Why are RPMs shown rather than torque?

[IdunBrokdItAgin]

May sound like a damn silly question on it's own but the real question is why do both cars and bikes show RPMs as a read-out as opposed to torque?

Most lay people, such as myself, look to RPM as an indicator of "fast" (as in higher means "faster" in both terms of acceleration and cruising speed - when gear ratio taken into account). However, having just read a thread from another forum of optimum places to change up (in RPM terms) it seems to strongly allude that change up points are best selected for the points where torque is strongest (calculated both in the current gear and the next gear).

So, if acceleration is best judged by torque, why do bikes/ cars not have a torque read-out (either in addition to, or instead of, RPMs)?

Are bikes and cars just working on old technology instrumentation read-outs? And, if a dyno machine can measure torque at any point, why can't a modern automobile?

Lots of questions but I am genuinely interested in the reason behind why torque is not displayed.

[ellipsis]

....just ride it mate...

[davebullet]

G'day mate.

Probably no technical reason. I'm sure there are physics equations and means for a bike to measure the mass load, subtracted from an ideal zero load and you have torque available.

I suppose revs are there first and foremost to stop you blowing up the engine. Then rev limiters came along with ECUs and largely prevented the rider from doing that (except at cold).

Maybe it's do with dials and linear gauges. I mean revs are linear and bike independent. You can hop from one machine to the next and get the same readout.

A torque calculation / tacho system might be too susceptible to people modding their bikes. Different exhausts, fueling and cams etc... change the torque curve.

Having said that the Bugatti Veyron reads out HP.

I suppose most people just find an already taken dyno of their bike and identify the rev range where the max torque is.

And finally.... we ride triples which basically mean you have max torque all the time, so would be redundant :rockon:

[nadroj]

I have a torque meter on my bike - it's called a bum-ometer!

[Cloggy]

Not a silly question at all. I agree with you, it would be nice if both car and bike manufacturers could include where the engine's optimum operating range is on the rev counter. I've seen this on some trucks.
Also agree with Dave, one of the reasons I bought my Triple is for the very reason they start making torque down low in the rpm range. You don't need the rev the snot out of it to get it to move. Although taking it to the redline is a lot of fun as well.

[Owl]

RPM - Visual aid for deaf people, cause deaf people can't torque:shutup:

:facepalm:

Sorry, but on a serious note, have you ever seen a deaf person driving a manual without a rev-counter:eek5:

[marty]

I always thought the speedo was the fast indicator. And the fact that the dashed white lines on the road have turned to a solid one, and lamposts look like fence posts.

[Bass]

Indicating RPM is relatively straightforward and inexpensive. Torque output however depends on: -
RPM
Throttle setting
Fuel type and purity
Air temperature
Engine temperature
Air humidity
plug condition
etc
etc

I have seen it done using a load cell in the drive line which actually measured the torque rather than calculating it. However it involved slip rings which all but negated the value of the exercise because the load cell ouput is in millivolts and so the slightest bit of crap on the slip rings screws up the signal.

[puddy]

May sound like a damn silly question on it's own but the real question is why do both cars and bikes show RPMs as a read-out as opposed to torque?

Most lay people, such as myself, look to RPM as an indicator of "fast" (as in higher means "faster" in both terms of acceleration and cruising speed - when gear ratio taken into account). However, having just read a thread from another forum of optimum places to change up (in RPM terms) it seems to strongly allude that change up points are best selected for the points where torque is strongest (calculated both in the current gear and the next gear).

So, if acceleration is best judged by torque, why do bikes/ cars not have a torque read-out (either in addition to, or instead of, RPMs)?

Are bikes and cars just working on old technology instrumentation read-outs? And, if a dyno machine can measure torque at any point, why can't a modern automobile?

Lots of questions but I am genuinely interested in the reason behind why torque is not displayed.
The boy racers just can't squeeze in another gauge!

[Shadows]

All I want to know how fast my wheels are turning and how fast my crank is spinning.

The seat of my pants takes care of the rest while I concentrate on the shit unfolding in front of me.

[Crasherfromwayback]

can be used as another speedo. You don't need a torque read out...you can feel it through your bum cheeks!

[IdunBrokdItAgin]

Thanks for the replies.

So it sounds like it is theoretically possible, for an automobile, to calculate its torque - however there are many variables and modern technology wouldn't be accurate enough to accommodate all of them.

Interesting - I reckon the person who designs a practical working solution would make a fortune - won't be me though as I am just not that clever.

[SMOKEU]

A torque gauge will be of little use as you just have to know where in the rev range the peak torque is developed, and drive/ride by the tacho, shifting just under the redline for maximum straight line acceleration.

