[Pioneer4x4]

OK, I did go out Friday evening and made 3 more runs.
Summation, car IS quicker, definitely. Not quite as much as I hoped, but close.
Also, I was fairly dumb, stupid, brain fog, rookie move, that my first 2 runs of 3 had incorrect final trap speed.
Why you all ask, how can everything else on a time slip be correct other than the final MPH at the end of the ¼ mile?
Well, for those of you that don't know, they don't measure you speed AT the end. They measure the time between 2 points right before and at the end to figure out the average speed over that last bit. And why was mine incorrect? I was lifting as I passed the first mark, not the second. So not only did I lost that smidgeon of acceleration, but I decelerated a good bit. My ETs weren't affected much, not at 110mph over 60' or whatever it is, but my MPH was wonky.

Rounding to the 100th of a second and tenths in MPH my best run before the Performance Update was
1/8 mile ET 8.24 seconds
1/8 mile speed 86.2 MPH
1/4 mile ET 12.79 seconds
1/4 mile speed 110.0 MPH

AFTER Performance update
I made 2 runs where I lifted too early. The 2nd run was better, but they were virtually identical.

1/8 mile ET 8.04 seconds (.2 quicker)
1/8 mile speed 89.9 MPH (3.7 MPH Faster)
1/4 mile ET 12.48 seconds (.31 quicker)
1/4 mile speed 109.4 MPH (.6 MPH SLOWER) <- Me being dumb

Then my third run after I figured out that I was the problem, not my car or math...
1/8 mile ET 8.01 seconds (.23 quicker)
1/8 mile speed 89.9 MPH (3.7 MPH faster)
1/4 mile ET 12.43 seconds (.36 quicker) (Now the quickest car I ever drove/owned)
1/4 mile speed 112.8 MPH (.28 MPH faster)

Weather was similar, maybe not quite as chilly, not that it matters much.
Also, I am wondering if the battery pack was warmed up, it would be quicker? I did think of putting on the heat at max for a while, but didn't do it much. But the car was overall a smidge quicker each run, when you'd think that it would be a bit slower as peak voltage drops.
I was hoping for an ET of under 12.4 and dreaming of a 12.2x. Also, I was expecting more like 114/115 MPH.
Anyway, I am pleased. I have a quick car, fun, cheap to drive, no drama, and my wife approves/permitted it all. A win all the way around!
Maybe I'll go again when it is HOT. So warm pack, and thin air. And remove everything loose in the car/frunk, maybe even pop the back seat bottom out, mats, all of that. And maybe get someone that isn't over 250 with clothes and helmet on! (Yes I wore a helmet this time!)
Also, video links to come.

 

[Pioneer4x4]

First run against a modified supercharged 2017 Corvette Z06 running 10s

Second run against a modified Mustang of some kind. (I ran against him the 3rd run and he red lighted (trying to beat me))

 

[M1STER_GR1M]

Awesome info! Thanks, Pioneer!

I'm curious how/if those numbers would change after bumping up the Speed Limiter setting in OrBit 👀

 

[Pioneer4x4]

Awesome info! Thanks, Pioneer!

I'm curious how/if those numbers would change after bumping up the Speed Limiter setting in OrBit 👀

Zero, never going that fast. Maybe in a ½ mile event. I wish it had a bit more torque off the line, that's about it. It never approaches slipping (at the prepped track). I did have Sport mode on FWIW as well. The only thing I can think of that could possibly be done, is to swap in the gear ratio of the Single Motor cars.
Supposedly they are 10.5ish:1 instead of 8.x:1 So 20% more torque at the wheels, but fades earlier to the same max power, and lower max speed until the motors grenade, but should still be good for 130mph, since that was pub lished for the single motor (actually 129)

 

[Pioneer4x4]

Also, I used the Launch app once, and got a 4.1 0-60 on the strip.

