DamonB

I labled some things on my charts above. About a third of the way down you see "catch wiggle". The lateral chart shows the car in a right turn at fairly high cornering forces. The forces then dip for a moment before normalizing again. At the same time you can see on the acceleration chart the rate of acceleration fluctuating. From looking at the lateral g one of two things happened: either the car momentarily began sliding (less cornering force when tires are sliding) and then caught again all by itself, or the car started sliding and I unwound the steering slightly for an instant to catch it. Given the fact that I was playing with the throttle a lot at the same time I was most likely unwinding enough to catch the car and then continued on.

About halfway down there is a second wiggle that coincides with the upshift to third. That little wiggle may very well be me removing my right hand to upshift and then grasping the wheel again, or it may just be a correction to get pointed where I wanted. I don't remember the car being dicey there as I was conservative in that spot. I figured it more important to get the car rotated in cleanly so I could accelerate early. If you flubbed it and had to catch the car in that spot you'd be really slow through the fastest part of the course.

Towards the bottom I have labled the rear moving around. This was the long, banked right hander just before the finish. I was turning in first, braking very hard and then balancing the steering and throttle again as I rounded the turn. During the brake spike I had to shuffle the steering around slightly to keep the car pointed where I wanted. What's interesting about this instant is there is a huge brake spike and at the same time I'm turning the car fairly hard to the right. This shouldn't be possible; if all the grip is being used up in braking how can the car keep cornering so hard? Remember this turn was banked. Since it was banked you could slow the car pretty aggressively as you were heading uphill onto the banking while at the same time turning the car.

DamonB

I ran second gear until exiting the slalom. Then upshifted to third, braked and turned downhill into the pucker corner. I didn't want to upshift in the turn itself because I figured I'd be pretty busy so I always shifted before going in. I carried third around the pucker corner and rotated into the slalom just after. While entering this slalom I downshifted back to second and carried second to the finish. I never sweat upshifts too much. I will often upshift slightly early if I feel the "perfect" spot to upshift will place too high a work load on me. I don't want the car trying to wreck itself at the instant I only have one hand on the wheel


I know in my case I couldn't go through that slalom any faster. I drove conservatively in that one spot but on my final run I entered faster and was breaking the rear tires loose pivoting around every cone. I made it through but was then slow into the pucker corner. I had good scores that run but it was more than a half second slower than my quickest.

Umrswimr

I added to Damon's chart with a few things of my own..



I had a substatial "coast" in the middle of the front slalom area which usually shows up as about a 0.15G decel and is marked as such on the map. Damon did the right thing- tag the brakes if you need to slow down.

Additionally, Damon and I both feathered the throttle in the middle of the sweeping left corner to maintain speed. It's funny that we both did the exact same thing, despite being in different cars. I guess we both wanted to get the car settled before we started downhill on the backside of the corner.

Finally, I have two spots on the bottom banked corner that show low cornering usage. This is a result of the front end giving out in understeer. As I mentioned before, this corner was a bit pinched at the entrance and exit. Dmon chose to brake a little longer before the corner and steer the car with the throttle. I entered a little hot, had to tag the brakes in the middle (he just lifted) and then roll onto the throttle again which caused the second understeer spike at the corner exit. He definately took this corner better.

DamonB

Here's a vid from a kart on the same course. While I was running 57's he was running 48's. The course doesn't look near as tight when you are a little kart

44 seconds in is the "pucker" corner. The kart just flies right through there without slowing down

http://users.waymark.net/darrint/run...camWeb2005.WMV

DamonB

We had another event this past Sunday at the smaller but very high grip concrete lot we often use. This is the site that is level except for one end which is sloped for drainage. The big thing I notice lately is that since switching to grippier rubber my scores have gotten poorer. I am not yet certain if this is me underdriving or the fact that since these tires have such tremendous cornering grip the on-camber corners really skew the scores. I would tend to think it's me still adjusting to the tires. If I can improve my scores over the next few events or so we'll know for certain it's the nut behind the wheel (it usually is).

The start of this course is at the bottom. The entire site is flat except for the very top of the course which makes those two corners on camber. The second of the two corners (top left of the map) is on camber as you enter and then plunges downhill as you apex and finish the corner. If you get on the power as early and hard as usual you will find the rear end trying to pass you out of this corner. I also have tick marks for each second displayed on the map to make it easier for everyone to keep track of where I am in my descriptions; I should have done that all along and will try to remember to continue.

The cursor on the map is 18 seconds into the run and I'm at my second hardest braking point (spike to the left on right accel strip chart). This is heading into a medium speed left hand 180 that opened onto what is essentially a straight. Coming out of this corner in my car I held the throttle to the floor and then backed off slightly as I steered down the curvy straight and to my hardest braking point for the left hander at the top right corner of the map. I backed out more than I should have.

I approached this corner differently then I would have a year ago. A year ago I would have trail braked in very hard, rotated the car and then got on the power at about the 21 second tick mark. I wouldn't have been able to get on the power earlier because I would have been trail braking so heavily through the first half of the corner. This weekend I did the complete opposite of what I would have done then. This weekend I slowed down early before I even got to the corner. The cursor shows me on the brakes hard and from that point on I had the throttle down all the way around the 180 left hander and down the curvy straight until finally having to slow for the left hander at the top right corner of the map. I have changed my overall strategy a little in that I no longer seek to stuff the car into the corner at the absolute highest speed, I seek to maintain the throttle to the floor for the longest period of time around the track/course.

