Limitless limitless pinion advice-

[green98tj]

I have limitless with a Castle 1717 motor, XLX2 ESC, corvette CR7 body, stock 34 tooth spur. I've tried a few pinion gears but I'm not getting the speed that I want. Didn't even break 100mph. Most recently I used a 34 tooth pinion. The logs say no temp issues. However, I only got 47k rpm and 67% power out. Seems obvious to go to a smaller pinion based on the logs but with that motor/esc combo I would not think I would have to. Any advice? logs attached. the last run had 34 tooth. before that it was 27 tooth. Thank you!

 

[LibertyMKiii]

Welcome to the forum.

#1 is figure out why you are only reaching 67% power.
I'd start by going through the esc throttle calibration process again.

which radio are you running and how long are your runs in ft?

 

[green98tj]

Welcome to the forum.

#1 is figure out why you are only reaching 67% power.
I'd start by going through the esc throttle calibration process again.

which radio are you running and how long are your runs in ft?

Thanks. That's a good idea. I will try recalibrating. I have the spektrum DX5 transmitter and a SR6100AT receiver. I use AVC. Good question about the length of the run. I have not measured it but I would say about 1000ft.

 

[LibertyMKiii]

Thanks. That's a good idea. I will try recalibrating. I have the spektrum DX5 transmitter and a SR6100AT receiver. I use AVC. Good question about the length of the run. I have not measured it but I would say about 1000ft.

I suspect the re-call will fix most of your issues. Once it does I wanted to share next steps for you....

That Spektrum radio has fairly limited range. Common results indicate the range limits are around 700-800 ft so you are likely pushing the limits of that radio soon at the 100mph mark.
Innovation RC has a good quality video on how to install a signal booster on a radio. This may be something you need to do soon as you near 100+mph.

For a smooth speed run I generally say 10 feet per mph, so this would be around 1000 ft at 100mph.

You likely already know much of this, but the ideal run has a smooth gradual acceleration. Hold full throttle for 3-4 seconds, followed by a smooth deceleration. As you already know this car will eat up that long road quickly!

Good luck and be safe while doing this. Guys have been seriously hurt being struck by a 13+ lbs car at 80+ speeds.

 

[green98tj]

Thanks. More great advice. I'll look for the booster.
I measured my run using the GPS and found my run is between 600 and 700 ft. 1000 ft sounds about right. I did once get to 114mph with a smaller engine/esc combo. with a 600fr run, it was a challenge to get to that speed without spinning out when accelerating and to stop in time. Since the current upgrade it has been one thing after another and have not reached 100mph since.
Last night I recalibrated, took her out, hit the throttle, and heard a grinding noise. Replacing the main input gear is next on the list.

 

[LibertyMKiii]

The bearing for that one takes alot of abuse.
Probably worth changing that bearing at the same time.

One problem after another pretty much sums up speed running. (probably RC cars in general)
It is challenging, but so rewarding when you hit new personal bests.

 

[RedondoBeachRC]

As mentioned earlier, look at re-calibrating the transmitter and ESC.

As for determining pinion, I would look at amp load, ESC/motor temps, and voltage for determining when to go up or down on the pinion. If your amp loads are low, temps are cool and voltage isn’t sagging excessively you can look at increasing your pinion size.

However, there are a bunch of things to consider such as the way you’re driving it, how far you’re driving it, batteries you’re using etc as these all play into the equation.

For example, a novice like me may cap out at 100mph on a setup but a skilled driver may get 5-15mph or more on the exact same setup.

Post your data logs, battery info, motor kv, GPS screen shot etc. the more info the better in helping you reach your goals.

If this helps; I use a Spektrum 160A ESC, 2050kv Spektrum motor, 27t pinion, 46t spur (from an infraction), (2) 4S CHNL 70c g+plus, and Perfect Pass. I’ve gotten to 109mph with this setup

 

[SrC]

I suspect the re-call will fix most of your issues. Once it does I wanted to share next steps for you....

That Spektrum radio has fairly limited range. Common results indicate the range limits are around 700-800 ft so you are likely pushing the limits of that radio soon at the 100mph mark.
Innovation RC has a good quality video on how to install a signal booster on a radio. This may be something you need to do soon as you near 100+mph.

For a smooth speed run I generally say 10 feet per mph, so this would be around 1000 ft at 100mph.

You likely already know much of this, but the ideal run has a smooth gradual acceleration. Hold full throttle for 3-4 seconds, followed by a smooth deceleration. As you already know this car will eat up that long road quickly!

Good luck and be safe while doing this. Guys have been seriously hurt being struck by a 13+ lbs car at 80+ speeds.

+1
All excellent points there.
Need alot of space. Radio range is most important to speed running. Or it can't be done.
And need to absolutely reach Full ESC power out.

 

[green98tj]

Happy Holidays/Merry Christmas,
I recalibrated and am up to 79.8 power out and got up to 96mph. It was a pretty nice run. Was able to hold the throttle open for more than just a split second. 44 tooth spur, 34 tooth pinion and to repeat, 1717 castle with XLX2 ESC. The data from the last run is attached. Any ideas on the 79.8 power issue?

Thank you!

 

[LibertyMKiii]

Happy Holidays/Merry Christmas,
I recalibrated and am up to 79.8 power out and got up to 96mph. It was a pretty nice run. Was able to hold the throttle open for more than just a split second. 44 tooth spur, 34 tooth pinion and to repeat, 1717 castle with XLX2 ESC. The data from the last run is attached. Any ideas on the 79.8 power issue?