 

[M1STER_GR1M]

Zero, never going that fast. Maybe in a ½ mile event. I wish it had a bit more torque off the line, that's about it. It never approaches slipping (at the prepped track). I did have Sport mode on FWIW as well. The only thing I can think of that could possibly be done, is to swap in the gear ratio of the Single Motor cars.
Supposedly they are 10.5ish:1 instead of 8.x:1 So 20% more torque at the wheels, but fades earlier to the same max power, and lower max speed until the motors grenade, but should still be good for 130mph, since that was pub lished for the single motor (actually 129)

I get that you might not get close to the top speed and there's always the possibility that the setting doesn't actually do anything, but we still don't really have any concrete evidence one way or the other, at least not that I've seen. I'm curious if it would raise the threshold for the speed throttling, at the very least. 🤔

 

[Steeeeve]

I get that you might not get close to the top speed and there's always the possibility that the setting doesn't actually do anything, but we still don't really have any concrete evidence one way or the other, at least not that I've seen. I'm curious if it would raise the threshold for the speed throttling, at the very least. 🤔

I have reason to believe that setting doesn't do anything. Don't ask how I know

 

[M1STER_GR1M]

I have reason to believe that setting doesn't do anything. Don't ask how I know

I'm gonna have to ask lol

 

[Pioneer4x4]

I have reason to believe that setting doesn't do anything. Don't ask how I know

Doing a bit of Test and Tune yourself?

 

[Steeeeve]

I'm gonna have to ask lol

Doing a bit of Test and Tune yourself?

Let's just imagine, hypothetically, that a friend of mine changed that setting while I left mine alone. If, in this imaginary scenario, I was able to stay right behind him up to and after, hypothetically, hitting the 127mph speed limiter, then I'd conclude in this hypothetical scenario that the setting had no effect on his car's behavior.

 

[M1STER_GR1M]

Let's just imagine, hypothetically, that a friend of mine changed that setting while I left mine alone. If, in this imaginary scenario, I was able to stay right behind him up to and after, hypothetically, hitting the 127mph speed limiter, then I'd conclude in this hypothetical scenario that the setting had no effect on his car's behavior.

That's pretty much how I would analyze that completely hypothetical situation as well 😂🤣

 

[Pioneer4x4]

Hmm, I need to do some math and see what our cars might hit in a ½ mile event

 

[Pioneer4x4]

Hmm, I need to do some math and see what our cars might hit in a ½ mile event

W.A.G. (based on real math) 135-145 and about 20 seconds. Maybe I'll go to the Kansas event this year and see!

 

[Steeeeve]

W.A.G. (based on real math) 135-145 and about 20 seconds. Maybe I'll go to the Kansas event this year and see!

You'll hit the speed limiter at 127 (205 kph, I believe). The model I've been using suggests 1/2 mile in 19.7 sec at 127mph. It hits the speed limiter at 17 seconds and 0.4 miles. But I'll add that we're probably getting fast enough that this model is no longer super trustworthy - would be interesting to see what happens if you're able to get a proper timed 1/2 mile run.

 

[Pioneer4x4]

You'll hit the speed limiter at 127 (205 kph, I believe). The model I've been using suggests 1/2 mile in 19.7 sec at 127mph. It hits the speed limiter at 17 seconds and 0.4 miles. But I'll add that we're probably getting fast enough that this model is no longer super trustworthy - would be interesting to see what happens if you're able to get a proper timed 1/2 mile run.

What model is that? I worked out that I was accelerating about 2.2 m/s^2 over the last 1/8 mile, then assumed a starting speed of 112.5 mph, and 1/2 mile at somewhere between 1.7 and 2m/s^2 and I came up with that WAG of about 20 seconds as well. Only need to model after the 1/4 mile since I know what that is now ;-)
P.S. Math is cool!

 

[chazglenn3]

All of the P2s are speed limited to 127mph

 

[Pioneer4x4]

All of the P2s are speed limited to 127mph

Let's just imagine, hypothetically, that a friend of mine changed that setting while I left mine alone. If, in this imaginary scenario, I was able to stay right behind him up to and after, hypothetically, hitting the 127mph speed limiter, then I'd conclude in this hypothetical scenario that the setting had no effect on his car's behavior.