This idea all started for me after studying the classic racing line is slow article.That concept for me was pretty profound. The goal in racing competition is to complete a prescribed distance in the least amount of time. Simple right? The guy who covers the same distance in the least amount of time wins. Any car is capable of a certain rate of acceleration and that acceleration is determined by the power of the engine, the traction available and how often the driver mashes his right foot to the floor. Once in the car the available power and traction is out of the driver's hands, but he has complete control of the gas pedal. The more time the driver spends with the gas pedal on the floor the quicker his lap time will be. I don't care if his car is slow or fast, has narrow or wide tires, has wings or no wings. IT DOESN'T MATTER. Any car will complete the given course most quickly when the throttle is held open for the greatest amount of time through the lap; no matter what transmission, tires, aero, suspension, drive wheel configuration or anything else you can think of. Any car accelerates at its highest rate when the throttle is completely open and if you can hold the throttle open longer you will cover the set distance more quickly.

Picture a drag race. What's the fastest way to the finish? Launch hard and hold the throttle fully open while optimizing your shift points for maximum acceleration until you reach the finish. Road racing is no different! Sure you have to slow down to go around corners but just because the course is not a straight line does not mean the throttle is no longer the defining element in your lap time!

So back to the event this past Sunday. 10 seconds into the run I turn the car into a 180+ degree right hander that leads onto a short straight. This straight leads into a 180 degree left at 19 seconds which opens onto a much longer straight. The earlier I can get on the throttle coming out of the corner before the straight the greater acceleration I will have as I proceed down the straight. The greater my rate of acceleration the faster I will go and cover greater distance in less time. I did make a tradeoff though. By slowing early for the turn at 19 seconds I was not covering the distance between the 180 degree turns as fast as I could have, but I make up for it by getting to hold the throttle down longer for the longest straight. The longest straight represents my greatest potential to cover distance most quickly because it allows me more time of acceleration and thus more speed. The earlier I can build my acceleration in that corner before the straight the faster I will cover the distance of the straight itself. The decision I made was to trade some speed on the short straight for a bigger payoff on the longer straight. I backed out of the gas earlier than I could have on the way in, but in doing so I was able to hold the gas down even longer on the next section. The real tradeoff was not cornering speeds or distance, it was choosing the plan that offered me the most time to hold the throttle open.

Even so I still began backing out of the throttle too much as I proceeded down the straight. I came out of the corner with the throttle floored but then began backing off as I curved to and fro down the "straight". You can see that by the fact my rate of acceleration begins to taper off between 20 and 26 seconds. At 26 seconds I had to mash the brakes hard to slow for the 90 degree left that was coming. I brake for 1 second from 26-27 seconds and then am already hard on the gas again as I initiate the left turn. Again I slowed down a little earlier so I could hold the throttle down through the entire corner and into the next left hander; maximize my time on the gas.

Umrswimr

Wow. You made a huge change in driving style here. How were your times?

I've seen "Give it up early", but you gave it up REAL early on some of those.

Was this at Pennington again?

DamonB

I thought they were great until the Z06's ran I ran early and was considerably faster than all the other stock cars but once again the vettes had no trouble putting half a second on me. I left early so they may have gotten even faster yet.


Yep. This course was actually straights joined by big corners so I concentrated on getting on the gas early everywhere I could. Only slalom was a 5 cone into the finish.

DamonB

I finally pulled out a win this season. In most events SS has been pretty close and several times I've only been a few tenths off the winner which left me way back in third; it's been competitive and fun. This event was on a site that has the lowest grip of anywhere we run, it's very smooth asphalt which was resealed a few years ago. Back then it rained and the surface was literally undrivable; incredibly slick. Now the surface is worn some and grip is much better but still less than normal.

I've been thinking the past few events of stiffening up the rear shocks much more than what I normally run. The Hoosier is able react more quickly than the Victoracer I was used to and I figured that would allow me to stiffen up the rear end so it will respond more quickly without making the car break loose (the front is already very stiff). The soft rear made the car more difficult to rotate quickly in tight fast sections as the rear wouldn't load up and follow the front. At high yaw rates it would lag behind and try to slide due to momentum once the front turned in. Basically the front end would start turning way before the rear end and I would have to wait for it to catch up before heading back another direction. This particular surface has also always given me a constant throttle on push in slow and medium speed corners so I figured stiffening the rear would make it easier for me to rotate the car. It worked out even better than I expected. The car never went loose but I could point the car very easily while using the throttle and without the front end pushing. The car felt great.

My scores are still consistently lower than they were on the old tires. Geez says I'm doing a good job in turns but in very fast transition areas there is still something I have not figured out yet with this setup. The area from 15 to 20 seconds is a slalom that still shows low usage and I distinctly remember the car trying to slip wide through here if I tried to go faster. The other areas look pretty good so maybe that section was a little slicker than the rest of the course, or maybe I never mastered it. At 29-31 seconds and 41-42 seconds there is low usage but that's due to turbo lag. The corners just before them were pretty slow and so it took longer for the boost to come back and power the car. Geez saw higher acceleration rates elsewhere when I had the car wound up so it scored me low here. The key in knowing this is that the areas are fairly straight sections and the acceleration chart shows the rate of increase being less aggressive in those areas compared to others, even though I recall having the throttle floored. In other areas of acceleration on the course the car was able to maintain boost and build speed more quickly. Geez sees this and figures I wasn't aggressive enough with the throttle in the poor areas. I distinctly remember the car bogging slightly out of these corners so I'm pretty certain there was nothing I could do.

I feel the first half of this course was very technical and getting the car placed properly was essential. There were some very tricky slaloms and offset gates leading into offset slaloms that demanded the driver be very agressive not only with speed but with placement. Being a foot off in a couple places would absolutely kill your entry to the next. I can't be certain since I don't have data from the other cars but from what I could see there was a huge visible difference in speed between the "fast" drivers and the "slow" drivers from about 13 to 27 seconds.