If you're in a cage towing a heavy trailer then it's a good idea to keep as close to the maximum torque RPM as possible.

[hayd3n]

A torque gauge will be of little use as you just have to know where in the rev range the peak torque is developed, and drive/ride by the tacho, shifting just under the redline for maximum straight line acceleration.

If you're in a cage towing a heavy trailer then it's a good idea to keep as close to the maximum torque RPM as possible.

you'll actually find the bike faster if you know when to change gear its not necessarily just before the red line

[Bonez]

....just ride it mate...Ditto. Less torque more riding.

[SMOKEU]

you'll actually find the bike faster if you know when to change gear its not necessarily just before the red line

Having looked at many dyno charts, I have found that peak power is usually just before the redline, after which power output drops rapidly. There are of course exceptions to this observation.

[george formby]

I've seen rev counters with the peak torque area highlighted by different colours & I think some of the new digital tachos change colour through the sweet spot. My thoughts on RPM, formed as a learner rider, are that it tells me when the engine is about to blow up. Red means danger:shit:

[psycho22]

Having looked at many dyno charts, I have found that peak power is usually just before the redline, after which power output drops rapidly. There are of course exceptions to this observation.

Those will presumably be only inline 4 charts as V-Twins make there peak power a fair bit before the redline.

[Blinkwing]

Sorry, but on a serious note, have you ever seen a deaf person driving a manual without a rev-counter:eek5:

Yes. Any questions as to how I ride? :bleh:

[avgas]

Seeing as most here can't read a torque wrench.......giving a torque gauge on a bike is just going to cause problems.

As for the RPM.......last time I did gear changes using a torque scale the front wheel never touched the ground.

[Flip]

The boy racers just can't squeeze in another gauge!

The boy racers are all torque!

What would you show on a torque gauge, the actual torque being made by the motor or the theroretical torque that the motor could made if it was being fully loaded at what ever RPM the motor was running at.

It would also be difficult to do, I suppose you could measure the stress in the bell housing with a strain gauge but the bell housing would have to be redesigned so that it included loaded elements.

[ellipsis]

Red means danger:shit:

....neil said that, red means 'run' son....numbers dont add up to nuthin'...

[Old Steve]

Cost, it's cheaper to provide a tachometer. I don't know how expensive it'd be to provide a torque-ometer.

Or would that be a Newton-metre meter?

That's the same reason why oil pressure is shown on gauges and not oil flow rate. Oil flow rate is more important than oil pressure. Just imagine your oil line has a tap fitted to it, you close the tap and you have maximum oil pressure but no oil flow. How long does the engine last?

[bogan]

just you wait a few years, then they'll all have em! The lecity bikes have current instead of rpm, and current = torque :yes:

[manxkiwi]

Pretty sure I read somewhere that the new six cylinder 1600 BMW has an available torque display instead of of a tacho.

Perhaps you could Google it and see what they say?

[superman]

If I haven't been counting up the gears I have no idea what gear I'm in unless I can compare speedo and revs.

Though torque being shown would be interesting, especially in a racing situation. Might make just that bit of difference you need to gain the advantage.

[IdunBrokdItAgin]

A torque gauge will be of little use as you just have to know where in the rev range the peak torque is developed, and drive/ride by the tacho, shifting just under the redline for maximum straight line acceleration.

If you're in a cage towing a heavy trailer then it's a good idea to keep as close to the maximum torque RPM as possible.


you'll actually find the bike faster if you know when to change gear its not necessarily just before the red line

This is exactly my point - I, like lots of other riders, wrongly assumed that the fastest acceleration is gained by wringing the crap out of the revs (changing just before the limiter).

I finally found out last night that it isn't. Set change points to ride the peak torque line would ensure optimal acceleration. Plus there might be strategic change up early points for certain gears.

Fascinating stuff - for example the thread I was reading was around the triumph street triple when standing race starts. Changing up points proposed (based upon a dyno chart) were:
1st 3,250
2nd 4,000
3rd 6,750
4th 8,500
5th 9,500

Where as before I read that I honestly believed that maximum acceleration was by changing at peak revs (12,500) in every gear.

This all lead me onto re-examining what the point of the tacho was. It isn't for acceleration purposes that is for sure, hence why a torque gauge would be useful, in addition to the tacho gauge.

I have only been riding for about two years and I'm still liking how I am finding out new things all the time.

And yes I do need to stop thinking so much and get out and ride more LOL.

[davebullet]

Unless you are slickety smooth, gear changes waste precious time and forward momentum, so the lesser skilled might have faster acceleration outside the peak torque range with less gearshifts (to a given speed).

