Poll: Shifting at redline vs by ear

  • Thread starter AlexDB9
  • 65 comments
  • 4,609 views

What is the best method to shift?

  • At redline

    Votes: 22 20.0%
  • By ear

    Votes: 88 80.0%

  • Total voters
    110
Actually, I say "I'm glad I live on top of a hill"... I also say "What the **** are you going on about?" this isn't a situation that needs analogies - if you think you can make a point then you can 100% make it by applying physics directly to the situation at hand... I'm not an expert so I'm happy to be corrected, but I'd rather be corrected by someone who can apply physics to the situation at hand, not someone applying ******** to an irrelevant analogy.

That was a perfectly valid analogy but I see when people run out of arguments they just throw some swear words at their opposing side.

When I push down the throttle pedal all that matters at any time is the horsepower coming from the engine (at least when going in a straight line), and even if torque is the main contributing factor to horsepower it doesn't matter one bit how that horsepower is produced.

Maybe pictures help...
m4v4ofz.png
 
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Well, light travels faster than sound,💡 so I'm going to start looking at the rev counter instead of listening, I need all the time reduction I can get :sly:

I don't imagine you'd be playing much GT Sport if you were blind.
 
Well, light travels faster than sound,💡 so I'm going to start looking at the rev counter instead of listening, I need all the time reduction I can get :sly:

I tried manual the other day and I was all over the place :lol: accelerating and changing up was fine, but I had a disaster when I needed to turn, reduce speed and drop gear at the same time. Auto for me :)



Maybe not but blind skiing is a thing in the paralympics.

Do they shift at the redline or earlier? :)
 
I tried manual the other day and I was all over the place :lol: accelerating and changing up was fine, but I had a disaster when I needed to turn, reduce speed and drop gear at the same time. Auto for me :)

No guessing blind skiers have only one gear like electric cars.




Do they shift at the redline or earlier? :)
 
That was a perfectly valid analogy but I see when people run out of arguments they just throw some swear words at their opposing side.

When I push down the throttle pedal all that matters at any time is the horsepower coming from the engine (at least when going in a straight line), and even if torque is the main contributing factor to horsepower it doesn't matter one bit how that horsepower is produced.

Maybe pictures help...
m4v4ofz.png
Without sufficient Torque, you will not be able to accelerate to that RPM in certain gear. Sufficient torque surplus translates into raw force that counters drag and resistance and accelerates you to the desired velocity(or RPM). You may have all the power in the world, but try accelerating from 0 to 60 in 6th gear. Trick is to shift gears high enough in the RPM band, so the RPM's in the next gear do not drop to much below the max tourque value.

.
 
In PSVR I think some of the cars gauges display different to the 'games' redline.
Not a PSVR thing. Obviously PVSR gauges work the same way that in cockpit view. In which many times the red line is different from the game gauge.
 
I can shift by ear with no problem and like to play with no HUD & from cocpit.

Only problem is downshifting on cars not showing gears good enough or at all.
 
Without sufficient Torque, you will not be able to accelerate to that RPM in certain gear. Sufficient torque surplus translates into raw force that counters drag and resistance and accelerates you to the desired velocity(or RPM). You may have all the power in the world, but try accelerating from 0 to 60 in 6th gear. Trick is to shift gears high enough in the RPM band, so the RPM's in the next gear do not drop to much below the max torque value.

No this is simply not true, you shift in the RPM band where the *power* is high, not necessarily the one where torque is high (although of course there is a correlation).

Here again the picture of the M4 diagram:
m4v4ofz.png


You have the best acceleration if you stay within the max. *BHP* range between 5500 and 7500 RPM when shifting, NOT by staying in the max. torque range between 2000 and 5500 RPM!

At *any point* in the RPM range the BLUE curve will determine how fast you can accelerate, NOT the GREY one!
 
