Haybusa Parts and Service Member Support

Author Topic: Speed Trap read  (Read 168 times)

Offline speedduck

  • Post Whore
  • ****
  • Posts: 655
Speed Trap read
« on: September 13, 2017, 01:37:14 PM »
 Hi guys,
I think you know a lot of land speed history in US,
Do you remember any case of speed traps failing, giving wrong readings ?

Reasons are pretty simple, traps are set wrong, or wind moving them, sun reflections etc.

We had one case this summer, the organizer did not find anything wrong with their equipment, and did not admit there was anything, but,
i have always GPS device on the bike, also most of the fast guys has. You can pull the data and see if there was something on the way you should correct, and,
my speed was way up on the speed traps, GPS was showing slower, also i knew the bike was not capable of that high speeds.
But it remained a mystery what happened. I, and most of other guys, did not accept the official results, it would be just fooling yourself.

Offline FlaminRoo

  • Rider
  • ***
  • Posts: 162
Re: Speed Trap read
« Reply #1 on: September 13, 2017, 04:12:17 PM »
Depending on what height thay are set at, a leaf, piece of paper, even a rodent can trigger the traps beam,, happens quiet often in DragRacing  :)
First Australian to ride a motorcycle 200mph at Bonneville,,

Online KZScott

  • Post Whore
  • ****
  • Posts: 627
  • Gender: Male
Re: Speed Trap read
« Reply #2 on: September 13, 2017, 06:55:34 PM »
i have a drag strip pass with a 600+ mph mid. thats the only one that comes to mind.
01 ZX-12R 8.84 @ 156.3 on dot tires, pump gas, NO power adders.... turbo 8.47 @ 164
00 ZX-12R 8.62 @ 165.2 no bars, slicks, Pump Gas, 55 shot... turbo 8.32 @ 173
00 ZX-12R  1: 222.046 1.5: 226.390 Loring AFB Worlds Fastest NA Kawasaki
00 ZX-12R street turbo 1: 227.9 1.5: 234.1 Loring AFB
00 ZX-12R LSR turbo 1: 263.1  1.5: 266.5 Loring AFB Worlds fastest ZX-12R
Fabricator/Engine builder @ RCC Turbos

Offline speedduck

  • Post Whore
  • ****
  • Posts: 655
Re: Speed Trap read
« Reply #3 on: September 14, 2017, 03:45:39 AM »
i have a drag strip pass with a 600+ mph mid. thats the only one that comes to mind.

Could that be if you did a wheelie partly over the traps, rear wheel cutting the first beam and front hitting the second.

This time we had issues on the mile, the difference was smaller, some riders just thought they had a amazing run. In zero wind.

I had the easiest bike to ride for years, i could open the throttle on first gear, it hovered a bit but stayed down, shifting was easy using quickshifter.
I did 3 runs, speeds were 204.5  , 204.5 and 205. Official speeds from the traps were 212.5 , 206.9 and 203. On the GPS log it showed i closed the throttle just 40-60m after finish line.
My friend who was the first on the track said immediately there was something fishy, he got 10mph extra compared to GPS, and that would be his personal best by a marginal.
So, asking the organizer if they had some issues with the timing, they ran a check, remeasured distances and reboot the program, nothing found.
Not everyone had false speeds, slower cars were spot on, well, those who also carried their own device.

Drama here was they got a new track record, and asking the guy who did it , he also had a race GPS, did not find a data to back it up.
Well, later on, he did improve his personal best on another track, and those equipment was inspected by riders delegation, all good.

Online RansomT

  • Post Master
  • *****
  • Posts: 1069
  • Gender: Male
Re: Speed Trap read
« Reply #4 on: September 14, 2017, 06:26:56 AM »
Now we do know that GPS readings can be waaay off especially at high speeds and acceleration?  While I haven't researched this exhaustively, I have spent a great amount of time examining how GPS units work and why they can be wrong.  It all started when I was getting different readings from the ground based lasers and my GPS unit while at 1 mile events.  Now, of course, the high $$$ units, are not nearly as off, but I'm talking about units that NASCAR and such uses.


GPS erroneous readings happen because of 2 factors: 1) sample rate (which is the reason for lower than true speed).  can be and are often, 1 or 2 per second, even though some units claim down to 1/10th per second.  2) built in logic (which is the big factor for higher than true speed).  So basically, because of the 1 per second sample rate, built in logic tries to fill in the gap between samples. It looks at several previous samples and tries to predict what the next speed "should" be.  If it over shoots the actual speed, which they do often, they don't report the true sample but rather an average of what the satellite sample reports and what their logic says.  After a few 1 second samples, it will correct back to the correct speed. 