I don't think this course somehow gave my car an advantage over the vettes, I think I just figured out some wrinkles the rest didn't discover. At the same time there must have been a few more I didn't figure out. I turned the fastest time of any stock car (which SS should but it's never me ) save for a terribly fast DS Integra driven by national champ Brian Fitzpatrick. Brian moved to our region recently and I didn't realize who he was other than he was ungodly fast. He turned a 61.2 to my 61.7, beating me by half a second in a car that should be considerably slower. I have plenty left to learn yet.

The map shows my fastest run of the day; my sixth run. We were making 5 runs on this day but I lucked out and on run 5 I stopped for a cone that was down about 32 seconds in. I then used this "free" run to try something different around a few corners to see what happened and get ready for my last run. I was able to shave another .25 seconds off on the last one but it should have been much more. The spot where the bullseye (60 seconds in) is the spot where I lost it. The red bar on the strip charts shows I had just been steering to the right and then you see a short, quick correction spike to left before turning right again. Even though I was backing out of the power at the exit of the slalom to slow for the next corner I still carried too much speed around this last slalom cone and the rear took a big step to the left. You can see me come out of the power even further, steer left to save the car and then come back into the power and continue turning right. The car never actually turned sideways but I was forced to back out and move the front of the car over about 2 feet further to the left then I wanted to be. That hiccup alone was worth at least a couple tenths.

Even so it was still a considerable improvement throughout the day. My first run out of the box was miserable. The tires had some pickup on them from the previous event and it took half of the first run before the front end started to work. Even then I was still feeling out the new shock settings and so wasn't too aggressive for that latter half; I turned a 65.0. Run 2 was a 63.3, Run 3 was very aggressive through the first half of the run with a 62.3, Run 4 a 62.0, Run 5 was a rerun where I experimented in the final slalom and the final run was a 61.7.

Umrswimr

Congrats on your win, Damon!

DamonB

As usual the Corvettes came back and ate my lunch the following weekend After walking this course I knew I was in trouble as it was a short course and had some very tight and slow turns that I knew would find me down on acceleration compared to the Chebbies. On a good note I am still improving my scores on the Hoosiers and have become more and more successful at pitching the car around harder through hard transitional areas. The winner in SS ran a 34.8 to my 36.1. There were 3 key corners where the vettes were smoking me: the left hander into a long slalom at the bottom right and then the two 180 degree turns before the finish. These turns were so slow I couldn't keep the rpm up. The turn into the slalom wasn't so bad as I could rotate the rear to point the car and keep rpm up as I accelerated hard through the slalom but the 180's were just ugly power wise in my car. They were too quick for first gear and too slow for second. My co-driver wife decided to come back out after staying home for months planning our wedding and playing in our new home. She posted a 38.7 and drove better than I expected after her long stint of not attending any events.

The map of my quickest run is posted below. Jacqueline didn't start Geez on each run so her map is her second best run. I thought this time I'd just go through the entire run comparing our graphs and showing the differences between our runs. I have illustrated graphs of our friction circles along with lateral g, acceleration g, transition rate and of course the course map. I didn't bother correcting my map and you can see some of my corners look sharper than hers. Those are corners where I was sliding the rear of the car a little to point the front in without giving up as much rpm (boost).

First the start at the lower center of the map. On my charts you see the acceleration spike up at launch, breathe the throttle to make the hard right turn just after the start and then punch it hard again before shifting to second at 4 seconds (time is down the left side of the charts). Notice the sharp spikes to the right in the transition rate chart as I work the throttle and steering. Jacqueline on the other hand does not launch nor turn in as hard as I. The easiest way to spot this is by noting the differences in transition rate as her graph shows no big spikes to the right.

The first left hand turn was important as it leads into a very large and very fast 5 cone slalom with the fourth cone offset forcing you to slow there before accelerating briefly and making the 90 degree left at the top right corner of the map. My goal was to get into that slalom with as much rpm as possible so I could take advantage of the long acceleration opportunity of the slalom. As we turn left into the slalom you can see that my lateral chart has a flatter peak while hers is pointed. My chart also has a much flatter slope there which means faster transition. The spikes in my transition rate chart confirm this. This means I turned the car in quicker and the flat peaks of my lateral chart mean I spent more time cornering at higher g. She does have a nice burst of acceleration after the first left turn; more than I did. I carried more speed out of that corner and so couldn't speed the car up as much as she could at that point. Both of us breathe out of the throttle as we make the second right on the course traveling through the slalom now. She is again able to accelerate more aggressively than I as we turn back left heading through the slalom. This is again due to the fact that I was already traveling faster here and the next turn insisted I not accelerate as hard. Always keep in mind the acceleration chart shows change in speed, not speed itself. The fact that I had the car working harder here is again illustrated by the sharp spikes in my transition rate chart.

The red cross bar on our charts was the hardest braking point of the course. The car had to be slowed down hard before entering the left turn at the top right corner of the map. Both of our accel charts have a small spike back to the right while under braking. There was a bump in the braking zone that upsets the car as it crest just enough to show in the accel chart. The spike in mine is sharper because since I'm going faster I slam over that bump harder. Looking at the friction circle you can see my braking being done in a straighter line while hers fades out to the left. By keeping my braking straighter I could slow the car more aggressively since I was not turning but only slightly. After turning the car in she does an excellent job of getting all the way into the gas and accelerating the car across the top of the map. Note the time hash marks on the map. At 15 seconds I have already exited the left hander and she is just turning in. Where'd my big speed difference come from? Look all the way back to the start. 5 seconds in I'm already turning into the first left hander and she's nearly a full second behind already. Her start was not near as aggressive and so my speed advantage keeps building and building all the way through the course.