At *any point* in the RPM range the BLUE curve will determine how fast you can accelerate, NOT the GREY one!
Not convinced. The only thing that accelerates mass is excess force. That force comes directly from tourqe. At max bhp, your torque starts to drop, and you do not have any more force to overcome increasing drag and acceleration stops. In other words your speed stagnates. Bhp is for high speed, but only high torque will get you there fast. I would actualy try to shift just pass the torque peak, so as the rpm drop, tourqe starts to rise back up.
 
I lookup the torque and power chart, then decide where to shift, ...when I get used to the engine tone, that's it... not even looking at the bar...
 
Not convinced. The only thing that accelerates mass is excess force. That force comes directly from tourqe. At max bhp, your torque starts to drop, and you do not have any more force to overcome increasing drag and acceleration stops. In other words your speed stagnates. Bhp is for high speed, but only high torque will get you there fast. I would actualy try to shift just pass the torque peak, so as the rpm drop, tourqe starts to rise back up.
Try it for yourself :cheers:
 
Do explain.... :)
I'll give a clue. Doing your own research is better. :D

Ever wonder why the rev range gets narrower as you go through the gears?
Ever wonder why when you shift, the revs land on a specific number?
Or why cars can peel out in first, but not sixth?
 
Not convinced. The only thing that accelerates mass is excess force. That force comes directly from tourqe. At max bhp, your torque starts to drop, and you do not have any more force to overcome increasing drag and acceleration stops. In other words your speed stagnates. Bhp is for high speed, but only high torque will get you there fast. I would actualy try to shift just pass the torque peak, so as the rpm drop, tourqe starts to rise back up.

I am not that much of an expert either, but as I was interested in the topic and did some research a few weeks ago, and since then I find it kinda annoying that people talk about torque, because while it is interesting that it is the main driving force for the power of the engine, for everything else it is a redundant information and what really counts when driving is only power.

Here the article I found back then: https://danielmiessler.com/study/horsepower/
The main point is the conclusion:
So a technical answer to the question of, “What makes acceleration: torque or horsepower?”, is torque—but torque at the wheels, not at the engine. And since we’re talking about torque at the wheels and not at the engine, the best answer is horsepower, because horsepower encompasses not only the engine’s torque but the total torque that gets delivered to the wheels.
 
I'll give a clue. Doing your own research is better. :D

Ever wonder why the rev range gets narrower as you go through the gears?
Ever wonder why when you shift, the revs land on a specific number?
Or why cars can peel out in first, but not sixth?
Uhm, I have a guess. Because as the gearing gets higher, they use smaller and smaller cogs. Smaller cogs are increasingly harder to rotate, and so a car in first gear (which has the largest cog, and therefore easiest to spin) can immediately put down its full power whereas a gear in its highest gear (and therefore the smallest cog) will not be able to spin the smallest cog at the optimum RPMs quick enough, and so it drops out of the optimal powerband and "bogs" down. Hopefully my guess is somewhere close :D
EDIT: @FKAustria1911 got me first (and has a better answer :lol:)
 
An example of why TQ is acceleration, not HP...
1975 Corvette 3670 lbs, 165HP@3800/255 lb-ft@2400 = 16.12 @ in the 1/4 mile
2014 Ford Focus 3000 lbs, 160HP@6500/146 lb-ft@4450 =16.7 sec @ in the 1/4 mile

If HP determined acceleration, the Focus would kill the old Vette every time with it's 670lb weight advantage and mere 5hp disadvantage...


The following is stolen from a smart guy...
Torque is the rotary equivalent of force. For a constant mass, linear acceleration is proportional to the sum (net) of all the applied forces (F=M*A). Likewise, angular acceleration is proportional to sum of the torques applied (T = I * W). Note that it's the net sum of the torques (or forces) involved that determines if there is associated motion. If the sum is zero, there is no motion. If the sum is non-zero, there is acceleration or deceleration. In a system like an automobile, you can convert from torque to force given the inertias and lever arms involved (and vice versa). A car with a given motive torque (at the driving tires, not the engine crankshaft) will continue to accelerate until the sum of the resistive forces (or torques) is equal to the motive at which time the vehicle will maintain a constant velocity. If one were to write the equations of motion for a high fidelity simulation, in addition to the basic mass of the vehicle, you would model each of the resistive elements including the aerodynamic and hydrodynamic (lubricant) drags, friction, inertias of the wheels, tires, brakes, rear axle, driveshaft, transmission, clutch, pressure plate, flywheel, rotating assembly, accessories, etc. Then you'd need the gear ratios, final drive ratio, tire diameter and the power (or torque) curve of the engine.