[IdunBrokdItAgin]

Unless you are slickety smooth, gear changes waste precious time and forward momentum, so the lesser skilled might have faster acceleration outside the peak torque range with less gearshifts (to a given speed).

Totally agree - more time will be lost on my sloppy gear changes than any clever change points can make up for me.

Don't get me wrong - I'm not thinking of launching off at every set of lights with the change up points posted above.

It was more about my understanding of my bike improving - by getting rid of my assumption that higher RPMs means faster acceleration.

[SMOKEU]

Unless you are slickety smooth, gear changes waste precious time and forward momentum, so the lesser skilled might have faster acceleration outside the peak torque range with less gearshifts (to a given speed).

I reckon I can change gear in around a second, it's not that hard. Just back off the throttle at 18,000RPM, slam it into gear and nail the throttles straight away.

[psycho22]

I reckon I can change gear in around a second, it's not that hard. Just back off the throttle at 18,000RPM, slam it into gear and nail the throttles straight away.

I'd say thats about average for most bikers.

Besides unless you're racing on the track or going down the drag strip it's not going to make any difference whether you change gear in 1 second or .5 of a second.

[tigertim20]

May sound like a damn silly question on it's own but the real question is why do both cars and bikes show RPMs as a read-out as opposed to torque?

Most lay people, such as myself, look to RPM as an indicator of "fast" (as in higher means "faster" in both terms of acceleration and cruising speed - when gear ratio taken into account). However, having just read a thread from another forum of optimum places to change up (in RPM terms) it seems to strongly allude that change up points are best selected for the points where torque is strongest (calculated both in the current gear and the next gear).

So, if acceleration is best judged by torque, why do bikes/ cars not have a torque read-out (either in addition to, or instead of, RPMs)?

Are bikes and cars just working on old technology instrumentation read-outs? And, if a dyno machine can measure torque at any point, why can't a modern automobile?

Lots of questions but I am genuinely interested in the reason behind why torque is not displayed.

tourque isnt a necessary readout. you can feel how much the thing is pulling when you wind her out.
rpm on the other hand, well its certainly handy to know where red line is, and how much you are stressing the engine

[LBD]

Right, to answer the first question...Unlike RPM, too mush torque does not make a hand grenade of your motor.

Peak power is just below the red lineusually but peak torque is often 50 to 70% of the max RPM.

Power does not accelerate, torque does.

Re screwing the ring off it for fastest acceleration....it is not the max engine torque that counts, it is the maximum torque at the gearbox output shaft or rear wheel so what you need to do is...

1) Get the engine torque curve for your bike
2) get a list of the gear box ratios for your bike
3) Get MS XL and learn how to make graphs
4) Column 1, list the torque values at 50 rpm increments to the red line
5) Column 2, multiply the engine torque values by the 1st gear ratio
6) Column 3, Multiply the engine torque values by the 2nd gear ratios
7) So on for 3rd, 4th, 5th and 6th.
8) Then make a pretty graph of all the torque values after the gearbox ratios

Still with me?

9) now if you study the graphs you will note that after peak torque is reached, it then begins to drop off.

10) at some point the graph of the dropping of value meets the rising torque value of the next gear up....that is the optimum gear shift point, between those two gears.

11) do this for 1st to 2nd, 2nd to 3rd, 3rd to 4th ect. you will find the optimum shift up point will shift slightly for each.

And that is how you calculate the fastest acceleration shift points.

[avgas]

This all lead me onto re-examining what the point of the tacho was. It isn't for acceleration purposes that is for sure, hence why a torque gauge would be useful, in addition to the tacho gauge.
Errr actually it is.
You are looking at the result, and expecting the equation to equal it. e.g. x = y
If you were given a torque gauge, you understand it is a curve right......so how would you know if you had hit the peak for that particular gear?
That is where the rev counter comes in - as you ride more, you learn more about where the sweet spots are according to engine revs. These may not be the actual peak torque points - but ranges as to where to ride in each gear. e.g. In the street triple you mention below 1st would have a ideal range of say 1,000-4,000, 2nd 2,000-5,000.....
say we call each one of these ranges a1, a2, a3..... for each gear. Now using this tool (rev counter) you have an appropriate time to change gears.
y = ax (where a can be substituted for what ever gear you in).
Where as trying to do this directly via torque gauge will be like playing a round of blackjack.....how high do you go before changing. Change to low and you never get peak torque, however if you go to high - you break 21 and sorry you missed the peak.

Ok the fact I just had to explain to you how to ride a bike has convinced me this is too hard for you......get a scooter. Most people figure this out in the first week on a bike.

[kinger]

....it's not going to make any difference whether you change gear in 1 second or .5 of a second.

It can make a huge difference if you're carrying a pillion.
Clutchless changes aren't difficult, have a learn.

