculator of choice. What I can give you in terms of values that will get you in the ballpark when it comes to calculations is: Set KV to 80% of the motor's indicated KV to account for load and your voltage to 3.5V/cell. The rest of the values are fixed and then you can play around with gearing for whatever speed you intend to achieve.
https://scriptasylum.com/rc_speed/top_speed.html

Edit: Since you're running a dual motor setup, you should 85% of KV will probably be closer to what they'll achieve since it will run a bit more efficient with a second motor. Godspeed and good luck.
 
I'm just starting out myself and my goal is to start with a 70 to 80 mph run and when that gets easy make a change to my setup. If you're just starting off and want to go 150 to 180 mph you must have more time and money than I do to build a new Limitless every week Just saying start slow.
 
Last edited:
What you're asking for is how to wreck your car in the shortest order. I would implore you to reconsider jumping into speed running at 150mph as I can all but guarantee that you'll total your car out on the first or second outing. But I'm not going to spend much time on trying to talk you out of your plan as you're obviously dead set on going down this path, come hell or high water.
What I can tell you is, those batteries won't get you to 180mph, but I don't think that's going to be your issue as I don't expect that you'll get anywhere near there. But I'll be happy if you prove me wrong.
This is my speed calculator of choice. What I can give you in terms of values that will get you in the ballpark when it comes to calculations is: Set KV to 80% of the motor's indicated KV to account for load and your voltage to 3.5V/cell. The rest of the values are fixed and then you can play around with gearing for whatever speed you intend to achieve.
https://scriptasylum.com/rc_speed/top_speed.html

Edit: Since you're running a dual motor setup, you should 85% of KV will probably be closer to what they'll achieve since it will run a bit more efficient with a second motor. Godspeed and good luck.
Thank you i appreciate your help and honesty
 
What you're asking for is how to wreck your car in the shortest order. I would implore you to reconsider jumping into speed running at 150mph as I can all but guarantee that you'll total your car out on the first or second outing. But I'm not going to spend much time on trying to talk you out of your plan as you're obviously dead set on going down this path, come hell or high water.
What I can tell you is, those batteries won't get you to 180mph, but I don't think that's going to be your issue as I don't expect that you'll get anywhere near there. But I'll be happy if you prove me wrong.
This is my speed calculator of choice. What I can give you in terms of values that will get you in the ballpark when it comes to calculations is: Set KV to 80% of the motor's indicated KV to account for load and your voltage to 3.5V/cell. The rest of the values are fixed and then you can play around with gearing for whatever speed you intend to achieve.
https://scriptasylum.com/rc_speed/top_speed.html

Edit: Since you're running a dual motor setup, you should 85% of KV will probably be closer to what they'll achieve since it will run a bit more efficient with a second motor. Godspeed and good luck.
Thank you for you guidance and honesty
 
Ok im back with a new dilemma I'm stuck between a few options for wiring from my batteries to my esc's. From what I can see with Raz's build he runs his batteries in "series" to cut down on the amount of wires and to have the build look cleaner as well as something about amerages, resistance, and voltage (See video for his explanation). Are there any wiring gurus that could explain how charging would be done if I will have 2 4s batteries connected to one qs8 plug. Will I need a certain kind of charger stronger charger than normal? Ive been hearing about "balancing" how does that work pretty sure that's the clear plug on the battery.i just ordered Raz's qs8 plugs off of amazon also

He explains wiring here ^ at 19:20

https://www.towerhobbies.com/product/s2200-g2-ac-2x200w-smart-charger/SPMXC2010.html
Charger I been considering.^

Screenshot 2023-01-15 at 10.15.19 AM.png



Screenshot 2023-01-15 at 11.52.45 AM.png
 
Ok im back with a new dilemma I'm stuck between a few options for wiring from my batteries to my esc's. From what I can see with Raz's build he runs his batteries in "series" to cut down on the amount of wires and to have the build look cleaner as well as something about amerages, resistance, and voltage (See video for his explanation). Are there any wiring gurus that could explain how charging would be done if I will have 2 4s batteries connected to one qs8 plug. Will I need a certain kind of charger stronger charger than normal? Ive been hearing about "balancing" how does that work pretty sure that's the clear plug on the battery.i just ordered Raz's qs8 plugs off of amazon also

He explains wiring here ^ at 19:20

https://www.towerhobbies.com/product/s2200-g2-ac-2x200w-smart-charger/SPMXC2010.html
Charger I been considering.^

View attachment 270172


View attachment 270174
If you want to charge 4 batteries simultaneously, then you’ll need a charger with 4 charge ports. You cannot wire lipo batteries together for charging.

Balancing the cells is very important to prevent a lipo from becoming a fire hazard. These things can burn your house down if you aren’t careful. I’m serious. I’d strongly recommend reading up on lipo safety before you move forward.
 
If you want to charge your batteries in a time efficient manner I’d recommend a getting a 1000w charger, power it off a a separate 24v psu and parallel charge.

Speed running isn’t cheap and taking a short cut to get to the top isn’t wise.