Thank you!

I am not experienced with the DX5, but maybe a setting is off for the throttle in the radio?

Also sometimes when you squeeze the trigger to calibrate the throttle on the ESC you might over squeeze. Try doing it more gently.

 

[green98tj]

Good Morning Everyone, I recalibrated again and made three nice runs down my street and back. 92% power out. I went ro a 36 tooth pinion and top speed went down to 92mph. At this point I'm thinking I just might need a longer run. I probably only have about 600 ft of workable street. Not sure about the 36 tooth pinion. Wondering if I might be better off going down to 34 or so especially with my short run. Data is attached. Any ideas or advice? thanks as always!

another screenshot

 

[LibertyMKiii]

Good Morning Everyone, I recalibrated again and made three nice runs down my street and back. 92% power out. I went ro a 36 tooth pinion and top speed went down to 92mph. At this point I'm thinking I just might need a longer run. I probably only have about 600 ft of workable street. Not sure about the 36 tooth pinion. Wondering if I might be better off going down to 34 or so especially with my short run. Data is attached. Any ideas or advice? thanks as always!

View attachment 192679
another screenshot

Check out this thread and specifically post #13
We need to look at one specific run closely to see how the throttle, amperage, rpm, and voltage look.
https://www.arrmaforum.com/threads/speed-runners-reading-castle-data-logs-and-esc-settings.37182/

I agree that 600ft is very short for attempting 100+ mph. Try to get on a longer road and count out loud as you pull the throttle back. Ideally you want it to take 5-7 seconds to reach full throttle.

 

[green98tj]

Here's a screenshot of the last run. I forget the exact speed. mid 90's.

 

[vwturbowolf]

Here's a screenshot of the last run. I forget the exact speed. mid 90's.

View attachment 193933

You need to zoom in the graph just to show the run from where you start to where you let off, and then take a photo of that and the data at the bottom for us to be able to read.

Like this

 

[green98tj]

Hit 109mph yesterday. Tried different batteries. Used Zeee 9000mAh/100C.. Was Using the SMC V2 800mAh/120C batteries which are good. I believe, but these were worn out.

 

[green98tj]

108
108 mph run yesterday. Power out was 99.1. RPM nearly 70k. 34 tooth pinion. Getting there. Any thoughts anyone?

 

[vwturbowolf]

108
108 mph run yesterday. Power out was 99.1. RPM nearly 70k. 34 tooth pinion. Getting there. Any thoughts anyone?

Can you add the data figures on the bottom.

108
108 mph run yesterday. Power out was 99.1. RPM nearly 70k. 34 tooth pinion. Getting there. Any thoughts anyone?

From first glance it looks like your run up to full speed is a little fast. Around three seconds. Try to spread that out to around 6 and it’ll help the load that’s put on the battery.
Also if it is the 1717 1650kv I don’t think you will reach that high rpm. Limit is 56k and will voltage drop you should be seeing 35-45k

Go to the drop down tab and edit pole count/motor info,
Make the gearing numbers 1:1
Type in the kv and 4 pole
That will correct the rpm numbers


You are getting a ton of voltage sag. Down to what looks like 24v on 8s and that basically your batteries not being up for the challenge
They’ve dropped to 3v per cell during the heaviest load. Lower than 3.2 is gonna cause some battery damage as well

 

[LibertyMKiii]

108
108 mph run yesterday. Power out was 99.1. RPM nearly 70k. 34 tooth pinion. Getting there. Any thoughts anyone?

Please take a minuite to read this thread.
It will help you navigate the castle logs and then we can help you better.
In the logs don't enter the gearing as it then modifies the RPM values. (all mentioned in the thread)

https://www.arrmaforum.com/threads/speed-runners-reading-castle-data-logs-and-esc-settings.37182/

 

[RedondoBeachRC]

Shouldn’t the the power output and throttle input plateau when it’s at full throttle?

 

[green98tj]

Liberty-thanks for the info. I'm working on figuring out how to add the data

Can you add the data figures on the bottom.

From first glance it looks like your run up to full speed is a little fast. Around three seconds. Try to spread that out to around 6 and it’ll help the load that’s put on the battery.
Also if it is the 1717 1650kv I don’t think you will reach that high rpm. Limit is 56k and will voltage drop you should be seeing 35-45k

Go to the drop down tab and edit pole count/motor info,
Make the gearing numbers 1:1
Type in the kv and 4 pole
That will correct the rpm numbers


You are getting a ton of voltage sag. Down to what looks like 24v on 8s and that basically your batteries not being up for the challenge
They’ve dropped to 3v per cell during the heaviest load. Lower than 3.2 is gonna cause some battery damage as well

Thank you for the info!!!

Please take a minuite to read this thread.
It will help you navigate the castle logs and then we can help you better.
In the logs don't enter the gearing as it then modifies the RPM values. (all mentioned in the thread)

https://www.arrmaforum.com/threads/speed-runners-reading-castle-data-logs-and-esc-settings.37182/

Thank you. I am working to get that bottom part included but it's weird that print screen and the castle export both don't show it. reading your guide. Thanks.

Shouldn’t the the power output and throttle input plateau when it’s at full throttle?

I don't know. Should they?