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building sand drag race 1/5

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Old 01-30-2016, 12:13 PM
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dxprince
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Default building sand drag race 1/5

Hi,

am building a drag race 1/5 buggy to do 200ft hill climb,
I have right now LBP5898/3d 198A 32V 6500W 1100KV.

am wondering if any one here build something samiler or suggest a top ESC or motor...here my buggy
https://www.dropbox.com/s/1fmkdq1adl...04420.jpg?dl=0

waiting to here from you Masters
am attaching a youtube link for one of the races,


https://youtu.be/htzByEOHGBk
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Old 02-03-2016, 07:26 AM
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If you want one of the best esc's have a look at MGM. MGM is one of the few besides the Fighter Cat esc you have that do more than 8s. As for motors Neu and Lehner have been at the top forever. A rising cheaper alternative for motors is Poseidon.

Be aware your current 5698 1100kv motor has a max voltage of 8s but in a short burst environment like drag racing should be able to take more. I'd be tempted to go higher voltage but wouldn't go higher than 10s though as then the rpm is nearing 40k which is probably about the rpm limit. If you're going to buy a new motor I'd go with something more like 700kv and run 10s or 12s. You'll then have more than enough power to pull any gearing you want and keep accelerating at the top end.

Personally I'd start with the esc. Once that's decided then you know your voltage limitations. More voltage equals more power so I'd go as high as possible but 12s just makes sense. 6s packs are commonly available, easy to mount etc. once you decide on voltage then you need to do some calculations with voltage and Kv to make sure your motor stays within its rpm limit. You want the motor getting close to its rpm limit though as under load the actual rpm will be less. Use 3.7v per cell (nominal lipo voltage) as no pack is going to maintain 4.2v per cell when under load. Go as long as possible on the motor, longer equals more torque.
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Old 02-03-2016, 12:22 PM
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hi
thanks for the reply
I found these ESC Alien 450A 3-16S Sport2 Car-72 mosfet ESC HV
am still struggling with the motor as I couldn't find motor which can handle 12s in the /spec.

am thinking of using 12s of Lihv...
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Old 02-03-2016, 12:54 PM
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Originally Posted by Maj_Overdrive View Post
If you want one of the best esc's have a look at MGM. MGM is one of the few besides the Fighter Cat esc you have that do more than 8s. As for motors Neu and Lehner have been at the top forever. A rising cheaper alternative for motors is Poseidon.

Be aware your current 5698 1100kv motor has a max voltage of 8s but in a short burst environment like drag racing should be able to take more. I'd be tempted to go higher voltage but wouldn't go higher than 10s though as then the rpm is nearing 40k which is probably about the rpm limit. If you're going to buy a new motor I'd go with something more like 700kv and run 10s or 12s. You'll then have more than enough power to pull any gearing you want and keep accelerating at the top end.

Personally I'd start with the esc. Once that's decided then you know your voltage limitations. More voltage equals more power so I'd go as high as possible but 12s just makes sense. 6s packs are commonly available, easy to mount etc. once you decide on voltage then you need to do some calculations with voltage and Kv to make sure your motor stays within its rpm limit. You want the motor getting close to its rpm limit though as under load the actual rpm will be less. Use 3.7v per cell (nominal lipo voltage) as no pack is going to maintain 4.2v per cell when under load. Go as long as possible on the motor, longer equals more torque.
/could you please explain more about how I can make sure my motor stays within its rpm limit! pls
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Old 02-06-2016, 08:12 PM
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Originally Posted by dxprince View Post
hi
thanks for the reply
I found these ESC Alien 450A 3-16S Sport2 Car-72 mosfet ESC HV
am still struggling with the motor as I couldn't find motor which can handle 12s in the /spec.

am thinking of using 12s of Lihv...
I've seen those esc's (also in your pic posted above) made by other manufacturers as well, I believe Fighter Cat is one of them. Anyway, I haven't seen the best reviews on them, but they are inexpensive.

As for finding a motor to handle 12s, you just need to be looking in the right places. You're not going to find a 12s rated motor from Leopard or any of its clones. But as I said before you can run a motor on a higher voltage than it's rated for, especially for short periods like drag racing as long as you're within the rpm limit. The least expensive 12s rated motors I know of is Poseidon's 22 series http://poseidonrc.com/brushless-motor.html. Neu motors has plenty of options in their 22 series and they're a higher quality than Poseidon.

As for calculating motor rpm to stay within the rpm limit, that's easy. Just multiply Kv by voltage. 1000kv times 20v equals 20,000rpm. 12s fully charged is 50.4v, but you don't want to use that number. Voltage will drop under load, how much depends on your batteries but 3.8v under load is about average, if you want to be safe use 4.0v per cell. So 12s under load at 4.0v per cell is 48v total. Multiply by 1000kv and we get 48,000rpm. Most 58mm diameter 1/5 motors have a max rpm of 40,000 so obviously we'll need a lower Kv. 800kv at 48v works out to under 39,000rpm so that'll work and is probably as high of a Kv you'd want to go with anyway.
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Old 02-08-2016, 04:03 AM
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Originally Posted by Maj_Overdrive View Post
If you want one of the best esc's have a look at MGM. MGM is one of the few besides the Fighter Cat esc you have that do more than 8s. As for motors Neu and Lehner have been at the top forever. A rising cheaper alternative for motors is Poseidon.

Be aware your current 5698 1100kv motor has a max voltage of 8s but in a short burst environment like drag racing should be able to take more. I'd be tempted to go higher voltage but wouldn't go higher than 10s though as then the rpm is nearing 40k which is probably about the rpm limit. If you're going to buy a new motor I'd go with something more like 700kv and run 10s or 12s. You'll then have more than enough power to pull any gearing you want and keep accelerating at the top end.

