Originally Posted by bs6ef
i do admire you for thinking out of the box, most people don't have the imagination or possibly skill to do what you have done. When i first read our thread i strongly disagreed with your vision of the future of 12th, partly because i felt that you where trying to mess with my class of racing and partly because i have seen and raced against against a converted car before in the past, and to be honest it just didn't work. However after a certain amount of debate with a friend of mine who works as an engineer for a very well known formula one team i have decided to take the plunge and give it ago myself and see what happens. As part of my testing i will be comparing lap times and ave lap times as well tyre wear.
To help me out Roland what setup have you been using and what car are you running
Let me begin by answering your last question. Iíve tested with the very first edition of Diggity, which I shelf now because a special nut that hold the rear pod to the chassis keep coming out. For now, I have CRCís Blood Knief, T-Force, a two years Diggity and in the middle of putting electronics on a Speed Merchantís Rev 4. All of these cars are more than two years old. The reason Iím telling these cars are that old is to rebut those who assume you need to buy the newest car or some kind of conversion kit.
Besides being $200 cheaper than a conventional set up and a lot less tire wear, what people would care is how the car performs on a track compare to a car with a conventional set up. Let me introduce you Donny Lia, the current IIC 1/12 Stock A-Main winner, the track/hobby shop owner at http://www.360rcspeedway.com/
Iím going to use his lap time to compare so people can see how the 2-cell set up perform. On the current layout, people would do 10.1, 10 flat, better driver do 9.8, occasionally 9.7 and they would finish with a low 47 laps or high 48 laps. One Friday night, I and Donny did a mid 49 laps. We both were doing more 9.7 and 9.6 and a few 9.5. Iím not trying to compare my driving to Donnyís driving; Iím a decent driver, but certainly my line wasnít as clean as Donnyís, but the speed of Monbaís 5400kv with 1.7Ē tire and 88/16 gear ratios definitely help. That was a two yearís old Diggity. My Bloody Knief with this motor: http://www.hobbycity.com/hobbycity/s...ess_Motor_(FIN
is capable of same performance.
These speeds of these two motors are right in between 27T and 19T brushed motor.
Iíve also try this:
Itís slow. The best I could do was a 10.9, more than a second slower.
May I suggest you try this:
Based on the max. amp load on this motor, 9 amp., compare with the 42ooKv.,max amp load of 10amp., this should have a speed very close to the current stock speed.
Itís only my estimation, the following motor may give you similar speed as 5.5T as you mention in your post:
Use this battery:
I recommend this battery now instead of the 1800mah battery, I will explain in the future post.
For those who donít have an esc yet, you can save yourself $100.00 and get this:
You can also use this esc for 1/10 scale, if you only race 17.5 or 13.5 class. Or order this:
With this esc you can use any motor down to 5.5 T. Iíve tried this esc myself on an X-ray with 17.5T, it actually gave me more punch than my Speed Passion on a JRX-S type R. Maybe itís the sensor-less design, but it need to be confirmed by expert whether my thinking is right or not. I think this esc and Speed Passion are made by the same manufacture, based on the program cards available to them. Both program cards have 95% resemblances to each other. I also cross-tested both esc and program card, and they worked. You may want to get it as well; it makes parameter change a breeze, and here itís the link:
As I test more and more, here are more reasons to try my set up, specially for those who blah blah why theyíre dead against my idea, why they donít want to buy new item that they have no use for other class. For those who already have a brush-less esc, then all you need is a $20.00 motor and a $20.00 battery. If yours is a sensor type, you simply remove the sensor cable and run the esc as a sensor-less type.
Cogging issue? Well here are my findings:
With both sensor and sensor-less type, I intentionally push the car backward; give a throttle, the car would go forward right away. No cogging here at all.
Under normal running,
With the EZ Run esc, if you gear it right, there will be no cogging issue. With 3100kv motor mentioned above, its speed is slower then a brushed 27T, with a max amp load of mere 7A. I could gear to a point, and it would perform flawlessly. But one more tooth on the pinion, it will show some cogging specially if you try to get it going from dead stop. Is it a good thing? I think so. It make so easy, even a beginner can tell right away if any motor he choose to run is over gear or not. Thatís means your gear selection is beyond the capacity of the motor if it cogs. The same cogging happen when I first tried my 6800kv Momba motor. With a 17 teeth pinion, it would cog right away. With a 16 teeth pinion, it would cog 4 minutes into running, when the voltage of the battery drop to a certain point, the cogging happened. Once I change to a 15 teeth pinion, I could go very fast through the whole battery. No cogging at all and the motor was only 150 degree after 11 minutes of running. When geared right, the following motor also has no cogging issue; running at a speed like 8T brushed motor for about 10 minute and came back with 160 degree.
With my Speed Passion run as sensor-less, it can run all the motors, like the EZ Run does, with the same gear ratio. Then I tried to push it and see if it would cog if over geared. It did not cog at all with my Momba 5400 kv geared at 21 teeth instead 17 teeth pinion, supposedly the right gear with the EZ Run esc. It went faster than a 7T brushed motor, can you imagine this; but it was fast only for the first three minute, then it slowed down a lot. The temperature was 240 degrees. With this supposed ďbetterĒ esc, you can unknowingly over gear, resulting in a less quality run, too fast in the beginning and too slow half way through. So in a way the $50.00 esc is actually a better esc in this case, IMO.
As for as the set up for chassis, toe-in or toe-out, camber and caster are all varied with different cars of mine. But lighter side spring and harder front spring seems work well on all cars of mine.
In the attached pictures, I want you to pay attention to the tires. I purposely use those beat-up tires to see if they would hold up. They do. Since the car is so much lighter, it became less critical as far as traction from softer tires is concern. If the edge of tires broke off and become sharp, just trim it with scissors like the picture illustrated. So far Iíve been running BLACK all around, and it lasts twice as long. Next week, I want to try a harder compound and see if it will work. I think it will, and if it does, the cost to run 1/12 on tire will further reduce. That will be a really good thing.
ďWhen i first read our thread i strongly disagreed with your vision of the future of 12th, partly because i felt that you where trying to mess with my class of racing and partly because i have seen and raced against a converted car before in the past, and to be honest it just didn't workĒ
I only wish the best can happen to 1/12 scale, and Iím working on it even though Iím facing so many objection voices.
Just a Reminder: See pictures I posted on post#78 for detail how to mount the motor.
Wish this will help.