Gears and batteries are the cost of doing business….
 
If you want to charge 4 batteries simultaneously, then you’ll need a charger with 4 charge ports. You cannot wire lipo batteries together for charging.

Balancing the cells is very important to prevent a lipo from becoming a fire hazard. These things can burn your house down if you aren’t careful. I’m serious. I’d strongly recommend reading up on lipo safety before you move forward.
In the picture you can see that the positive wire from one battery and the negative wire from another battery are soldered to the same qs8 plug while the other positive and negative are joined by what it seems to be qs8 bullets which means that two different batteries are in fact wired together and must be charged somehow because I don't think he's unsoldering them to charge them individually. The second picture is the same thing except the second set of positive/negative cords are connected to a qs8 plug instead of qs8 bullets and sealed with heat shrink. Zoom in to the first and second pictures. My question is how are they charged safely.
If you want to charge your batteries in a time efficient manner I’d recommend a getting a 1000w charger, power it off a a separate 24v psu and parallel charge.

Speed running isn’t cheap and taking a short cut to get to the top isn’t wise.

Gears and batteries are the cost of doing business….
The charger I linked is the same price as most of these 1000w chargers your saying I should get I wasn't planning on taking short cuts.
 
In the picture you can see that the positive wire from one battery and the negative wire from another battery are soldered to the same qs8 plug while the other positive and negative are joined by what it seems to be qs8 bullets which means that two different batteries are in fact wired together and must be charged somehow because I don't think he's unsoldering them to charge them individually. The second picture is the same thing except the second set of positive/negative cords are connected to a qs8 plug instead of qs8 bullets and sealed with heat shrink. Zoom in to the first and second pictures. My question is how are they charged safely.

The charger I linked is the same price as most of these 1000w chargers your saying I should get I wasn't planning on taking short cuts.
I’m sorry if I came across being rude....

The short cut comment was in regards to gearing and batteries. It's already been stated that you should start off slow and work your way up to 150mph. Speed running is expensive and crashes are just part of the hobby. I am curious why you chose to build a 2 motor platform since it increases costs and complexity dramatically without a proportional improvement in top speed. 150 is not too difficult on a single motor setup.

Re: chargers, I just meant to say that many chargers don't achieve their stated output unless you use an external PSU, preferably 24v and you will want as much wattage as possible, Chargers with built in power supplies generally aren't as powerful and not as cost efficient.

GL!
 
Ok im back with a new dilemma I'm stuck between a few options for wiring from my batteries to my esc's. From what I can see with Raz's build he runs his batteries in "series" to cut down on the amount of wires and to have the build look cleaner as well as something about amerages, resistance, and voltage (See video for his explanation). Are there any wiring gurus that could explain how charging would be done if I will have 2 4s batteries connected to one qs8 plug. Will I need a certain kind of charger stronger charger than normal? Ive been hearing about "balancing" how does that work pretty sure that's the clear plug on the battery.i just ordered Raz's qs8 plugs off of amazon also

He explains wiring here ^ at 19:20

https://www.towerhobbies.com/product/s2200-g2-ac-2x200w-smart-charger/SPMXC2010.html
Charger I been considering.^

View attachment 270172


View attachment 270174
Raz's wiring looks like a single battery but it's not. It's just super clean.

In the first picture he has connection from first battery to the second battery with an 8mm Bullet connector. He has showed this before where just uses bullets. He probably has a special charging cable for that setup.
1673893234544.png


The second picture is a series configuration with a jumper. He has two jumpers on the side of the batteries.
1673893872394.png


Another shot of his bullets (on his latest build). The bullets are on the ESC and the QS8 on the battery. There is another QS8 hidden in the shadows. It's still a series circuit.
1673893652829.png


The idea is to have the least resistance possible. More wires add, smaller (thicker) gauge wires and connectors all add resistance to the system. It's only miliohms but it adds up when you are on the ragged edge. Realistically, I wouldn't worry about it until you're running 180 in an open wheel.

If you look at the last picture he could actually clean this up even more. Start by placing the batteries 180, where the connectors are closer to the ESC. Then shorten the ESC wires and upgrade to a smaller (thicker) gauge wire. I also suspect the QS8 connectors are a weak link and maybe two connector pairs in parallel might help lower the impedance?

Would it make a difference in the real world? The math says it does, but in reality there are so many variables it's hard to say. It's all theory and to conclusively say what works and doesn't work you need a highly controlled environment with high precision instruments. For all I know he might get better performance by removing all of the stickers?
 
Raz's wiring looks like a single battery but it's not. It's just super clean.

In the first picture he has connection from first battery to the second battery with an 8mm Bullet connector. He has showed this before where just uses bullets. He probably has a special charging cable for that setup.
View attachment 270632

The second picture is a series configuration with a jumper. He has two jumpers on the side of the batteries.
View attachment 270640

Another shot of his bullets (on his latest build). The bullets are on the ESC and the QS8 on the battery. There is another QS8 hidden in the shadows. It's still a series circuit.
View attachment 270639

The idea is to have the least resistance possible. More wires add, smaller (thicker) gauge wires and connectors all add resistance to the system. It's only miliohms but it adds up when you are on the ragged edge. Realistically, I wouldn't worry about it until you're running 180 in an open wheel.

