P90D Performance/Power Data

[Pete90D]

Nice work, but the accelerometer ossilations are odd. It swings from +6 to -4 g's and affects the speed calculations. Could the vbox be vibrating during that section of the pull?

It's pretty solid on the windshield, but I have no idea what's going on with the Gs

 

[P85]

Nice Pete,

Would be nice to se a comparison run with a P85D/P90D running Insane mode..

 

[Hans (Amsterdam)]

It's pretty solid on the windshield, but I have no idea what's going on with the Gs

I'm not an expert but it seems to be a resonance frequency of 3 - 3,5 Hz. So could be that your Vbox is shaking.
You can do a test by simply hitting your Vbox a little and see if you get the same resonance frequency.
If not maybe it is the windshield that is shaking (acceleration, wind pressure ? ) and you could try moving the Vbox to another solid position.

 

[Pete90D]

I'm not an expert but it seems to be a resonance frequency of 3 - 3,5 Hz. So could be that your Vbox is shaking.
You can do a test by simply hitting your Vbox a little and see if you get the same resonance frequency.
If not maybe it is the windshield that is shaking (acceleration, wind pressure ? ) and you could try moving the Vbox to another solid position.

I just ordered a PerformanceBox, which is what fiksegts appears to be using in his 3.05s P85D run. I don't know if it will make a difference, but it does have a faster update frequency. I'll also need to give the VBOX back to sorka so this will let me test things as updates arrive.

 

[ScepticMatt]

The g force seems much more linear in this one - up to 55, so I think that power (P = m * a * v) should be higher as well, unless this is a measurement error.
Napkin math: 1 g = 9.81 m/s^2 , m = 2250 kg, v = 25 m/s (~55mph) => P ~= 550 kW.

Edit: Nevermind. Thinking about it again, it's probably just change in scale that's throwing me off.

 

[sorka]

Nice work, but the acceleration ossilations are odd. It swings from +6 to -4 g's and affects the speed calculations. Could the vbox be vibrating during that section of the pull?

It's doesn't have an accelerometer and he's using an external antenna so it wouldn't matter. You don't need to mount the vbox at all when using an external antenna.

- - - Updated - - -

I just ordered a PerformanceBox, which is what fiksegts appears to be using in his 3.05s P85D run. I don't know if it will make a difference, but it does have a faster update frequency. I'll also need to give the VBOX back to sorka so this will let me test things as updates arrive.

Keep in mind that the PBox has a frequency of 10 Hz and the VBox is 20Hz. It was the reason I ordered the vbox and gave up having the display of the PBox.

- - - Updated - - -

One more thing to try. To make sure it thinks it's connected to the external antenna, run the iOS app looking at the satellite count and then place any metal plate over the vbox (not the external antenna) and you should see the satellite count unchanged. If you tried that without the antenna plugged in, the count would go to zero.

 

[Pete90D]

It's doesn't have an accelerometer and he's using an external antenna so it wouldn't matter. You don't need to mount the vbox at all when using an external antenna.

- - - Updated - - -



Keep in mind that the PBox has a frequency of 10 Hz and the VBox is 20Hz. It was the reason I ordered the vbox and gave up having the display of the PBox.

- - - Updated - - -

One more thing to try. To make sure it thinks it's connected to the external antenna, run the iOS app looking at the satellite count and then place any metal plate over the vbox (not the external antenna) and you should see the satellite count unchanged. If you tried that without the antenna plugged in, the count would go to zero.

Ah you're right it is slower. I didn't see a lateral G measurement with the VBOX sport, which is one thing I want to measure. I'd like to see if I can pull the 1G Elon mentioned.

I haven't tested putting metal over it, but the satellite light is a constant solid green the whole time.

 

[Matias]

Whatever the reason, the G readings can't be real. From +6 to -4 G:s in 0.1 seconds... I think you would need to hit brick wall to get that. And with crumble zone, would even that cause so fast deceleration?

 

[Pete90D]

Whatever the reason, the G readings can't be real. From +6 to -4 G:s in 0.1 seconds... I think you would need to hit brick wall to get that. And with crumble zone, would even that cause so fast deceleration?

The PerformanceBox shows up Friday so I can test both of them and see what's going on.

- - - Updated - - -

Just sent an email to RaceLogic to find out more.