[marty]

a torque-o-meter would be simple to create.

a shaft that twists under load with 2 pickups - 1 at the driven end, one at the drive end. the split between the two pickups measures the torque output.

[BASS-TREBLE]

Pretty sure I read somewhere that the new six cylinder 1600 BMW has an available torque display instead of of a tacho.

Perhaps you could Google it and see what they say?

I too have read that and I'd imagine it makes cruising on them even easier since you know exactly where to change without thinking about it

[nadroj]

Concentrate on the road not the guages. Experience will tell you when to change gears thru sound and feel.

[Bass]

a torque-o-meter would be simple to create.

a shaft that twists under load with 2 pickups - 1 at the driven end, one at the drive end. the split between the two pickups measures the torque output.

What you say is true and strain gauges would measure the twist very well. However, where are you going to mount it in the drive train so that it doesn't have to go round and round?
The signals that the measuring devices produce are very small so that commutators/slip rings etc screw them up completely.

[imdying]

Maybe because using too much of your torque won't destory the motor, but too many RPMs will?

[psycho22]

It can make a huge difference if you're carrying a pillion.
Clutchless changes aren't difficult, have a learn.

I ride with a pillion a lot and I actually happen to use clutchless changes too.

However a quick gear change, clutchless or not, doesn't necessarily make it a smooth one.

But anyway I was talking in terms of acceleration rather than smoothness.

[marty]

What you say is true and strain gauges would measure the twist very well. However, where are you going to mount it in the drive train so that it doesn't have to go round and round?
The signals that the measuring devices produce are very small so that commutators/slip rings etc screw them up completely.


luckily, I'm just an ideas man - someone else can figure out how to make it work

[schrodingers cat]

a torque-o-meter would be simple to create.

a shaft that twists under load with 2 pickups - 1 at the driven end, one at the drive end. the split between the two pickups measures the torque output.

Close but no cigar. Ford (MoCo) developed a driveshaft steel in the late 90's which gave an altered resistance figure dependant on the amount of force twisting it. It did required a trasmitter and reciever but that sort of electronics is ho-hum these days.
Lots of cool tricks you can do with that technology i.e Measure input shaft force and output shaft force, apply gearing mutiplication math and then weep as you see how inefficient the gearbag is

Elegant engineering also just to actually measure what interests you rather than apply endless bullshit to the equation.

Gear shifting: on a sequential gearbox a slow shift would be 0.2 sec.
0.1 if you were trying hard, 0.15 sec without much thought

If using an ignition cut flat shift, typical cut times are around 11 thousanths of a second. The 'dog' only needs the force off it momentarily to disengage. Re-engaging sorts itself out as the there are a few degrees rotation availible between front face and back face engagement. The undercut does the rest.

Torque - o -meter
Once you know the torque curves absolutes become irrelevant as variances due to external factors is less than 3%. It is sufficient to have a target RPM plus or minus 100 rpm.
Unless RPM is measured from a crank angle sensor it is at best a guide anyhoo.


The theory is all very wonderful for cluttering up the interweb. What you you really want to achieve and how much are you prepared to spend to learn it?

As for me? I'll just be riding mine.

[LBD]

On an electronic engine torque can be calculated electronically ie:
X amount of Torque can be produced at a given RPM, the torque being produced will be a calclation of actual fuel injector pulse width divided by maximum pulse width available at that same RPM, you then would know what % of the available torque you are using

[schrodingers cat]

On an electronic engine torque can be calculated electronically ie:
X amount of Torque can be produced at a given RPM, the torque being produced will be a calclation of actual fuel injector pulse width divided by maximum pulse width available at that same RPM, you then would know APPROXIMATLY what % of the available torque you are using

Fixed that for you. Engineering requires precise language

[Shadows]

Fixed that for you. Engineering requires precise language

If that is so, then it should be spelled "approximately".

[LBD]

Fixed that for you. Engineering requires precise language

yes okay,:facepalm: within the tolerances of general public understanding then...but you get the drift

[jonbuoy]

What you say is true and strain gauges would measure the twist very well. However, where are you going to mount it in the drive train so that it doesn't have to go round and round?
The signals that the measuring devices produce are very small so that commutators/slip rings etc screw them up completely.

Its not that hard, send power through the slip ring and you can put some electronics in there, convert it to something you can superimpose on top of the power supply and sniff it off the other end.

[Bass]

Its not that hard, send power through the slip ring and you can put some electronics in there, convert it to something you can superimpose on top of the power supply and sniff it off the other end.

I thought about putting the amplifier into the rotating mass and yes, that would work. It's still a pretty rigorous environment and not one that I'd care to design for.
I never said it was impossible - I've seen it done - my point was that it's not easy.

