V 2 torque

[VT1000r]

Does any one know if a v twin has the potential to produce more TORQUE than an inline 4 of same displacement. I know there's ALOT of factors. The v twin if there both 1000cc has 2 500cc combustion chambers that's a lot of force pushing down on the crankshaft but an i4 ha 250cc combustion chambers that fire twice as much per 720 degrees, so it got me confused. Also the engines are taking in the same amount of fuel and air per 720 degrees as well as compression ratios being the same and bore and stroke of the i4 being half of that of the v twins, and same rev limit. Please if anyone knows can you please explain or if anyone has theories thanks.

[KermitLeFrog]

The measurement of the torque of a rotating engine gives a completely meaningless number. The torque number, on it's own, tells you absolutely nothing.

What we are interesting in is power, the capacity to do work. Power is torque multiplied by revs. E.g. A hydraulic radial motor (used in some industrial applications) makes maximum torque at zero revs. At which point it's making zero power and can do no work.

Obviously if you increase torque or revs you increase power. A torque x B revs = C power. 2A torque x B revs = 2C power. A torque x 2B revs = 2C power.

Engine design is about producing the best sort of power at a particular range of engine revs (not always maximum power but also how the power is delivered as the revs change). To give another example, the Aprilia Tuono 1077 V4 engine is based on the RSV4 engine but due to an extra 79cc and different tuning it make more torque revs for revs (and thus more power) than an RSV4 engine up to 12400 revs. It peaks at 11500 revs. Over 12400 revs the smaller 998cc RSV4 engine makes more power and has a higher power peak at 13500 revs. So, if you are happy to keep the revs of your RSV4 between 12400 and 14000 revs the smaller capacity RSV4 is always making more power than the Tuono. Anywhere below 12400 revs the Tuono is the faster bike. But, who wins on the racetrack? The RSV4.

This is not really answering your question as engine design is hugely complicated by so many factors but the point is don't get hung up on torque figures. It's always about power. Also, bear in mind that dyno graphs show power produced at full throttle. (The Tuono graphs start at 4000 revs as the bike won't accept full throttle below that speed). Even integrating the power curve over a particular rev range dosen't give you the full story, you need tractive force plotted against gear ratios.

Sorry for being slightly off-topic but, as you said, there are many factors. But, in the death of it, it's nothing to do with torque. It's all about power.

[Stephan]

Firestorm has similar torque on wheel as cbr600f4i because its power band is pretty narrow. That is why 600 cc has the same speed. Lower peak torque on engine, but geared to similar torque on wheel.

1000 2cyl vs 1000 4cyl there is no comparison, partly the same reason as above, another is that 4cyl has more area on valve intake, producing more power.

[8541Hawk]

While I wouldn't say torque is a meaningless number, I do agree with not getting to hung up on spec sheets.

With that, the way I tend to describe HP & Torque is: HP is how much work can be done and Torque is how fast that work can be accomplished.

That is why a modern 600cc I4 has a higher top end than a VTR (it has more HP so can do more work) but the VTR will leave the 600cc I4 on corner exit ( it has more torque so it does its work faster)

Also the biggest factor in determining how much torque a engine makes is not piston size but length of stroke.

This is why most I4s have low torque numbers as they must keep the stoke short for the high rev capability.
Also V twins tend to have a lower rev limit due to piston size but this also allows for a longer stroke which is one of the reasons why V twins tend to make big torque numbers.

So to answer your question, whichever engine has the longest stroke will make the most torque all other things being equal.

[Stephan]

I dont agree that 100hp l4 600 is slower in corner exit than 100hp vtr, my experience is different. Vtr is faster in relax mode and low revs, but ride hard mode is comparable.

[KermitLeFrog]

Surely if two bikes, same weight, same drag, at the same road speed make the same power they will accelerate at the same rate. One may be making higher torque at lower revs than the other but if the power is the same, engine speed and torque numbers make no difference.

[Stephan]

Acceleration is determined by torque on wheel, not power. Thats why bike is accelerating faster on lower gears, while engine still has the same power

[KermitLeFrog]

Acceleration is determined by torque on wheel, not power.

No. It's caused by "Tractive Power" (google it). Which changes as the revs and gears change.

Thats why bike is accelerating faster on lower gears, while engine still has the same power

Correct. The bike has more tractive power in lower gears.

Torque on the wheel does nothing unless the wheel is moving. Not moving there is no power applied and no work done. Work is required to be done to accelerate the bike. Work is equivalent to energy. Basic physics. Work is converted to kinetic energy.

Trust me, I'm right. This misunderstanding of torque is very common.

[Stephan]

Well, ok, not sure you use the correct term, as google found tractive lower as weight multiplied by coefficient of traction.
If only difference between the gears is torque, rpm and power stays the same, I am fine to say it like this.

[KermitLeFrog]

Acceleration is determined by torque on wheel, not power.

Sorry, this is correct. And, in fact, it's a much clearer way of expressing things. Using power is less clear.

See below:

Tractive Force

[VT1000r]

The measurement of the torque of a rotating engine gives a completely meaningless number. The torque number, on it's own, tells you absolutely nothing.

What we are interesting in is power, the capacity to do work. Power is torque multiplied by revs. E.g. A hydraulic radial motor (used in some industrial applications) makes maximum torque at zero revs. At which point it's making zero power and can do no work.

