data aqusition does not tell you that you at 7/10 vs 10/10ths it does not know. I can tell you alot about what you are doing in each place on the track. It can hel you if you are not getting 100% from a spot or two. It cannot tell you if are going 7/10ths. Data aqustition cannot tell you what the limit is any corner. With the right understanding it can tell you alot about what you are doing, but it can't tell you what you could do. Sure you can look at the results and attempt to get some ideas. You still need to put it in practice on the track to really find out.

Any time you exceed the limit you will experience some loss of control. Quite simply you CANNOT reach the limit with crossing it. Now crossing the limit does not mean crashing. Crossing the limit can locking up the brakes on threashold braking. It can mean powersliding the car after too much trailbraking. It can mean backing off the power due to wheel spin. It can mean missing an apex by car length because you could not slow down. It can mean a wiggle in car. It can mean that feeling of bad understeer. It can mean just going slower. It can mean a trip into the marbles. It can be safe controlled trip in to the grass. It can mean a uncontroled trip into the grass.

Personally I have spun many times. This past two weekends I went to PIR. In those 4 days of track time I had one spin in a hairpin. I just pushed to hard on a qualfyig lap and did a 1/2 spin. Nobody around. No big deal. I also overcooked it in to turn 2 (trail braking decreasing radius corner) a few times. Sometimes that mean going deeper and wider than plannned and losing time. Other times it mean a little powerslide and correction. Once it mean give up and go straight off through the grass and on to the banking to rejoin the track at the hairpin. Very low risk of any damage in any of those cases. I did learn quite a bit. I do know that to be fast I need to be 9.9/10ths in that corner every time around. That takes work and some times you mess-up. If am running DE I don't dare push it as hard. Why should I? What is to be gained? In racing there is everything to be gained and it is places like that where you can win and lose races. Heck if there were a wall there it would be EVEN MORE important as those few that had the guts to try to find the limit there would be reward. Those not willing to push for fear of damage would be left behind. Racing is that way. It is aways risk vs reward thing. In DE the rewards are low and so are the risks. In racing the rewards are greater and so are the risks. F1 guys are not afraid to spin or even crash the car. Sure none want to, but the realize it happens some times. Personally I am not willing to wreck my car. So there are places I will be very careful pushing it hard. In those places a guy who does not care so much will probably find the limit faster because he is willing to challenge it more. Turn 1 PIR is one of those places. I have though for a long time that I could go through flat out in 5th gear, but I break because I fear and error can resulting wall contact. Over time I have going faster and faster through there, but without wanting to risk it those steps have been small. Therefore the speed increase has taken time.

Here data aqustion can be help full. It may show that I am only pulling .5g's Other places on the track I am pulling .7g's at similar speeds. So maybe I can push it to .55g's and get faster.

 

M758: Yes, DAS can tell you where you are at 7/10 versus 9/10. First of all, as I previously stated, you can build a history of your car on each and every turn. Yes, you can clearly see oversteer, understeer, brake lock-up, blown blip, .... It absolutely can tell you what the limit is on any corner (subject to not changing conditions i.e. rain) if you have approached it, or better, gone slightly past it. It is much easier to see than you would think.

Also, unless I am working on a particular exercise, I try to drive near 10/10 because if you don’t, you have little experience at the limit, and that is the experience you want. Perfect practice makes perfect (specific risks aside .. walls, …)

 

If i drive around a track a 7/10th if the car limit, but think I am at 10/10th how does the DAS know this?

 

I think we are greatly oversimplifying this process.

Let me see if I can lay out what you are saying...
1) Run a few laps on your own to get a baseline DAS set of points.
2) Convince the best driver that you can find to take your well set-up car and drive it 10/10's and that you won't ask him to pay for damages. (where is ghettoracer when we need him?)
3) Then overlay his data points with yours.

Yes, maybe you will learn that you need to trail brake a bit more going into turns. My question is "how much?". Can you really just look at a data point and say, "gee I need to trail brake X% more into that turn"?

 

10/10s of your personal limits or 10/10s of the car's limits? There's a slight difference.

I used to think I drove near 10/10s and then I realized that my technique was all screwed up. I probably was driving near 10/10s using that technique, but now I'm driving at 8/10s and I'm going much faster. It would have been interesting to see what a DAS showed between the two techniques.

 

Colorchange

"carousel at Road America (110+ mph),"

Wow, that's flying. Is that at track out?

What kind of car?

 

Hey Guys;

This thread is a rocket!

I have always been a shut up and drive guy, not too concerned with analysis or choosing something to work on or whatever. Seat-of-the-pants all the way.

Some friends of mine have GPS/accelerometer based data acq systems (along with engine acq!), and I always thought they were idiots spending all their time looking at laptops when the rest of us were hanging and bangin and relaxing between runs.

I must admit though that my interest is piqued. I must admit I want to know!

M758, I'm with you completely on the limit thing. You never know where it is unless you cross it, and your personal limits will remain low unless you stretch them. I don't think that can be argued. I know that from martial arts training. Things I didn't think I'd ever figure out are indeed doable. As has been said, it is a cost/benefit thing. That's true of anything, eh?

I guess last year was my year for stretching! I have always been an excellent driver. Not racer fast because I don't take racer chances, but tidy, smooth, and quick. I still have never spun, but I did have two offs last year. They are still praying on my mind.