[marty]

Close but no cigar. .

Works on 5000hp/7000ftlb aircraft engines so I'm sure would be fine on a 50hp bike.

Interestingly, aircraft piston engines are not measured in torque - power is measured in manifold pressure (or vacuum as the case may be depending on the engine) - turbine engines are measured in torque. Some by shaft twist, some by a clever means of helical run gears and pistons that increase an indicator oil pressure as torque comes on. That psi is converted to a torque reading (or just read in psi as is the case in smaller (750hp) engines)

[Swoop]

May sound like a damn silly question on it's own but the real question is why do both cars and bikes show RPMs as a read-out as opposed to torque?
Kiwi drivers' cant work out how to use their fucking indicators, let alone giving them something else to think about.

Sorry, but on a serious note, have you ever seen a deaf person driving a manual without a rev-counter:eek5:
A deaf mate (some years ago) rode his motorcycle very happily, by feeling when to change gears through his butt. No need for a rev counter.

[CHR1S]

A MAP/Vacuum gauge is handy with the loss in density you get with altitude, dunno why they put one in a sh*tbox Camira I once had..

[marty]

you really won't start to see a reduction in performance until about 4500-5000', or when you are at WOT and still climbing. To see a reduction in MAP in a climb you woud have to lock off the throttle at your starting altitude, then climb, and not touch the throttle - you would see a drop then of about 1"/1000'.

I fly a normally aspirated aircraft regularly to 12000' - WOT height is usually around 5000', at 25". Continuing a climb means at 12k I am only at 18-19" - a pretty serious drop in performance. The same engine with a turbo will hold 30" all the way to 16000' :) Of course, the turbo engine only has 1/2 the life of the normally aspirated, but it's a heap more fun :)

[scumdog]

A MAP/Vacuum gauge is handy with the loss in density you get with altitude, dunno why they put one in a sh*tbox Camira I once had..


An excellent tuning/economy indicator.:yes:

[BMWST?]

its actually quite simple isnt it?
I know for example that my car develops maximum torque at 4000 rpm......hence if i want max performance i manipulate the gears to get the rev counter at about 3500.....
On the bike i just use the butt o meter..if there doesnt seem to be the required urge i just change down a gear,its so easy on a bike.If i think i will require more urge than i have NOW i just blip down a gear

[BMWST?]

An excellent tuning/economy indicator.:yes:
in my car i call it the guzzle o meter its marked in Litres/ per 100 k(from 0 to about 40)

[Paul in NZ]

Look - really shouldnt post this because I'm sure someone will get all upset... and frankly I'm not bothered either way.

RPM's are used because its always been historically availiable on 'sporting' vehicles. You can probably run your GSXR1TRIPLEHORNET thingie at max rpm nearly all day now without it imploding into a heap of molten slag as the engine management system wont let that happen. Just the same way it modifies engine output in 1st gear to stop you killing yourself. This has not always been the case.

If you look at (just as an example) the 1980 Moto Guzzi LeMans in my shed. It has an orange bit on the tacho. That means you can rev here quite often, have fun but dont over do it. After the orange bit is a red bit which means you better not rev to here too often and if you do be prepared to spend big $$ because there IS NO rev limiter or anything else except for physics. ie open the throttle all the way and it will destroy itself happily. The two colours were widely understood and all is happy.

Go back 10 years to my 1970 Triumph twin. It has the tach option fitted. A good old Smiths 0 to 10,000 rpm jobbie. There is no red line or any other mark at all but trust me, even thinking about a number like (say) 8,000 will see you looking at a big hole in the engine and wondering how you will explain that to the wife.. That tach was fitted to heaps of different vehicles so marking it with a red line was not done cos it differed.

As you go back in time the expectation of the maker on the ability and knowledge of the operator has changed. Owners of sporting machinery were expected to have a more advanced knowledge of all this.

Today the makers assume nothing and try to make bloody sure you cant blow it up (at least until the warrenty runs out) so you have leds, lights, dials and whistles and warnings galore.

Seriously - you are on the right track but try to learn this shit faster before your knowledge curve crosses your speed curve and you recieve a nasty accident...

Oh - and just ride the bloody thing - it can go faster than you can calculate shit.

[johan]

This is an interesting topic.

When accelerating, I try to to keep the RPMs between max torque and max power, which would be between ~7500-10,000 on the 998.
(these bikes seems to be tuned to produce most torque close to max power)

The ratio between 5th and 6th gear is very close so I shift earlier between those higher gears.

2nd gear spins up so quickly I sometimes hit the revlimiter, so I try to short shift from second to third.
(the electronic hard revlimiter is at 11.500 which is a really bad place to be for this engine, and it will throw you over the bars)
First gear is useless.
From 3rd to 4th to 5th I have the shift lights set to 9500.

