Viper TA Track Attack #10, Mosport 9-1-14...instruction, datalogging, Corsa's

[Bruce H.]

I like to use each track day as an opportunity to further explore the limits of the car, and improve my driving comfort level and skill. This is about my 10th day on track with the TA, and I accomplished both goals fully. I had a long time track friend (and instructor) give me some pointers, as well as use his Qstar datalogger to analyze my progress.

The first session was used to familiarlze him with my driving, and for him to make suggestions for improvement. He's done HPDE's, lapping days, time trials, raced Formula Mazda here over the years, and instructed with BMW, PCA, Ferrari and many others for years. He quickly noted that I was braking too much going into corners, not getting on the throttle early enough on exit, and taking too wide a line through some corners. We worked on those, and you'll see and hear him saying "no brake", "off"(the brake), "more throttle", and "squeeze, squeeze, squeeze" (the throttle) in the video.

This video shows the last few laps of the day, and all are in the 1:35's which is very good for this track. I'm following a 911 GT3 through light traffic, using 3rd gear onto the long back straight, except on the last lap where I grab 2nd to set up a pass. He doesn't give me the required "pass-by" signal so I lift off the throttle big time. I tend to use the highest gear possible in corners because the engine has enough torque to max out tire grip under high cornering loads, but I'll use a lower gear occasionally when I want more acceleration as I straighten the wheel. You can see the GT3 pull away on corner exit with me doing that, but I reel him in easily going into the next corner. Sometimes it's just nice to follow another quick car around the track, and 911 GT3/RS and Turbos are my favorites to follow!

https://www.youtube.com/watch?v=n43mjdgvA10

I was surprised how much less braking was required for corners, how much more speed I could carry through them, and how conservative I had been on throttle application exiting them. I'm continually surprised at the amount of grip the car has, and how much more there is each time I probe that. The front Corsa have been wearing much quicker than the rears, and I've been examining them carefully waiting for signs of cording or delamination. I saw some stress cracks just before the 9th day on track, which became worse there, and at the start of this day I could see a couple of spots where it looked like a very thin skin of rubber had peeled off. By the end of the day the cracks had spread further around the tires and gashes had appeared that looked to penetrate ~3/16th of an inch to what was probably the cords. These were close to the outside and inside edges of both front tires. I suspect all of these signs are related to high heat, the heat on the inside "edges" having a serious effect even though there was still significant tread over much of the inside "face", and the TA's 2.5 degrees of camber seemed to maximize the tire's life. I installed new front tires the following day as I was back for day 11 the day after that.

http://i49.photobucket.com/albums/f262/GT2860RS/Viper%20TA/Viper%20brake%20and%20Corsa%20tire%20pictures/IMG-20140902-00130_zpsccc87eaf.jpg (http://s49.photobucket.com/user/GT2860RS/media/Viper%20TA/Viper%20brake%20and%20Corsa%20tire%20pictures/IMG-20140902-00130_zpsccc87eaf.jpg.html)

http://i49.photobucket.com/albums/f262/GT2860RS/Viper%20TA/Viper%20brake%20and%20Corsa%20tire%20pictures/IMG-20140902-00129_zps67bffa1b.jpg (http://s49.photobucket.com/user/GT2860RS/media/Viper%20TA/Viper%20brake%20and%20Corsa%20tire%20pictures/IMG-20140902-00129_zps67bffa1b.jpg.html)

I've been very impressed with the Corsa tire, and found that they never lost their grip from heat cycling or wear. I alway reset the car's Peak G Meter before an event so I can see if grip changes, and on this last day of useful life they provided the same 1.5 g left and right...and provided their best ever grip under braking, up from 1.44 g to 1.5g! That's what I call good to the last lap, and the video above ends with that actual last lapl

We programmed the data logger with markers at each corner's entry and exit so that we could monitor cornering speeds and elapsed time through them, and were able to see a significant improvement by the end of the day in every one of them! It's now a matter of me becoming more comfortable with the new lines, less braking and earlier throttle...and that's what I'll be working on in Track Attack #11.

I hope some still find these threads interesting and informative, and if so I will continue to post them. Many of you may never track your own Vipers, but I hope this gives you a glimpse into a side of the car that you mightn't otherwise experience. Hopefully the shared experience will help other track rats in some way, or encourage others to consider tracking their's. I can reasonably assure you that you won't find a more capable car to track than your Gen V is right off the showroom floor, and a 1:35 lap at Mosport will be among the very fastest of any bone stock production car.

