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Old 03-02-2008, 07:25 AM   #676
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There is a significant performance difference between a budget/hobby grade and a professional grade esc. I'm not familiar with Futaba esc's, but if you look at say, LRP, their budget esc has a max rating of 60A, with a voltage drop of 0.320V. Their best esc has a max rating of 360A, and 0.005V voltage drop. Keep in mind that these numbers were measured @25deg C, and since the budget esc will get hotter faster (more resistance=more heat build up), the difference in voltage drop will also grow during the race. Alone the difference in voltage drop would give you approx. 4-5% better punch off the line and out of corners at the beginning of the race, more by the end of a heat. They have more powerful FETs and have a much lower internal resistance, hence they can channel electricity from the battery to the motor much more efficiently.
Also keep in mind that batteries also play an important role. If your competitors are using the latest and greatest high voltage batts and you're racing with a 2 year old sport stick pack, there is no wonder they can accelerate faster.
The cheapest, easiest and first upgrade that anyone should do is to switch to better batt connector and to solder the esc directly to the motor. I assume you've done that already?
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Old 03-02-2008, 10:29 AM   #677
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The cheapest, easiest and first upgrade that anyone should do is to switch to better batt connector and to solder the esc directly to the motor. I assume you've done that already?
I am using powerpole connectors already and have soldered the wires directly to the motor, as I am racing in a silver can class we are limited to 1500 nicads and everyones uses Sanyo 1300s which are not very old so should be on an even peg on that count
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Old 03-02-2008, 10:43 AM   #678
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There is a significant performance difference between a budget/hobby grade and a professional grade esc. I'm not familiar with Futaba esc's, but if you look at say, LRP, their budget esc has a max rating of 60A, with a voltage drop of 0.320V. Their best esc has a max rating of 360A, and 0.005V voltage drop. Keep in mind that these numbers were measured @25deg C, and since the budget esc will get hotter faster (more resistance=more heat build up), the difference in voltage drop will also grow during the race. Alone the difference in voltage drop would give you approx. 4-5% better punch off the line and out of corners at the beginning of the race, more by the end of a heat. They have more powerful FETs and have a much lower internal resistance, hence they can channel electricity from the battery to the motor much more efficiently.
OK, I think I see, the specs for the Futaba 230CR that I have are Current- Forward: 90A Reverse: 45A
On resistance: .0035 Ohms, which I see when compared to the next one up is Current- Forward: 200A Reverse: 100A
On-resistance: .010 Ohms, I can see a large difference would it be possible that when I give it full go off the line the motor is trying to draw more that the ESC is capable of delivering? Thaks for all the help guys.

I am staring to get third in the A Final for this calss after only half a dozen races and am keen to learn more a sneak up another place or 2!!
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Old 03-02-2008, 10:56 AM   #679
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The stock futaba esc is pretty ordinary. While the resistance of some of the better escs is lower in my opinion its the big caps which offer the most advantage as they help to maintain the power as the motor draws current under acceleration.

Walk around and check out what escs the top drivers are using. If you see things like LRP QC2s or Novak GTXs then that can be quite a significant advantage.

Also tyres can make a huge difference (assuming you are not using a control tyre).
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Old 03-02-2008, 11:27 AM   #680
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The stock futaba esc is pretty ordinary. While the resistance of some of the better escs is lower in my opinion its the big caps which offer the most advantage as they help to maintain the power as the motor draws current under acceleration.

Walk around and check out what escs the top drivers are using. If you see things like LRP QC2s or Novak GTXs then that can be quite a significant advantage.

Also tyres can make a huge difference (assuming you are not using a control tyre).
Cool will do on next race day, we are not using a control tyre, but am using the same brand as most and am learning which rated tyre to use as the day changes, I couldnt believe it when I learnt the hard way how much differnece tyres made!
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Old 03-02-2008, 01:36 PM   #681
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Hey guys, my search thread tool isn't working right now, so I'll ask.... How do Lipo batteries fit in the tub chassis? I'm considering one of these for VTA and would love to run lipo. Anyone with any luck? I fear not the Dremel tool.
Ben
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Old 03-02-2008, 10:34 PM   #682
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I dont think ive seen anyone ask about fitting a lipo into the cyclone s tub chassis.

People ask in the main cyclone thread and the thing you have to watch for is that it fits under the right middle bulkhead. I suspect that you will have problems finding a lipo to fit, especially since the sides of the battery area are rounded.
I think orion make one which is shaped like a stick pack.
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Old 03-03-2008, 12:27 AM   #683
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While the resistance of some of the better escs is lower in my opinion its the big caps which offer the most advantage as they help to maintain the power as the motor draws current under acceleration.
I appologise for being off topic, but just wanted to expand on mangoman's statement.

The main purpose of these power caps are to maintain power delivered to the esc itself so it can continue to operate properly during high amp draw situations, e.g. heavy acceleration, where it is possible that the voltage drops below the operating voltage threshold of the esc. Many glitches during acceleration are caused by this because the esc and rx temporarily stops working (we're talking in the area of micro, or maybe a few miliseconds) until the voltage is restored.

The energy that these power caps can hold is very small. Novak's power cap has a rating of 25V 2700uF. That's 2700 millionth of a Farad at 25V which equals to 0.0675 Joule. Hardly enough to directly have a significant impact on acceleration, but enough to bridge the times where the battery voltage drops, allowing the esc to continue to operate properly, and hence indirectly allowing the car to accelerate better.

