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+--- Thread: stock performance at the track (/showthread.php?tid=2014)
- stentech1 - 12-01-2009
I stated that abs will not prevent lock up if the car attains a slip angle that is so extreme that wheel rotation is not possible this is when a car is travelling sideways. But if the car is not totally side ways and wheel speed sensors are still sending output signals the abs system will prevent lock up. If the car rotates but does not get completely sideways wheel speed is detected and abs will want to continue wheel rotation, even if it is toward an object you don't want to hit. I am sorry I was not getting a dig you are a great driver and get around very well. I was just making a joke about Porsche's ability to come up with new marketing terminology every year. I have read in numerous publications that the cars with the pasm system can get a bit nervous when in the full stiff mode in fact I recall reading that when testing at the ring the cars were set to soft settings and produced more predictable handling and better lap times. When the pasm is set to full stiff it increases both compression and rebound dampening forces. This does not allow the platform to transfer weight as predictably as in soft mode and when power is applied too abruptly because of the suspension not allowing weight transfer to the rear a spin can happen more easily. Especially with how much power the newer cars make resulting in an over steer condition. If the car spins and the wheels lock they will remain locked up but if the brakes are released in an effort to save it the abs again may become active.
- Terry - 12-02-2009
It really is hard to tell exactly what is going on with the new systems because even a subtle change can be a big deal at the limit. You may well be right about PASM but the bad result may depend on a combination of factors which are impossible to reproduce. Like, I'm at the limit in a high speed corner and there is a bump which affects only one side of the car, as opposed to a more gradual rise which lifts the whole car, as opposed to a slick spot, etc. In stiff mode on a smooth track, the car does not feel nervous, but even a smooth track isn't smooth all over. The 'ring, so I'm told, is in no way a smooth track and the Porsche testers run it with PASM on soft - but I know that I'm faster if I can run on firm, by 1-2 seconds at Summit Point for example, even though that track is far from smooth. For me, the problem is power-on oversteer at corner exit, always on worn Toyos or Advans (at least so far). I just need to be more sensitive at that point, given the way my car puts down the power...
- betegh9 - 12-02-2009
Terry!
I don't know about that "power-on oversteer at corner exit" stuff. I don't have that problem in my 40 year old car............ Looks like tcnology is getting worse, rather than better, or is it that my car does not have the power?
hock:hock::dude:
- bobt993 - 12-02-2009
Terry,
In my experience, the "Ring" is actually pretty smooth in comparison to Summit. The original Carousel and the "mini" Carousel are a bit rough and unchanged (concrete). Unlike our tracks they built the foundation extremely well. The biggest challenge on the Nurburgring is elevation changes and very late apexes (over 70 of them). From the couple of times I drove a 7 GT3 (yours included thank you), I thought the power was intoxicating and easily a handful. If I had the chance again, I think I would try and push the PASM system with hot corner entry and little or no exit throttle. I think the system is so well designed that if driven correctly, it is faster on than off. I don't think slow in fast out works well with the massive reserve power the car has. Kenny experienced this when Chris drove his car at Tbolt. More entry, more apex speed and no acceleration required till the corner was basically completed. Anyways, I think the GT3 is an awesome car and I enjoy seeing them out there tearing up the track. I am not sure I would be comfortable really pushing one hard at the speeds they can go.
- Terry - 12-02-2009
Trust me, Nick, the power makes a huge difference. I drove a 1988 Carrera for 3 or 4 years on the track and power oversteer was never a problem - just keep the pedal down after the apex and you were fine. A different experience at around double the HP, even with another 500 lbs. I am thinking that Bob is spot on (higher corner entry speed and less acceleration coming out) but big ones are required to pull it off.
