When to Shift Gears for MAX Acceleration [SIMRACING & REAL LIFE]

[@Luckydoggg9976]

Hey dude, could you please also explain in a video how "fast" a manual car should shift and how much throttle to apply? Sometimes I get a feeling that more gradual throttle gives me faster acceleration and faster shifts sometimes lower acceleration? Does it have anything to do with clutch slip/engine bay temperature? Thanks a lot for reading! Subscriber acquired!

[@LastTenth]

Hey Daniele, thanks for subbing!! It really depends on how aggressively you want to shift. For a gentle upshift in a manual car, I'd say it should take around 0.25s, between the start of the lift and when you get back on full throttle again. The throttle should be an immediate full lift, then immediately back on full throttle. I've generally not known a gradual throttle to give more acceleration. If the clutch is slipping, then the clutch is the problem, not the throttle application. Here is one example: kzbin.info/www/bejne/fqKUhKKgr6aCZ5Y A harsh, aggressive upshift would be faster but I don't really do them anymore. There's not that much benefit and gearboxes don't really like them as much. Also you're usually upshifting on a straight so there's really no need to rush your hands. Downshifts generally will take a bit more time. I don't have good data for it but I reckon it takes around 0.5-1.0s. With downshifts we can't be as lazy with our hands because we're generally braking heavily or about to turn in. Here are 2 examples within 10s: kzbin.info/www/bejne/rH3Pi5yuhbhpbq8 Thanks for the suggestion. I will put together a video in the future.

[@Luckydoggg9976]

@@LastTenth you the man, but how do I know if clutch is the problem? What symptoms do I see when clutch slips?

[@LastTenth]

@@Luckydoggg9976 No problem! A clutch shouldn't slip. Regardless of how much torque the engine produces, it should have a clutch spec'd for that output. When the clutch slips, you'll see the revs climb when you're on throttle, but the car doesn't accelerate (as much as it should)

[@Luckydoggg9976]

@@LastTenth that could be very possible then, maybe the clutch manages the hp better if put down "more gradually" as opposed to slipping if put down more aggressively... I'll make some test and keep y'all updated (if anyone is facing the same problem I hope at least I can be of help)

[@LastTenth]

@@Luckydoggg9976 Probably. If you keep the clutch plates within static friction, it can probably hold more torque than if you just dropped it and get into kinetic friction.

[@sixx_xlr2]

its a crime how you don't have more subs

[@LastTenth]

Let's fight this injustice together! 💪If you be batman, I can be your robin.

[@sixx_xlr2]

@@LastTenth EXELENT....now, were going to need a butler.... unless this was a reference that went over my head

[@TheDrSwank]

🤫 we need secret bro

[@LastTenth]

@Formula Otaku オタク This channel is gonna have to do really well before I can afford a butler...

[@TITAN_JULIANG]

Completely agree

[@RetroSnakey]

Absolute killer video. While I've loved racing and math for decades, I never put them together. These explanations are spot on! Great work!

[@LastTenth]

That's awesome Snakey, time to put them together! I have a background in physics so it's hard for me to not look at everything through that lens (watching scifi films with me can sometime suck). I bet if you put the two together you would elevate your driving immensely.

[@unclereefer37]

So much gold! You are really sharing all the race secrets of the ages. Please keep up the fantastic content

[@LastTenth]

Hah, hardly secrets. Just levelling the playing field!😉

[@LearningFast]

Torque at a given speed is just Horsepower. You don’t need to calculate wheel torque. You can simply look at the Horsepower graph and see where it is higher for a given output speed.

[@Ilyaloverally]

Не совсем так. Крутящий момент на колёсах включает в себя потери в трансмиссии, что может сменить пик мощности на колёсах. Например на двигателе у тебя будет 120 hp / 6000 RPM, а на колёсах будет 70 hp /5200 RPM

[@SlyNine]

It will not change the peek power of the engine. The wheels, at any given speed, will always feel the most force when the engine is able to push the hardest.