People often act as if torque is a low RPM phenomena and power is a high RPM phenomena but both apply across the working RPM range of the engine. If you know RPM, you can convert from one to another. Horsepower is the more useful term in that you don't need to know the RPM. If you know your engine has 300 HP average between shifts, you can determine what the associated maximum acceleration will be. If you know you have 300 ft-lbs of engine torque average between shifts, you still need another piece of information before you can determine your maximum acceleration. That piece of information is RPM which allows you to convert to HP so you can determine how much engine power can be traded for wheel torque (via gearing) to accelerate the vehicle. Of course, if you have the wheel torque to begin with, you don't need the engine HP but that wheel torque will change for every gear you are in (or for every change in final drive ratio or tire diameter). Note that I use average here to simplify things. To be more precise, it's the shape and area of the curve that matter.

Dan Jones
(not me)

Now, back to me...
I used to drag race competitively (and still do for fun), and I can assure you that is one motorsport that requires an optimal shift point be utilized every time (one misjudged shift by as little as 100-200rpm can cost you .05seconds... half a car at 110mph... that is a significant win in class drag racing).

In order to calculate shift points, you use TQ/rpm, and transmission gear ratios... not HP... HP is merely a measurement(calculation) of TQ relative to rpm. If HP had anything to do with calculating max. acceleration, there would be a 5250 somewhere in the above notes calc. parameters.
My current engine makes peak TQ at 4800rpm, peak hp at 6300rpm, yet, runs fastest when shifted at 7500rpm.
The shift point has nothing to do with peak numbers, and everything to do with average TQ over a given rpm range when multiplied by gear ratio, or, "power under the curve".
Since the TQ this motor makes drops off very slowly in the upper rpms, it makes better average TQ well beyond it's peak, once the gear multiplier is factored.

The M4 in the game is essentially unaffected by short shifting because it's still making a tonne of average TQ lower in the rpm range, and as noted has close transmission ratios to keep the "geared TQ multiplier" high.

Don't think of a high rpm car as one that has lots or "HP vs TQ", rather that it makes its TQ in high in the rpm range, or, as in my car TQ falls off very slowly after peak, therefore being able to take advantage of the rpms and gear multiplication.

In game, I just shift when the limiter rev counter thingy flashes green... or when it sounds good... or when required depending on if I'm exiting a corner or whatever.
In real life, I have the vehicle dyno'd in race trim at operating temperature, then run the cals.

That's all I've got.
 
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Uhm, I have a guess. Because as the gearing gets higher, they use smaller and smaller cogs. Smaller cogs are increasingly harder to rotate, and so a car in first gear (which has the largest cog, and therefore easiest to spin) can immediately put down its full power whereas a gear in its highest gear (and therefore the smallest cog) will not be able to spin the smallest cog at the optimum RPMs quick enough, and so it drops out of the optimal powerband and "bogs" down. Hopefully my guess is somewhere close :D
EDIT: @FKAustria1911 got me first (and has a better answer :lol:)

You are on the right line, and would probably get there on your own, but let me help you...
Gearing is a TQ multiplier (and yes, the larger cog has more teeth, therefore a higher multiplier)
Say your engine makes 300lb.ft average in it's most usable range... and you have a 4.56 rear gear ratio...
If 1st gear is 3.31:1 x 4.56 x 300tq = 4528tq at the wheels.
If 6th gear is 0.63 x 4.56 * 300tq = 861tq at the wheels.
Since there is so little average TQ at the wheels, it really doesn't make much sense to stay in that gear long, and, does make sense to use that gear at the most efficient average TQ the motor is making... so the gears get closer to keep you in the most optimal rpm range, and, are shorter because there's no point hanging around at 861 vs 4528... but, in order for the car to faster, the gearing has to get higher (numerically lower) in order to create mph.
 
