Abstract torque

[Stormin Ben]

Simply put, torque is rate of change of power

If the power curve is getting steeper the torque will be rising, when the rate the power increases slows down the torque curve dips
It is the SHAPE of the curve that is important and will relate to what you feel when riding, the numbers themselves are only valuable as a comparison between motors

In your dyno graph you would feel a definite kick in the pants at 6500 and then 7500 rpm

[KermitLeFrog]

Simply put, torque is rate of change of power

If the power curve is getting steeper the torque will be rising, when the rate the power increases slows down the torque curve dips
It is the SHAPE of the curve that is important and will relate to what you feel when riding, the numbers themselves are only valuable as a comparison between motors

In your dyno graph you would feel a definite kick in the pants at 6500 and then 7500 rpm

This is an unusual way of looking at things. Power is a product of torque (a rotational force) and engine revs (a rotational speed). "If the power curve is getting steeper the torque will be rising" is not strictly correct. Torque may be falling but power rising. "If the power curve is getting steeper the rate of change of torque will be increasing". The way you are expressing it is a bit of tail wagging the dog. Power is a product of torque.

Off-topic but, I used to work with rotary hydraulic motors. Interesting beasts. Maximum torque at zero revs!

[Dendrob]

Simply put, torque is rate of change of power

If the power curve is getting steeper the torque will be rising, when the rate the power increases slows down the torque curve dips
It is the SHAPE of the curve that is important and will relate to what you feel when riding, the numbers themselves are only valuable as a comparison between motors

In your dyno graph you would feel a definite kick in the pants at 6500 and then 7500 rpm

This is an unusual way of looking at things. Power is a product of torque (a rotational force) and engine revs (a rotational speed). "If the power curve is getting steeper the torque will be rising" is not strictly correct. Torque may be falling but power rising. "If the power curve is getting steeper the rate of change of torque will be increasing". The way you are expressing it is a bit of tail wagging the dog. Power is a product of torque.

Off-topic but, I used to work with rotary hydraulic motors. Interesting beasts. Maximum torque at zero revs!

What drives the hyd motor? A pump. What drives the pump?

Put a steam engine on there and you have the ability to stall to zero rpm on full torque.

Hee hee.

[Stormin Ben]

.This is an unusual way of looking at things. Power is a product of torque (a rotational force) and engine revs (a rotational speed).

<Pedant mode on>
Its a chicken and egg thing, you can calculate torque from power
Torque (lb.in) = 63,025 x Power (HP) / Speed (RPM)
Or power from torque
Power (HP) = Torque (lb.in) x Speed (RPM) / 63,025

"If the power curve is getting steeper the torque will be rising" is not strictly correct. Torque may be falling but power rising.

Important phrase in my quote is GETTING STEEPER, not the power is getting higher

Maximum torque at zero revs!

Cool - but hard to get your head round

[Dendrob]

.This is an unusual way of looking at things. Power is a product of torque (a rotational force) and engine revs (a rotational speed).

<Pedant mode on>
Its a chicken and egg thing, you can calculate torque from power
Torque (lb.in) = 63,025 x Power (HP) / Speed (RPM)
Or power from torque
Power (HP) = Torque (lb.in) x Speed (RPM) / 63,025

That's cross multiplying. Rearranging the equation to find an unknown quantity.

In our bike, torque is just the middle man anyway. An exchange currency for linear force. The piston moving down applies a forwards force to move us along.

[Dendrob]

.This is an unusual way of looking at things. Power is a product of torque (a rotational force) and engine revs (a rotational speed).

<Pedant mode on>
Its a chicken and egg thing, you can calculate torque from power
Torque (lb.in) = 63,025 x Power (HP) / Speed (RPM)
Or power from torque
Power (HP) = Torque (lb.in) x Speed (RPM) / 63,025

That's cross multiplying. Rearranging the equation to find an unknown quantity.

In our bike, torque is just the middle man anyway. An exchange currency for linear force. The piston moving down applies a forwards force to move us along.

I think your point is valid though. For example should we think of the torque moving us along or the power? Obviously both, but I'm starting to "get" the chicken and egg thing you said. If you want an inclination of how fast a bike will go, it's pointless looking at how much engine torque it has. You look at how much power there is.

