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Max acceleration line out of a corner

Old 07-06-2018, 12:10 AM
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Default Max acceleration line out of a corner

I was just thinking about how I exit corners on the track. Obviously a standard racing line has you switching from trail braking to max cornering, to beginning to accelerate, unwinding the steering as you accelerate to stay at the perimeter of the g-circle. Now, in a (relatively speaking) low power car like an NA S2000, you're going to be at full throttle through much of the exit of many corners, since available grip will exceed the car's ability to accelerate. So in response you can apex earlier to carry more speed through the corner, and obviously try to get on the throttle as early as possible. All standard.

The thought I just had though—could it make sense to actually slightly straighten out the steering a tiny bit early, allowing you to get to full throttle a bit earlier, and make it up by turning more slightly later? I'm only talking about a small difference here, but basically instead of gradually increasing steering angle into the corner then gradually decreasing out of it, you would increase on the way in, then get on the throttle a little bit early and temporarily unwind the steering a little bit while you do, to maintain traction—then dial in a bit more steering to finish the corner, finally gradually decreasing it onto the straight as usual. One case where I think this makes sense is in corners where the inside curb can upset the car a bit, but it's still faster to take it. In that case you can straighten out somewhat as you take the curb, allowing you to get onto the throttle even though the car's unsettled somewhat, and then add a bit more steering once it settles down. I'm wondering whether it would ever make sense in a more general corner though, where the only thing unsettling the car is the weight transfer and the force through the driven wheels. Can anyone with more experience tell me if I'm making any sense here?
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Old 07-06-2018, 10:59 PM
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Assuming corner entry speed is constant, drive the line that lets you open the throttle as early as possible. Do whatever you need to do with the steering to accommodate without having to countersteer more than a few degrees. I think you basically said this but just in a lot more words.

But if you're ever 'turning more slightly later' mid-corner, you're doing it wrong, assuming a standard single apex corner.

Also, if you've entered the corner correctly, you won't be at full throttle mid-corner. You're probably just too slow during corner entry if you can go full throttle mid-corner.

From around 2:50 in this video, see that I'm in 4th gear but still have enough torque mid-corner to not be able to go full throttle through the esses. This is because my corner entry speed is high enough. Also notice the sweet zero counter-steer while exiting the last S at around 3:05.
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Old 07-06-2018, 11:27 PM
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Agreed, if you have optimized/maximized the corner entry speed, the rest is dictated for you by tire grip and thats what you are driving against or with, so it really doesn't matter how little power you think you have, you can still over power the tires/corner if you are at the edge of adhesion through the first half of the turn. If you have created enough margin through the turn to feel like your experimenting with throttle application/timing and feeling like the car is low on power/bogging through the turn, then your entry speed is too slow. This car makes enough power with a lot of rubber for most tracks to stay on top of the wave if you will, and not get bogged down. It is a momentum car yes, which means late brake/high entry speeds. This is where the S2000 shines. Also ideally the quickest way around a steady state turn is setting your proper steering angle/set up for corner entry and it doesn't move until you unwind for corner exit, with any "steering" correction done through the turn via the throttle.

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Old 07-07-2018, 12:20 AM
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Originally Posted by s2000Junky View Post
ideally the quickest way around a steady state turn is setting your proper steering angle/set up for corner entry and it doesn't move until you unwind for corner exit, with any "steering" correction done through the turn via the throttle.
This is exactly it! Well said. The rest of your post was spot on too. I find it easiest to drive any car using the throttle to 'correct steering'. Compared to higher horsepower cars, it's more paramount to do so in an S2000 since we don't have an abundance of power.

It does seem like M. Schumacher uses a slightly different technique where he employs a kind of a hybrid approach of what we said. Sure, he maintains a high corner entry speed but he is also not shy to use the steering to correct while keeping a gentle throttle ingress/egress curve. This is some next level shit though and I think the key to getting there is to master throttle induced steering first.

In short, all cars are 'momentum cars' no matter how much horsepower you have as seen by the technique employed by Schumacher in his high powered F1 car. The difference in lap times is probably just more pronounced at our amateur levels of driving with an under powered S2000.
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Old 07-07-2018, 01:27 AM
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^^^ Good stuff
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Old 07-07-2018, 05:37 AM
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Just watch a spec miata race. There are a dozen cars within inches of eachother going around corners in a gentle 4-wheel drift....126 hp but feathering the throttle so lightly and in a constant slip angle. So for any car and current conditions (weather, tire pressure, etc).....there is an optimal slip angle.....too little and your not fast enough, too much and your scrubbing speed.

i don’t know how to really define a momentum car but I can tell you the brake usage on a spec miata is drastically less. On the Miata the brakes are used to set the pitch/yaw of the car and that’s it. Very little pad/rotor usage. I have 16 sprint races + practice and qualifying (4 race weekends). on a set of my current Hawk Blues. With the s2000 I don’t recall how many weekends I could get but it might be half that. My s2000 I used significant braking, getting into the ABS and we even measured rotor temps a few times near 1000 degrees.
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Old 07-07-2018, 05:00 PM
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I think I was watching a video of spec miatas at Lime Rock Park and they never really lift the throttle, they just use left foot braking. I was amazed! I have been working on AutoX and have found it tough sometimes to keep the s2000 at the proper power level. You want to keep enough rotation of tires to allow you to use the throttle to steer, but it isn't always easy with super sticky tires. if you miss it by even a little, you can't just break the tires loose on command. It is important to carry enough speed to keep it on the edge of grip. Once you do it right you just know...
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Old 07-07-2018, 05:26 PM
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Yeah, I was thinking about my original post a bit more, and I realized what I was really thinking of were just early apex corners that have a lot of room to go wide on the exit. So it's not a matter of straightening out then steering bit more, but just starting to unwind it as early as possible to get on the throttle, and then using that space through the exit to not turn too sharply. In other words, properly apexing to use all the available track on the exit, given the power the car has.
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Old 07-07-2018, 07:42 PM
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If your not “steering into the slide” and routinely dropping 2 tires in the grass on a car that isn’t a down force car....you are leaving a lot of speed on the table.

(FWIW- your 1st post perfectly describes how you drive an aircooled 911, the rear engine, light front requires this or it understeers....it’s what’s so fun about the car)

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Old 07-08-2018, 06:57 AM
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Originally Posted by Nate Tempest View Post
Yeah, I was thinking about my original post a bit more, and I realized what I was really thinking of were just early apex corners that have a lot of room to go wide on the exit. So it's not a matter of straightening out then steering bit more, but just starting to unwind it as early as possible to get on the throttle, and then using that space through the exit to not turn too sharply. In other words, properly apexing to use all the available track on the exit, given the power the car has.
Unlike the big power cars, it is much more difficult to late apex this car properly. If you have a big V8, you can make up for lost speed. In AutoX its not generally about the late apex anyways, just going the shortest distance. Its not that our cars are horribly underpowered by any means, but they do require a bit of speed to keep the tires on the loose side. I finally got the car dialed a little closer to match my driving style as before, I just couldn't get the back end loose and if I did, it was around in a circle.
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