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You are on the right line, and would probably get there on your own, but let me help you...
Gearing is a TQ multiplier.
Say your engine makes 300lb.ft in it's most usable range... and you have a 4.56 rear gear ratio...
If 1st gear is 3.31:1 x 4.56 x 300tq = 4528tq at the wheels.
If 6th gear is 0.63 x4.56 * 300tq = 861tq at the wheels.
Since there is so little average TQ at the wheels, it really doesn't make much sense to stay in that gear long, and, does make sense to use that gear at the most efficient average TQ the motor is making... so the gears get closer to keep you in the most optimal rpm range, and, are shorter because there's no point hanging around at 861 vs 4528... but, in order for the car to faster, the gearing has to get higher (numerically lower) in order to make mph.
Very informative! Thanks :D
Wouldn't have gotten there myself though, since I haven't taken the time to study transmissions and all yet :lol:
 
An example of why TQ is acceleration, not HP...
1975 Corvette 3670 lbs, 165HP@3800/255 lb-ft@2400 = 16.12 @ in the 1/4 mile
2014 Ford Focus 3000 lbs, 160HP@6500/146 lb-ft@4450 =16.7 sec @ in the 1/4 mile

If HP determined acceleration, the Focus would kill the old Vette every time with it's 670lb weight advantage and mere 5hp disadvantage...

The Corvette is faster because it has more HP in the lower RPM range, simple as that.
My point is not that the max. HP is a useful number and that max. torque isn't. The max. values alone are both useless.
My point is that to know how the car will accelerate I primarily want to have the HP over RPM diagram. Of course that could be calculated also if you had the torque over RPM curve. But if I have the HP over RPM curve why do I need to talk about torque, it doesn't add any information. And I will not shift where the torque is this or that but where the HP is this and that.
And for the M4 I will shift so that I will always stay between 5500 and 7500 RPM because power is a flat line there. If you end up below 5500 RPM when shifting you will lose time and if you shift past 7500 RPM you will also lose time.
This information can be directly seen from the blue power curve, while the grey torque curve contributes no additional information at all.

Sure if car A has more max. torque and car B has more max. HP then it is certain that car A will have more HP than car B somewhere in the RPM range, and that is why it *might* be faster. But you can only say for sure if you see the curve, and better the power curve than the torque curve, as there you can see it directly (all other things like weight equal).

Here is another example, this is the diagram for my CX-5 G192 with 192 HP and next to it the 175 HP Diesel (says Mazda 6, but they use the same engine in the CX-5):
1929do5d.png
175dxxri2.png

So the Diesel has 17 HP or 12 kW less than my naturally aspirated gasoline fueled G192.
But it has 420nm max. torque while mine only has 256nm, so the Diesel has a more than 50% higher torque than my G192.

And guess which car will accelerate faster from 0 to 100 km/h? My 192HP G192, not the Diesel! (and not because the G192 engine is a bit lighter than the Diesel engine)

Sure I would have to rev my G192 like crazy close to 6000 RPM all the time and the Diesel will push forward much better at lower RPMs, because it has more *power* in that range. But still to get the max. out of the Diesel you look at the blue power curve and not at the pink torque curve, you would try to stay at ~4500 RPM where the max. HP is on the blue curve and not at ~2000 RPM where the max. of the violet torque curve is.
And if I would shift my G192 around the max. torque at 3250 RPM I would be completely screwed and probably take 20s from 0 to 100 km/h instead of 8.1s.
 
You are still looking at engine only output, and ignoring trans gearing (rpm drop, shift recovery and time spent under the curve with gear multiplication...).
it also appears you are looking at manufacturers marketing data, vs true dyno results, so, take those with a grain of salt.
It's all been laid out in front of you... it's late, I'm tired, and...
of course you are right, you do what you need to do.
 
