When To Shift Gears For The Fastest Acceleration
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- čas přidán 11. 06. 2024
- When Should You Shift Gears For Maximum Acceleration?
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In order to accelerate as fast as possible, it is necessary to know exactly when you should shift gears. Maximum acceleration occurs when wheel torque is as high as possible. This gear shift should occur when the engine torque has dropped low enough that the lower gearing no longer offers a torque advantage. For many vehicles, this will occur at redline. For vehicle with lots of gears, or very close ratio gears, this may not be the case. In order to determine when to shift gears, you'll need to know your horsepower/torque curve (dyno), your transmission gear ratios, your redline, and your final drive ratio.
Note: some cars have more than one gear reduction in the transmission, as does the Honda S2000 explained in this video. You'll need this number if you want to fully calculate the wheel torque.
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NEW VIDEO EVERY WEDNESDAY! - Auta a dopravní prostředky
here's a trick, once you're in sixth, shift to the gear marked "R". this engages "Race" gear which will maximize speed.
Dont forget to pull up the ring to engage hyper-mode!
Should have researched this method before trying it today :/
This joke is played out
LMAO
i thought r was for rocket gear:(
Armed with this knowledge my civic can best anything.
Gamerred you didn't need to know this.... VTECH bests everything anyways...
Now you can outrun some other civics yay!
Now i can beat that enzo....again
swap 4th and 5th gears from an ITR and you're good to go. :)
Pffft, my Ariel Atom would beat your Civic, it's lighter. ;)
I shift when I hear the bald eagles scream.
murica!!!
hahaah so patriotic!
to much 1320
Let freedom ring!
Is it OK to shift past redline, for example, a car with a redline of 6500 rpm, but the cutoff is at 7100?
Every time I shift, I run through all these calculations in my head.
If that is the case you are making the same mistakes. It is a good approximation but neglected the torque required to accelerate the engine and the rest of the drive chain.
can you make a video on why mustangs always crash into crowds? I've been studying this for a awhile but I just can't find the answer. :(
Probably because crowds won't stop talking about Mustangs crashing into crowds.
you see the one at houston cars and coffee the other day?
MRios1128 same...
basically what happens is the driver is not used to so much power, tries to do a burnout/power slide, panics, hits the breaks shifting weight off of the rear wheels and makes the slide worse
ego and traction control function disabled.
"VTEC ̶k̶i̶c̶k̶s̶ ̶i̶n̶ ̶y̶o̶ changes it to a different cam profile"
its hard for me to listen to the video and read the comments at the same time
Welcome to adhd
Same 😂😂😂
"You rev it and rev it and rev it until the valves come out and dance on top of the bonnet, and then you change gear." - James May talking about a very small Fiat engine
should do one video shifting for best fuel economy possible
Eddie Linares thats just shifting lowest rpm possible
ya, but would just like the hear the math behind it. That's why I like to watch these videos
Oh absolutely! I would love to be able to do that math for my car too. It's a really small turbo diesel and could potentially get great consumption figures (3.4L/100km) but I've yet to hit those numbers. Perhaps an episode on this would let me understand my engine a little bit better.
My Subaru is really unhappy at below 2000rpm, vibrating and stuff... Maybe that's part of the reason whyEJ205 has such terrible gas mileage? :)
@klikkitse Highest gear on cruise control just below turbo's entry point(depending on the car it should be under 2000rpm or maybe a bit lower, like 1500rpm). Drive your car like that on a cool day(10-15°C) on the highway and you will get that consumption. But don't do that too much, because in my opinion it is not really healthy for the car.
There should be a kickstarter to get EE a bigger whiteboard.
Or maybe a GoFundMe so you can have a larger screen. :P
the savagery!!
DomitionX dammm 😂😂😂 roasted
XD Maybe a patreon for a yellow dry-erase marker for that sexy S2000
Ha! I've got one, but I only recommend it if you use AdBlock: www.patreon.com/engineeringexplained
TLDW: shift at redline
LOL
What does TLDW mean
@@gsteel98 too long didn't watch
Lol
thanks
Awesome video as always! I think shifting early to make more power is probably more common with cars that come with very small factory turbochargers that make a lot of midrange torque but fall off pretty hard between 6000-7000.