Thanks to Ralph and the whole Viper Team for such an extraordinary track/GT/exotic/sports car! And if anyone has any doubts as to the TA's and Gen V's track creds, I think the 2014 C&D Lighning Lap comparo does an excellent job of backing up Randy Pobst's setting of the production car track record at Laguna Seca! I consider it bad luck to discuss how many times I've been passed on track, but I can say that my experience over the last two track days with a wide range of supercars fully supports those test results :)

Bruce

[allans]

Bruce, Thanks for the post, i always enjoy reading them. I think what impresses me most is your mature attitude, which quit frankly, is often missing in many threads. This provides us all with realistic expectations for the car by actual track participants and creates (for me) a desire to keep getting out there. Stay safe, Allan

[Bruce H.]

Thank you very much Allan. The Gen V track community is still quite small, and the more we share the more we can all benefit. I've spent quite a bit of time going over the data logs from this day and another two days later where I made further improvements utilizing the new cornering strategies discussed above. The extra few laps let me relax a bit more with them, and it all started to become automatic. I'll show the data-logs comparing the two days results in the up-coming thread covering the second day of logging. You stay safe out there as well!

Bruce

[WhiteSnake]

Thanks for the great information from your actual track experience. Please keep posting!

[Bruce H.]

Datalogging

I borrowed a friend's QSTARZ BT-Q1000eX GPS Lap Timer to log the day's sessions. Here is a screen shot of the first lap in the above video (Lap 6 @1:35:411) and the last lap shown where the 911 GT3 doesn't give me the pass-by (Lap 10 @ 1:36:420).

http://i49.photobucket.com/albums/f262/GT2860RS/Viper%20TA/TA%20Datalogs/201497173215_zps26b2ee4d.png (http://s49.photobucket.com/user/GT2860RS/media/Viper%20TA/TA%20Datalogs/201497173215_zps26b2ee4d.png.html)

You will see the track outline with markers that we have added for the Start/Finish (S) of each lap and for each corner's entry and exit (1 through 16). Information is gathered and displayed in the charts on the left for each of those points, with Lap 6 shown on the left in green and Lap 10 on the right in brown. The top chart shows the elapsed time from the Start (S) to each each of the markers, and the difference in time between the two laps in shown in brackets on the right. You will see that the differences are negative in the beginning where I was driving faster in Lap 10 compared to Lap 6, and in other places it becomes positive as I'm slowing down as I'm getting too close to the 911.

The bottom section of the chart shows sector times, which are the times between markers. This allows you to compare times to run through each corner, or in between corners, with 1-2 being Turn #1 and 3-4 being the downhill T2, and 10-11 being the long uphill back straight. There is also a difference shown in brackets at the right indicating how the sector times compared between laps, with a negative time indicating that the Lap 10 time was lower.

At the bottom you will see a graphical representation of the data plotted against distance (in meters) on the X-axis and vehicle speed (in kilometers/hr) on the Y-axis. The Lap 6 plot is in green again, Lap 10 in brown, and the plots begin at the Start (S) marker, and the yellow dots along the plots indicate the crossing of each of the 16 corner markers. I can place a curser at any point along the plots and see precise vehicle speed, time into the lap and distance travelled. This is useful because the plots displayed only show speed and distance, and not which car is in the lead at any given point on the track. That data is displayed in the charts, but only at the marker points, and not in between points.

Now for the analysis. I had happily followed the GT3 for a number of laps as I worked on my new corner strategies at a comfortable pace, usually lifting a bit at the end of the straight where I would be getting closer to him, and didn't want to crowd him. But after doing that for several laps I thought it was time to let the TA off the chain and put a little effort into it for Lap 10. I did that on the front straight (Start) and you can see the brown plots through the first two corners are at higher speed, significantly in places. Between marker 6 and 7 I was close enough and backed off a little where the brown plot dips below the green. At this point I was about a 1/2 second ahead of my fastest lap 6. I then resumed my pace from 7-10 down the hill into the two tight rights that lead onto the back straight. I also grabbed 2nd gear instead of 3rd at marker 8 to set up a pass. On to the straight at 10, red plot gaining speed at a steeper rate initially while in 2nd gear, a brief pause for the 2-3 upshift, and acceleration in 3rd until I abort the pass, shift a bit early to 4th and lift off the gas to let the GT3 go. At that point on the track I was 6/10th of a second ahead compared to my best Lap 6, and down into the 1:34's which I would log two days later!