[@mociczyczki]

@@SlyNineyea true but higher gear ratio generste bigerr losess some say and it must be consider as well feg peak power is flat and wide on 2 gear asssuming we are on the same speed can be slightly less contact path force than at 3 assuming both gear at this speed are on peak power 👌🏻 it porbably dont do to much as feg me cb 500 at higher gear ratio than feg mt660 diffrencess in gear rstio is +/- 1,5 times so cb 50% higher gear ratio through whole speed range in regard to race 👌🏻 cb ups at 10 k rpm +/- vs mt on 6,5-7 k rpm +/- cb have 20 % more power at engine crank according to tech spec though test show more like 15-17% diffrences 👌🏻both have simialr drag wieght asf yet cb still accelerate quicker assumption ? assuming similar gearbox construction this losess are way less than 20% on 50% biger gear ratio 😉👌🏻 but still count 😉👌🏻thats best is to have graph of force /thrust /contact path fprce or at set whell radious drive whellll torq on each gear like he show in this video if you race 👌🏻if this force graph on each gear never cross you must spin engine to rpm limiter on each gear for max acceleration this mean basicallly that for this engine power increase very rapidly all the way up to rev limiter = very narrow peak power + enough big diffrences between gear lenght 👌🏻 vs if they cross than up to this point where they cross on each gear is perfect time to upshift 👍🏻good egzample of this is r6 vs r7 on motostaz test comaprision r6 ( at least this specified year r6 or cos of some mods on it ) you need to rev on each gear 1 rpm before hit rev limiter „up to rev limiter” on each gear espeiclally on lower gear where diffrences between gear are bigest thats most important on higher misteake with this dont be cost rider in race as much but still 👍🏻 vs r7 you must ups for max accelerstion on each gear waaaay before engine hit rev limiter 👍🏻 r6 spin to much biger rpm but it have much more narrow peak in regard to diffrences between gear lenght THATS WHY 👍🏻

[@intermsofreality]

The graph really helped. Thanks.

[@kevin_m]

Your videos are so great! Thanks for this breakdown 😊

[@Lfrm-420]

Dude your videos have so much thought and so many physics that no one talks about. 730ish subs. F yt for not helping give you to the algo u deserve. Plz keep the vids coming

[@LastTenth]

Thanks for saying that myco! So far I'm really enjoying sharing things I've learnt in these videos. I'm still very new to YT and not really sure how to get the algo working for me. But I will do my best to keep delivering quality information. I suppose if ppl watch it, YT will promote it...

[@Lfrm-420]

@@LastTenth its hard to get a channel growing man. Im sure youll get it figured out. Think evolving the channel and mix real life with sim? Idk just off the top of my head.

[@racekraft]

@@Lfrm-420 Thanks. I do plan on introducing IRL stuff. Motorsports season is just starting here so I will be trying to create some content.

[@crisautomoto3569]

Awesome video

[@mundanesunrise2480]

this might be a bit late to the party, but im so glad i found your channel, just watched this video and the torque & power one. Few years ago i have made an acceleration simulator, where you basically input a lot of data for a car and, an initial speed and a final speed. For acceleration finding the optimum up shift point i used the exact same logic, my algorithm calculated how much torque there was in each gear at every speed available to that gear. When the torque in the current gear went below the next gear or the gear run out of rpms, it was time to shift up. I did add another condition thought, very rarely encountered, an edge case, but in some cases, the torque in the current gear might go below the torque in the next gear, yet, if you rev it out, it might climb up and on average offer more torque, thus better acceleration. This might happen if the engine torque curve is a bit weird and it just so happened that it was at the perfect aerodynamic point in the speed range.( i calculated the force that pushes the car foward as the torque at the wheels - slowdown forces, which mainly is drag). I managed to compare results to irl's friends cars and we got relatively close results, of course with some amount of error because its very hard to get good aerodynamic coefficient and tyre friction coefficient values. I'm just so glad that i can be assured now that my ideas were right. Thank you! 😚

[@LastTenth]

That sounds pretty sophisticated. Are those cases usually when there's a torque dip?