 

[ScepticMatt]

And with crumble zone, would even that cause so fast deceleration?

easily, a frontal crash into wall is much, much worse. (that's without seat belt or airbags, seat-relative)

http://www.wired.com/2011/04/crashing-into-wall/
human tolerance to linear acceleration

g-force - Wikipedia, the free encyclopedia

 

[Matias]

^Thank you! Very interesting.

 

[sorka]

When I get the vbox back, I'll do some more runs and see if it's as steady as before. That will at least tell us if it's an instrumentation failure or there was some environmental difference between the two cars or their locations.

Pete, did you get a chance to check signal lock by covering up the vbox with the antenna attached?

 

[Pete90D]

When I get the vbox back, I'll do some more runs and see if it's as steady as before. That will at least tell us if it's an instrumentation failure or there was some environmental difference between the two cars or their locations.

Pete, did you get a chance to check signal lock by covering up the vbox with the antenna attached?

I haven't checked the signal coverage since I first got it to verify the location got a good signal. I did email RaceLogic and they said that mounting it anywhere but on metal can cause interference. I had it mounted against the pano roof exterior so I didn't put strong 3M tape on new paint. I'm waiting to hear back from them on what they would recommend.

 

[sorka]

I haven't checked the signal coverage since I first got it to verify the location got a good signal. I did email RaceLogic and they said that mounting it anywhere but on metal can cause interference. I had it mounted against the pano roof exterior so I didn't put strong 3M tape on new paint. I'm waiting to hear back from them on what they would recommend.

The antenna is magnetic but it nothing on the roof was ferris based metal to hold it. I tried the front appliqué, the middle of the movable panel and the rear panel. They all produced about the same results.

Being within 50 feet of my garage in the driveway was enough to induce noise. The only place I got a truly clean signal was out on wide open country road with nothing but fields.

 

[Pete90D]

The antenna is magnetic but it nothing on the roof was ferris based metal to hold it. I tried the front appliqué, the middle of the movable panel and the rear panel. They all produced about the same results.

Being within 50 feet of my garage in the driveway was enough to induce noise. The only place I got a truly clean signal was out on wide open country road with nothing but fields.

They got back to me and said the sunroof is a bad idea because the glass reflect GPS signals. It also has to be parallel to the ground so it can't go on the side of the car. He also mentioned there were some trees that would cause issues, which probably caused the fluctuations.

What is really interesting is that he said the best 0-60 was 3.07s, but vbox verify said 2.810. I hope his was not 1ft rollout because that would mean the data is now way off.

 

[fiksegts]

I tape the external antenna to the rear hatch window.... inside the car...

do we have any higher speed data?

 

[AWDtsla]

View attachment 92790
g-force - Wikipedia, the free encyclopedia

This chart says you can only hang upside down for 6 seconds before it's "intolerable". Hmmmmmm.

 

[Andyw2100]

What is really interesting is that he said the best 0-60 was 3.07s, but vbox verify said 2.810. I hope his was not 1ft rollout because that would mean the data is now way off.

I tape the external antenna to the rear hatch window.... inside the car...

fiksegts--isn't the 3.07 referenced above your time?

Edit: Disregard the above. I thought Pete90D was talking about other recorded times, not his own. (I'm not sure why I was thinking that.)

 

[Pete90D]

This chart says you can only hang upside down for 6 seconds before it's "intolerable". Hmmmmmm.

Oh it totally is. I thought the headaches were bad 30-60 when I was upright, but L-mode upside down was way intolerable. And I couldn't see a damn thing.

 

[sorka]

They got back to me and said the sunroof is a bad idea because the glass reflect GPS signals. It also has to be parallel to the ground so it can't go on the side of the car. He also mentioned there were some trees that would cause issues, which probably caused the fluctuations.

What is really interesting is that he said the best 0-60 was 3.07s, but vbox verify said 2.810. I hope his was not 1ft rollout because that would mean the data is now way off.

Yea, that's the difference between with and without the 1 ft rollout. It's usually between 0.25 and 0.3 seconds.

If you were near any trees at all, that would cause reflections. I didn't get stable rock solid until I was out in open fields.

You could try taping some aluminum foil to the underside of the panoroof right underneath the antenna.