The datalogger also lists the lap times of every lap I drove that day, and I could analyse all of them. I was also able to compare my results to my friend's logs driving both a BMW E30 race car and his M3 track car. We felt that I should be able to carry the same speeds through every corner as his BMW's, which I wasn't at the beginning of the day in some cases, but by mid-day I was matching and exceeding every one of them. Where his cars are sliding and drifting through every corner in order to do those speeds, the TA was very composed as you can see in the video.

So the value of datalogging is in comparing sector to sector times and speeds through each corner in an effort to identify your highest speeds, and try to reach them in every lap you run. You can compare data on laps where you use different lines, braking, throttle, gear selection, etc to see the effect they produce. This is an invaluable tool to consider once you're reached a certain skill level and comfort with the car and it can help you get to the next level. I was never that interested to use one in the past for my lapping days, but I'm glad I've given it a try now with the TA and the renewed interest in tracking that has created. Something for others to consider.

[VENOM V]

All great stuff Bruce. Interesting that my instructor at Spring Mountain had much of the same feedback- I was surprised how much I was overbraking on corner entry. My lap times are significantly faster and I'm much less hard on the brakes and tires after honing my brakin skills. And ditto on my coach pushing me to get on the throttle earlier upon corner exit, it seems I was doing well through most of the corner but really improved my exit speed after the coaching.

And my front Corsas looked EXACTLY like yours on their final day before being put to rest, except I didn't go quite as far as you did. I had signs of delamination all the way around as you did, and was worried that a tire would come apart, so I cut the weekend short. More on that later when I post my Sonoma adventure.

I'm looking into video/lap timers and data loggers now, leaning hard towards getting the SmartyCam HD for starters.

And keep those awesome Track Attack reports coming! Can't wait to hear how the coaching with Kuno goes.

Todd

[Bruce H.]

Hey Todd,

I think it's easy to get into less effective cornering strategies when you have a lot of power to compensate for that when you put the hammer down. My modified Supra TT's torque curve wasn't as linear, which encouraged me to accelerate later to prevent the rear tires breaking loose. Viper's power delivery is linear but can do the same if not respectful with the throttle, especially in lower gears. Guys in lower powered "momentum" cars know they can't reduce speed any more than is absolutely necessary in corners as it's harder to gain it back. My friend tracked a stock powered E30 Bimmer for years on this track and literally hardly used the brakes for that reason. But the good news is that we can drive the Viper like a momentum car in the corners and still have the advantage of crazy power for everywhere else!

I'm usually one gear higher than I could be in corners. I did that originally as I was learning the car, and not focused on being particularly fast, but have a feeling it may be the quickest and safest way around the track now that I'm driving rather close to the limits of grip. Higher gears naturally put less torque to the wheels, and the car feels more stable at the limit when a slight squeeze or lift of the throttle results in less weight transfer and change in grip. I also find that I have been squeezing on the throttle at the apex but there's enough dead travel at the top of the pedal that power doesn't come on until it is further depressed. I'm dealing with that by starting to squeeze the pedal before the apex so that it does react by the time I reach the apex. Also still not heel and toeing. The brake pedal goes lower than the throttle under hard braking on my car and it's too easy to accidentally apply throttle when you don't want to. I seem to be able to generally blip the throttle before or after braking, or not rev match without upsetting the car. I may address this by adding pedal covers on the brake and clutch pedals only. Maybe it could be addressed with a change of brake fluid or lines. How's the GTS in these regards?

I'll be interested in your data logger feedback. The one I borrowed is very basic compared to what you're considering, and I would want one that at least adds throttle and braking information if possible.

And thanks for the thread encouragement Allan, Whitesnake and Todd. It takes hours just to review and upload video that best illustrates a useful point, and then to do the thread as well. There sure aren't many of us tracking the Gen V yet to establish a knowledge base...and I hope a few others will share their experiences as well.

Bruce