[@mundanesunrise2480]

@@LastTenth The main factors for that behavior to happen are torque dip, relatively high aero drag and specific gear ratios. It is quite rare to see this scenario. Modern race cars have more or less close to a flat torque curve while consumer cars always are always designed to have as low as possible drag to benefit fuel consumption. You might see this in some older race cars, but even there it is quite an anomaly and when found people would try to fix it, imagine how annoying and unintuitive it would be for the driver to accelerate towards the end of the gear, then the torque dip feels, and then torque picks up back again and you again feel the car pushing you harder. I've only encountered it 1 time, it was some like 90s bmw (modified) it happened from 3rd to 4th gear. The aero drag scales quadratically with speed and for most cars at around 3rd-4th gear it would be at or over 100 km/h when the drag dramatically starts increasing, so thats why it tends to happen there.

[@LastTenth]

@@mundanesunrise2480Wow a truly edge case. Thanks for the context!

[@justamanchimp]

This data is so useful! I intuitively kinda worked this out somehow just over years of driving but I do think this data is super useful for general rule of thumb of how to optimally shift. I factually know this now which is a great thing. I think it's important to remember that in real life, data aside, there are a load more variables that you should consider, too. You shouldn't use the data approach for every scenario because it just doesn't work like that all the time in real life. For a quick example, "short shifting", where you intently shift up early, sacrificing torque to maintain traction and control out of a corner exit, which in turn can make you faster out of a corner under certain conditions. This is an example of something that we know is a useful tool in racing, but completely defies the argument the data is testifying to. It ultimately comes down to the fact that "optimum" isn't always best, especially in a race scenario. In this scenario, there's way too many subjective variables to objectively say what is better. I guess I'm making the point for people watching that it's important to use data as guide and not necessarily as a rule. Take it for what it is. Thinking about it, perhaps the video should be called "Optimal Shift Timing for MAX Acceleration" and add "... In a straight line". Then I guess you cannot argue much lol. Love the video, really well thought out, I appreciate it, I subscribed, fascinated to watch more, so cool that there are KZbinrs for this kind of thing nowadays!

[@SlyNine]

Or you could just look at the horsepower curve.

[@LastTenth]

Thanks for the Sub Jon! And yes you are correct. As shown in the example in the video, this is applicable to acceleration at full throttle (straightline or otherwise). There was an earlier comment from another viewer who asked about shortshifting and I gave my views there. I mentioned there that I will make a video on shortshifting at some point, so stay tuned!

[@justamanchimp]

@@LastTenth Awesome looking forward to it 👍

[@WolfTangoFox]

Another excellent video, thanks!

[@LastTenth]

Thanks for following my videos!

[@wm973]

Excellent explanation of a complicated and rarely taught subject. Great Stuff!! Thank you!!! Q: Is there a time or condition for shifting at less than optimal shift point or sometimes called short shifting? I've heard of it but never talked about.

[@LastTenth]

Yes, absolutely WM. It's a great question and I actually have plans to put a video together about it, but I'm not sure when so I'll give a sneak peak here. Many often use shortshifting to save fuel, but imo it may or help or hurt you depending on the engines efficiency. I talk about it in this video: kzbin.info/www/bejne/e4WwpWmhdturfZI. Shortshifting does become useful when you're exiting a corner between gears but you don't need all the acceleration. For example a car may produce too much torque in low gear in a tight corner and short shifting will drop the car's wheel torque, which will make it easier for the driver to manage the throttle. Another similar one is if you're exiting a corner where you cannot use all of the car's torque, and that a higher gear can produce enough acceleration anyway, you can shift early during partial throttle when you're not using max acceleration which won't cost you time, instead of later at full throttle which will cost you time when you need max acceleration.

