Motor RPM.

[TheStenchOfSpeed]

Just wondering how much motor rpm some of you guys are seeing on your faster top speed runs. Trying to learn a little about these motors ratings and how that relates to real world speed. The fastest I have seen so far is just shy of 30,000 rpm.

The Stench

[AnthonyV]

1650kv X 25.1v = 41,415 rpm theoretically.

I'll be doing some data logging tomorrow so I'll chime back in with some results.

[BennyG6]

those would be rpms with wheels off the ground , after figuring out weight of car and the power transfering to the wheels on the ground your probably more looking at a more realistic 3.7-3.8V goin through the car .. I highly doubt its getting 4V to the wheels

[TheStenchOfSpeed]

That's what I'm looking for.....actual rpm under heavy load.

[AnthonyV]

I did some runs today... I saw 32,400-32,500 at 98mph (GPS Verified). I got a very nice datalog of the 98mph pass.

[TheStenchOfSpeed]

I did some runs today... I saw 32,400-32,500 at 98mph (GPS Verified). I got a very nice datalog of the 98mph pass.

Ok, great info. What mph did the telemetry say? Had to be 107 or better?

[AnthonyV]

98MPH on GPS and 114MPH on Telemetry. Voltage was 21.8 - 22.2v up top. I pussed out though because I kinda feathered the full throttle. That run was the first time I've actually hit full throttle on a run and stayed completely planted on the ground.

[TheStenchOfSpeed]

What's the rollout on those foam tires?

[AnthonyV]

That should answer all of your questions, lol. As you see, I pussed out on the throttle after about 100mph on the datalog. The 'almost at 100' was a reference to throttle not speed. This feature on the traxxas app is really awesome being that you can record everything including voice/sounds.

And as far as how the tires launch compared to a stock XO-1...

[TheStenchOfSpeed]

I was just wondering about the tire height though. How tall is that tire versus the stock XO-1 tire, and have you recalibrated to account for any difference? Just wondering.

[AnthonyV]

Stocks are 4.2" and the BSR's are 4.1". I have not used a caliper to check the current height after running them for several sessions. I have not changed anything on the traxxas app... I was getting skewed readings before as far as the MPH telemetry goes with the stock slicks. I would have changed the settings in the app for the tire size but you cannot program a custom height unfortunately.

[TheStenchOfSpeed]

Yeah, I know. I wish they would come out with an update that would allow entry of any tire size. Interesting none the less. I don't know how fast mine has gone, because I'm waiting on the traxxas gps sensor. I was just wondering how yours compares. It looks like the TRX app uses some fuzzy math. I don't see how 32,500 rpm with a 4.1 inch tire, a 34/46 gear and a 2.85 rear gear equals 114 mph? Something is fishy.

[AnthonyV]

Is the ETA on the 6551 GPS still early July? I would really like to add this to the XO1 but now I have a boat too. I'll probably end up with the GPS system as well as the Bushnell radar gun.

I have been meaning to sit down and figure out the mathematics behind the telemetry... but it's kind of a waste of time. I know how off the readings are at this point so I can kind of calculate my top speeds based on what the Telemetry says. I need about 116-118mph on the telemetry to clock 100+ on a GPS.