Any reason I should change this habit?

Is there a link to this other site where they were discussing this, I'd like to learn more.

cheers

[The Stranger]

having just read a thread from another forum of optimum places to change up (in RPM terms) it seems to strongly allude that change up points are best selected for the points where torque is strongest (calculated both in the current gear and the next gear).


Do you have a link to the other thread you mention please? I'd be interested to see their proof/conclusions.

I can dig it on say VTwin, but not so sure on an IL4.
Gears convert revs to torque. I would have thought that wringing out in first to drop the bike in second even if after the torque band is probably still a winner as you have more revs to convert to torque through the gearbox.

Either way, that's why I select a bike that develops it's torque high in the rev range, then you get the best of both worlds peak engine torque and peak torque as a result of the gear box too.

[White trash]

This is an interesting topic.

When accelerating, I try to to keep the RPMs between max torque and max power, which would be between ~7500-10,000 on the 998.
(these bikes seems to be tuned to produce most torque close to max power)

The ratio between 5th and 6th gear is very close so I shift earlier between those higher gears.

2nd gear spins up so quickly I sometimes hit the revlimiter, so I try to short shift from second to third.
(the electronic hard revlimiter is at 11.500 which is a really bad place to be for this engine, and it will throw you over the bars)
First gear is useless.
From 3rd to 4th to 5th I have the shift lights set to 9500.

Any reason I should change this habit?

Is there a link to this other site where they were discussing this, I'd like to learn more.

cheers

That seems to be a shitload to remember mate.

Buy a Japper. K7 GSXR thousand for example. Little red bit starts at 13.5, set the shift light to 13. Change gear when it flashes. Simple as :D

[The Pastor]

isnt torque a constant?

at full throttle you make X talks

at half you make 0.5X talks?

[johan]

That seems to be a shitload to remember mate.

Buy a Japper. K7 GSXR thousand for example. Little red bit starts at 13.5, set the shift light to 13. Change gear when it flashes. Simple as :D

Yes, maybe I'm doing it wrong, them Gixxers always seems to go faster than my trusty old one.

[Deano]

That seems to be a shitload to remember mate.

Buy a Japper. K7 GSXR thousand for example. Little red bit starts at 13.5, set the shift light to 13. Change gear when it flashes. Simple as :D

You have a different tack to Drew then ?

He simply loads up the gear lever and waits for the limiter to kick in, hey presto !

[White trash]

He simply loads up the gear lever and waits for the limiter to kick in, hey presto !

Fuck that! My yoshi computer had about 1000-1500 rpm of over rev built into it. Wouldn't wanna be repeatedly thrashing it to 15K through every gear.

No mechanical sympathy whatsoever that cunt........

[Maki]

May sound like a damn silly question on it's own but the real question is why do both cars and bikes show RPMs as a read-out as opposed to torque?

Most lay people, such as myself, look to RPM as an indicator of "fast" (as in higher means "faster" in both terms of acceleration and cruising speed - when gear ratio taken into account). However, having just read a thread from another forum of optimum places to change up (in RPM terms) it seems to strongly allude that change up points are best selected for the points where torque is strongest (calculated both in the current gear and the next gear).

So, if acceleration is best judged by torque, why do bikes/ cars not have a torque read-out (either in addition to, or instead of, RPMs)?

Are bikes and cars just working on old technology instrumentation read-outs? And, if a dyno machine can measure torque at any point, why can't a modern automobile?

Lots of questions but I am genuinely interested in the reason behind why torque is not displayed.

Because there is no point. The more gas you give it, the more torque it puts out. The rpm where your engine puts out max torque should be stated in your owners manual.

Acceleration is not best judged by torque. Horsepower is what you want if you want to accelerate fast. With the right gearing/leverage I can produce more torque with my little finger than a big block V8 can at the crankshaft. The problem is that the torque produced by my little finger is very slow and produces little energy while the big block engine might be spinning at thousands of rpm and thereby putting out a lot of energy/horsepower/kilowatts.

[LBD]

isnt torque a constant?

No!...I I thought you would know that...

[schrodingers cat]

Works on 5000hp/7000ftlb aircraft engines so I'm sure would be fine on a 50hp bike.



If the technology is scaleable in a linear fashion then I'm sure it would. My point is that there are other ways to do it more common for this application

Also note that constants are fairly easy to measure. Transiants not so

[marty]

large turbine engines can have quite rapid torque fluctuations - from zero to 3800ftlbs in say 3 seconds. the torque meter seems to keep up.

[Cloggy]

isnt torque a constant?