The Corvette is faster because it has more HP in the lower RPM range, simple as that.
My point is not that the max. HP is a useful number and that max. torque isn't. The max. values alone are both useless.
My point is that to know how the car will accelerate I primarily want to have the HP over RPM diagram. Of course that could be calculated also if you had the torque over RPM curve. But if I have the HP over RPM curve why do I need to talk about torque, it doesn't add any information. And I will not shift where the torque is this or that but where the HP is this and that.
And for the M4 I will shift so that I will always stay between 5500 and 7500 RPM because power is a flat line there. If you end up below 5500 RPM when shifting you will lose time and if you shift past 7500 RPM you will also lose time.
This information can be directly seen from the blue power curve, while the grey torque curve contributes no additional information at all.

Sure if car A has more max. torque and car B has more max. HP then it is certain that car A will have more HP than car B somewhere in the RPM range, and that is why it *might* be faster. But you can only say for sure if you see the curve, and better the power curve than the torque curve, as there you can see it directly (all other things like weight equal).

Here is another example, this is the diagram for my CX-5 G192 with 192 HP and next to it the 175 HP Diesel (says Mazda 6, but they use the same engine in the CX-5):
1929do5d.png
175dxxri2.png

So the Diesel has 17 HP or 12 kW less than my naturally aspirated gasoline fueled G192.
But it has 420nm max. torque while mine only has 256nm, so the Diesel has a more than 50% higher torque than my G192.

And guess which car will accelerate faster from 0 to 100 km/h? My 192HP G192, not the Diesel! (and not because the G192 engine is a bit lighter than the Diesel engine)

Sure I would have to rev my G192 like crazy close to 6000 RPM all the time and the Diesel will push forward much better at lower RPMs, because it has more *power* in that range. But still to get the max. out of the Diesel you look at the blue power curve and not at the pink torque curve, you would try to stay at ~4500 RPM where the max. HP is on the blue curve and not at ~2000 RPM where the max. of the violet torque curve is.
And if I would shift my G192 around the max. torque at 3250 RPM I would be completely screwed and probably take 20s from 0 to 100 km/h instead of 8.1s.

I can bet that the diesel version will beat petrol version 0-100 for about 0.5s for sure... and I'll go for diesel in those two examples with no doubt, higher fuel economy, and more "power".

I found this BTW
Mazda Atenza 25S 0-100kmh 8.4sec
Mazda Atenza XD 0-100kmh 8.1sec
both are FWD and 6-speed manual

So yeah... torque over power for sure...
 
im just going to leave this here:

Note this video he continually repeats "for one gear ratio", And... if you stopped listening at 3.35, you would think HP is the driver, but if you continue listening you will hear him note that TQ is manipulated by gearing...
Now, we are not talking about one gear ratio, we are talking about when to shift... remember?
So, in another video by the same chap, he explains how things work in conjunction to one another (again, looking at one entity as a sole determining factor is a faulty way to determine acceleration in a machine with multiple means with with to "work")
So, here is the video on when to shift...

Note that he recommends dyno'n your car rather than relying on manufactures data.
Note that HP is never a factor in the calculations.
Now... don't be fooled by his example as an answer that "redline" is the be all and end all, it simply is the case in his demonstration... instead learn from what he has provided... maximize average wheel TQ in each gear.
Case in point where redline is not correct...
When I raced my car in showroom stock condition it had a factory fuel cut off at 6250rpm... aka redline.
However the TQ curve combined with the factory gearing meant the car ran hardest when shifted at;
5600 from 1st to 2nd - 5400from 2nd to 3rd - 5250 from 3rd to 4th.
Also note his example of the 1st to 2nd shift, do the math on that shift and I'm betting it comes out over 10,000rpm, which means - exceed redline.

Again, it's average TQ when combined with gear multiplication that is going to provide the quickest acceleration.
Since HP is just a calculation based on rpm divided by 5250, it never comes into play... it's a made up means of measuring.
 
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