At the top left corner of the map we go into a left turn. This turn is uphill at turn in, levels at the apex and then flows downhill. She does a great job here. Her lateral chart shows a flatter peak at 21 seconds meaning she got the car turned in and maintained more cornering force through the turn than she did elsewhere. This was her best corner this on this run as you can see the entire entrance, turn and exit are highlighted in light blue; over 90% usage.

At 23 seconds in I'm beginning to turn into the first of the ugly 180's. You see me hard on the brakes (note the large transition spike) and then let the car off the brakes a little gently just as I turn the car into the left. As soon as the car begins to rotate I'm hard on the throttle all the way around the corner before slowing again and accelerating all the way through the right hand 180. Both the left and right handers here show nice flat peaks which signify that the car maintained cornering force for a long period of time through the turn. Jacqueline initiates her braking at about 26 seconds. She also pauses slightly as she lets the car off the brakes gently and accelerates the car as she turns in. Good job. At 29 seconds she is mid corner with her lateral force peaked and she backs out of the gas before accelerating again. Most likely the amount of cornering force startled her and she backed out of the gas because she didn't trust the car. She quickly changes her mind and speeds it back up though. At 32 seconds she slows the car for the next 180 and begins turning the car in. She turns in more abruptly and I think startles herself again because you see her unwind the steering a little before regaining confidence and turning the wheel back harder.

At 32 seconds you can see my lateral force to the right begin to taper off slightly. I was letting the car exit this turn with just enough wheel spin to tuck the nose to the right. You can see I accelerate through the turn and then hold the throttle steady at about 32 seconds as the car takes the yaw angle I want under the throttle and I hold it steady. I then shoot back over the left before stabbing the brakes and pulling hard right into the finish. I did the same thing at the beginning about 6 seconds in as I was rotating into the first left hander. The throttle comes up and then I hold it as the rear slips around the amount I want. I then breathe it for an instant to catch the rear as I rotate back to the right.

When comparing two drivers and one is faster than the other you can key in really quickly on the differences by looking at the transition rate chart. The driver with higher transition rates is getting the car to change speed and direction more quickly than the other driver and how that is being done can be shown by the other charts. Overall Jacqueline did an excellent job that day (remember this map was not her fastest run) and shows many of the same things I did not too long ago, mostly that she doesn't realize how much faster the car will turn in and stabilize on the different tires. The magnitude of the forces suprised her a couple times even though the car never broke loose. As she drives it more and gets more confident in the different feeling car I'm sure her charts will look much different.

DamonB

Two weeks ago was a study in patience. We went to Houston to run the SW Div and I looked forward to the fun courses that are always there. I have always felt I've underdriven the car since I'm not very familier with this site and so I had spent weeks mentally planning to be very aggressive when I got there.

Unfortunately the tires picked that weekend to decide "game over" and turn nearly useless. I had been told that when the Hoosier begins to decline in grip over its life that it happens instantly and that is the truth! The tires were fine the previous event and then in Houston they were nearly undrivable right from the get go; I couldn't believe how bad they got. Jacqueline drove first and since I was working the course I didn't have the chance to speak with her about the car but it was obvious it had no grip in the rear at all. She did an admirable job driving it as this car really spooks her when it goes loose but she kept pushing. I was absolutely murdered by the V710 shod vettes, finding myself about 5 seconds off the pace each day on a course the fast cars were doing in about 56 seconds. I literally could not accelerate the car as I got instant wheelspin any time I even considered putting power down. I can't remember ever having the car sideways so constantly.

I spent the entire weekend making every change I could think of and I could make the car different but only slightly better grip wise. Tire temps show the tires still heated fine but the adhesion was not there. Cooling them didn't help either as they weren't greasy, just done. The grip was so terrible I knew right away that it was a tire problem because no handling problem could make the car that bad. In the end my best times were when I forced myself to drive patiently and not overdrive the car. This resulted in my personal bests but still far, far off the pace of everyone else.

Looking at my scores (image "db" below) they are not too bad. Not my best by any means but they show the issue wasn't completely me as the fact that the car just could not generate any grip. Notice how low all the sustained readings are in the stats box. Looking at the lateral strip chart you can see the car all over the damned place. All the sweeping turns that should have nice flat tops at peak cornering g are completely non-existant. As the cornering force peaks you see the line begin squiggling back and forth. This is the car breaking loose at both ends and me juggling the throttle and steering trying to keep the car on course without slowing too much. The acceleration chart shows me going all over the place with the throttle as the car was turning, using a combination of turning the front in and rotating the rear out to change direction. The idea was to keep my momentum up as much as possible since I couldn't accelerate aggressively and the friction circle shows I made good use of what I had. I was just stuffing the car in and hoping I could find some way out the other side. Miserable.

Looking at Jacqueline's stats (image "jb" below) you can see that she was able to generate more g than I in nearly every direction. Since I was drifting the rear of the car around so much I was not generating as much cornering grip as she was. Looking at our acceleration traces you can see mine are much more wild as I was constantly on and off the power trying to speed the car up but also modulate the wheelspin and the rear end trying to over rotate. Her friction circle shows that she didn't attempt much braking and turning since the rear of the car was so out of control. It was tricky to manage the rear and I did in fact spin the car on my third run on the first day. I was drifting the car slightly around a corner juggling my hands and my feet but as the surface transitioned to downhill midcorner I got caught with too much power on and the rear broke very quickly. I knew the car was immediately sliding too far out to make the next gate even if I could save it so I made a half hearted attempt and then just dipped the clutch, locked the brakes and let it go around.

I tried to make the tires last through one more event this past Sunday. The grip was better merely because I was on concrete rather than asphalt but it was still poor. Luckily the course was full of faster, more gentle turns and so didn't demand fantastic transition speeds. The tires are certainly shot as 3 of them are corded now I'll get maps up from that event in a couple days as I have not gone through them yet.

