[Sven59]

Originally Posted by wnta1ss

No, that PDR was not truly accurate in it's reported 1/4 mile times. Had errors which varied, sometimes two tenths off, other times close, or even very close. Error was not consistent, so you don't know if the time it gives was close or way off unless you have a real piece of test equipment, namely dragstrip timing lights, to tell you. The onboard timer is for entertainment only.

How do you know that if it isn't verified by other equipment?

[wnta1ss]

Originally Posted by Sven59

How do you know that if it isn't verified by other equipment?

Cal was kind enough to give us the PDR readings and the real dragstrip timing light readings for 9 runs on the dragstrip. It's in his thread linked from his 1/4 mile thread. Below is a comparison of PDR to real timeslip using his data. Since the PDR reads to 2 decimal places, I rounded the real times to the 2nd decimal place for this comparison.

1 of the runs, the PDR was optimistic by .22
1 of the runs, the PDR was optimistic by .20
1 of the runs, the PDR was optimistic by .19
1 of the runs, the PDR was optimistic by .13
1 of the runs, the PDR was optimistic by .09
1 of the runs, the PDR was optimistic by .04
1 of the runs, the PDR was optimistic by .02
2 of the runs, the PDR was pessimistic by .01

Definitions: by optimistic I mean a better time, and by pessimistic I mean a worse time than the dragstrip timing lights recorded.

[17CamaroZL1]

Originally Posted by wnta1ss

No, that PDR was not truly accurate in it's reported 1/4 mile times. Had errors which varied, sometimes two tenths off, other times close, or even very close. Error was not consistent, so you don't know if the time it gives was close or way off unless you have a real piece of test equipment, namely dragstrip timing lights, to tell you. The onboard timer is for entertainment only.

No, it wasn't exact, but very close on nearly every run. From the conversation with the driver, we think tire spin may be part of the inconsistencies, but we don't know for sure. If it is, then the less spin you have, the more accurate it will be.

I prefer a time slip from the strip myself, but even then, you can get a bogus reading from time to time. Debris blowing through the traps, animals running through them, etc. I've seen it happen. In those instances the PDR would be way closer to being accurate. Entertainment or not, the PDR is close enough to give someone an idea of what they can expect at the strip with similar traction and air.

[Sven59]

That's good, but will need more data. 1 car is not a good sample. But averaging a tenth off isn't bad.

[17CamaroZL1]

Originally Posted by wnta1ss

Cal was kind enough to give us the PDR readings and the real dragstrip timing light readings for 9 runs on the dragstrip. It's in his thread linked from his 1/4 mile thread. Below is a comparison of PDR to real timeslip using his data. Since the PDR reads to 2 decimal places, I rounded the real times to the 2nd decimal place for this comparison.

1 of the runs, the PDR was optimistic by .22
1 of the runs, the PDR was optimistic by .20
1 of the runs, the PDR was optimistic by .19
1 of the runs, the PDR was optimistic by .13
1 of the runs, the PDR was optimistic by .09
1 of the runs, the PDR was optimistic by .04
1 of the runs, the PDR was optimistic by .02
2 of the runs, the PDR was pessimistic by .01

Definitions: by optimistic I mean a better time, and by pessimistic I mean a worse time than the dragstrip timing lights recorded.

Actually, even though the PDR shows 2 decimal places, it seems to only read to 1. If you notice, it always has a 0 in the second decimal place.

Also, if you notice his best runs on the track have the PDR and time slip pretty much identical. That proves our (Cal and I) theory that less tire spin equals more accuracy. More testing under different conditions will need to be made to draw a better conclusion, but being within a tenth or less most every time is pretty impressive to me.

[newmoon]

To claim a time of 11:40s based off of the car's PDR is ridiculous. To date the fastest M6 ZL1 has run 11:80s in mid winter weather at a drag strip. It seems to be consistant or slightly quicker than M6 Hellcats, and slower than 13/14 500s.

