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Originally Posted by heavychevy
(Post 1597763626)
I considered that but eyeballing the video Mero carries 2 more mph through oaktree (comparing fastest laps) and ends up at 175 vs 164. He also carries more momentum and the car washes out a bit on him so his throttle application was delayed, quite possible Poor-sha was back on the gas first. And yes you can late turn in and late apex and early throttle and get higher speeds on a straight.
I timed from 150-160 mph and Mero's car did it in 2.2 vs 3.6 seconds. And thats if you count after the dip that occurs with the shift to 5th. Included it's over 2 seconds delta. Call it what you want. These cars are not putting down anywhere near the same hp at those separate moments. It would take Heat soak, drag from wing angle, much slower exit, less than full throttle and early braking to add up to 11 mph. We know he doesn't leave much on the table on exit or braking. Also about 8 tenths delta from the end of the curb exiting oak tree to the first brake marker. That's several (almost 5) bus lengths at 160 mph You can see the frost on the ZR1 Mero drove. I would attribute it to the cold weather at least some. But no other factors make this scenario fit completely. |
Originally Posted by heavychevy
(Post 1597763626)
I considered that but eyeballing the video Mero carries 2 more mph through oaktree (comparing fastest laps) and ends up at 175 vs 164. He also carries more momentum and the car washes out a bit on him so his throttle application was delayed, quite possible Poor-sha was back on the gas first. And yes you can late turn in and late apex and early throttle and get higher speeds on a straight.
I timed from 150-160 mph and Mero's car did it in 2.2 vs 3.6 seconds. And thats if you count after the dip that occurs with the shift to 5th. Included it's over 2 seconds delta. Call it what you want. These cars are not putting down anywhere near the same hp at those separate moments. It would take Heat soak, drag from wing angle, much slower exit, less than full throttle and early braking to add up to 11 mph. We know he doesn't leave much on the table on exit or braking. Also about 8 tenths delta from the end of the curb exiting oak tree to the first brake marker. That's several (almost 5) bus lengths at 160 mph You can see the frost on the ZR1 Mero drove. I would attribute it to the cold weather at least some. But no other factors make this scenario fit completely. |
Originally Posted by SBC_and_a_stick
(Post 1597766818)
Maybe GM is icing the intercooler water, depleting the fluids in the car to bare minimum (not just fuel). Things I wouldn't do with my car if I wanted to be driveable the next day... Big delta though. Math in motorsport sometimes doesn't add up.
Anyone else notice how great the conversation has been without.....um........beetlejuice? |
Originally Posted by heavychevy
(Post 1597766933)
Poor-sha's sample was taken on his 5th lap, it's just as possible that the ZR1 only makes max power for the first lap or two and drops off considerably once heat sets in. He was in traffic for the first two so we can't say for sure. This platform is still based on the C7Z which clearly has/had heating issues. Unlikely they completely eradicated heat soak and power loss from where they started. If he hits 170-175 or so in his later year event, this convo is moot. That takes A LOT of courage to trust the braking at that point.
Anyone else notice how great the conversation has been without.....um........beetlejuice? |
Poor-sha/Mero; different days, different pilots, different cars. Hard to compare and so many different factors.
Call me coy, but I keep harping on the weight side... Just an example on how things can be skewed.. I found the AP racing weights mentioned by Poorsha (thanks BTW!) https://www.corvetteforum.com/forums...post1590745949 http://www.brembo.com/it/company/new...t-brembo-freni For the fronts AP say 3 pounds heavier than CCM, Brembo says 7 pounds heavier for a total delta on 25 pounds...no big deal I surmise but when added all together with other factors.. Brakes weight, 3ZR trim versus 1ZR 200 (pounds delta), A8 versus M7 (70 pounds+ delta) , run flats versus Pirelli scrubs( cannot recall the weight difference from Poorsha man) and we are starting to talk about two different cars...and two different trained pilots.. Just pointing out some basics of why the math may not add up... |
Pirellis are super light. Almost certainly erase the weight added by brakes. The M7 would be the lighter of the two, no? Based on trim?
BTW, the manuals seemed to consistently hit higher top speeds in the Z06 on track. Now that I have looked at it. The car Milner lapped RA in had been hot lapped all day by press and pro drivers. It only reached 154 mph. I can show you videos of amateurs going several mph faster (up to 10) than Tommy Milner's 1:29 in C7Z's but still a few seconds slower. Almost certain this is heat soak related. Tommy top speed 154 (heat soaked) Vinnie 158 buddy of mine (races trans am now) Eric 164 (November in cold weather) |
All true. Poor-sha shared the considerable weight savings of scrubs plus 18 inches..
But now with the "heat soak" factor I guess I lost the plot of what we are pursuing... I thought heat soak was introduced as a slowing factor..but we are also saying Mero and Millner enjoy slower straight line speeds but faster laps heat soaked..? Assuming parity of driving abilities...then it reasons that a heat soaked heavier A8 ZR1 is still faster than a non heat soaked lighter M7? My head hurts.. LoL Cheers. |
Lol, no, just trying to find the root cause of the top speed discrepancy. The pros and test drivers will have a faster lap time regardless. But we are trying to find why the same ZR1 can be 11 mph slower on the same straight. At first we thought it was gearbox,driver discrepancy, weight, etc. But you have to look deeper in this case. Hot laps kill the top speed of the car though it can still turn fast laps.