The good news? My Kumho V710's arrived from Tire Rack today and I'll make my first runs on them this Sunday after having them heat cycled

DamonB

Results from this past Sunday with the same dead (and now corded!) tires but this time on concrete rather than asphalt. You see the exact same trend of the car's inability to maintain cornering grip on the lateral chart as on the ones posted above. The car was much easier to drive since the concrete surface is grippier than asphalt but overall the car was still slow due to lack of traction.

This course was a 2 lapper with the start at the bottom. Once you get 49 seconds in you are once again on the same part of the course you started and make another loop around to the finish. From 49 seconds to the finish the course map should overlap perfectly but it does not because of drift in the accelerometers mostly due to the fact that the surface is not flat.

The bullseye at 17.5 seconds is the instant before the front end completely washed out as I entered the left turn too fast. If you look at the lateral strip chart you can see g immediately drop just below the red line. I was braking very hard and turning into the corner but as soon as the front end began to push out I had to come off the brakes to try and keep the car turning. You see my brake reactions in the accel chart. I ended up pushing out very wide and having to bring the car far back over to the left as the course map shows. This left me with no speed whatsoever heading into the slalom and is shown by the very low usage there. This one was obviously not the fast run that day

I'll be back at the same site this Sunday on Kumho V710's. I have no idea if I'll be quick right away or will be changing things all day long, but with my co-driver and I each getting 6 runs it should give me plenty of opportunity to sort the pressures and shocks with the new tires.

Umrswimr

I was wondering what happened to ya, Damon. I was flipping through the SCCA results page and I noticed you got uncharacteristically creamed by the Z06's. You planning on getting some new tires this season?

See you at the next event!

DamonB

Yep.

DamonB

Is the Kumho V710 really a fast tire? YES! This past Sunday was the first time I've been on the V710 and it certainly did everything I was told it could do. The grip from this tire is just amazing, especially on concrete. I was sustaining 1.3+ g and spiking to nearly 1.4g in the turns. After making 6 runs on the tire I don't feel I yet have the tire pressures optimal, but I feel I'm close. Everyone else I've spoken with has ended up running less pressure in the V710 vs a Hoosier or Victoracer and right now I'm a couple pounds below what I ran in those tires as well. I think I have more to gain by experimenting with the front vs rear pressure but the car already feels excellent.

The biggest difference I notice in the V710 compared to any other race tire I've driven on is the steering response; it feels like a Victoracer would if you set its air pressure too low. The grip is there but the steering response can seem slow and sluggish until you realize how the tire acts. The car felt good my first few runs but I had not figured out the timing yet on when to turn the wheel heading through the slalom. I was turning in as usual but the tire lagged so far behind the steering input I would then over compensate by turning the wheel even further. This immediately setup a push. Once I got adjusted to how the tire loads up during turn in I found myself turning in sooner and not get alarmed that the front hadn't changed direction yet. It will come but it doesn't load up as fast as the Hoosier did. I think this is mostly due to the V710's soft sidewalls which I noticed when I mounted these tires; they were not as stiff as the Hoosiers when I mounted those. On the flip side even though the V10 has soft sidewalls it does not try to roll over during cornering even though I'm running lower pressures than the Hoosier. That's an interesting combination I have never personally run across, usually soft sidewalls demand higher pressure.

Overall after one event I'm very impressed with the tire; it's certainly the fastest I have ever driven. Like all other different tires though it does require adjusting your technique to maximize what you get out of it.

DamonB

Here are the plots on the V710. The event was at the same grippy concrete site as the previous one. Looking at the map the start is at the top. The start is very narrow and very slow due to a very tight right turn just off the starting line. Launching hard was useless as you had to round the first corner at a walking pace before nailing the throttle down the straight. This lot does have some elevation changes and as usual that skews the scoring. I'm using the same plot as always on the map: 90% or better is light blue, 80-89% is dark blue, 70-79% is violet and below 70% is red.

From the start you see the car launch and make the first right turn at so-so usage. The start and first right hander was so narrow and slow that I took it easy. After the right hander the map turns to light blue as I floor the throttle. The small red blip here is where I shift to second. Geez sees me storming down the straight and then sees my acceleration slow for an instant during the upshift. The course had a section that was traveled over twice. If you follow the map the car comes off the start and then heads down a straight and into a right handed loop. The first half of the loop is a big sweeping turn with elevation changes and the second half of the loop is a slalom. The first time around the car exits the slalom to the right and travels the loop again. Once it reaches the slalom the second time it exits to the left and finishes the course. The two loops should ideally overlap but do not due to drift in the acclerometers. I did not bother to correct that on the map.

Traveling down the straight after the start the map turns from light blue to dark blue. That instant is when the car begins climbing a hill up into the corner. Even though the throttle is still fully open Geez sees the acceleration of the car slow because I'm climbing a hill. Geez doesn't understand uneven topograpy and so it grades me lower because it sees my rate of acceleration drop while climbing the hill. As the car begins turning right and crests the hill the map once again starts reading some blips of higher usage since the ground is level, but then usage immediately drops again as the car goes downhill into the right hander before the slalom. This right turn is on level ground and so usage rises again only to fall once more as I enter the uphill slalom. Once through the slalom and onto level ground things start looking more normal again. Since the start on this course was so damn fast and on a flat surface Geez decided I was capable of really ripping the car fast. The loops and slalom were on uneven surfaces that prevented the same level of acceleration and cornering grip so Geez grades me lower there.

The real fun is in the sustained g readings! This tire has terrific grip but is also very easy to drive to the limit. When pushing harder around the loop my car would stay perfectly neutral and just slip out wide rather than plow or snap loose. It was very easy to tell what the tire was doing.

The map from my fastest run is below.