I was doing that in my twin turbo charged 335i and today I raced my buddys cammed 3v I thought I was gonna get walked similar to the last runs but I started to shift at 7k and I beat him top end my car is stock
7:42 question: "so when would it not be ideal to shift at redline?"
my answer: "when backing up?"
You're an engineer and obviously a skilled artist... That's the best blue s2000 drawing ever! (I know you were kidding, I'm just being funny)
No, it's absolutely wrong! Top always down! :)
the S2K has even a spoiler
that proportional hood length.
I thought it looked more like a 2005 than a 2002
To be fair though, that drawing would have been decent if he said it was a Honda S800
man... you go through such a great deal of mathematics to explain your videos in the greatest detail which I appreciate!!! Sad to say all 583 folks who gave you a thumbs down just wanted you to say "shift from first to second at "x" rpm" etc...
Jason, thank you for such incredible content on your channel. Always a pleasure to watch any of your content.
Such a great video! My EMS allows me to set a shift light (CEL) for each individual gear. Even though I'll be autox'ing and won't leave second gear, it'll be nice to see my shift points and pay more attention to the course vs constantly eyeballing my rpms. Thanks so much!!!
I wanted to see a video of you actually shifting, the thumbnail brought me here lol
+TylertheGeek28 video coming soon of 9K in the S2000!
Can we get a version of the graph with the GT350 instead? :)
hey can you do a video on the cooling system as it runs through the engine?
it's pretty simple in theory, it's just a heat exchanger, but I've never seen an engine block in that detail so it would be cool to see how the water flows through the engine in order to cool it :P
noob
Thanks for your informative comment.
It has holes and the cooling liquid goes there. It's not simple to design I guess
Now I can smoke BMWs with my 1999 Škoda Fabia 1.4 MPI.
In this case you could've just explained this whole thing based on power. A transmission just transforms a set of torque and rpm into another set of torque and rpm - the product of both (power) stays the same going in and out of the transmission (losses aside). So for max acceleration you just want to shift in a way that gives you more engine power (equally more wheel power) after shifting, which means shifting at max or almost max rpm with most automobile engines. There's some layouts with massive power drops in the higher rpm range (like some older truck-/van- td's) - with these you might loose too much time staying in that drop-zone for too long, even if power after shifting might be higher than when shifting earlier.
Anyway... just wanted to mention that simplified power-thing - would've fit in perfectly, given your juggling with torque, rpm and gear ratio figures; even if you essentially explained the same thing and came to the same conclusions.
First time I thought "well maybe I would've explained it a little differently" in one of your videos though - and I watched them all (or maybe 92% or so).
Killer s2k sketch. I recognized it immediately.
Cheers from a german fan and engineering colleague.
I am a little slow right now, mentally speaking, but so far your comment makes sense. Power is torque x rpm. So you are keeping all that variables in mind. It makes sense that you want the most power at all times, so, you have to be in the peak of the power curve. Normally redline hits when power starts to drop. And also, power starts to drop many rpm after torque drops off.
I guess car manufacturers always tune they cars so the redline is little after you should make the shift (like 200 rpm or so). Your goal is to maintain the engine in the happy zone.
THANK YOU FINALLY. Ive been trying to explain this to people for MONTHS and all i hear is "no you always wanna shift at your hp peak so power doesnt fall off"
Now you can slap them with knowledge! :)
But of course this is the case for this specific car. Maybe in another car the torque drops much more vertically. You still have to do the math for your vehicle (if you don't have an S2000) to convince them :P
Now this puzzled me a bit at first, since i remember that power was torque times RPM. However, it is torque and RPM at the wheels that we maximize here (and therefore the power we get on the street). The RPM in the graph is at the engine (before the gear box that drives the wheels).
You can do all of this with power, and it's quite a bit simpler though. You do want to shift so your power doesn't fall off, but what they're missing is that if you shift at the power peak, your power falls off because you're way below the power peak in the next gear. You want to shift at the correct point so you're making just as much power in the next gear as you are in the current gear, so you want to end up straddling peak power with your shifts.
Wrong... if you want to go faster... shift down... then down again... and when you get to the lowest gear... shift down again. Fast and Furious has taught me all I need to know about racing.