But how much does one lose with that straight line speed. It's certain that Tommy Milner, with a non heat soaked car would have gone substantially faster at Road Atlanta. As would Poor-sha have at VIR. I think GM really put the results of the testing for this vehicle in the hands of the media. If they did all the other tests and driving impressions before the hot lap tests, it could affect the times significantly. 9 or 11 mph difference is near a second lost ON JUST ONE STRAIGHT. Compound that over a lap and https://cimg2.ibsrv.net/gimg/www.cor...cf94f33cff.jpg So keep this in mind when the test results come out. There is a much bigger window with max vs average performance in the ZR1. I have in the past done calculations based on straight line speed at VIR main course. I estimated a car 10 mph slower on the main straights to be at LEAST 2.5 seconds slower overall on the lap losing time on front straight, back straight and the straight into the esses mostly and a few other small spots in there. Poorsha was 6 or so seconds slower than Mero in his first time at VIR in the ZR1. I contend that non heat soaked, he does low 2:55 or so. Driving the same as he did before. But it would have to be clean laps, cold weather, cold car and hot tires. Not at all easy to do with slicks before heat soaking the engine with warm up laps. The ZR1 may not test well in independent hands based on this. If they drove it a bunch before hand and heat soak it. It's gonna cost some time in performance stats. |
I'm a data driven guy, give me a video of a car's lap and a stop watch and I can tell you exactly where time is lost to another vehicle, every time.
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What was the air temp during both runs? Cooler air during mero’s run would be a notable advantage even if heat soak wasn’t the root cause (which it could still be) Regardless, a 700+ HP supercharged and heavy car probably isn’t the best “race car.” Meaning repeated fast consistent laps but the sheer performance available can make for a great hot lap car given the right conditions. If I was running a YouTube channel, I’d shift from “hero laps” to showing people the average and car behavior over a 20min continuous run as that would demonstrate close to actual track experience. That would give a better indication as to which cars are really cut out for this type of activity. Long term tests would include multiple track days so you can add up consumables, issues and other findings. |
Originally Posted by Newton06
(Post 1597763409)
Mero could (and was likely) simply getting on the gas earlier and more aggressively.
Coming though Oak Tree or Hogpen with a minimal improvement in corner speed or throttle application nets a big delta at T14 & T1 respectively. I doubt the car he was driving was a 'ringer'.... |
Originally Posted by meadowz06
(Post 1597771277)
BINGO. He is a PROFESSIONAL driver!
Anywhoo back to the topic...... A European GT2 RS owner says that Manthey (a Porsche factory race team outfit and aftermarket supplier) ran a 2:31 at Spa in their modified GT2 RS. The same car did 2:35 on regular cup 2. There is a video of the cup r run on YouTube. And this was a pro driver they use. 4 seconds is a long time. Spa is a long lap at 4.3 miles but much of it is WOT where grip time is not being gained or lost because of traction. Just an FYI since the GT2 RS ran multiple types of tires at the the test. |
Originally Posted by heavychevy
(Post 1597777151)
It doesn't take a professional driver to get the max speed in a straight line. In fact pro's are more inclined to brake a tad earlier tan some DE drivers because the important part is having the car settled for entry, and early turn in, rather than late braking.
Anywhoo back to the topic...... A European GT2 RS owner says that Manthey (a Porsche factory race team outfit and aftermarket supplier) ran a 2:31 at Spa in their modified GT2 RS. The same car did 2:35 on regular cup 2. There is a video of the cup r run on YouTube. And this was a pro driver they use. 4 seconds is a long time. Spa is a long lap at 4.3 miles but much of it is WOT where grip time is not being gained or lost because of traction. Just an FYI since the GT2 RS ran multiple types of tires at the the test. |
Originally Posted by meadowz06
(Post 1597781708)
Professional driver has better cornering speed AND better straight line speed. The total package.
In this case Mero has more seat time, better weather and a car making more power on its hot lap. |
Originally Posted by Telepierre
(Post 1597767515)
Poor-sha/Mero; different days, different pilots, different cars. Hard to compare and so many different factors.
Call me coy, but I keep harping on the weight side... Just an example on how things can be skewed.. I found the AP racing weights mentioned by Poorsha (thanks BTW!) https://www.corvetteforum.com/forums...post1590745949 http://www.brembo.com/it/company/new...t-brembo-freni For the fronts AP say 3 pounds heavier than CCM, Brembo says 7 pounds heavier for a total delta on 25 pounds...no big deal I surmise but when added all together with other factors.. Brakes weight, 3ZR trim versus 1ZR 200 (pounds delta), A8 versus M7 (70 pounds+ delta) , run flats versus Pirelli scrubs( cannot recall the weight difference from Poorsha man) and we are starting to talk about two different cars...and two different trained pilots.. Just pointing out some basics of why the math may not add up...
