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Critique my VIR vid please (be gentle)

 
Old 03-30-2008, 11:16 AM
  #301  
PogueMoHone
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Post of the Year... and it is only March!

Originally Posted by TD in DC View Post
Ok, wanna, one of my friends e-mailed me and suggested that a further explanation of my original point may be helpful, and that you might take it the way I meant it, as a helpful discussion. So here goes. I mean this as peer-to-peer discussion, not as if I think I am great and talking down to you or anyone else. I do not, I assure you. Also, these are general comments, and there are always exceptions, but hear me out.

At the level we drive (non-pro DE drivers), the condition of your tires should have little to no impact on your line. The only effect tire condition will have is to lower the limit, but the techniques we use to get the most out of ourselves and our cars within the limit does not, generally speaking, change with the actual level of the limit (i.e., tire and/or track conditions).

That said, bad tires can affect your confidence, as can a new track. The impact of lack of confidence (and I don't mean that as an insult, sometimes lack of confidence is another way of saying wisdom) is that you move your turn in LATER . . . not earlier. Why? The earlier you turn in, the less room you will have at track out. The later you turn in, the more room you will have at track out. The apex should not change. With a constant apex, one of the most important variables is the turn in point, which is a major factor (but not the only factor) in the attitude of your car at the apex (how much turning you have done by the time you hit the apex). If you turn in early, you have to do more turning in the last part of the turn (post-apex), which gives you fewer options if you lose traction or make a mistake. If you turn in late, you have to do more turning in the first part of the turn (pre-apex), which gives you many more options if you make a mistake, and will give you more room at track out. This is why I could not understand your explanation. Turning in later is more conservative . . . turning in earlier is less conservative. Turning in later makes it easier to leave yourself room at track out. Turning in earlier makes it harder to leave yourself room at track out. The same is true regardless of whether you have great tires or bad tires.

This discussion assumes that you are not doing lurid "rally" style slides on the track, which would be slower under nearly any circumstance I can imagine. IF you are doing lurid rally style slides around oaktree, then, yes, you would want to turn in early and keep your nose around the apex so that you can slide out to track out. But that doesn't count here.

Also, your turn in point has nothing to do with how hot you enter a corner, which I understand to be entry speed. Want to come in hotter? Brake less. Want to make in less hot? Brake more. You can do this with respect to any turn in point.

Now, with respect to a high HP car like yours, I would think that you would have a later turn-in point than a low HP car like my former race car. (I learned what I am about to explain from Cervelli, who is a great instructor). Why? Well, think of it in terms of a friction circle. In an ideal world, the circle would be perfectly round and we would be able to pull at least 2Gs in Braking, 2Gs in Cornering, and 2Gs in Acceleration. Unfortunately, this is not a perfect world. I am going to use 1G as an example (although many of us can pull more than 1 G in braking and cornering): We can pull 1G in braking, 1G in cornering, and WAY, WAY less in acceleration. In my ex race car I think it was something like 0.14 or 0.2 Gs in acceleration. For the sake of the example, let's assume 0.1 Gs for my car and 0.5Gs for your higher HP car. Why do we care about the difference in acceleration? Because we want to get the most out of our car's particular characteristics on track out. If I can only pull 0.1Gs in acceleration, that leaves me 0.9Gs for cornering. By contrast, if you can pull 0.5 Gs in acceleration, that leaves you only 0.5 Gs for cornering. Why do you care? This says that I should get most of my turning done in the second half of the corner (post-apex) because I CAN'T accelerate and thus I DO NOT NEED much for acceleration and CAN USE almost everything for cornering. So, I would try to make the first half of the corner (pre-apex) a larger radius than the second half of the corner so that I can carry in as much speed as possible and rotate the car relatively late in the corner rather than killing my speed too early since I can't get it back. By contrast, you, in comparison, CAN accelerate and thus YOU NEED some of your Gs (actually, in my example, half) for acceleration out of the corner and thus can't use everything for cornering. So, maybe you should be trying to rotate the car more in the first half of the corner (pre-apex) so that you don't need so much cornering Gs when you are accelerating out of the corner. In other words, make the radius of the second half of the corner larger than the first half. How would you do this? Maybe going deeper, turning in later and rotating the car earlier so you can get back on the gas earlier. This is another reason why I didn't understand your comment about focusing on turning in earlier.

I also think that maybe you should try to eliminate as much coasting/maintenance throttle as you can. The most unstable period for most cars is the transition period (e.g., going from braking to acceleration, or acceleration to braking). Most cars tend to be more stable in if they are under some force (e.g., braking, cornering or acceleration). In corners, most cars tend to be more stable if they are under braking or acceleration. Think of a waiter running with a full, but open, bottle of wine on his tray. It isn't so hard to run full speed once you get going, but the trouble comes when you try to stop and start again. When you are coasting or using very slight maintenance throttle, you are prolonging the periods of transition, and the car could more rapidly transition from oversteer to understeer or vice versa than when you are under throttle or braking, where you can set the car and feel the set (of course, you can push it too far, but my point is that YOU are actively controlling the car). Coasting and maintenance throttle is also slow. So, my instructors have always come down on me very hard with respect to coasting and maintenance throttle. It is better to be on the gas or on the brakes. If you are having trouble getting on the gas early, maybe you should burn off more speed going into the corner. So, you ideally would focus on coming into the corner at a speed that allows you to get on the gas and smoothly (you don't have to get on full throttle immediately) building through the apex and to track out. One nice transition, not maintenance and then full throttle (which is what it sounded like you were doing in your video). Once you reach the point where you can do that safely, then you can start working on increasing entry speed, which may delay the point at which you can go from brakes to throttle (but since you entered faster you may still be faster out of the corner), until it forces you to back off the throttle due to oversteer or understeer (at which point you can slow down a bit on entry). Of course, coasting and maintenance throttle is perfectly stable if you are below the limit, but where's the fun in that? More importantly, do you really want to be cementing bad habits while driving below the limit that can bite you if you try them at the limit?

I sincerely hope you and others find this further explanation helpful. I have not made one snide comment to you, and the only reason I took a break to write this out was to add to the conversation in a positive way. Ok, that's not entirely true, I am hiding from my kids who are all on sugar highs.



P.S. I would never give someone a hard time if they want to learn and are willing to take criticism. It is hard not to have a little fun with people who seem to think too much of themselves at all levels of driving (this comment was not directed at you or anyone in particular). This is all supposed to be fun.

P.S.x2 Dammit. I feel a graph coming on.
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Old 03-30-2008, 11:57 AM
  #302  
38D
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Originally Posted by largeandturbocharged View Post
3400lb Daily Driver with me in it and yes, that was just a leisurely drive around RA during a DE. What's really Horrid is watching guys today at RA in factory RSR's turning 1:29's and 1:30's...now that IS Pathetic!

L&T

P.S. See you guys soon in GT1R and we will see how horrid I drive.
Let me know what races you'll be at so I can critique the times .

100% agree that a 1:29 in a 996 RSR is not good. Leh did a 1:21 in 2007.
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