Woot! Thanks. It seems at the point I’m at on the track I’m working on, it’s all subtle gains from finding a bit more exit speed.
Even if you switch up your perspective from % throttle to % tire load/traction, you could still argue that, in general, 50 -> 100 is preferable to a constant 75 because when you drive with a constant throttle you are surrendering the opportunity to influence how energy flows in you car longitudinally (and therefore where, when, and how that energy creates loads in your tires). For example (excluding lateral forces for simplicity/clarity):
Constant 75% Throttle
If you approach a turn, roll back to 75% throttle and turn in, then when initiating the turn there is effectively very little longitudinal energy on (or being transferred to) the front end, which can limit the amount of speed you can carry at the turn-in point. As the turn progresses, the act of turning (the scrub and/or energy required to generate and maintain slip angles) does gradually (or cyclically) transfer more energy longitudinally to the front end until the energy reaches is peak at the turn’s apex/rotation point. Then that energy gradually rebounds from the front end and travels longitudinally to the rear end… producing the load/traction you need to complete the turn.
In this scenario the longitudinal energy movement in the car is very slow and subtle, because it is being left up to ‘nature’ (the combination of speed, corner radius, track/tire interaction, etc.) to determine when, where, and how energy moves and tire loads are created. The other potential issue is that since longitudinal energy moves so slowly in this scenario, the required transfer of energy/load front to rear at the critical moment when the car rotates at the apex happens very slowly. So, for a moment neither end of the car has the load it needs for optimum traction (a concept which TJ mentioned above). To summarize; constant 75% throttle produces a relatively unloaded entry and a relatively slow longitudinal energy transition at the rotation point, both of which can cost you speed/time, and both can also impact your confidence due to the ‘unloaded’ feel they produce.
Varying throttle from 50% to 100%
In this scenario, you are using the throttle to take control of how longitudinal energy move through your car and produces tire loads/traction. If you roll back the throttle to 50% (instead of 75%) you are effectively doubling the amount of longitudinal energy on (or being transferred to) the front end, which means you should have a relatively more loaded/planted front end for turn-in, which means you should be able to turn in with more speed/confidence. As in the 75% version, energy builds gradually/cyclically, but this process started with more energy (a bigger longitudinal ‘push’), so the energy builds to a peak a little more quickly, meaning that the ‘rotation’ point occurs a little earlier than the actual ‘apex’ of the turn.
Since there is more energy momentum at play when the car rotates, it will do so more aggressively. Therefore you must use the throttle to take control of transferring the energy needed to manage the rotation to the back end (instead of just letting the natural energy ‘rebound’ do so like in the 75% approach). So, you begin rolling on throttle, which continues to feed energy to the rear end, which builds slip angles to their peak and maintains them longer, which slightly alters your trajectory out of the turn, which lets you carry/build more speed out of the turn.
All that said, written out, these two approaches seem quite different, but in reality, the differences are very, Very, VERY subtle. But ‘subtle’ is where the 1/10s hide.
Ok that makes sense. So the act of squeezing it in does feel more stable. It’s not unstable at 75, but it’s potentially unstable. The acceleration through does hunker car down in comparison.
This is interesting stuff. I love Lewis shooting analogy, and the eye tracking is a close look at what the best guys are actually doing at the wheel.
If you’ve found any more of this kind ion thing, I’d love it if you’d post it here.
Thanks for sharing.
Great example of this is at GKVC? Kart track in kart Kraft. There’s a left sweeper at the end of the back straight. The turn can be taken in the traditional manner, brake, turn, go. However, you can simply throttle, lift, throttle. If you time the throttle pause correctly (it’s short) and then floor it, the induced understeer from the weight transfer and subsequent accel flies the kart through the turn 3-5 mph faster. There’s not many people playing, but as I climbed my way up the leaderboard in TT, this was the corner I’d pull on the ghosts easily.
2 turns later is the opposite. Uphill corkscrew left. This is one of those turns that trying to have throttle input going through the kart will kill your momentum. Sometimes you just have to be patient and wait for the kart to turn before trying to get in throttle.
So far I have learned that yes, generally trying to get in throttle as early as possible, with as little brake as possible is a good way to go about things.
But, there are some pretty big exceptions. You do need to flow kart through some turns, and as such, some turns do not allow you to accelerate trough them until the kart comes around. These turns require patience. The window for earlier throttle is there, it’s just a longer wait for it.
Dom that’s exactly how we take that turn at GVKC in real life too, just lift for a moment at the turn 2 left and if you hit it just right and get back on the gas you scoot right through the S that follows… didn’t know they had our track in Kartkraft — even more excited for the console release now, sounds fairly accurate. The corkscrew monza turn after has a couple lines, still trying to figure out the best there; all I can figure out is run wide at the exit
Wow! Great to know thanks. It’s kinda the same as turn 1 at etown but with a lift.