Nope,
The formula is horsepower = torque x rpm / 5252
Torque is measured in pound-feet in this equation, not newton-metres
Interesting bit about this is that at 5252 rpm, horsepower and torque figures are equal.

[LBD]

large turbine engines can have quite rapid torque fluctuations - from zero to 3800ftlbs in say 3 seconds. the torque meter seems to keep up.

And a reciprocating steam engine produces maximum torque at.....Zero RPM

[CHR1S]

If the technology is scaleable in a linear fashion then I'm sure it would. My point is that there are other ways to do it more common for this application

Also note that constants are fairly easy to measure. Transiants not so

Not really cutting edge technology, been around for a long time in aircratft! It's relatively straight forward when you have an axial shaft (no idea how you'd set it up on your conventional 4 banger) with a power turbine at one end and a load at the other, a reference shaft, measure the degree of twist and you have an instantanious unit to indicate torque. Sweet set up for $3 million dollar engine..it get's very expensive if you get it wrong :yes:

So totally agree wth ya, me tacho can do the job for now!

[IdunBrokdItAgin]

So, apart from the weird KBer random replies telling me that I should be riding a scooter and that I will have a nasty crash because my speed curve is higher than my knowledge curve (WTF? - get over yourselves - the question was about instrumentation readouts), what I am taking from the replies is that some aircraft engines give out this basis already but it would be un-economical to introduce this to automobiles.

This maybe a thing that we see on automobiles of the future though (rather than RPMs as an indication point of when something may occur - to an instrument showing when something actually occurs)?

Also, seems to me that a lot of riders do not fully understand torque at all (not saying that i do though). This thread was intended to answer a late night question I had - seems to have done that, and educated myself and a few other people at the same time.

Thanks for all the replies people - it has been very enlightening.

[onearmedbandit]

Haven't read the thread entirely, so someone may have already stated what I'm about to, and that is marketing. Remember when the R6 came out with it's stratospheric rev limit? Which turned out to be BS anyway. But it worked, as many people made the decision to buy one based partly on how high it could rev. Making a bike that rev's slightly higher than the competition or last years models helps sell your product. We all know torque is improved (generally) year to year, same with power. But we want speedo's that go past 300 and rev counters that sweep through massive arcs.

[imdying]

Would be easy and cheap for the OEM to include. Run a bike up on a dyno, get the torque curves for sufficient throttle positions, build a map from that, stick any type of gauge you like on that displays the torque output for the motor at the given TPS/RPM. It's not likely it actually has to measure the torque for what the OP is talking about. Hell even the figure isn't really relevant, it could even just show a percentage of maximum torque. They only need to dyno a sample of production engines to build the 'map', all of those bikes are likely to be within a few percent at any given TPS/RPM.

[bogan]

Would be easy and cheap for the OEM to include. Run a bike up on a dyno, get the torque curves for sufficient throttle positions, build a map from that, stick any type of gauge you like on that displays the torque output for the motor at the given TPS/RPM. It's not likely it actually has to measure the torque for what the OP is talking about. Hell even the figure isn't really relevant, it could even just show a percentage of maximum torque. They only need to dyno a sample of production engines to build the 'map', all of those bikes are likely to be within a few percent at any given TPS/RPM.

and when you put an aftermarket exhaust system on it? or if you put enough stickers on the fairings? the increased torque would need to be measured and added otherwise the system would be pretty useless.

[imdying]

and when you put an aftermarket exhaust system on it?That's only a very minor change to the torque curve, and isn't going to change the shape of it very much.... 50%TPS @ 3000rpm is still going to be around (say) the 60% of maximum torque output mark. It would be far from useless in the situation you describe. Well, no more useless than the entire concept is anyway.

Besides which, the OEM don't care about how you screw up your bike with aftermarket rubbish... their gauge read fine when it left the factory. Of course, it wouldn't be any more useless than any bike with a gearbox driven speedo and a sprocket change.

[onearmedbandit]

The other option of course is to just get an in-line 4cly 1000cc sportsbike. I know how much torque it makes at any point in the rev range. Lots.

[bogan]

That's only a very minor change to the torque curve, and isn't going to change the shape of it very much.... 50%TPS @ 3000rpm is still going to be around (say) the 60% of maximum torque output mark. It would be far from useless in the situation you describe. Well, no more useless than the entire concept is anyway.

Besides which, the OEM don't care about how you screw up your bike with aftermarket rubbish... their gauge read fine when it left the factory. Of course, it wouldn't be any more useless than any bike with a gearbox driven speedo and a sprocket change.

actually depending on the system it can make a huge difference to where the power comes on. Not sure if % readout would be the way to go, as sombody said, having a bike that gets the needles furthuest around is a coveted title! The OEM maybe doesn't care, but the consumer might.

