TORQUE TALK !

[mike-s]

For what its worth

rf900=281 w/me in gear, (87kw) (309kwatt/tonne)
gpx750=273 w/me in gear, (59kw) (216kwatt/tonne)
carolla=1132with just me, (86kw) (75kwatt/tonne)

[Strika]

Yeah power to weight is important too. But I was more thinking about the pure number of torque units needed to shift a heavier object initially. ie- they build a car engine to produce higher torque numbers lower in the rev range to enable it to get off the line!

[mike-s]

as you can see i re-edited my post ane cleared it up a bit.
also the example of 250hp/2500rpm for a truck vs 140hp/12krpm for a bike.
I was mainly posting for that person who was power/torque confused.

[Strika]

as you can see i re-edited my post ane cleared it up a bit.
also the example of 250hp/2500rpm for a truck vs 140hp/12krpm for a bike.
I was mainly posting for that person who was power/torque confused.

Yeah I understand what you were saying, and agree, I was more trying to make the point that with more weight, the torque figure nneds to increase at lower revs in order to move it initially.

Frogz made the point of likening gearing changes to changing a lever ratio also. Which effectively increases torque, but not in numbers, more in numbers for a given road speed! I found that interesting too.

Does anyone have a real understanding of the realtionship of power and torque in actual acceleration?

[Smitty]

Yeah I understand what you were saying, and agree, I was more trying to make the point that with more weight, the torque figure nneds to increase at lower revs in order to move it initially.

aah now Strika ...we get technical
in order for torque to be usable
we need to be harness it.....hence the flywheel

low torque and a BIG flywheel (once rotating)
has can move a vehicle that is heavier
than one with higher torque and a small flywheel

hence
dragracers use big flywheels*
and bikes use...small ones


*not Top Fuel...but sedans

cheers

[mike-s]

Think of torque as the ability to overcome inertia, or lack therof (i.e. when stationary).

The more power (torque) you have to overcome inertia, the easier it will be to turn the drivetrain. thusly a bike with 20nm* of torque at 2500rpm (say about a 400-500cc bike) has to rev till about 7000 (where it has 40-50nm* of torque, and the engine is turning faster to do the same work), slip the clutch and drop it to hoist the front up. However a bike with 45+nm* of torque at 2500 only really has to roll on vigerously to hoist the front up, there's more power available to do the same level of work (not taking into account different vehicle weights and suspension dynamics).

[*] the above figures were plucked out of thin air for the example.

oh and smitty, flywheels only work to "store" the intertia provided by the engine, theres a whole nother level of "stuff" happening when you start putting flywheel weights in as well as engine capacity.

[Johnnie5]

Yeah I understand what you were saying, and agree, I was more trying to make the point that with more weight, the torque figure nneds to increase at lower revs in order to move it initially.

aah now Strika ...we get technical
in order for torque to be usable
we need to be harness it.....hence the flywheel

low torque and a BIG flywheel (once rotating)
has can move a vehicle that is heavier
than one with higher torque and a small flywheel

hence
dragracers use big flywheels*
and bikes use...small ones


*not Top Fuel...but sedans

cheers

except that racers use a lighter fluwheel to get the motor to spin up quicker

[Smitty]

except that racers use a lighter fluwheel to get the motor to spin up quicker

not the blokes I know who race manuals......
however
your comment is why lots go the auto route in dragracing
a flexplate...is light

cheers

[Johnnie5]

except that racers use a lighter fluwheel to get the motor to spin up quicker

not the blokes I know who race manuals......
however
your comment is why lots go the auto route in dragracing
a flexplate...is light

cheers

not quite

most go auto for reduced time in gearchanges and for the high stall

[GForce]

for a car if you use a lighter flywheel, you can rev quicker on the straights but when going up hill, you lose torque.

[HemiDuty]

According to Gran Tourismo anyway.....

For the track I will stick to concerning myself with power figures (and run off areas ), as long as it makes good smooth power in a 4-5k band I am happy, as long as I can get more of it!