neeraj.juneja

Mods, please do not delete this thread.

Hey xbhpians, I was wondering why people tell us about torque figure and power figures.
What does it actually signifies?
I mean like 22Nm @ 9000rpm
and power like 18 Bhp @ 9000rpm?

This these things are anyhow related to bike acceleration?
considering as example of the following which figure are good?
ZMR - 17.6Bhp @ @ 7000rpm ; 18.25Nm @ 6000rpm
R15 - 17Bhp @ 8500rpm ; 15Nm @ 7500rpm
XYZ - 18 Bhp @ 10500rpm ; 16Nm @ 8500rpm

I mean like, whose pickup will be great, butter smoothness etc?

Aryan

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rachitkdogra

Hi Neeraj,

The definitions of Torque and BHP can get really confusing at times as both of them are units used to measure power of an engine. I once came across a very simple definition for both of them in Overdrive and I will qoute it.

"Torque is the pulling power of an engine, BHP is how quickly Torque is put to road". To just make things a bit more simple in Layman terms. Trucks have huge torque as they need more pulling power and lesser BHP as they dont need to go quick. Cars have more BHP and lesser torque as compared to trucks because they need to go quicker and does not need that large pulling power.

When it comes which accelarates faster? A bike with slightly higher torque or slighlty higher BHP I think one cannot generalise because going faster for a bike also depends upon other factors like gearing, power loss etc (In other words how the power is put to road. Every bike does it differently).

Generally bikes with higher BHP should accelarate quicker but again you cannot generalise.
Bilkes with higher torque needs less gear changes as the engine has more pulling power in each gear again I am not generalising.


As for smoothness of engine. I dont think BHP or Torque can any way be related to engine smoothness. Only thing is under normal driving bike with higher torque should run more relaxed.

These are my 2 cents.

Rachit

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abhijeet080808

In very simple terms, torque is the pulling power and the rpm up to which this pulling power is available defines the power of the engine.

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rx135to135LS

from what i remember from the school physics, torque is the initial force required to move a object from a stand still position to start moving.
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burninrubbr

BHP is how fast you go (top speed) and torque is how fast you get there (acceleration)

ironman

Torque is the result of a force that causes an object to rotate about an axis.
The Horse Power is measured according to the rate of rotation of an object(here it's a wheel we're talking about).
BHP is just the HP/raw power of an engine measured against an engine brake.
Based on the design of an engine which includes various factors, the peak power(BHP) and the torque vary.

You can have an engine with more torque but less power and also an engine which has less torque and more power as rachitkdogra said. You can also have 2 engines with the same capacity but one with higher torque (lower Bore/Stroke ratio) and the other with higher BHP (higher Bore/Stroke ratio). The acceleration, top speed,etc. go by the design of the engine, transmission, weight and power losses.

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Hyperion

I dont think thats correct.

I think the power is a function of torque and engine speed (RPM).

So an engine that produces less max torque but revs higher can produce a higher power output (e.g. Ninja 250R) than an engine which produces greater max torque but is unable to rev so high (e.g. Machismo 500 LB)

Acceleration is directly related to the power output of an engine. The amount of power that a bike generates at a given RPM decides how quickly that bike can accelerate from that RPM . Generally, torquier engines (means which have a wide RPM range through which they produce good amount of torque) are quicker off the block. But peakier engines (engines with a very narrow power band) tend to produce higher power (at higher RPM) but one needs to keep them within their power band to obtain brisk acceleration.

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nikhil9860

bhp means how fast u hit a wall

and

torque means how far u take the wall wen u hit it ..

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d@rk nemesis

Basically power = force X velocity


and force = mass X acceleration

so power = mass X acceleration X velocity


but velocity = distance/time

so substituting again,

power = mass X acceleration X distance / time


but mass X acceleration X distance = work

and since torque is the same as work,


power = torque/time


or in other words torque represents the work done and power
represents the rate at which work is done.

we can rewrite the above as,

power = torque X rpm

rpm basically stands for 1/time since it effectively it stands for rotations (a dimensionless quantity) divided by time.

So since power is the rate of work, it can be increase due to two factors. either by increase in work, or the increase in rate.

basically you can produce high power by doing a small work at a heavy rate, as well as by doing a heavy work at a small rate.