[imdying]

actually depending on the system it can make a huge difference to where the power comes on.For example?

The consumers won't care... most of them don't even care their speedo is out, and that one actually has (financial) consequences.

[imdying]

The other option of course is to just get an in-line 4cly 1000cc sportsbike. I know how much torque it makes at any point in the rev range. Lots.Works for me... every gear is a good one :yes:

[White trash]

The other option of course is to just get an in-line 4cly 1000cc sportsbike. I know how much torque it makes at any point in the rev range. Lots.

You're damn right. And 2010 R1s make more power than you'd expect at any one particular point in the rev range......

[bogan]

For example?

search for some stock vs full exhaust system dyno charts, the point of an exhaust system is to gain power, a lot of the time you get a choice whether to gain mid range or top end, ie, shifting the torque curve around. Different header and tailpipe lengths tune the gas flows for different rpm ranges.

[onearmedbandit]

search for some stock vs full exhaust system dyno charts, the point of an exhaust system is to gain power, a lot of the time you get a choice whether to gain mid range or top end, ie, shifting the torque curve around. Different header and tailpipe lengths tune the gas flows for different rpm ranges.

Not many people do full system changes though, unless you're racing. Most common choice is just an end-can on road bikes, and that makes 5/8 of fuck all on most modern (with some exceptions) performance bikes, other than weight loss and a fruitier note.

[imdying]

search for some stock vs full exhaust system dyno chartsI have seen plenty; the gains are negligible, and not enough to noticeably reduce the effectiveness of such a gauge.

Do you think being wrong by a couple of % would make a difference in any case?


As an aside, do you see such a gauge being marketed towards the sort of bikes that are given full race systems.

[onearmedbandit]

You're damn right. And 2010 R1s make more power than you'd expect at any one particular point in the rev range......

Yeeeah...for an R1.

[White trash]

Yeeeah...for an R1.

Enough to spin up nicely and highside my sorry arse :D

[onearmedbandit]

Enough to spin up nicely and highside my sorry arse :D

You're having me on right. There is a story to tell here Jimmy, and I feel like you're not sharing with us.

[bogan]

I have seen plenty; the gains are negligible, and not enough to noticeably reduce the effectiveness of such a gauge.

Do you think being wrong by a couple of % would make a difference in any case?


As an aside, do you see such a gauge being marketed towards the sort of bikes that are given full race systems.

yeh, personally I'd expect a higher degree of accuracy from such a guage as any rider should be able to feel when the peak torque is anyway. I don't really see a market for it at all tbh, race or otherwise.

[imdying]

yeh, personally I'd expect a higher degree of accuracy from such a guage as any rider should be able to feel when the peak torque is anywayReally? You'd study it that hard? Surely all it would be good for is an indicator that you're in the meat of the torque curve? Hell all I'd want is a light that comes on when I've dropped out of the 70% of max torque zone.


I don't really see a market for it at all tbh, race or otherwise.Me either, but if there was, that's the easiest most reliable way to go about it.

[White trash]

Really? You'd study it that hard? Surely all it would be good for is an indicator that you're in the meat of the torque curve? Hell all I'd want is a light that comes on when I've dropped out of the 70% of max torque zone.

Me either, but if there was, that's the easiest most reliable way to go about it.

Tell ya a bit about pointless guages. New R1 has a little indicator that tells you how far it's opening the throttle. Its very freaking cool but I kinda don't see the point in it except to see if you can get it to deliver maximum throttle of course. And if you're doing that you've got a death wish if you're staring at the little bar lights.

[imdying]

That's cool... useless but cool :D

Ironically, the only people a gauge like this would be good for (tourers I expect), already have bikes with torque everywhere, so it's a bit moot. But if people wanted it, that's how I'd go about it.

[bogan]

Really? You'd study it that hard? Surely all it would be good for is an indicator that you're in the meat of the torque curve? Hell all I'd want is a light that comes on when I've dropped out of the 70% of max torque zone.

yup, I mean it's pretty easy to tell when it's in high torque zone cos you gotta hold on harder! So for the guage to be any use to me, it'd have to tell me how much torques I'm getting, and how much my mods have added and where, so it'd basically be a dyno as you ride.

[imdying]

Would be nice, except for the nasty burn on your arse where your wallet used to be :D

[jonbuoy]

I can see why a Truck or a Aircraft might need one, those engines are going to be slugging away in climbs or pulls for longer periods of time. A bike is going to spin pass through those peaks pretty quickly until you get up to the speed you want. Even on the motorway your not going to sit in fourth for long periods of time just because it puts the engine in the "sweet spot".