DamonB

Here's the map from Jacqueline's best run of the day. She drove very well once again and her scores show it. The main difference between she and I is that she still lacks throttle aggression. I like to press it to the floor whenever possible and she's still learning that there are more times it's possible than she thinks I've been really happy with her execution lately but I just have to get her comfortable with standing on it harder more often and slinging the car around hard through transitions. She drives very smoothly but so smoothly that she doesn't allow herself to pitch the car around as hard as it is capable.

I was a few seconds faster than she on this course and you can see why in the sustained readings. I was pulling the car around the loop much faster than she and made quite a bit of time on her. The other place I had a real advantage was down the straight after the start. I was stomping the throttle open earlier, harder and holding it longer than she. Though her actual scoring values on her map are lower than mine you see the exact same trends of usage going up and down as the car travels the uneven surface of the loops and slalom. That section was trickier than it looked.

She still did a great job that day and was more comfortable with the car than I expected. It takes her much longer to adjust to changes than I and she did well. Hopefully a few more events will see her confidence improve and she'll speed up.

DamonB

Here are the same maps side by side with a few other stats thrown in; she on the left and me on the right. Geez can compute all sorts of performance data but I never bother using it. This course however had such a long burst of brute acceleration I thought it would be fun to look at.

The 0-60 times are longer than what the car is capable because we were not going in a straight line. We had to start and travel around the first corner slowly before we could finally stand on it. I got to 60 mph a full second and a half quicker than she and even more telling I did it in a distance that was 60 feet shorter. That meant I got to spend those 60 feet still accelerating before having to brake and make the right into the loop. Her terminal speed before braking was 61 mph whereas mine was 67 mph. The difference was of course due to how quickly we accelerated the car. Comparing the acceleration strip charts from the top to our terminal speed at the red line you can see I have more area under my positive acceleration curve than she. One key to my being able to do this was that I turned the car into and out of the first turn more rapidly than she as evidenced by the lateral charts. She took more time turning the car in, didn't corner it as hard and spent more time turning out of it than I did. While she was still rotating out of the corner I was already hard on the gas and heading down the straight.

She chose to steer, unsteer and go to the throttle at the same times I did but since she operates the controls at a slower rate is takes her longer to get the tasks accomplished. Since she takes longer to get the task accomplish she doesn't get to spend as much time maintaining the car at the limit. If she had spun the steering wheel faster into and out of the first turn she could have gotten on the throttle sooner. When she did get on it she rolled into it rather than stomping it to the floor. She does an excellent job of being smooth and trying not to overly upset the car, but when you are at such slow speeds there is nothing wrong with just banging the inputs in. The car is traveling so slowly the chassis and tires don't care.

DamonB

This past weekend was a 2 day Divisional event and most of the Corvettes that trampled me in Houston a month ago were in town. I spent the weekend still coming to terms with the feel of the V710's and am now comfortable. Everyone on this tire insists they need little air pressure so I spent all weekend bleeding them lower and lower. Currently I'm at 33 psi front/31 psi rear but may end up even lower yet. For some perspective I ran 38/36 on the Victoracer and 42/40 on the Hoosier S03.

The grip of the 710 is amazing and I recorded my highest peak cornering loads ever (1.4+ g!!) this past weekend even though the surface is asphalt. Next weekend I return to concrete and I wouldn't be suprised if they get even higher yet, but this tire is a very different from what I've run before. The sidewalls are very soft in the lateral direction so the slip angle at high cornering forces is pretty huge due to the fact that the contact patch can twist so far away from the wheel direction. The tires transition slowly because of this and now that I've got the pressures so much lower they feel even more sluggish. The previous event on concrete had a large loop and I realize now I was underdriving that entire section even though it felt good at the time. Because these tires take on such a large slip angle it takes a larger steering input to get them to their limit. Previously as the turn required winding the wheel further and further into the car I mistook that for a push coming on and didn't speed the car up. This weekend I forced myself not to lift unless the car started to absolutely plow and was suprised at 1) how much steering angle I really needed and 2) how much cornering grip the front end had even when hard on the power with all the weight transferred to the rear.

I made changes to the car all weekend trying to get suited to the new tire. I bled static air pressure down about every other run. My first run on Saturday was at 38/36 but by Sunday I was at 33/31. The front of the car felt good other than still gaining confidence in the speed of the steering but the rear end felt a little slow to change direction. Sunday's course had a very long and very fast section of tricky offset gates and slaloms and on my first run I could feel the rear end of the car really lagging as the front turned in, forcing me to slow slightly lest the rear end come around. I have always run the rear shocks fairly soft in order to put power down but the outright grip of these tires doesn't require that crutch. I went from fully soft on the rear Konis to only half a turn from full hard and the rear immediately sped up and was much easier to drive in the very fast sections. On my second run that day I dropped 2 full seconds with the shock change alone. These tires are easier to drive at the limit than the Hoosiers as they don't snap hard, you just feel the tire give up and start sliding yet remain easily controllable. I think these tires are easy to drive if you can force yourself to come to terms with the slow steering.

So how'd I do? The V710 shod Z06 Corvettes still stomped me. I wasn't DFL as when the Hoosiers died and the gap was closer but I still wasn't competitive with the fast drivers in SS. The FD truly is in no man's land when it comes to classing because my times were faster than every other stock and street prepared class (save one multi time national champ in ESP). The only cars faster than I were the faster SS cars along with the Prepared, Mod and fastest of the SM2 cars. I think I drove best on Saturday but still pretty well on Sunday and was left in the bottom of SS for the weekend; 8th out of 11.

I made four runs on each day and was able to really get my times down as the day went on except for Sunday. I feel my fastest clean run on Sunday was still a second slow of what I should have been capable of.

