Limitless Speed Running 101

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I think there are many ways to skin a cat.

Starting on lower 3s or 4s voltages is a good thought, but will require much higher quality batteries, which imo can be large financial deterrent if you don't already have some. Conversely, you could probably achieve a similar affect running a 6s setup with cheapo batteries and work up from there.

I certainly wouldn't go straight "to the moon" with 6s or 8s worth of onyx packs and a TP motor. That's more KT style.

I think what liberty is suggesting is start small and work your way up.
 
My current goal is learning rather than mph milestones. Tires, aero, transmitter distance and settings, suspension, reading data logs and understanding when I’ve reached a system’s limit.

2s and or 3s should be your focus then. You will learn a bunch.
If you want to message me privately once you start running and pulling logs, or I am happy to comment on a forum thread for all to see.

You will see as you take baby steps and gear up the loads and temps increase. There is a point where the speed didn't go up and the RPMs went down but the temps went higher and you know that you went to far at that point.

The other thing you will learn is how the motor performs loaded. Once you know that gearing is much less of a guess. My very first pass on 4s was at 142 mph because I already know this motor from learning on 2s and 3s.

I track lots of data. This one is the wattage required for each speed. I am pulling the wattage right at the end of the run before the brakes are applied.
The first cluster is 2s runs, the second is 3s runs, and the last is my 2 initial 4s runs.

Watts to MPH Capture.PNG
 
Lower voltages and lower speeds help you understand gearing better and see where the setup gets maxed out.
It is learning that translates to higher speeds and higher voltages, but at those higher speeds you can have some bigger variations run to run. So the learning is more solid at lower speeds and voltages.

I have been 127 on 3s so there is plenty of speed to be had at that power level.
but is that really true? lower voltages means starting off with a motor with higher KV. You can still learn about set ups and gearing with a lower kv motor and higher voltages. I think the real point is to learn about the car and work your way up, which can be done with higher voltages just as well as with lower voltages. I'm not suggesting the OP get a 1717-1650 and go to 8S immediately. I'm just saying that MMX8s/1717 would give the OP a reasonable starting point and he wouldn't have to buy another motor. I've never run the 1515, however I'm thinking that heat may be an issue. OTOH, I've never had an issue with heat running my MMX8s/1650 so it removes one less variable to worry about.
 
but is that really true? lower voltages means starting off with a motor with higher KV. You can still learn about set ups and gearing with a lower kv motor and higher voltages. I think the real point is to learn about the car and work your way up, which can be done with higher voltages just as well as with lower voltages. I'm not suggesting the OP get a 1717-1650 and go to 8S immediately. I'm just saying that MMX8s/1717 would give the OP a reasonable starting point and he wouldn't have to buy another motor. I've never run the 1515, however I'm thinking that heat may be an issue. OTOH, I've never had an issue with heat running my MMX8s/1650 so it removes one less variable to worry about.

Here are some of the big reasons to start on low voltage
- Lesser traction issues = reduced crashes for a newb
- Easer to learn throttle pull (higher voltages are more sensitive) (if you have tried 8s you know)
- Smaller variations in top speed due to different throttle pulls (assuming you don't have a throttle control)
- These smaller variations in final runs will translate to better data to compare and understand the learning from.

You could absolutely start learning on 6s and have a giant spur gear so that the car only goes 80mph but the car will have "snappy" power and a new driver likely will have more crashes starting on higher voltages.

I began on 6s and 8s 4-5 years ago, and learned more this past year working on 2s and 3s than any of my prior 3-4 years speed running.
Not everyone takes 5 years to figure it out, but that was my learning curve due to starting with the wrong platforms and having limited resources for a few years in the middle. Loved the journey all the way through. It has been a great hobby.
 