The question I have is not why. I know why I went off in both cases. I can distill each down to their very essence. I am still miffed that I ruined my perfect record: driving very quickly but never in the grass! I am more bothered by whether or not they were necessary. Could I have made it?

You couldn't pick two better places to off. The Left Hander at Lime Rock and South Bend at VIR (Hey Z... you said you are confident in South Bend? You are slow there... trust me!! ) Even tight 'ol Lime Rock... there's acres of room there. I CHOSE to go off rather than chance a spin. Part of me regrets that sane choice. Guess that's why I'm not a racer.

I know one thing. My car looks like a beat piece of $hit to most people, but I love it to death and don't want to wad it. If I do I will be done for a long time. It's taken me 13 long, frustratingly poor years to get it to this point, and I'll be damned if I take any crazy risks to no ultimate purpose.

Must be nice to do it with impunity, though!

 

Z, to jump back a few posts (I don't check this thread in a day and it grows to 6 pages!)...

Don't stress so much about driving off line. You should not be so reliant on "the line". Be more reliant on your understanding of car control (you've demonstrated glimpses to me... ), your car, your experience, etc... Driving off line is really nothing more than knowing how all the pieces fit together and putting them together on the fly. It is not unlike learning a new track. How do you think pro drivers are able to run near record pace on tracks they have little experience at? They just know what they and the car is doing...

 

https://rennlist.com/forums/showthre...02#post1082202 , please read JohnM's post. I think it is very informative (not that I understood the whole thing).

 

I really enjoy this discussion as you guys appear to get it (forklift excluded), and if not, ask reasonable questions.

M758: If you are only driving at 7/10 instead of the car's 10/10, your friction circle may not look like a circle at all, and will look like a small circle. Instead of pulling 1.2 g's in the corner, at 7/10 you may only pull 1.0 g. It is clear as a bell. I am going to pull some examples from my car to show you guys what I am talking about and you will see how easy and powerful the analysis is.

Brian P:
Yes this will work well. You can also do it by yourself by pushing different turns each lap. Eventually, if you are reasonably good, you will have a selection of turns at the limit. Now, the software will even take you best turns from a day and put them together to show you what the fastest lap you could run if you strung all your best turns together. It is way cool. And yes, the data is that obvious. The car's limits is all we are concerned about. It is up to the driver to achieve that cars limits, and this is exactly what the DAS tells you, how close to the car’s capabilities you are driving.

Mike in Chi:
Yes, the 110 at the carousel is high but not that high. Countach and tuned 996tt.

Redlineman:
The GPS based units are great if they got one of the good ones, like $10,000. I generally agree with you. For my personal opinion and ability, I need to go past the limit as I am learning it in order to feel it and learn to feel it better. Really excellent drivers (I am no where near) have so much better feeling that they recognize it so early that the can hang around the limit a lot of the time and rarely have major errors. I don't normally leave the tarmac when this happens but I either have to lift, miss an apex, have to brake longer, ... Only when I make a really big mistake do I go lawn mowing.

 

.....oh that's right I'm "stupid", I remember. Thanks for reminding me again Professor Color.

 

This thread is great.
Data aquisition is always a good thing if kept in perspective. I know, because I have been in much better driver's cars, that relying on data aquisition out of context is wrong. Better driviers are able to take corners faster while putting less g-force stress on the car. They do this by being smooth. If we were to compare their data to mine, it might seem that I am driving more to the limit of the friction circle when all I was doing, in fact, was driving more erratically.

The way I guage my progress is to keep track of my lap times, check the tach at track out and at the braking zone following straights.

I am not a racer. I agree that racers need to find the edge to be competitive. I was nearly 10 seconds off the mark of the fastest lap time posted in what would be my race group. If I were in the race, I would be out. But I do DE, mostly because I am still learning but also because I am not ready to take those chances.

I work on smoothness all the time. Since beginning DE, I drive on the street practicing techniques learned in DE. I don't take turns anywhere near the limit but I try to drive the line and practice my transitions all the time. This has helped me become a smoother driver, which has made me faster and safer

 

Mitch: I disagree with your statement faster drivers put less g stress on the car. While I agree that they drive smoothly (minimal car upset or in your words, less erratically - yes), they are by simple physics generating higher continual g loads than a slow driver (an erratic driver might generate slightly higher peak loads). What I think you might have been thinking is the shock component of g's is low, that is true, the car is smooth, but is under larger (lateral especially) g loads, kind of like a fighter jet.

I agree completely with your practice of smoothness and transition focus. This is developing the "feel" I talked about earlier.

I am working on posting some actual data from my DAS. It's going to take me a few hours to put it together.

 

I would be interested in seeing your data. If it does work, then I will install it. I am always looking for more analysis. I realize the pro's use alot of data aquisition but I always thought that was to determine how the driver screwed up after a bad outcome. I can see how the friction circle would be more rounded and possibly larger for the better driviers and more ragged for me!! Does your system analyze all components like throttle angle, steering input and tach readings as well?

 

Mitch: They use it to evaluate drivers! Yes, I have all the inputs you are looking for. I'm still putting the data together. Don';t think you won't see ragged data from me. I'm going to say this now and repeat it over and over again.

I will not be presenting this data to show I am a great driver I AM NOT. I am showing the data for analysis purposes only so please no personal attacks.