[@PRIVERA30]

Thanks for all your videos. I compete in the Swedish Time Attack with my Suzuki Swift Sport 2019. I downloaded the spreadsheet, but I found only the data for the car gear ratios, final drive, and the wheels/tires. I can’t find the torque outputs by RPM. The maximum power - Output - Horsepower: 140 PS / 138 HP / 103 kW @ 5500 rpm and the maximum torque: 230 Nm / 169 lb-ft @ 2500 rpm Do you know where I can find the torque outputs by RPM for my car? TIA!

[@LastTenth]

Hey thanks for asking this question on through my discord. I have answered it there.

[@user-ux1hj8hr3m]

Great video dude got a new sub for sure

[@LastTenth]

Thanks for the sub J!

[@daniocampo1992]

Fantastic video good sir

[@CharlesK441]

Awesome 👌 👏🏾 👍🏾

[@Chubbza5]

Thanks for the quality content! Where do you find the torque outputs by RPM? Not many dyno sheets available for LMP out there. Great calculator by the way. Thank you!

[@LastTenth]

You're Welcome! That's gonna be tough. I just find whatever is available on the internet. For street cars, its usually readily available. For race cars, if it's not easily found, there's usually some proxy engine out there, especially for GT cars. For things like protos and formula, I'm not sure how you'd go about it tbh.

[@martywrx]

Excellent video mate 👍 subscribed

[@LastTenth]

Thanks for the sub Marty!

[@napadzieracing6015]

Where I can find "how much torque engine produces"? In Assetto files, or? I am interested in Mazda MX5.

[@LastTenth]

It's in the AC data content data files. You should find apps that can extract that data. You could also google what the torque curve is.

[@alexisbeuve8199]

I love your content, keep doing it :)

[@LastTenth]

Thanks I will do my best to keep it up!

[@onepairgames]

Hey it's me again. I was wondering if you could do a video on tyre conservation and management. I generally tend to overdrive (I think at least). In the first part of any race I have much better pace, but I start to experience huge a drop in tyre performance and that is probably because of me pushing the tyres a bit too much. Could be braking? Acceleration? I pay attention to the steering lock applied, but the first 2 area is probably something I could improve at.

[@LastTenth]

Hey Martin! Hopefully one day I can do one. I'm not particularly good with my tires tbh and it's something I intend to work on. I tend to chew them up a lot more than me peers and teammates. When I've figured it out, I'll definitely put a video together. That said I've had some success with minimizing steering as well as reducing brake pressure.

[@Fabian-rl2oe]

Amazing channel keep going your doing great stuff. Love the videos 🤩🤩

[@LastTenth]

Thanks for the encouragement and support!

[@peterfitzsimons6335]

This is a great video with great knowledge. Wish I could understand what your saying but I’m too stupid haha.

[@LastTenth]

Nobody is too stupid to learn… too lazy, yes, but not too stupid.

[@yungdomino4718]

@@LastTenth backhanded roast lol

[@gameurai5701]

Unfortunately I don't know what you mean by gear ratio and final drive. I have never heard of those two terms before. I just started shifting gears yesterday after playing sims for a whole year. It was always too hard for me to do. I did it in both AMS2 and ACC in single-player mode.

[@LastTenth]

No problem. It's good that you bring this up because sometimes I don't realize I'm not explaining things fully enough. Gear Ratio is the ratio of the number of rotations of a one gear to the number of rotations of an adjoining gear. In context it refers to the selectable gears in a transmission. Final Drive is also a gear ratio, but just refers to a final gear that affects the drivetrain, all the time.

[@jordanhoyle577]

Wow only just seen the subs I thought you had a huge Chanel by the looks of the video

[@LastTenth]

haha thanks Marc! Spread the word! Let's make the channel huge!

[@RallyRat]

The calculations are quite a bit easier if you can use a horsepower graph. Pick a shift point from the HP graph, see what RPM the new gear puts you in. Pick a higher shift point and test again if HP in the new gear is less than at the shift point, or vice versa.