Personally I'd start with the esc. Once that's decided then you know your voltage limitations. More voltage equals more power so I'd go as high as possible but 12s just makes sense. 6s packs are commonly available, easy to mount etc. once you decide on voltage then you need to do some calculations with voltage and Kv to make sure your motor stays within its rpm limit. You want the motor getting close to its rpm limit though as under load the actual rpm will be less. Use 3.7v per cell (nominal lipo voltage) as no pack is going to maintain 4.2v per cell when under load. Go as long as possible on the motor, longer equals more torque.

one more question I highlited as you see above , you said longer mean more torque, do you mean the motor length e??
thanks for the info, am very glad that I am getting this info from ,

Dxpricne
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Old 02-08-2016, 03:59 PM
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Yes I'm referring to motor length. Longer motors have a longer stator. Longer stator means more magnet surface area to act on the windings which equals the potential for more power.
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Old 02-09-2016, 02:02 PM
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I just received my 12s Lihv,
Their is many motor with around 38v upto 65v my question but with 30000rpm,
So
What will I lose or I gain if I used my 12s Lihv, will the motor exceed the rpm limit?
I know that limit with zero load so do I still will reach my max rpm with all the load?!

Thanks
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Old 02-10-2016, 10:34 AM
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Look ok at the chart above from Poseidonrc's site. They have a rpm limit of 30,000 on their big 22 series motors. Now have a look at the Kv for each motor and the max voltage. 400kv multiplied by 75v equals 30,000 rpm, 600kv multiplied by 50v equals 30,000rpm. So if you go by their chart and get a 600kv motor there's no way it will exceed 30,000rpm on 12s unless it has no load on it and the batteries are fully charged. Put it in the vehicle, apply full throttle and the battery pack voltage is likely to drop to at least 4.0v per cell or 48v for the whole pack, 48v multiplied by 600kv is 28,800rpm.

Now that 28,800rpm is the max theoretical rpm the motor will reach but in reality it's going to be lower. First of all Kv is rated without a load. The exact Kv with a load depends on the amount of load and the motor's power output. A 600kv motor on 12s the Kv under the load of you're vehicle is probably going to be more like 500-550kv. So at 48v the max motor rpm is going to be more like 24,000-27,000rpm. This is a nice safety margin to ensure the motor won't reach its max rated rpm.

The max rpm rating of a motor is just the max rpm. It doesn't matter if the motor is loaded or unloaded, if it exceeds the max rpm problems can occur.
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Old 02-13-2016, 04:18 PM
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hi,
am comparing Leopard 58110/2y with the Poseidonrc's,
I noticed in the leopard website they specify the Max A ....where in the poseidon website you cant see it?!how important is that for my hill climb drag race?!

I have two battery both have same number of the cell/ C, but one has 5000Mah and the other has 3400Mah will it make any different on my 3Sec darg race??
how that could affect my 3Sec . hill climb drag race!!

thanks
omar
a61ek
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Old 02-13-2016, 11:33 PM
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Max A, is maximum amperage the motor can take. No Poseidon's chart doesn't specify max amps but you can very easily figure it out. Amps multiplied by Volts equals Watts, and since the Max watts is listed as well as the max volts you can figure out max amps.

As for your batteries, you're talking about the most basic of principles here. The 5000mah pack will be able to supply more amperage and sustain less voltage drop under load meaning more power. In my opinion, a high amp draw 1/5 setup like this should have batteries capable of 150amp sustained draw. You didn't mention the C rating of your packs but the 3400mah pack would need to be at least 45C and the 5000mah at least 30c to be able to put out 150amps. That's my personal opinion on what should be the minimum to keep everything safe, including the esc. If you're wondering why lower rated batteries can hurt the esc, Google ripple voltage and do some reading.

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Old 02-14-2016, 04:04 AM
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hi, the last rc truck I used was on 2008, then I stopped. I think choosing the brushless motor to suit your needs is getting harder than choosing a wife....

I will be using LIHV 3400mAh 6s 65-130c 22.8V (turnigy), I was looking at Max Amp I noticed a big different between both companies,
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Old 02-14-2016, 11:42 PM
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Originally Posted by dxprince View Post
hi, the last rc truck I used was on 2008, then I stopped. I think choosing the brushless motor to suit your needs is getting harder than choosing a wife....

I will be using LIHV 3400mAh 6s 65-130c 22.8V (turnigy), I was looking at Max Amp I noticed a big different between both companies,
You could keep things simple and just run a 2028 on 8s. I believe some people have run them on 10s but I have no idea what Kv or max rpm is on them and I'm not looking it up either. You already know what batteries you want to run, that means your Kv is basically decided for you. Now just pick a motor that's within your budget and you can get in your country. From what I've read the Poseidon should be a bit better than Leopard and Neu is better than both. But those are opinions of people regarding motor temperature while doing general bashing and racing, not 3 second drag races. The difference between these motors in a drag race environment is t going to be as great.

Don't even get me started on MaxAmps batteries. They're overpriced and you're paying for all their advertising. There is a possibility they are assembled better than other packs but the cells are not any better than most packs. They just use a unique rating system that even more inflated than other manufacturers to confuse people and make them think they're packs are worth the extra cost. Turnigy isn't bad and those ratings sound good. Others to consider are Hyperion, Polyquest, Thunder Power, Gens Ace, SMC and SPC, much better value for the money. If you're going to spend in the MaxAmps price range you'd be much better of with Hyperion, they're a far superior battery.
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