If you look at the last picture he could actually clean this up even more. Start by placing the batteries 180, where the connectors are closer to the ESC. Then shorten the ESC wires and upgrade to a smaller (thicker) gauge wire. I also suspect the QS8 connectors are a weak link and maybe two connector pairs in parallel might help lower the impedance?

Would it make a difference in the real world? The math says it does, but in reality there are so many variables it's hard to say. It's all theory and to conclusively say what works and doesn't work you need a highly controlled environment with high precision instruments. For all I know he might get better performance by removing all of the stickers?
Raz is just anal retentive about his builds. I honestly think it's more about satisfying his order compulsion and the (albeit minimal if any) performance gain is just an added bonus. If we were talking about the difference of removing 1-2 feet of wiring, I might be able to see the argument. But you can keep your wiring short without going to the lengths that he does and, I'm fairly certain, not incur any performance penalties.

You make an interesting point regarding QS8 connectors. While I don't think the connectors themselves are problematic in terms of resistance, the common practice of filling the cups with solder, on the other hand, might be. The specific resistance of solder is many times higher than that of copper so, ideally, you'd really just want the wire contacting the cup and a minimum of solder to bind the wire to it. I think the idea of filling the cup with solder making for a better connection is fallacious.
 
Raz is just anal retentive about his builds. I honestly think it's more about satisfying his order compulsion and the (albeit minimal if any) performance gain is just an added bonus. If we were talking about the difference of removing 1-2 feet of wiring, I might be able to see the argument. But you can keep your wiring short without going to the lengths that he does and, I'm fairly certain, not incur any performance penalties.

You make an interesting point regarding QS8 connectors. While I don't think the connectors themselves are problematic in terms of resistance, the common practice of filling the cups with solder, on the other hand, might be. The specific resistance of solder is many times higher than that of copper so, ideally, you'd really just want the wire contacting the cup and a minimum of solder to bind the wire to it. I think the idea of filling the cup with solder making for a better connection is fallacious.
Totally agree, there is diminishing return when you fill the cup. In the end the connection is really only the surface of the mating connector pair anyway. Some high current connectors are crimped. And I never see the power company out there with a soldering iron repairing the power lines. They are also mechanically captured.

I'm thinking (based solely on witchcraft and wives' tales here) that the filled cup would be mechanically stronger. Since I used my Magic 8-ball for the engineering on this one, I'd love to hear any contrary thoughts.

People play games with testing to get better numbers and there is no engineering datasheet that I can find for the QS8 design. I've seen the QS8 connector current rated at like 500A, which seems a bit high as generic 8mm bullets are like 200 Amp. Maybe it's a peak vs sustained? I dunno? The datasheet would call out max current as well as mating cycles, AC/DC voltages, insulation ratings, operation temperature, etc... We all use them in good faith and assume that we have the "real" QS8 connectors.

So it would make sense that the QS8 (on paper) is the weak link. But it's not like it will explode if you exceed the current rating, it will give you plenty of warning and look like this. In this case I didn't have it fully seated.
IMG_4455.JPG
 
Totally agree, there is diminishing return when you fill the cup. In the end the connection is really only the surface of the mating connector pair anyway. Some high current connectors are crimped. And I never see the power company out there with a soldering iron repairing the power lines. They are also mechanically captured.

I'm thinking (based solely on witchcraft and wives' tales here) that the filled cup would be mechanically stronger. Since I used my Magic 8-ball for the engineering on this one, I'd love to hear any contrary thoughts.

People play games with testing to get better numbers and there is no engineering datasheet that I can find for the QS8 design. I've seen the QS8 connector current rated at like 500A, which seems a bit high as generic 8mm bullets are like 200 Amp. Maybe it's a peak vs sustained? I dunno? The datasheet would call out max current as well as mating cycles, AC/DC voltages, insulation ratings, operation temperature, etc... We all use them in good faith and assume that we have the "real" QS8 connectors.

So it would make sense that the QS8 (on paper) is the weak link. But it's not like it will explode if you exceed the current rating, it will give you plenty of warning and look like this. In this case I didn't have it fully seated.
View attachment 270675
I've seen a wide range of max current specs for QS8 connectors. I've seen as low as 150A and as high as 500A so I'm not really sure what to make of it. And, as you pointed out, there's no mention of whether this is peak or sustained current rating. At this point though, I've seen enough and done enough to just trust that they work for the 600-700A max current envelope of speed running (assuming the connector is seated correctly ;)).

Early on when I was looking at switching over all of my power connectors, I briefly considered QS10 connectors because, hey...10 is two more than 8 so that's better, right? They're a little bigger and have a higher max current rating but I quickly threw the idea over board when I saw the price. I honestly can't remember exactly what it was, but IIRC, it was somewhere around 20-25€ per connector pair. I said, no-de-no-de-no-no-no-de-no-no....QS8 will do me just fine.
 
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