[@LastTenth]

Yes it IS easier that way, but I passionately hate trial and error. I like to get definitive solutions whenever possible - do the calculation once, then be done with it. The math can be shortened by looking at shaft speed instead but the actual wheel speed can be handy in some situations.

[@LockDots84]

@@LastTenth you're an engineer aren't you?

[@LastTenth]

I’m not. I think I’m just a bit anal plus a bit OCD. Good guess though. Want another try? 😄

[@tonesthegrey6452]

Aren't the HP and torque peaks at different points in the rev range for most engines?

[@louisnortje1977]

struggling to find the rmp torque specs needed for the Audi R8

[@carnonPL]

I think I'm doing a mistake looking at power output and not torque. I'm usually reving to rev limiter and in some cars it is faster. Can you please explain this?

[@LastTenth]

Hi, what is it that you would like me to explain?

[@carnonPL]

@@LastTenth I don't drive irl yet so I always look at dyno when thinking about getting better acceleration (Assetto Corsa, BeamNG drive or Forza Horizon). Usually I rev over red line. I alwayes thought that HP is more important in race cars than Torque so now I wonder if HP even changes anything in acceleration?

[@LastTenth]

@@carnonPL Have you seen this video? kzbin.info/www/bejne/mWSxqa2KpruGjc0si=Q-TIrGr0fHBCEqZQ

[@tonesthegrey6452]

The natural question I asked is "What the h*ll does homey drive (on the street?) that produces 1500 ft/lbs of torque and revs to 7800RPM?!?".

[@LastTenth]

That's wheel torque.

[@sz3509]

anyone who plays assetto the 458 gt2 is a great example. the car flashes' red lights at 7100rmp but you can rev it out all the way to 8200. Not a lot of people know this lol

[@LastTenth]

Great info! I remember being in the 458 GT2 in AC a looooong time ago but never thought much about the rev lights - I was too preoccupied figuring out the aero lol. I think the SRF in iRacing is the same iirc.

[@sz3509]

@@LastTenth you have no idea how excited i am for iracing! im currently saving up for a wheel setup. i like the safety rating they have i wish ac had it as well lol but yes i love gt2 lobbies! everyone has a different pace because the setups play a huge role!

[@racekraft]

@@sz3509 that’s great! Wait till you get into private leagues.

[@dracosubs6141]

can you do one in mph

[@scottoconnor3484]

I downloaded the spreadsheet, entered all my data, and the result places my ideal shift points almost exactly at redline in every gear. Coincidence?

[@LastTenth]

Probably not. It’s likely by design.

[@chota.cabras]

Wonder if there is any way to see it on Motec (?)

[@LastTenth]

See what in Motec?

[@chota.cabras]

@@LastTenth never mind! you did a full video about gearing

[@jiajianhou426]

How do you get this chart for real cars without a Dyno tho?

[@LastTenth]

You can't. Somebody has to have dyno'd it. No different than in a sim; somebody would have had to dyno the real thing.

[@eidanhe]

I filled in all the columns in the table and everything made no sense

[@CUSTOMADE13]

engdgement comment

[@LastTenth]

engaged

[@chonglers1513]

Finally I can now smoke anyone at the lights in my honda civic

[@LastTenth]

Just make sure you don’t post any incriminating evidence 🤣

[@SlyNine]

Horsepower will also tell you where the engine produces the most torque at the wheels. Hence power. Just keep the engine where it produces the most power... Torque * RPM / 5252. I'm not sure I understand why you've over complicated this. Nothing is wrong, just way more complicated than it needs to be.

[@LastTenth]

The power curve alone cannot tell you which gear gives you more acceleration at a given speed. If it could, you would shift every gear at the same RPM, but as we've seen that's not always the case.

[@SlyNine]

Of course, there's the power curve you have to think about, separation between the gears and how that lines up with the tracks layout. But at any given speed max power will give you max acceleration.

[@SlyNine]

​@@LastTenththe same way a CVT would be the best transmission. Tho engines would struggle to be at max power the entire race. This was shown in F1 testing with cvts iirc.