[Dendrob]

Maximum torque at zero revs!

Cool - but hard to get your head round

Place where I worked late eighties (power transmission company) supplied some mechanical gear units for the water treatment industry. Can't remember the exact figures but the output shaft only rotated at a fraction of an rpm. You had to go get a cup o tea and come back to see the keyway had moved position. The output torque was several thousand Nm. But the power required was a fraction of a kW. The mechanical efficiency was poor due to the number and type of gears, around 50%, but as the power requirement was so low it didn't matter.

[bigtwinthing]

i think you need to ride more, and enjoy that experience. Like I've said, if it thrills do it. I can't see jamoi and lloydie hooning it down the road and thinking anything else that "wombles thats fast" not sure they have a calculator working out bhp, crank wheel etc, however Boys whats your take on it?

[tony.mon]

To me, the numbers themselves aren't important, they are merely comparison points.

If I measure an engine in a bike and get certain numbers, then change something and measure it again, to see if the second set of numbers is different to the first.
Then you know if the work or mod you have done has been effective or not.

The actual number doesn't matter much, as a bike with less HP and/or torque may be quicker than you due to better tyres, better, more confident rider, rider weight etc.

[Wicky]

Here's an abstract depiction of my bike's torque...

[tony.mon]

Here's an abstract depiction of my bike's torque...

Thank God! Something I can relate to at last.....

[KermitLeFrog]

Place where I worked late eighties (power transmission company) supplied some mechanical gear units for the water treatment industry. Can't remember the exact figures but the output shaft only rotated at a fraction of an rpm. You had to go get a cup o tea and come back to see the keyway had moved position. The output torque was several thousand Nm. But the power required was a fraction of a kW. The mechanical efficiency was poor due to the number and type of gears, around 50%, but as the power requirement was so low it didn't matter.

Back in the mid 70's I was working at the train loadout at a place called Paradurdoo in Western Australia. There was a huge hopper full of iron ore and a train underneath it. Can't remember the exact figures but there were 200 wagons and each wagon held 200 tonnes of ore (ish). There was a machine running (slowly) alongside the track with four hydraulic motors powering a pinion on a fixed rack. It had a big arm that came down between the wagons and moved the whole train a wagon length at a time; which was then filled up with ore. I was told it could move a fully laden train with the brakes on every wagon. I spent most of my time replacing blown hydraulic hoses....

[bigtwinthing]

To me, the numbers themselves aren't important, they are merely comparison points.

If I measure an engine in a bike and get certain numbers, then change something and measure it again, to see if the second set of numbers is different to the first.
Then you know if the work or mod you have done has been effective or not.

The actual number doesn't matter much, as a bike with less HP and/or torque may be quicker than you due to better tyres, better, more confident rider, rider weight etc.

Poppers ( he hasn't paid me to say this either) on that old VFR would have blasted my butt on an R1 on my Devon Ride. Its how you ride them and Tony I agree, you feel more that the numbers add up .

[Dendrob]

Place where I worked late eighties (power transmission company) supplied some mechanical gear units for the water treatment industry. Can't remember the exact figures but the output shaft only rotated at a fraction of an rpm. You had to go get a cup o tea and come back to see the keyway had moved position. The output torque was several thousand Nm. But the power required was a fraction of a kW. The mechanical efficiency was poor due to the number and type of gears, around 50%, but as the power requirement was so low it didn't matter.

Back in the mid 70's I was working at the train loadout at a place called Paradurdoo in Western Australia. There was a huge hopper full of iron ore and a train underneath it. Can't remember the exact figures but there were 200 wagons and each wagon held 200 tonnes of ore (ish). There was a machine running (slowly) alongside the track with four hydraulic motors powering a pinion on a fixed rack. It had a big arm that came down between the wagons and moved the whole train a wagon length at a time; which was then filled up with ore. I was told it could move a fully laden train with the brakes on every wagon. I spent most of my time replacing blown hydraulic hoses....

No relief valve in the circuit then!

[Dendrob]

Here's an abstract depiction of my bike's torque...

I don't know why, but I'm starting to get the feeling you're not on board with this.

Fair play.

But if you plot rear wheel power against crankshaft rpm the resulting torque will be every bit as abstract.