Thank you for all of these informative videos. You have helped me better understand a lot of things about my car. Your reviews are great too. Keep it up and enjoy that S2000.
I did the math for a 2.0 tdi from Audi with 140kW, which has a big drop of torque after 3000rpm. As it turns out, the gears in the 6-speed manual are perfectly matched to the engine (what should be expected). When you shift from 3. to 4. at 4500 rpm (redline) the engine drops to 3300rpm but the wheeltourque stays the same. If you shift earlier, you get less torque that in the lower gear. Same for 4. to 5. So even with a diesel engine, that has peak torque form 2k to 3k rpm, you should rev it to redline.
I love how you use the words "of course" so frequently, as if I know this stuff. That's why I'm here!
One of the best educational YT videos out there. Good stuff.
Congratulations as always for the hugely explanatory videos!
This dude always impresses me.
how do i shift in automatic..?
or did my auto shift ?
I can make my auto upshift if i let off the gas a little bit
Yours must be a fake automatic.
Real automatic shifts, automatically.
More misconceptions and misinformation.
Most automatic transmissions do shift automatically, can be manually shifted and can be tricked to shift in auto mode by manipulating the throttle.
Most automatic transmissions sense the load, either by a mechanical governor or through electronic sensors controlling the shifts to maintain a compromise of performance at less than 75% full throttle or compromise fuel economy at more than 75% full throttle.
did i won the election ? vote Trump and shift up.. lol
TrumpCorp. I can't vote Trump, I live in Canada.
I love your videos and the juicy details. Good on you for the details. My favorite car channel of the year :3
Brilliant explanation Jason.
Its also why for race cars you need different gear sets for different tracks, you pick the longest gear so it just redlines on the longest straight and then space the others so each down shift puts you as high up the torque curve as possible while allowing 1st and second to be short enough for the start and not leave any gaps (obviously in practice lots a bit more complicated).
F3 teams literally travel with cases of gear ratios which they swap around.
I geared my BAC Mono in this way for Silverstone and it makes a big difference.
This would be more interesting for a small turbo car (1.6T~150-175bhp) and a diesel car (2.0T 140-170bhp) - the kind of cars most people drive across the pond.
DuBstep115 so you want to
Know for a useless vehicle
Rather than have it for a vehicle
You will actually drive?
VTEC actually acts a lot like a turbo...sorta mild at low RPM, then a big kick in the butt when the turbo spools/VTEC kicks in. Your torque curve would be similar.
James Butler 5.7 useless? 😂
SBeckerDTD yes, no one drives 5.7litre cars because it would cost £300 to fill the tank with dirty petrol. I, like about 58% of
The population drive a diesel therefore it would be interesting to know. However I have done my own experiments and find that changing at 2000-2300 is optimal for low noise and smooth driving.
James Butler Weird. I don't know anyone who drives a diesel car.
To sum it up, it all depends to grear ratios and torque delivery throughout the rpm range. Nice video.
great explanation by the way. I have been watching your videos for a very long period of time. keep it up
This is a fantastic video.
Great job explaining all of the numbers!
It would usually be the case that you'd shift at redline or just before the limiter in the vast majority of cars, unless you have very closely spaced gears and restrictive top end. For example my Peugeot 206 HDi seems a bit limited when you go in the 4000-5000 range, (possibly due to the computer limiting the fuel though).
I used to think in terms of where the average power within the range you use the gear is greatest but it is probably simpler to think in terms of torque.
Obviously if you have a CVT you'd just keep it at the power peak.
Its fantastic how you make those complicated things clear for us, thanks and hello from Russia!
Happy to hear it, thanks!
It's fantastic how he made the CONCLUSION clear for us. The complicated things stays complicated, at least for me. I just wait till the end until he said, 'So that means is, basically running out to red line and then shift gears. And that's gonna be the case for tons of other cars out there...' then I was like, oh so that's how I should change gears.
And then move on.
Thanks for all your great, knowledgeable videos. I love how it's all fact/science based, gives me a ton of confidence in my SI!
I feel as if this video was made for me as I've always asked whether going to redline was always the quickest way and now I know that most of the time it is. Thank you
"When is shift ideal not at red line" You learn me good!