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well I think you and I are more or less on the same page as far as starting slow. Here would be my reasons for starting with "higher voltage", ie 1650-1717 Kv
-more room for growth in the future without having to purchase a new motor
-you can practice multiple runs without overheating the motor which means more fun time and less wait time. I've done 5 or 6 back to back passes without having the motor overheat
-extracting the most speed out of 2S/3S/4S is challenging, and granted, you will learn more, however, I would argue that there are merits to a simpler set up (higher voltage/lower KV) would allow you to reach your target speed faster, and once that is achieved, you can fine tune your skills and car with lower voltage.

personally my target speed is about 130 since my road is suboptimal and it's plenty fast (aka scary). I'm pretty much there now and my new build(s) are going to be using lower voltages and I'm going to fine tune the cars....
 
Good discussion here. Thanks guys. I definitely plan to start slow one way or another.

A quick motor question - why don’t I see more people use the Hobbywing 5687 for speed running? It fits in the stock orientation and looks like a beast of a motor (on paper).
 
Good discussion here. Thanks guys. I definitely plan to start slow one way or another.

A quick motor question - why don’t I see more people use the Hobbywing 5687 for speed running? It fits in the stock orientation and looks like a beast of a motor (on paper).
that's a definite 8S motor. People tend to use the 2028 castles for low KV.....
 
well I think you and I are more or less on the same page as far as starting slow. Here would be my reasons for starting with "higher voltage", ie 1650-1717 Kv
-more room for growth in the future without having to purchase a new motor
-you can practice multiple runs without overheating the motor which means more fun time and less wait time. I've done 5 or 6 back to back passes without having the motor overheat
-extracting the most speed out of 2S/3S/4S is challenging, and granted, you will learn more, however, I would argue that there are merits to a simpler set up (higher voltage/lower KV) would allow you to reach your target speed faster, and once that is achieved, you can fine tune your skills and car with lower voltage.

personally my target speed is about 130 since my road is suboptimal and it's plenty fast (aka scary). I'm pretty much there now and my new build(s) are going to be using lower voltages and I'm going to fine tune the cars....

Agreed, if you want the shortest path to higher speeds then the high-voltage setup is the way. You might miss some understanding of what is seen in the logs along the way. Guys add gearing or remove gearing but don't really know why that decision was made. Or realizing they could change their FD with a different spur between their 2 last gearing attempts and find a sweet spot there between the 2. I like to focus on FD ratio instead of what the pinion and spur are....

There are plenty of people that pick this stuff up very quickly so I am not saying my way is the only way. Just what I feel is the safe approach.

I was trying to help a guy break 120 on 6s and his data was all over the place with 6s runs. The same gearing can have 5 runs that look totally different.
I think throttle control devices like the perfect pass would help quite a bit, reducing some of the human error out of the equation.
Good discussion here. Thanks guys. I definitely plan to start slow one way or another.

A quick motor question - why don’t I see more people use the Hobbywing 5687 for speed running? It fits in the stock orientation and looks like a beast of a motor (on paper).
Hard to say.... I have never seen one being used in a speed runner over 120 mph.
Might work just fine.
 
but is that really true? lower voltages means starting off with a motor with higher KV. You can still learn about set ups and gearing with a lower kv motor and higher voltages.

Just wanted to provide an example of an 6s or 8s motor running impressive numbers on 2s.

 
Just wanted to provide an example of an 6s or 8s motor running impressive numbers on 2s.

well to be fair, the 1721 isn't your typical motor. It's extremely versatile and I think even you pointed out somewhere that high speeds on 2s would be difficult secondary to amp draws.
 
I know that's the best plan, but I'm not quite ready to dedicate certain batteries to only speed running. And everything else I own is EC5.

At approximately what speeds and/or current can I expect to have problems? I imagine it can be unpredictable but I'd appreciate any insights on the topic.
You're just going to ruin your bashing batteries by speed running them. Then you'll have to buy more batteries for bashing and still have to go to QS8. Don't mix bashing with speed running you will regret it. good luck.
 
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