That uphill turn is brutal with the current physics build. So little steering input required. It’s almost as if you have to let the kart turn itself.
As it turns out, it can be done flat. At least in sim. It isn’t really worth it, though. It has to be perfect timing and angle and the speed gain, as compared to a slight throttle reduction, isn’t significant.
If you go through flat, the trajectory works but it does force you to approach the next turn more from the right.
Just the slightest lift, I’ve found the same thing! We have a new section of track with another monza that makes the left at the end of the straight into a long right; should be fast!
Soo tempting to power through the next part but patience is rewarded.
I took a look at race monitor and the times for x30 are similar. I’m currently running 40.8 there which is a bit faster than average but within the range. I see 40.96 a in a race for first extending to 42ish for slowest.
Looks like the track and physics are pretty accurate.
I’m less than a tenth off the #2 USA spot for the track. Now if I could just figure out that final turn onto the straight…
First off I would like to say hi to everyone here, I was just reading some of the posts at the forum and I came to this one and felt like I belong here . I drive rental karts at the local track once in a week or two, the track is 800m long and karts are much weaker than probably anyone is driving here. They are Rimo Alpha² karts with 270cc engine, 9hp. So basicaly im an amateur driver, that started to really get into the karting last summer. I do have all the laptimes on the paper [20-ish sessions in the period of 1 year] and I decided to study my progress over the course of one year.
First off all, when I look at the laptimes, I see the fastest laps of the sessions are mostly between laps 8-10 [10min/9-10 laps, 49,607 my all time best and a track record of just under 48s, usually takes about 50-50,5s]. That seems to be very similar to your “go-time”. Now we do have problems with consistency between karts but it is usually around the lap No. 6 that my pace starts to pick up. Unfortunately, I still dont have any videos or data about my driving but I feel im driving the best when I relax, when I dont fight the kart and start to “flow” around the track. I feel that back then [November 2018] when I got the fastest lap, I wasnt aware of what good or bad I was doing. After the winter break, I was not able to find that old pace and im still trying to do so, that “flow” I remember very well, not thinking much about the corners themselves, no brake smashing, just throttle mostly.
About the throttle effect on grip, I experienced that as well. In some corners, just slight push on the right pedal gives you so much grip instead of sliding and tyre screaming, although Im still finding the right balance.
I must say that what you described completely matches my experience [even such short and plain one] and that you can call that a breakthrough and try to implement some of the learned things into your driving technique.
Long story short, I pick the pace up at around lap 7/8, I felt that flow on the track, it had amazing effect on laptime, I use throttle as a way to increase grip levels in some corners and it works, as long as you balance it well.
I hope it helped to share my experience with you and that it gave you positive attitude towards new changes and further improvements, hopefuly I can learn a lot from you guys as well, seems like I will come back here very often from now on. All the best
What would happen to your brakes when you’d do both throttle and brake? Wouldn’t that hurt the pads or engine?
Let me start off with this; I was never thought of as one of the best drivers on a Kart, but I counted myself in the top 3 or 4%. I remember the day I learned how to drive a kart. It was at the River Kart track near Fresno California. There was this one turn, almost 180 degrees and pointed somewhat. You had to brake hard to make that turn. This is what I did; I drove, in a straight line, as deep as I thought I could, I broke hard into the corner in a straight line. I never flapped the throttle, feeling, if I did so, I wouldn’t make the corner. At the moment I thought I was going slow enough, I turned left into the corner. At my 1st opportunity to do so, I got back on the gas and powered out of the corner. Making the exit part of the track as wide as possible, I would occasionally miss my exit point, dropping a wheel off the side of the track. I never let off the gas when this happened, if it looked like I might drop a wheel, I just touched the brakes lightly. Never let off the throttle, if possible, in these situations. It cools the engine slightly, meaning less HP. I once was offered new brake pads from a vendor, he said others were using them and he said they thought they were super. I went out in the 1st heat and after 3 or 4 laps, those pads wouldn’t hardly stop me at all, apparently with my breaking techniques, I just got them too hot. Never had that problem with Airhart pads.
Happy my thinking was useful to you. I would say that I still stand by the idea of trying to keep the kart on boil and more surgical braking.
That being said, there are gonna be times when you have to wait to get on. Remember that acceleration effectively causes a “push” or understeer. This is great for most turns but occasionally you will need the kart to rotate a bit before you get back on.
Depends on your definition of pushing. My definition is, if you notice it, it’s pushing. No front tire, in a turn, is on a rail, so I imagine there is always some side movement to the front tire in a turn. Pushing, in my thinking, is turning and not following the line you intended. When that happens, you turn a little more and really start noticing a push. I’ve always corrected a push with narrowing the front tread width, or, widening the rear tread width, after that, a change in seat position, more weight on the front wheels, less weight on the rear wheels. This idea that there’s a magic “ideal” (one-size-fits-all) weight distribution, is, in my opinion, wrong!
That track is so fast! Felt like you were wide open the whole time!