7:43 "So when would it not be ideal to shift at redline?" Seems like a normal sentence to me...
I was poking fun at what you wrote on the whiteboard :D Great vid btw!
you misquoted the whiteboard
Would you do another video on when to shift fears to get the maximum fuel efficiency?
This is very important in Diesel cars: I have a 2.2HDi car (406 coupe), and despite the fact it redlines at 5000rpm, peak power and peak torque occur at much lower RPM. The torque drop betweeen 4000 and 5000rpm is huge, and after downloading my torque curve to a spreadsheet I was able to figure out it was only logic to push 1st gear to redline, because of the output ratio difference from 1st to 2nd. All other gears should be shifted well below redline. Very nice video!
thanks for making this video, you bring it down so I can understand this!
When? Paul Walker taught me to shift whenever I can.
All the way into 9th gear.
A.K.A Ghost Rider...
Basically, power when you leave the gear equals power when you enter the next gear.
Exactly
Precisely
So much simpler and exactly the same result. Me thinks that he doesn't understand power.
ExactlyPrecisely saved me 8 minutes and 39 seconds
oh my God. *insert thank you gif*
Exactly. Usually he is good. But he should have researched this better. Heard youtube has changed payment policy. People have to make videos more often. It is making many desperate. Quality will go down.
This was wonderfully explained! Thank you!
Love this channel. Keep it up Jason!
Great video, Jason. Most modern petrol cars do behave like this. Diesels often do not, and turbo petrol/diesel engines are just more difficult to compute for. Could you make a video about dyno performance of turbocharged motors in different gears? They dyno worse in lower gears as the engine revs quicker in those gears, making lag more evident. Sometimes it makes sense to shift sooner to be on the next gear (especially for engines with a low boost threshold) and stay on boost longer than to wind out the motor while experiencing turbo lag the entire time in first or second. This video would be relevant because of the popularity of turbocharging these days. Thank you very much!
Do they not have any form of boost/lag control?
@@melody3741 Factory cars don't however they do usually run recirc valves which should help largely elminate lag between shifts.
Can you Make a video showing relation between weight and horsepower. For example a race with something that weighs 200lbs with 200hp. Vs. 2000lbs with 600hp
Always enjoy your videos thanks!
Great explanation and presentation, this helped a lot! Thanks for posting!
#notifsquad!!!!
I, like Dulcich from Engine Masters, always shift at redline.
If nothing else, do it for the sound!
math and science for (shifting, throttle input, ignition timing, manifold pressure) for best fuel economy while accelerating, cruising, and decelerating...please.
Great video, I really enjoy the application of math and science that you connect to real world scenarios.
this is great video. That formula helped me understand this allot better.
I usually just shift my S2000 when it starts bumping at the top and wont let me go fast no more
Blake Calabrese you're wearing out the clutch faster.
How?
Engine limiter controls fuel injection.
RzVids how's that?
RzVids how's that?
I don't even have a tachometer so I only upshift when I feel the car isn't accelerating as quickly as it could if I'm entering a highway on leaving traffic lights and stop signs. On quiet streets though I upshift by sound, to save fuel I upshift as early as possible without stalling, quiet sound = saving fuel
Simpler method :
Max torque at the wheels is also Max power at the wheels.
Assuming no losses, power at the wheels is power at the engine.
Knowing the gear ratios, draw on the same graph for each gear power in function of the speed (same as power in function of rpm but scaling with the gear ratios).
Always be on the curve at the top. Done
Thank you for the link to the book. I just received it and cannot put it down now. Currently working toward my BSME after a 25 year career as a chassis and suspension designer. Cut my teeth on the original Viper, not a bad way to start. I really enjoy every one of your video's, your lingo sounds as if your are a product test Engineer.
I like most of your videos, but this one is saved to watch again later and do the math for my car. Love this one
When To Shift Gears For The Fastest Acceleration
: When the G29 shifting lights start blinking.
'Beautiful blue Honda S2000' - Ha.
Spent weeks on that sketch. Minutes on the explanation.
im dying😂😂😂 @engineeringexplained
Thank you for making this video.
Dude,I love your videos!