Hmm, needs tested for sure

 

[Pioneer4x4]

Also, IF the single motor cars actually do have a 20-25% lower ratio, and can also go that fast, then theoretically, the DM can go faster and still have the motor in safe RPM. Which I cannot confirm as much as I try, but seems like 14,000 RPM

 

[Steeeeve]

What model is that?

I got carried away a while back and made a spreadsheet to do numerical integration of the differential equation of motion. It makes a few assumptions:

1. Aggregate drag force is the sum of rolling resistance and aerodynamic drag
   1. Rolling resistance is assumed to be constant. Used a coefficient of 0.015.
   2. Aerodynamic drag is proportional to velocity squared. Used a drag coefficient of 0.278.
2. Motor power available as a function of speed is approximated by eyeballing dyno curves taken from about the 9 minute mark in this video:
3. Since I don't have great data about the behavior near zero velocity (dyno curves aren't really helpful there), I used initial conditions defined by the average results from my runs on a 1/8 mile drag strip (setting the time, distance, and speed). The model can then project into the future from there, to estimate 1/4 mile, 1/2 mile, whatever.

As the saying goes, "all models are wrong, but some models are useful." There's plenty to nitpick about this, but it seems to do a reasonable job and got pretty close to predicting your 1/4 mile results.

I worked out that I was accelerating about 2.2 m/s^2 over the last 1/8 mile, then assumed a starting speed of 112.5 mph, and 1/2 mile at somewhere between 1.7 and 2m/s^2 and I came up with that WAG of about 20 seconds as well. Only need to model after the 1/4 mile since I know what that is now ;-)

The acceleration will drop faster than that. My model agrees with 2.2 m/s2 average between 1/8 and 1/4 mile. At 1/8 mile it's at 2.94 m/s2, by 1/4 mile it's down to 1.72. Beyond 1/4 mile it'll just keep falling. By the time it hits the 127 mph speed limiter 0.4 miles in, it's estimating 1.30 m/s2.

P.S. Math is cool!

I couldn't agree more!

 

[Pioneer4x4]

I got carried away a while back and made a spreadsheet to do numerical integration of the differential equation of motion. It makes a few assumptions:

1. Aggregate drag force is the sum of rolling resistance and aerodynamic drag
   1. Rolling resistance is assumed to be constant. Used a coefficient of 0.015.
   2. Aerodynamic drag is proportional to velocity squared. Used a drag coefficient of 0.278.
2. Motor power available as a function of speed is approximated by eyeballing dyno curves taken from about the 9 minute mark in this video:
3. Since I don't have great data about the behavior near zero velocity (dyno curves aren't really helpful there), I used initial conditions defined by the average results from my runs on a 1/8 mile drag strip (setting the time, distance, and speed). The model can then project into the future from there, to estimate 1/4 mile, 1/2 mile, whatever.

As the saying goes, "all models are wrong, but some models are useful." There's plenty to nitpick about this, but it seems to do a reasonable job and got pretty close to predicting your 1/4 mile results.


The acceleration will drop faster than that. My model agrees with 2.2 m/s2 average between 1/8 and 1/4 mile. At 1/8 mile it's at 2.94 m/s2, by 1/4 mile it's down to 1.72. Beyond 1/4 mile it'll just keep falling. By the time it hits the 127 mph speed limiter 0.4 miles in, it's estimating 1.30 m/s2.


I couldn't agree more!

1 - sorry, I meany I actually used 1.5-2ms^2 finally, started higher.
I watched that video a while ago, need to do it again for sure.
A couple things I found out is, generally, EV Traction Motors produce near constant torque up to the point that the motor controller can produce max power, then it is near constant power. And the end point of the constant torque is around 4,500 rpm (I'll have to math that out as well)
Also, the increase of torque is only for a few seconds, maybe only 3.
So, I think of it like a normal car with a first gear that runs up to 4500 rpm, then turns into an infinite number of gears (or CVT) that the engine stays dead on its power peak. Which fits, torque drops off with speed after you hit the 350kW mark.
So what does your model say is theoretical top speed? What frontal area did you use?
Now I'll rewatch Misha and see if that graph even fits what I believe.