Results for the weekend are here

DamonB

Here are the maps from my first run and my last (fastest) run on Saturday, Day 1. Geez is measuring the performance envelope of the tire and grades you on how often you're able to maintain the tire at the limit. This does not have anything to do with lap time however and lap time is what competition is based upon. Even though my scores are nearly the same the first run was an 87.493 vs. my fastest run of 84.706; over a full 2.5 second improvement! The big improvement in lap time came from different tire pressures and more confidence in the tire's characteristics on this surface so I got more aggressive with entry speeds. Saturday's course layout was fun to drive but I didn't find it very technical at all, it was all speed maintenance.

I didn't change my opinion on how to drive the course, I just did a much better job of driving the course hard on my last run compared to my first. All of that came from increased driver confidence in my understanding of the tires. Comparing the acceleration charts of these two runs you can see that the fifth run (we only got four runs but I stopped for a downed cone 3/4 of the way through my third run. With the re-run I made 5 runs that day) shows much more certainty in throttle and brake application. I'm not pawing around trying to feel the tire out, I'm more deliberate and that's really where my huge gain in time came from. The friction circle also shows me being more comfortable with the car as I spend much more time at the edges on my fast run than on my first. I still made a fairly large mistake on the fast run and let the car push out too wide (82 seconds in) exiting the turn right before the final slalom. This forced me to slow and enter from an unfavorable angle; killing my time and usage there. Thank goodness it was only a very short section there before the finish lights but I most certainly lost a tenth or more there.

My peak cornering g of 1.44 came in the left turn at 31 seconds in. This surface is rough asphalt but there is a concrete patch right in the middle of that turn that measures about 12 foot square. I made the point of looking for that patch and driving across it with all four tires as the concrete has more grip than the asphalt. You can see the lateral acceleration spike up right when I hit that spot and I could feel it in the car too. The car was already turning hard but when I got to the concrete you could turn it even harder just for a moment. Notice that my first run doesn't show this spike even though I ran over it then too. After the first run I was actually counting on the increased grip of the concrete and so came in hotter than before; relying on that small patch of concrete to get me across the apex without spinning into the weeds.

DamonB

Sunday Day 2 was a more fun course IMO as it required more thinking and concentration. There was an especially tricky portion across the backside (from 40-55 secs) that consisted of very fast offset gates with randomly changing distance and offset between each gate. You really had to look far, far ahead through here to keep from going much too fast or much too slow. I never felt like I did an excellent job in that section all day because there was no rhythm to it, but everyone else I talked to shared the same opinion.

My first run through that area I had to be really careful because the rear end of the car was reacting so slowly. I normally have the rear shocks very soft to make it easier for the rear tires to accept big power applications (like when the second turbo comes screaming in) but it does become a handicap once speeds get really high and the transitions alternate back and forth at high rates because the soft rear shocks won't transfer weight as quickly as the hard front ones do. What this feels like in the car is that as the front sticks and turns in hard the rear tries to continue on where it was headed before changing it's mind and finally beginning to follow the front. The rear has just started coming around at about the time you now need to reverse direction and go the other way but you have to wait for the rear to settle on its new course before you can do so. If you don't wait for the rear to settle before asking it to change direction the other way then the rear tires will break loose as they just started turning one direction when the front is now headed in another; the rear will then snap and you'll have to catch it.

That's what I mean about one end of the car feeling slower than the other. The front axle seemed quick and eager to turn in and change direction but the rear axle seemed lazy and sluggish when asked to perform the same manuver. The reason this is so is because shocks control the rate of weight transfer. The softer rear shock settings I normally use are fine at lower speeds because the rear still got enough time to settle, but at higher speeds I actually had to wait before I could steer again because the front tires would settle into their new cornering attitude much more quickly than the rear. The sensation in the car is of the front hunkering down and turning in but the rear seemed to rise up and roll way over onto the outside tire while at the same time taking too long to load that tire so its cornering force was down. The rear shock changes showed up in my cornering power as well, but some of this was also due to pressures more to the tire's liking.

Once I stiffened the rear shocks the car was tremendously better through there though it was still difficult to drive that section correctly due to the technical nature of it. Undoubtedly my outright speed through there was much better with the stiffer rear setting. The downside was I had to be slightly more cautious in slower speed offsets because you normally attack these with much faster and harsher steering inputs. With the now much stiffer rear shocks the outside rear tire would try to load nearly instantly and thus shock the tire loose if you are trying to put much power down. I had to load the rear tires more gradually when at hard throttle and low speed.

The Day 1 trend of my inputs being more deliberate on later runs hold true on Day 2 as well. In general both my steering and brake/throttle inputs look smoother on the later run that day even though they are also more aggressive. The friction circle graph for the faster run is again more concentrated towards the edges and shows better trail braking execution as the lines in the bottom half of the circle are much rounder and smoother.

I could have solved the problem of the rear being slower than the front by softening and thus slowing down the front rather than stiffening and speeding up the rear. The next thing I plan to try if I have no trouble with the rear end trying to break loose under throttle is to soften the front shocks slightly. Since this tire changes direction so slowly I'm wondering if softening the front will be more to it's liking since it won't stress the tire as quickly at the instant of turn in. I'm also wondering if I can run the front sway bar stiffer. The reason I have not stiffened the front bar any further in the past was because any more bar gave me a push when on the throttle hard and transfering weight off the front at mid corner. Since the 710 has so much more grip I'm wondering if it would allow a stiffer bar without pushing and that would payoff in allowing me to get on the throttle even harder as I cross the apex because it would do a better job of keeping the rear tires more evenly loaded at all times.