I'm a bit confused here. I always thought that max HP provide the actual max acceleration, whereas an increase in torque will only increase the weight that the engine can move. Power measures how fast you put torque down and if 100 lb are enough to get you moving at all, more wheel HP translate to faster acceleration, not higher torque.
So with this logic, having a higher power output of the engine (which increases until 8800 in the S2000 example) matters more than the torque that falls after 7850 RPM. Am I right, or wrong?
That's right. Power / hp is the important. He considers torque and rpm so he is considering power. Remember that torque x rpm = power. It's sorta the same thing. I think that it's easier if you put everything in terms of power. And also, rpm in the wheels itself it's what it gives you the speed you are getting. Power makes the calculations easier since power should be equal in any stage of the transmission, having losses aside.
A more "geometric" approach would be to take dyno graphs for each gear (speed-hp plot) and see at what speed the lines cross. That's the optimal speed to change gear. IMG: s260.photobucket.com/user/cdcracing/media/ingearpower.png.html
akiskev yeah that graph makes it easy to understand. A lot of people think they should shift at peak horsepower because it drops after that, but they don't know shifting to the next gear results in more horsepower drop that revving it to redline
That is it.
akiskev An old issue of Hot Rod Magazine explained the intersecting power curve in each gear as optimal shift point. It added that, because of slight deceleration during a manual shift, you should rev slightly beyond the intersection point before shifting.
You change gears based on rpm and not based on speed....... it is so much more simple to do it this way then to try and match your shifts based on your speed.
*"An old issue of Hot Rod Magazine explained the intersecting power curve in each gear as optimal shift point."*
No, because those lines ALWAYS cross at 5252 RPM. In a truck diesel, you'd trash the engine before you got there...in a Wankel rotary, you wouldn't even be in the powerband yet! (It's probably a good estimate for a large, pushrod V8, though.)
Such a good teacher you make it simple enough for everyone to understand! Can you make a video on how to figure out brake horsepower a vehicle displays and maybe compare it to track cars numbers.
Very informative, great video I learned a lot, keep up the good work
Wish he would say "when vtec kicks in yo"
You shift gears when you want to overtake someone in a 5 min drag race
In my experience with driving an S2000, you end up in a lot of inadvertent drag races just building torque when taking off in 1st. Especially against pickup trucks, for some reason...
+DuBstep115 I saw a nice yellow S2k today while in an old 4Runner and I said "hey man, want to race?" And he looked at me and sped away
DuBstep115 240hp is not underpowered, short gearing and a high peak power is why fast hondas don't work well on highways
What sort of feckin' drag race lasts 5 minutes?!? Heck, a top-speed Bonneville run probably doesn't take that long!
bcubed72 come on bruh haven't you seen the real street racing documentary series from 2001 called Fast amd Furious
Thank you for drawing specifically my car, I feel special! Great vids btw.
So correct. Love the explanation.
"All we know is....HE'S NOT James May, He's James May's American Cousin!"
engineering explained I want two stroke exhaust's.
Are they not fascinating enough for a video??
I started reading on them and their quite an engineering feat.
it's like vtec for two stroke's
and fully tunable!!
Watch towards the end! czcams.com/video/z-7AkC3gh4w/video.html
Really good explanation. I just love a good physic/mathematical explanation.
Seriously one of the best youtubers ever. Well done!
this imperial system really fucks it up for me..
When do I shift in my Turbo Diesel that has peak torque at 1900rpm which tails off very quickly?
good question, would like to know that too :) ... what about diesel engines??^^
You apply the same principle. You must go a bit after the peak HP because when you shift into the next gear the rev will go down and you need to be in a good point of your powerband, so is the min/max better average that you have to know. Its the same principle.
ah thank you, nice :)
I also daily a turbo diesel, and this method helps:
If when I upshift, I feel a loss in Torque, I should've shifted later
If when I upshift, I feel an increase in Torque, I should've shifted earlier
It's not very scientific, but it works! And after a couple of tries you start to shift in the exact moment
Javier E Yep mate. Then its just a matter of checking the times.
Just the video I wanted. This guy is the best
Fantastic explanation!
