[HAMMERHEAD15]

Yep all the great engineering that went into this car and then they do something like that! Why not try to make it accurate!

[tbrennyZL1]

Originally Posted by HAMMERHEAD15

What sensor tell the car what the MPH is?

Originally Posted by HAMMERHEAD15

Yep all the great engineering that went into this car and then they do something like that! Why not try to make it accurate!

With the exception of the spinning it has proven to be pretty accurate for 1/4 mile runs compared to slips.

[JimmyJak]

Originally Posted by Android42019

It's the auto trans, it's super quick, someone I know on Instagram got a 3.2 with a car full of people.

........and a 200 lb set of barbells in the trunk

[HAMMERHEAD15]

Originally Posted by tbrennyZL1

With the exception of the spinning it has proven to be pretty accurate for 1/4 mile runs compared to slips.

We will have agree to disagree on that one!

[tbrennyZL1]

Originally Posted by HAMMERHEAD15

We will have agree to disagree on that one!

Have you ran at the strip and have some PDR videos and slips? I'd definitely like to see some good videos.

[HAMMERHEAD15]

Yes I have and yes I do! The PDR time is always slower than the track time.

[Blown355]

The one time I remembered to hit record before running down the track they were pretty close. PDR said 12.00, timeslip said 11.92.

[TLSTWIN]

You would think with all the abs sensors and such there is a logarithm that would calculate the distance covered based on the revolution of the front wheels, while the speed is calculated off of the rear wheels. There are abs sensors on all 4 corners monitoring wheel spin/slip. I would say it's gotta be fairly accurate based on that, or at least simple enough to correct, but I don't know car electronics

[travislambert]

Unless you're riding wheelies down the track, calculating distance from the front wheel speed sensors should be trivial. I can't imagine the GM engineers got that wrong. Are we certain that isn't what they're doing?

I would expect there is some calculation error due tire manufacturing tolerances, tire wear, tire sensor error, etc. that would impact the accuracy of the performance timers.

[HAMMERHEAD15]

Originally Posted by travislambert

Unless you're riding wheelies down the track, calculating distance from the front wheel speed sensors should be trivial. I can't imagine the GM engineers got that wrong. Are we certain that isn't what they're doing?

I would expect there is some calculation error due tire manufacturing tolerances, tire wear, tire sensor error, etc. that would impact the accuracy of the performance timers.

Turn Your PDR to record and do a burn out and see if the speedometer registers MPH. If it does then turn the wheels up to 60MPH and see if it clocks it. If it does then it can't be anywhere near accurate. Right?

[hashtag]

The other night I did not even really try. Temperature was in the 90s. I was thinking maybe a 4 sec 0-60 & achieved the advertised 3.5.

[17CamaroZL1]

My experience shows very accurate PDR times compared to the drag strip. Yes the PDR is always .1 to .2 seconds slower than your time slip, because the PDR starts timing the instant the car moves. The drag strip doesn't start timing until your front tires move out of the last staging beam. I've always heard the drag strip has .2 second rollout that isn't included in the time based on initial car movement, so it seems the PDR is very accurate. The in-dash timer seems to perfectly match the time slip, the couple of times I've tried it at the track, and the multiple times I've used it and PDR to record 0-60 runs on the street.

I've not recorded all of my passes like I plan to, simply because I forget to push record, but the ones I have even show my 1/4 mile time pop up on screen just as I hit the finish line. The only descrepency I've seen between the slip and PDR is the trap speed. One example, the video shows me hitting the first trap speed line at 125 and hitting the finish at 127. This should give me an average trap speed of 126, but the time slip was 123. I was running 18 psi in the rear tires, so maybe that's where the difference lies. More testing will definitely be happening. Last trip down the strip, I tried the recommended 26 psi and managed the same 1.89 60' I ran with the lower air, but I forgot to push record so I could match trap speeds. Maybe next time. Lol!

[17CamaroZL1]

With regards to spinning during a 0-60 run and creating a false fast time, my car is usually finished spinning by the time I get to around 30 mph. It's just a steady hard pull from there to 60 mph, so I've never encountered any false 0-60 times due to tire spin. My best so far is a 3.6 I did on the street with no prior burnout or anything. Just stop, hit the timer, and punch it. 3.8 is very easy to hit. I've only went over 4 when playing with launch control or spinning more than usual. I'm very confident the car will do better than the advertised 3.5 and I've likely done it at the strip, but haven't had the in-dash timer running on my faster runs. One of the times I did use the in-dash timer, I had a 1.95 60' and an 11.69 slip. The dash timer showed 3.6 0-60 and 11.6 1/4. My best 60' so far is 1.84, so it stands to reason that I likely had a 3.5 or better 0-60 on that one.

[dotfiles]

Originally Posted by 17CamaroZL1

My experience shows very accurate PDR times compared to the drag strip. Yes the PDR is always .1 to .2 seconds slower than your time slip, because the PDR starts timing the instant the car moves. The drag strip doesn't start timing until your front tires move out of the last staging beam. I've always heard the drag strip has .2 second rollout that isn't included in the time based on initial car movement, so it seems the PDR is very accurate. The in-dash timer seems to perfectly match the time slip, the couple of times I've tried it at the track, and the multiple times I've used it and PDR to record 0-60 runs on the street.

I've not recorded all of my passes like I plan to, simply because I forget to push record, but the ones I have even show my 1/4 mile time pop up on screen just as I hit the finish line. The only descrepency I've seen between the slip and PDR is the trap speed. One example, the video shows me hitting the first trap speed line at 125 and hitting the finish at 127. This should give me an average trap speed of 126, but the time slip was 123. I was running 18 psi in the rear tires, so maybe that's where the difference lies. More testing will definitely be happening. Last trip down the strip, I tried the recommended 26 psi and managed the same 1.89 60' I ran with the lower air, but I forgot to push record so I could match trap speeds. Maybe next time. Lol!

Yep, discrepancy between drag strip slip and PDR can be accounted for by the rollout before the strip starts timing vs PDR starting the timer the moment the car moves. At the strip your car has to move a bit before breaking the beams