You can actually see this at work; accelerate hard for a few seconds and then hit the brakes.  At the moment of the deceleration, your GPS can report an increase in speed and as you slow down it is actually reporting an average of what speed it "thinks" and what it is getting from the satellite ping.
Fastest 1.5-Mile Pass - 252.222
Fastest 1-Mile Pass - 244.2997
Half Mile - 211.47
Fastest Nitrous Bike
Production Bike
211.079 LTA. P/P 1350

Offline speedduck

  • Post Whore
  • ****
  • Posts: 655
Re: Speed Trap read
« Reply #5 on: September 14, 2017, 08:12:46 AM »
What most of the guys use here is Racelogic devices, V-box, Performance box or Driftbox, they have 1/10th s rate. Also some had Motec GPS-L10 , using 10hz.

https://www.racelogic.co.uk/index.php/en/

https://www.youtube.com/watch?v=qXGT0hznLV4

What i found out when i bought the P-box and tried it on 1/4" ml , it was showing higher ET`s , but then discovered it starts to count at the first movement when track clocks start when you cross the timing beam , a bit later.

Online Nosgsx1300

  • Mad Post Whore
  • ******
  • Posts: 2301
  • Gender: Male
  • RCC GT4088R WHOOOT
Re: Speed Trap read
« Reply #6 on: September 14, 2017, 02:29:30 PM »
Years ago DaveO was having real weird entry and exit numbers

He and some other people think they figured out.....................
the timing lights are at a certain Hertz, it is possible for the light to miss the "first half or second half" of your front wheel
giving one number off

Maxton I think lowered the lights and it got better
Dave Even thought it had something to do with the Chrome front wheel, so He swapped it
RCC GT4088R
2011 Loring 204.88mph "naked"
2015 Loring 220.01743 MPH Faired in fifth gear

Online RansomT

  • Post Master
  • *****
  • Posts: 1069
  • Gender: Male
Re: Speed Trap read
« Reply #7 on: September 14, 2017, 03:43:37 PM »
Funny how the GPS companies report how accurate their units are ...

http://www.gps.gov/systems/gps/performance/accuracy/
Fastest 1.5-Mile Pass - 252.222
Fastest 1-Mile Pass - 244.2997
Half Mile - 211.47
Fastest Nitrous Bike
Production Bike
211.079 LTA. P/P 1350

Online KZScott

  • Post Whore
  • ****
  • Posts: 627
  • Gender: Male
Re: Speed Trap read
« Reply #8 on: September 14, 2017, 06:04:27 PM »
i have a drag strip pass with a 600+ mph mid. thats the only one that comes to mind.

Could that be if you did a wheelie partly over the traps, rear wheel cutting the first beam and front hitting the second.

This time we had issues on the mile, the difference was smaller, some riders just thought they had a amazing run. In zero wind.

I had the easiest bike to ride for years, i could open the throttle on first gear, it hovered a bit but stayed down, shifting was easy using quickshifter.
I did 3 runs, speeds were 204.5  , 204.5 and 205. Official speeds from the traps were 212.5 , 206.9 and 203. On the GPS log it showed i closed the throttle just 40-60m after finish line.
My friend who was the first on the track said immediately there was something fishy, he got 10mph extra compared to GPS, and that would be his personal best by a marginal.
So, asking the organizer if they had some issues with the timing, they ran a check, remeasured distances and reboot the program, nothing found.
Not everyone had false speeds, slower cars were spot on, well, those who also carried their own device.

Drama here was they got a new track record, and asking the guy who did it , he also had a race GPS, did not find a data to back it up.
Well, later on, he did improve his personal best on another track, and those equipment was inspected by riders delegation, all good.
no wheelie at the 1/8th on that run, it was a NA stock motor/pipe zx12r with 9 over bolt on extensions. might have been a piece of paper or leaf blowing by at just the right time
01 ZX-12R 8.84 @ 156.3 on dot tires, pump gas, NO power adders.... turbo 8.47 @ 164
00 ZX-12R 8.62 @ 165.2 no bars, slicks, Pump Gas, 55 shot... turbo 8.32 @ 173
00 ZX-12R  1: 222.046 1.5: 226.390 Loring AFB Worlds Fastest NA Kawasaki
00 ZX-12R street turbo 1: 227.9 1.5: 234.1 Loring AFB
00 ZX-12R LSR turbo 1: 263.1  1.5: 266.5 Loring AFB Worlds fastest ZX-12R
Fabricator/Engine builder @ RCC Turbos

Offline speedduck

  • Post Whore
  • ****
  • Posts: 655
Re: Speed Trap read
« Reply #9 on: September 15, 2017, 02:39:28 AM »
I know, i may be too confident with the GPS accuracy.

I remember when they introduced the Racelogic products, everyone was saying the GPS accuracy is couple meters, or more, but the promotion video showed this guy writing in the air wawing the box and you could read on the screen what he wrote.

In the end, it did not hurt having these devices on board, running the mile, mostly we been using to see where did have a wheelspin , or take too long to change gears. Also comparing runs , if i had better first half or not, and did i run long or short.
I could do better on half mile, its been around 210mph, when hitting 250 on the full mile.