Why do this without 1 flat acceleration run on the s2000? I really wanted to hear that VTECH yo,
There's no 'H' in VTEC
No I meant VTECH, but there was none of that in this video either.
what about diesel engines? 2.0 tdi for example
dude, if it wasn't for you I wouldnt have known what I want to major in!! because of you I now know what I want to do which is mechanical engineer too but more into Motorsports engineering, I thank you for that. Keep up the great work, we're almost at 1 million subscribers.
Gg. How did it go and what are you upto now?
Thanks for this. My truck has a 5 speed featuring a very close 1-2 shift and after mathing it out, i have learned that first gear i should shift 500 rpm early and then redline every other gear
This man turned shifting in to my math teacher🤯
You could simplify this by just saying "shift when horsepower in the gear you're in drops below horsepower in the next gear." Power adjusts force/torque for speed.
Daniel Oliver yep, my thought exactly. He should do a video for a fast diesel and determine when to shift for max acceleration...
Ur channel is Unique! Congrats Sir... Keep up the real and great work
I have little to no car experience, and am very bad at math. But you made this veru enjoyable and even I understood the concepts. Thank you so much for a great video.
For best acceleration you always want to shift at the redline, and when your close to topspeed, kick in the *racegear*
(that's the one with a R)
Hello, there is a mistake in calculation: when you upshift from 1st to 2nd the gear ratio drops by 34.727%, it will increase by 53.2% in case of downshifting from 2nd to 1st.
Correct gear disadvantages here:
34.727%
27.58%
21.6%
16.36%
16.48%
Your number are for upshifts.
Your videos are super interesting for watching. Thank you.
Excellent video, thanks Jason!!!
Very useful! Ive always just looked at the dyno curve. And shifting gears right before it starts to drop off, and lands in the beginning of the peak torque. Now I can rev my CTR to the redline again! :P
Can you simplify that by saying: "Shift in case you reach higher HP" or does it not work this way?
Well, it doesn't really work this way for gears. You could be at peak HP in 6th gear, and your acceleration would be slower than mid HP in 2nd gear. You want to maximize (gear ratio * engine torque).
Thanks for reply! I was thinking about it this way: If you drive at certain speed and at that moment you wanna know if you should shift, it is basically the same as trying to find out "best acceleration at given speed". This is what you talked about in your video about CVTs and that's where you said that at given speed, you should go for maximum HP.
Nope you are actually wrong on this. You look at hp, since hp is (torque*rpm/5252), even if you apply gearing HP stays the same(-losses) and wheel has constant rpm at shiftpoint -> wheel torque scales with hp aka you don't want to shift before you get higher hp out by shifting or can't get any more rpm, usually the later one happens first
Shift to maximize horsepower. power = force * velocity. A gear exchanges force for velocity or vice versa without changing their product. To make it easier though, remember that a lot of vehicles can be shifted when they're about to hit redline, because the engine tends to make more power there than it does at whatever rpm you are at after the upshift. (if peak HP is 5300, redline is 6000, and the next gear will put you at 4000, you might rather stay in the current gear until you're about to hit 6000 and then shift, so you end up starting out at 4500 in the next gear instead.
Yay blue S2000! ;)
(2006 Laguna Blue Pearl)
Monte Carlo Blue 2000 AP1 ;)
So well explained! Amazing
Great video. This is probably not a very useful exercise for stock cars, but definitely for anyone with major modifications.
I would think you would want to shift from 3rd to 4th at about 8150 since your torque curve is dropping from 7850 on. If 8800 in 3rd = 6900 in 4th, and there's no difference between Wt@6900 and Wt@6250, that's 650 revs, so on 3rd you should shift at 8150, so you don't have as much drop, resulting in more overall power applied.
"there's no difference between Wt@6900 and Wt@6250"
You are not taking into account the gear ratio difference between 3rd and 4th gear as he explains in the video. At 6900 rpm and 6250 rpm the "ENGINE" puts out about the same torque, but torque that is applied to the wheels is less in a higher gear.
lb.ft...aaaaargh 'Muricans and their weird systems! :P
At least, when it comes to torque, use N.m as unity!
Interesting explanation btw.
Thanks for the video man. This really helped alot.
im going to use this to set up a shift light, thx so much. love the videos, very informative, and as always awesome white board demonstrations.