Paul, I don’t know you, but I really like your persistence to want to learn and share your thoughts!
(I think) I’m going to disagree with your thoughts on differing amounts of hp, and how they might impact your line / apex points / grip levels / etc. That said, I’m still a little unsure of what exactly it is you’re saying, so maybe we do agree???
The first and most important thing to understand is that in racing, we can rarely look at a single corner “in a vacuum”. We almost always have to look at a series of corners (or potentially at the track as a whole) and how the choices we make in one corner will impact the next one, and the next one, etc. As a result of this, we often have to compromise something in at least one of those corners to get the lowest combined time through the entire series of corners. What good is it for me to fly around the first corner, only to completely miss the next one?
If you had a track where each and every corner was connected to the next by a long straight, then and only then could you look at each corner “in a vacuum”.
The next thing to understand is where you are most likely to see varying lines, apex points, etc. in order to achieve a fast lap time, is probably in a series of corners taken by karts of differing hp / speeds.
I’ll share an example from experience. My club’s track has one series of corners that demonstrates this well. This series of corners features a 90-degree left hander, followed almost immediately by about a 45-degree right hander. These are 2 very critical turns. They lead to a short straight followed by a fairly wide 180-degree turn. If you screw up or get the first 2 corners right, you can lose or gain lots of time, and it makes the entry to the 3rd corner a good passing zone.
In a slower 4-stroke, you do not need to lift / brake for this section. This makes it a true “momentum” section for the 4-strokes, where scrubbing any amount of speed will hurt you. Therefore, the goal is to “round” off the first corner and make it as much of a constant radius turn as you possibly can. You then “round” off the second corner as well, and that’s that. Simple to explain, but the ability to execute separates the fast guys from the slow.
In a Rotax, etc., you absolutely have to reduce speed for the first corner, because if you don’t, you will run off the track on the exit and have no chance of making the next corner. So, the question becomes, do I only reduce my speed through the first corner enough to be fast through the first corner, or do I reduce my speed through the first corner enough to be fast through the series of 2 corners?
I’ll tell you that a lot of the guys with average to slower lap times are amongst the fastest guys through the first corner of this section. The guys with the faster lap times are some of the slowest through the first corner of this section.
The guys who take the first corner faster tend to approach it like a 4-stroke would, and try to “round” it off and make it a constant-radius corner. The trouble is by doing this, they are having to lift / brake to make the second corner.
The guys who take the first corner slower, approach the corner almost exactly as shown in Eric’s graphical illustration on the previous page, with a later apex. How do I know it’s slower? Because when I’m qualifying and I’m behind the slower guys entering this section, they gap me around the first corner. So why would the faster guys do this? Because it allows us to not lift around the more important second corner, at which point we drive past the other guys with ease who are lifting (or at the very least not on the throttle hard) at a point where we’re hard on the throttle.
Now onto where (I think) I disagree with you about grip levels…
If I understand your logic correctly, you’re basically saying that if one guy’s cornering slower than the other, it means he’s not using all of his available grip, so he’s going slower than he could.
One thing to remember is that a tire has grip available to do one of or a combination of 3 things – cornering, braking, and accelerating.
So just because you might be cornering slower than someone else, doesn’t necessarily mean that you’re not at the maximum level of grip available to you. Maybe you’re just using that grip for a different purpose than the other guy.
In my example above, the slow guy (who’s fast around the first corner) is dedicating almost all of his grip to cornering through the first and the second corner. Sure he was fast around the first corner, but by doing so, he was then forced to use all his grip for cornering in the second corner as well.
The fast guy (who’s slow around the first corner) is using his grip to brake, then make a harder initial turn in (the harder you turn, the more grip is used), but then he’s using his grip to accelerate before he’s even hit his late apex mark, which is much earlier than the guy who’s still using his grip for cornering. The REAL fast guys do this same thing with great handling karts.
That’s not how every corner should be taken, but in my opinion, this series of corners provides a great example of where you would want to apply the idea of “slower in = faster out”. Notice I didn’t say “slow in”.
I’m with the others – there’s no magic to any of it, and I do agree with others that you’re probably over-thinking / analyzing / complicating it. Hopefully this helps you understand a bit better what I think the rest of us are trying to tell you.