Obviously if you increase torque or revs you increase power. A torque x B revs = C power. 2A torque x B revs = 2C power. A torque x 2B revs = 2C power.

Engine design is about producing the best sort of power at a particular range of engine revs (not always maximum power but also how the power is delivered as the revs change). To give another example, the Aprilia Tuono 1077 V4 engine is based on the RSV4 engine but due to an extra 79cc and different tuning it make more torque revs for revs (and thus more power) than an RSV4 engine up to 12400 revs. It peaks at 11500 revs. Over 12400 revs the smaller 998cc RSV4 engine makes more power and has a higher power peak at 13500 revs. So, if you are happy to keep the revs of your RSV4 between 12400 and 14000 revs the smaller capacity RSV4 is always making more power than the Tuono. Anywhere below 12400 revs the Tuono is the faster bike. But, who wins on the racetrack? The RSV4.

This is not really answering your question as engine design is hugely complicated by so many factors but the point is don't get hung up on torque figures. It's always about power. Also, bear in mind that dyno graphs show power produced at full throttle. (The Tuono graphs start at 4000 revs as the bike won't accept full throttle below that speed). Even integrating the power curve over a particular rev range dosen't give you the full story, you need tractive force plotted against gear ratios.

Sorry for being slightly off-topic but, as you said, there are many factors. But, in the death of it, it's nothing to do with torque. It's all about power.

I agree with what your saying about power and all that but my minds a weird place a lot of crazy thoughts going on, but do you think that the v twin produces more torque than the i4 if stroke lengths are the same and they are getting the same amount of air/fuel per 720 degrees if let's say the v twin produces 2 power strokes both pushing down on the piston with 100ft pounds of force or the I 4 with 4 power strokes but each one pushing down with 50ft pounds and it's spinning say 10,000 rpm keep in mind the inertial forces and and what not at that 10000rpms.

[VT1000r]

While I wouldn't say torque is a meaningless number, I do agree with not getting to hung up on spec sheets.

With that, the way I tend to describe HP & Torque is: HP is how much work can be done and Torque is how fast that work can be accomplished.

That is why a modern 600cc I4 has a higher top end than a VTR (it has more HP so can do more work) but the VTR will leave the 600cc I4 on corner exit ( it has more torque so it does its work faster)

Also the biggest factor in determining how much torque a engine makes is not piston size but length of stroke.

This is why most I4s have low torque numbers as they must keep the stoke short for the high rev

capability.
Also V twins tend to have a lower rev limit due to piston size but this also allows for a longer stroke which is one of the reasons why V twins tend to make big torque numbers.

So to answer your question, whichever engine has the longest stroke will make the most torque all other things being equal.

I agree with what your saying about all that but my minds a weird place a lot of crazy thoughts going on, but do you think that the v twin produces more torque than the i4 if stroke lengths are the same and they are getting the same amount of air/fuel per 720 degrees if let's say the v twin produces 2 power strokes both pushing down on the piston with 100ft pounds of force or the I 4 with 4 power strokes but each one pushing down with 50ft pounds and it's spinning say 10,000 rpm keep in mind the inertial forces and and what not at that 10000rpms.

[KermitLeFrog]

I agree with what your saying about all that but my minds a weird place a lot of crazy thoughts going on, but do you think that the v twin produces more torque than the i4 if stroke lengths are the same and they are getting the same amount of air/fuel per 720 degrees if let's say the v twin produces 2 power strokes both pushing down on the piston with 100ft pounds of force or the I 4 with 4 power strokes but each one pushing down with 50ft pounds and it's spinning say 10,000 rpm keep in mind the inertial forces and and what not at that 10000rpms.

As (I think) Hawk said, it all depends on so many other factors. But, generally, 4s are designed to make less torque but at higher revs than a twin. This usually means more power for the same capacity. I think you are trying to compare one aspect of two different things.

[Beef]

I like the tractive force link.
Personally I think torque is very important.

With those graphs for tractive force, the acceleration dropped in each gear due to less torque available at the rear wheel(s), The higher the ratio, the more effort required to turn them. keeping those ratios the same, the vehicle weight the same, but add more torque, the acceleration would increase.

Look at tractor/tank stats, whilst they may not be the fastest vehicles on the planet, they can reach their top speeds whilst ploughing or dragging loads the same as they can unloaded.

Torque enables you to change up before the redline and still pull hard.

[KermitLeFrog]

I like the tractive force link.
Personally I think torque is very important. It is, but on it's own it does nothing. It's a force. Torque x revs = power

With those graphs for tractive force, the acceleration dropped in each gear due to less torque available at the rear wheel(s), The higher the ratio, the more effort required to turn them. keeping those ratios the same, the vehicle weight the same, but add more power, the acceleration would increase.

Look at tractor/tank stats, whilst they may not be the fastest vehicles on the planet, they can reach their top speeds whilst ploughing or dragging loads the same as they can unloaded. Not relevant

Power enables you to change up before the redline and still pull hard.

2Xtorque x Yrevs = Zpower. Xtorque x 2Yrevs = Zpower (double the torque at the same revs produces the same power as the torque at double the revs)

I sound like a broken record here but this misconception that torque is a thing that does work is simply wrong. It muddies the issue .