We'll see what happens on the high grip concrete next weekend but before making any changes I'll make at least one run with the car as it was at the end of the day Sunday. I'll experiment with the shocks and if I get happy with that I'll experiment with the front bar the following weekend. The weekend after that I'll be at a local road course and will log some actual track laps. The last time I went to Motorsport Ranch the batteries in my Palm went dead before I could download the runs The time before that I forgot to bring the Palm at all!

alberto_mg

thanks for the in-depth info and analysis. i learned a thing or two reading this.

DamonB

I'm just getting around to posting last weekend's results; been lazy. Last weekend was good as I managed an overall victory in SS. We were back on concrete and I was now running tire pressures that are about 7 psi lower than the first time. The V710's are really happy now One experiment for this event was to see how stiff I could run the rear shocks without the rear trying to go loose at turn in. This smaller and tighter course liked the soft rear shocks much better. The couple high speed turns were pretty tight and when trying to run the rear shocks stiffer the rear really wanted to walk around powering out of the corners even though this surface has more overall grip than the site of the previous event. Looks like I'm only going to be running a stiffer rear shock on higher speed courses that don't require harsh transitions. Because of the reaction I got from the rear shocks on this shorter and tighter course I don't see a stiffer front sway bar helping me either as I'm sure it will try and push.

I spent the day messing with pressures and shocks and am really getting happy with the car though I still have to really concentrate on the steering with these tires. The front is so dang slow to transition I really have to think about when to turn the car in, but it sure sticks well when it does turn. Steering feedback through the wheel is not as good as the Hoosiers were but I'm learning to live with it. You pick your evils and live with them.

Overall I was happy with the car and happy with my driving. I'm still coming to terms with the slaloms on these tires. The tires turn in slow and don't give excellent steering feedback so when truly hustling through the slalom I found I was strictly driving by timing my inputs and not really paying attention to what the steering wheel felt like. The best way I can explain is that if I waited to actually feel peak g in the wheel then I would have been late turning back the other way. I'd just steer when I thought I needed to (really damn early!) and the car would eventually go that way. Strange but I guess I'll get used to it.

My fastest time was a 42.1 to second place's 42.4. Jacqueline turned a 44.9 which I though was really good. Looking at her plots she was already a half second behind me just from the start to the first real corner so we're really going to start working hard on her launching and shifting. I never rode with her that day but thought she looked great from outside the car; her scores agree with that.

Here are the plots from our fastest runs. Jacqueline first, then myself.

DamonB

Looking at the results above you can see Jacqueline actually out cornered me in a couple places. I think this was due to the fact that I was purposely slipping the rear around the turn under the throttle in order to rotate the car and keep more power on. Since I was sliding I didn't pull as much lateral g as I could have, but on the other hand the nose was pointing into and through the turn more quickly and I was able to use more throttle through the turn. This course was fun but twisty and my goal was to maximize throttle angle everywhere on the course. I was braking exceptionally early and also speeding up exceptionally early, accelerating the car hard immediately after turn in and much before the apex in most corners. Frankly I'm suprised I won as I would expect to be close but not ahead of the vettes on such a course.

On the pic below I have isolated one single corner of the course and displayed the fastest run for each of us through that corner; it is the right hander from about 18-23 secs on my map above. The left of the pic is Jacqueline and the right is myself. The first thing you notice is the friction circle graphs. My trailbraking into this turn was nearly perfect as I have a nice full arc at the bottom of the circle as I transition from max braking to max turning to max acceleration. My braking before the corner was done in a very slight left turn as I set the car up as wide as possible to the left and then began to rotate into the right turn. Jacqueline's straight line braking is done with the car pointing towards the right slighty. She was pointing the car at the apex a little earlier than I was without bringing the car out wider first. She also comes off the brakes much more abruptly and turns the car in immediately after doing so; she wasn't trailbraking through the corner as I was. That is another concept she is beginning to understand and we'll work on later. Her friction circle shows that without a doubt she broke in a straight line and turned in the instant she came off the brakes. She also started accelerating at that instant so that was good. She did leave some tire grip on table though as from peak braking to peak cornering she is not using the edge of the circle.

The cursor on both our graphs is the instant of peak lateral g in that corner. My peak was earlier because I did more of my turning earlier, following my plan of maximum throttle angle as often as possible. By pulling the car around earlier I could get on the gas earlier. We are both doing 32 mph at the cornering peak there, but my entry speed to this turn (entry is at far right of each map) was 52 mph versus her 49 mph. Looking at the accel charts you can see I was also off the brakes and speeding the car up earlier in the corner compared to her. I could also speed up more aggressively because I got most of my turning done sooner in the corner. Therefore at the exit of this corner (top of the map) my terminal speed was 64 mph versus her 58 mph.

She has been doing a great job in how she chooses to handle the car IMO but she's still not aggressive enough with the throttle and the brakes. She has become comfortable with how hard you can make the car corner but I need to get her more acquanted with how hard you can slow down and speed up this car. That's where she is losing the majority of her time so that's the thing we are really going to work on.

DamonB

Here's some interesting measurements of distance traveled; Jacqueline on the left and myself on the right. The numbers in the boxes are the distance traveled from the starting line at the bottom to the point of the cursor on the map. You can see my lines were tighter and shorter than hers until the right hander we talked about just above. At that point I pulled the car out wide to the left before I turned in and gave up shorter distance for more room to turn in (and therefore didn't have to give up as much speed). I also moved the car out wide and covered more distance turning in for the left turn at the top left of the map. You see me losing more and more distance to her but I was making up for that lost distance by much increased speed. 9 times out of 10 I tell everyone that given the choice of shorter distance or higher speed choose shorter distance. The times I don't do that depend on the speed of the corner and what RPM I'm carrying through the turn. On this day on this tight course the increased distance kept me higher in the revs and on boost more often. It paid off that day but the key is knowing which choice to make for each turn on each course.