[Sven59]

Originally Posted by newmoon

To claim a time of 11:40s based off of the car's PDR is ridiculous. To date the fastest M6 ZL1 has run 11:80s in mid winter weather at a drag strip. It seems to be consistant or slightly quicker than M6 Hellcats, and slower than 13/14 500s.

You really hate ZL1S don't you. Admit it, you can get help if you admit you have a problem.

[17CamaroZL1]

Originally Posted by newmoon

To claim a time of 11:40s based off of the car's PDR is ridiculous. To date the fastest M6 ZL1 has run 11:80s in mid winter weather at a drag strip. It seems to be consistant or slightly quicker than M6 Hellcats, and slower than 13/14 500s.

The proof is in the pudding. If PDR proves within a .1 on the strip, then it's going to be the same on the street. Does 11.5 make you feel better?

[newmoon]

Originally Posted by Sven59

You really hate ZL1S don't you. Admit it, you can get help if you admit you have a problem.

Actually if any other brand x was claiming to be over 4-tenths faster than the manufacturer claims, anyone or any publication has ever run at an actual strip with timers I would be just as critical and you would be too.

[Sven59]

Originally Posted by newmoon

Actually if any other brand x was claiming to be over 4-tenths faster than the manufacturer claims, anyone or any publication has ever run at an actual strip with timers I would be just as critical and you would be too.

You might want to ask Big Dave, he ran 4 tenths faster than the factory claim with his 5th gen. Also with the 5th gen they did many passes and I believe that was a prepped surface. They just barely broke 12 and Big Dave managed to get that down to 11.591.

[17CamaroZL1]

Originally Posted by newmoon

Actually if any other brand x was claiming to be over 4-tenths faster than the manufacturer claims, anyone or any publication has ever run at an actual strip with timers I would be just as critical and you would be too.

GM claimed their times were made on an unprepped surface and AL O. that led the project said he fully expects their numbers to be easily duplicated and beat. Some manufacturers over rate and some under rate. Dodge under rated the power of the Hellcat, but claimed numbers that are nearly impossible for anyone to actually do on their own. GM seems to have rated their engine about right, but under rated what the car can do time wise, or least didn't throw out some hero run number like Dodge apparently did.

[newmoon]

Originally Posted by 17CamaroZL1

GM claimed their times were made on an unprepped surface and AL O. that led the project said he fully expects their numbers to be easily duplicated and beat. Some manufacturers over rate and some under rate. Dodge under rated the power of the Hellcat, but claimed numbers that are nearly impossible for anyone to actually do on their own. GM seems to have rated their engine about right, but under rated what the car can do time wise, or least didn't throw out some hero run number like Dodge apparently did.

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You may be right but until the car actually runs the number in a timed session at the strip we really shouldn't be stating that it is an 11:40s car. Am I wrong?

[17CamaroZL1]

Originally Posted by newmoon

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You may be right but until the car actually runs the number in a timed session at the strip we really shouldn't be stating that it is an 11:40s car. Am I wrong?

Well, like I said, I prefer seeing numbers on a slip too, but when you see slip times compared to the PDR and they're pretty much within a tenth for the most part.....it's hard to argue against. I believe he actually posted the 11.4 PDR video before he took it to the strip. I was kinda like you and dismissed it really, until he took it to the strip and posted up time slips along side the PDR. After seeing how close it is, I can see it doing that at the strip with better track prep. Everyone that posted about that particular track said how scarey slick it is from the tree to the traps and a few said they'd never go back there. Cal wants to put it on paper too, for this exact reason. Less to dispute.

[Zeke.Malvo]

Originally Posted by newmoon

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You may be right but until the car actually runs the number in a timed session at the strip we really shouldn't be stating that it is an 11:40s car. Am I wrong?

I agree.

The PDR times seem to range from very consistent (4 runs averaged only being off by ~.01) to mediocre (the other 5 runs averaging ~.17). Just going by statistics alone, the times are more likely to be off by .17 than by .01. My old GTECH was more consistent than that.