- bobt993 - 12-02-2009
Terry, I think if someone demonstrated it to you in your car you would pick it up right away. Very different sensation at corner entry. Feels very much like a soft brake pedal "oh sh#t" moment, then the car just grips and goes. After say 2- 20min sessions of scaring yourself, you start to reprogram your butt to say it's okay. The data is what is impressive. I found successively after just one session of building confidence that every successive lap yielded higher corner entry, mid-corner speeds. I watched my times drop consistently every lap at Tbolt. When I started getting 1:30xxx, I knew there was yet another second or two for entry to be made up. My next work in progress will be same mid-corner/exit, but less braking on entry with softer trailing. My method is going to be using less aggressive pads to start allowing less initial bit and easier brake release. I really wasted a lot of time focusing on exit speed years ago when the entry was just as critical and harder to re-learn. Now that I understand the process, I know every turn on at least 4 tracks we frequent where I can make up serious time with less wear on my tires and brakes.
I remember reading an article on lap comparisons between Schumacher and other F1 drivers of the day. Basically the data showed MS was braking earlier than all the other drivers, but released much earlier. Steering angle was busy with small changes, but gas was neutral until pretty far past the apex and then WOT. So he spent little time trying to do too much, but corrected for grip with the steering inputs.
Cumulative, he was a second a lap faster than his nearest competition at that track.
- stentech1 - 12-02-2009
The concept you are talking about is very important in all cars but particularly important in low power cars. The ability to maintain high corner entry speeds requires you to put aside the self preservation instinct the first few times but than it becomes clear that the platform remains more stable than when you are trying to make up for low entry speeds mid corner. On a motorcycle on the track you can not make up for blown entry speed midturn if you try to you are going to low side the bike. Setting corner entry speed requires less abrupt throttle application because the car is already at the cornering adhesion limit anyway. The application of throttle to make it up will often result in understeer or if it is applied too abruptly and weigh/ traction has not transferred to the back end it may result in loss of rear traction and oversteer. I was in the car with Bob at tbolt and he applied this strategy very effectively.
- betegh9 - 12-03-2009
I have found exactly what Bob is saying, particularly at TB. In many turns, I was tracking out not needing to use the whole track, so I figured that I could increase the corner entry speed............... but sometimes is "holy crap" time, till one gets used to it.
- ninjabones - 12-03-2009
bobt993 wrote:
Quote:I really wasted a lot of time focusing on exit speed years ago when the entry was just as critical and harder to re-learn.
I remember reading an article on lap comparisons between Schumacher and other F1 drivers of the day.
Bob, I wouldn't say that you were wasting time focusing on exit speed. Ross Bentley talks about this in his second Speed Secrets book. Essentially, he believes that every driver goes through mandatory step-wise phases of learning. The typical weekend warrier club racer begins his progression by working on corner exit, whereby generally speaking the guy who can get on the throttle earlier and earlier on exit will be faster.
After absolutely exhausting the car's abilities at corner exit, the next phase (which he describes as separating the club racers from professional level racers) involves the type of skills that you're describing, namely to carry more and more speed into the corner. Obviously, your speed sensing skills have to be spot on (pro drivers will consistently be within 1/2 - 1 mph at turn-in at every corner on every lap) and you have to have incredible position and traction sensing skills. The consequences of mistakes at entry are obviously more inherently dangerous and require a lot more experience, consistency, and skill.
At the F1 level, all the drivers have long since mastered corner exit skills (by the time they graduate from karting) and are able to consistently get everything out their cars at entry. The difference between Schumacher and the rest of the top echelon F1 drivers was mid corner speeds (Benltley's third phase), where he consistently drove 1-2 mph faster than his competitors.
So, I think that perhaps the techniques that you've been working on with Chris Cervelli may not necessarily be the right things to teach or emphasize to guys (like me) who aren't quite ready. I think that perhaps mastering corner exit first may just be part of the natural step-wise process.
- bobt993 - 12-03-2009
Glen, I understand, but the surprising result is exit becomes easy and intuitive once you push mid-corner. As Chris explained, every advanced driver knows when throttle can be applied. Learning how to get into the turn can gain you .5 sec per critical turn. Look at the corners on a track that require a minimum of two gear changes and do the math. 3 corners can yield well over a second with less car wear and less drama. I realize it is a hard concept to grasp as even Kenny said " I don't think I can do that yet.", but you need to start somewhere.
While I find exit critical it is the just as important to set up entry into the corner. One statistic that was a surprise was my theoretical lap times a now much closer to my fast lap in a session (.3 to .5secs) max. We need to get a data session together after the holidays.