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Real video vs Dragy or VBOX arguement...

ROH ECHT

K04 PLAY
Location
PDX OR
Car(s)
2007 MKV GTI
So, some of you long time members are somewhat acquainted with me. I am nearly 59 yrs and am not a keyboard racer. Recently on fb, someone messaged me for some K04 boost help. During the conversation he posted a pic of a VBOX 100km to 200km data with 9.x second. I, thinking this was with his boost issue, thought I would post my vid of 60 mph to 120 mph so he would have some reference for when his boost issue is sorted. Yes, 60 to 120 mph is different from 62 mph to 124 mph (equal to 100km to 200km). He follows watching the vid with statements that mine doing 60 to 120 mph in under 8 seconds is impossible...and that he wouldn't believe it until, as he said: "The only thing missing is valid Dragy or VBOX results...so bring them 1/4 mile times"... Yes, he said "valid. I replied GPS performance data app is more reliable than visual proof? Perhaps my speedometer is cheating...I do'no! I then posted my 1/4 mile video showing a few passes at 12.8 at 112 mph. He follows that by saying; it trapping 112 mph is from wheel spin...that wheel spin causes it to trap higher. But I never spin the wheels. It all made me question; "what the H _ _ L is going on in the world today?"

I have seen videos where GPS Performance Data apps are not accurate and can even be off a full second in a 1/4 mile pass. I've seen a VBOX 1/4 mile say the 1/4 mi was done in 11.8 seconds but the timeslip from the same run at the track was 12.8 seconds. He showed me his VBOX says his 100km to 200km is 9.x seconds and his 1/4 mile is 12.1 seconds at 116 mph. Is this the real world now? With that, he feels he has proved mine in no way can do 60 mph to 120 mph in under 8 seconds and that it can only be 10+ seconds...maybe high 9 seconds if DSG...yes, he said this.

So GPS technology is the only real proof? When we still must use our eyes to view both, the video or a VBOX screen. I have never believed people saying their GPS ETs and asked for track slips...but apparently the new time slip is from a GPS screen from some unknown slope on a road.

So, I will add/share the same video I shared with him.
But if you would like to show a VBOX or other GPS Performance Data screen pic beside your timeslip from the track for the same run to confirm accuracy...feel free to do so. In fact, a video would be better so to connect the dots.
 
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vwengineer

Ready to race!
Location
Switzerland
I find it gross from the guy you are trying to help to say that, especially since I trust you. Regarding the arguments of the guy and yours, I see valid points both sides.

I would see it like this track slip > GPS data > speedo video.

Speedo video:

+ a video is difficult to manipulate
+ real speedo data
- no indication of incline, so can be downhill or even on jack stands
- video can be speed up
- speedos are not 100% accurate and often overestimate real speed, in addition you can change the speedo behavior with VCDS

GPS data:

+ some of them display the mean incline of the road
+ quite accurate on a straight line
- not 100% accurate, depends on the number of satellites locked. Although real GPS speed monitors use high sampling rate and big antennas, they are more accurate than a smartphone but not always perfect.

So I would trust more a GPS log than a speedo video but would accept neither of them as proof
 

ROH ECHT

K04 PLAY
Location
PDX OR
Car(s)
2007 MKV GTI
Right, there are faults with them. I expect to be trusted, perhaps naively, when I said to him; the road I did this video on was actually a slight incline...more near the second half. But I get how some will be hesitant to believe another. My disgust was how offensive he got over it all. I even said to him "I was not trying to one up you or your car. I only provided the vid of what mine does from 60 to 120 on the speedo so you have some reference when your boost issue is sorted." He could do with it what he wanted. He could convert it from mph to kmph in assuming his speedo is off as well or disregard it all together. Yes, the speedo is off and I am aware of mine. When I drag it and the time slip shows the trap speed of 111 or 112 mph...and I see 115 or 116 on the speedo when it crosses the line. At 60 mph on the speedo, it is actually doing 58 mph. So my vid shows what is likely a 58mph to 115 or 116 mph run. It's about a 57 to 58 mph increase rather than 60 mph.

I was just thinking, out of curiosity, it might be interesting to see if any have run the 1/4mi with a Dragy or VBOX at the same time. So to see for themselves the accuracy of them.
 
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vwengineer

Ready to race!
Location
Switzerland
Yeah, I get your point. Some people do not deserve help at all.

In case you did not know, you can correct the speedo to display the real speed should you want to with VCDS (changing the impulse number). The car actually knows the real speed, if you use the climatronic secret menu, you can display it. For me it perfectly matches my GPS speed while the speedo is off by around 5km/h at 120km/h but the faster you go, the biggest is the error as you remark.

Regarding GPS accuracy, if they have the ability to record the track, a good check is to display the recorded track on Google earth and look how good it is at following the actual road. If the track cuts through cruves, then it probably underestimate the speed but if it wanders around the road and then back on it although it's straight, probably that the speed is overestimated. GPS is usually quite accurate on a straight section
 
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ROH ECHT

K04 PLAY
Location
PDX OR
Car(s)
2007 MKV GTI
Actually, regarding the speedo, I plan on my next next set of tires to be 235/40-18 @ 25.4"....rather than the current 225/40-18 @ 25.1". The slightly taller tire may correct it some.

If not...I may try the impulse number. But isn't the impulse number always in one direction if you change it? Meaning it always has the speedo reading higher regardless the number?

I believe the climatronic channel is 19.1 for speedo in mph. I can look and see what it knows.
 
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