Originally Posted by Telepierre
(Post 1597770117)
All true. Poor-sha shared the considerable weight savings of scrubs plus 18 inches..
But now with the "heat soak" factor I guess I lost the plot of what we are pursuing... I thought heat soak was introduced as a slowing factor..but we are also saying Mero and Millner enjoy slower straight line speeds but faster laps heat soaked..? Assuming parity of driving abilities...then it reasons that a heat soaked heavier A8 ZR1 is still faster than a non heat soaked lighter M7? My head hurts.. LoL Cheers. I think you guys are really overdoing the heatsoak theory. There's no way my car was heatsoaked on lap 5. The IAT was actually cooler (84.2F) on lap 5 than on lap 2 (87.8F).
Originally Posted by Robert R1
(Post 1597770672)
What was the air temp during both runs? Cooler air during mero’s run would be a notable advantage even if heat soak wasn’t the root cause (which it could still be) Regardless, a 700+ HP supercharged and heavy car probably isn’t the best “race car.” Meaning repeated fast consistent laps but the sheer performance available can make for a great hot lap car given the right conditions. If I was running a YouTube channel, I’d shift from “hero laps” to showing people the average and car behavior over a 20min continuous run as that would demonstrate close to actual track experience. That would give a better indication as to which cars are really cut out for this type of activity. Long term tests would include multiple track days so you can add up consumables, issues and other findings. As to your comment about running 20 minutes, I've posted lots of full sessions but the extra level of commitment required to get those last couple seconds isn't something I can keep up for 20+ laps. Also, unless you have the track to yourself you will spend most every lap in some traffic.
Originally Posted by meadowz06
(Post 1597781708)
Professional driver has better cornering speed AND better straight line speed. The total package.
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Heatsoak may be a bad word to use but the car could be pulling timing based on any number of parameters. I don't think we will know the full extent until the ECU is cracked and tuned. No theory explains it fully. Timing Pull IMO is the closest. If you added a bunch of wing, that can decimate top end speeds as well. All I know for sure is that 11 mph is not even close in terms of acceleration for two nearly identical properly driven vehicles. Transmission can't be worth more than a 2-3 mph. Other than aero or timing, nothing else comes close to explaining such an enormous deficit.
What we know as fact is that 755 hp is a lot of hp, and produces a lot of heat. Especially wihh FI. Also, the C7 (Corvettes in general due to small frontal area) has cooling issues, major ones with the Z06 making over 100 hp less. More hp equals MORE need for cooling. There is no magic cooling pill, but here is a magic timing pull. Lol. Cooler air may be worth a couple mph as well. Def not 11. Remember, GM is on the hook for this motor under warranty. The difficulty cracking the ECU is no coincidence. They can program what they want to protect their $$$$. So yes, part of my theory is based on distrust for car manufacturers and their bean counters. Given what GM released with the C7Z, their credibility took a hit in my eyes. If they are now gonna put out a car based on that same platform with 100 plus more hp, better believe they put some safeguards in there. It's all educated guesses right now. The data geek in me wants to know the answer. |
Originally Posted by Poor-sha
(Post 1597792635)
I just went back and read through the thread and both Essex and a customer who weighed the parts himself said the fronts were 3 lbs heaver than CCBs. The rear setup is actually 5 lbs *lighter* than the CCBs so overall you save about 4 lbs by removing the CCBs and installing the AP Racing kit front and rear.
55 lbs was the weight savings by going from Cup 2 tires on OEM wheels to 18" wheels and Pirelli slicks. Those also weren't my Forgeline wheels which might be a tad lighter. I think you guys are really overdoing the heatsoak theory. There's no way my car was heatsoaked on lap 5. The IAT was actually cooler (84.2F) on lap 5 than on lap 2 (87.8F). In my case it was 82F. In Mero's case I'm going to guess around 40F. I do agree that the cooler air was a significant factor. As to your comment about running 20 minutes, I've posted lots of full sessions but the extra level of commitment required to get those last couple seconds isn't something I can keep up for 20+ laps. Also, unless you have the track to yourself you will spend most every lap in some traffic. The data I provided earlier started with both drivers at WOT and ended with both drivers at WOT. Our starting speeds were very close (1 MPH). |
Originally Posted by heavychevy
(Post 1597781867)
There are plenty of examples of that not being the case. I even posted some. But I'll leave you to your generic delusions.
In this case Mero has more seat time, better weather and a car making more power on its hot lap. |
Originally Posted by meadowz06
(Post 1597834164)
So your telling me some drivers on this forum(non professional), could hang with Randy Probst? Delusional is your middle name.
You need to get out more. |
Originally Posted by meadowz06
(Post 1597834156)
Close is not equal! 3.5 does not equal 4!
Originally Posted by meadowz06
So your telling me some drivers on this forum(non professional), could hang with Randy Probst? Delusional is your middle name.
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