As implied above, you'll only benefit from a power cap when the motor creates such a high amp draw that the battery voltage drops below the minimum required by the esc. So several factors are at play, including the performance of the battery, the motor you're using and the esc itself.

I personally doubt that a silvercan would create such a big voltage drop that would necessitate the use of one, so in my opinion, a power cap will not benefit a silvercan in terms of acceleration. But there is still no reason not to put on the caps, as they do protect the esc from voltage spikes.
The difference in voltage drop is more significant. Take the example in my earlier post. By switching from the LRP AI Runner Reverse to a QC3 esc, you'll gain over 0.3V at the motor, which is huge!!


@bullfrog_racer: It sounds like you're starting to get pretty serious about racing. My suggestion would be to get a forward only esc. Reason is simple: esc manufacturers can only fit in a certain amount of FETs on the esc, lets say 10 FETs total. In an esc with reserve, 3 or 4 of these would be dedicated for reverse, so you only get 6 or 7 for forward, whereas in a forward only model, you get full use of those 10 FETs, and the more FETs, the more electricity can be "pushed" to the motor.
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Old 03-03-2008, 02:42 AM   #684
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@bullfrog_racer: It sounds like you're starting to get pretty serious about racing. My suggestion would be to get a forward only esc. Reason is simple: esc manufacturers can only fit in a certain amount of FETs on the esc, lets say 10 FETs total. In an esc with reserve, 3 or 4 of these would be dedicated for reverse, so you only get 6 or 7 for forward, whereas in a forward only model, you get full use of those 10 FETs, and the more FETs, the more electricity can be "pushed" to the motor.
Yeah I kinda have a competative streak in me!,

I have only had about 8 races but am enjoying it alot. I love gettting more from the car and I am discovering that thier is so much to learn, I am thinking about getting into brushless next season so may look at getting a ESC that can do both so I dont have to reinvest when I go brushless, would this be foolish? I was thinking of one of the LRP Sphere ESC I think they call it. Going to ask some questions about motor size for brushless next race day. Cheers for all the help guys, Iam sure I'll come with with some more questions sooner or later!
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Old 03-03-2008, 02:46 AM   #685
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If your trying to increase your acceleration, you need to increase your FDR (Final Drive Ratio = Spur/Pinion x internal ratio). So by decreasing your internal ratio, you're decreasing acceleration even further. Instead of playing around with the internal ratio, start with changing your gear ratio. Smaller pinion, or larger spur, or a combination of both will give you faster acceleration, but your top speed will decrease. Probably easiest to go get a pinion that is 1 or 2T smaller, if your motor mount allows it.
Thanks hyperdrive, how much difference would dropping a couple of teeth on the pinion make would it be noticable?

PS Thanks for putting me straight on the internal ratio, why would anyone want to fit the 18T pulleys if it has a negative effect on acceleration etc?
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Old 03-03-2008, 03:50 AM   #686
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I dont think ive seen anyone ask about fitting a lipo into the cyclone s tub chassis.

People ask in the main cyclone thread and the thing you have to watch for is that it fits under the right middle bulkhead. I suspect that you will have problems finding a lipo to fit, especially since the sides of the battery area are rounded.
I think orion make one which is shaped like a stick pack.

I found a picture of one with a TrackPower 4900 in it. I hope my Orion 4800s fit.

Ben
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Old 03-03-2008, 05:15 AM   #687
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Thanks hyperdrive, how much difference would dropping a couple of teeth on the pinion make would it be noticable?
A bit trivial this one... some people will notice the difference of droping a tooth, some won't. I guess it depends how well developed your driving skill is. Try some different pinions and see if that makes much of a difference on your lap times.

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PS Thanks for putting me straight on the internal ratio, why would anyone want to fit the 18T pulleys if it has a negative effect on acceleration etc?
Because sometimes that is exactly what is desired. Gearing should always be treated as a trade off between acceleration and top speed. It all depends on your motor, tyres, driving style, preference and track condition. For example, on a small, tight, high grip track, you'd best go for a higher FDR, whereas on a big, open, low grip track, it might be better to sacrifice acceleration for a higher top speed. There is no absolute rule regarding FDR.
The main reason why HB came out with the 18T pulley is to get closer to the recommended 3.5 FDR for 17.5 brushless motors. It's impossible with the 16T pulley. The closest I ever got was with a 65T spur and 40T pinion (48dp) which would've brought the FDR down to 3.96, but with the 18T pulley, it would be 3.52.
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Old 03-03-2008, 11:56 AM   #688
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Hey guys, my search thread tool isn't working right now, so I'll ask.... How do Lipo batteries fit in the tub chassis? I'm considering one of these for VTA and would love to run lipo. Anyone with any luck? I fear not the Dremel tool.
Ben

I run an orion 4800 and smc 5000 with no problems. I have the rtr cyclone s chassis and I assume that it is the same as the kit s chassis.
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Old 03-03-2008, 12:16 PM   #689
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I run an orion 4800 and smc 5000 with no problems. I have the rtr cyclone s chassis and I assume that it is the same as the kit s chassis.
Awesome! I was going to be shocked if nobody had tried a fitting a lipo.
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Last edited by sportpak; 03-04-2008 at 11:30 AM.
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Old 03-04-2008, 11:32 AM   #690
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Has anyone had any luck with AE or Losi shock springs? I haven't got the car yet and AE/Losi springs are easier for me to get.
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