Err,been asked this question in Fast and furious forum,but since i think this is quite a technical subject.
So,i trying to get my answer here
Should be quite useful for us in picking up new car in the future

some existed discussion in FNF forum
http://forum.lowyat.net/topic/1250660

This post has been edited by nujo87: Dec 7 2009, 09:40 AM

torque for sure, got horsepower but no torque like lorry.

depends, are you on a race track or on rally?

in mareasia especially in cities, torque ^^ in highway zoom zoom, hp

swt.. shouldnt this be in FnF?

I think you've got it reversed. Lorry engines typically have lots of torque to move big loads from a standstill but relatively low horsepower as it doesn't need to sustain high speeds.

yup correct..

torque = better acceleration
bhp = higher speed

So i got 1 of my answer tats is torque is for acceleration,n horsepower for topspeed.
Since my driving style is more depend on acceleration(mostly city driving)torque is more important for me i think


Another look like very simple but yet quite technical question i would like to ask
for old mitsu engine(4g18,4g13,4g15)their peak torque come at earlier RPM(2500-4500)

N campro engine(non cps)their peak torque come at later RPM(4000-6000)

Which 1 is more suitable for city driving/city short boost?

N since old mitsu engine can achieve torque peak at low RPM,will it be more FC?becoz no need to REV so high?
So old mitsu engine=Good FC n good boost power at <110km/h driving?

This post has been edited by nujo87: Dec 7 2009, 11:21 AM

You haven't seen how fast lorries can run without their heavy cargo, and how scary is their acceleration.

I think you mean better FC right? FC is "Fuel Consumption", so more FC is worst.
I'm not sure but I think FC should be better due to less RPM meaning less fuel combusted but FC is still highly subjective to driver and car characteristic. Peak torque at lower RPM is definitely better for city driving where there's a lot of start/stop/slowdown/pickup activity.

the mitsu 4g18 engine are better for city driving. this is known for a very long time d. the campro are meant to be driven in a more sporty way. its just the way it was design.

IC,tat means for city driving(mostly lower than 4000RPM),old mitsu engine/earlier torque peak engine r better,rite?
I think i got all my question answered,thx for urs opinion

n next time when im going to pick a car,i should ask for their torque curve graph for deeper understanding to tat car performance,B4 this discussion HP is the only thing i c when comparing car performance

This post has been edited by nujo87: Dec 7 2009, 12:54 PM

4k shift in city is insane lea.. normally is like 2.5k nia

besides i dont think they hav torque curve graph at car showroom besides the generic ones. lookin at the chart is one thing. understanding is another

Based on the description given by wikipedia on horsepower and torque, it looks like your torque is limited by the amount of horsepower that can be produced by the engine. Horsepower is the amount of power which an engine can produce. Torques determines that amount of power available at a given rpm. The amount of power produced due to torque cannot be more than the amount of power produced by the engine. In another word, don't expect a lot of torque from a car with low horsepower.

As long as a car can produce enough power to overcome resistance from friction and air resistance, it will accelerate. Friction and other resistances increases as the speed of a car increases. Having a car with peak torques at high rpms means that it will have a higher top speed as there's more power to overcome friction and air resistance at higher speeds. Having peak torque at lower rpms means having a car the can carry heavier loads but don't expect it to go fast.

A car running at lower rpms will use less fuel compared to one running at higher rpms. So in theory, a car that is running at lower rpms most of the time should consume less fuel. The problem with comparing fuel efficiency based on the running rpm of an engine is that different engines will burn fuel at a different rate at the same rpm.

no one will understand u

Firstly, let us understand the difference between force and torque.

for linear propulsion, the formula is F = m*a where
F = Force exerted on the object
m = mass of object (also known as inertia, i.e. the tendency of a stationary object to resist motion in a straight line) and
a = acceleration

so for a given amount of mass, the higher Force applied, the higher acceleration you get, make sense?

Okay now let us move on Torque. Torque is basically turning force in layman's term with formula T = F*d where
T = Torque
F = Force
d = Distance between point of Force and pivot.

If this is difficult to understand, think of a door. It is easier to open a door when you push it from the knob compared to if you push it nearer to the hinge right? That's torque acting.

Torque is therefore the analog to Force when it comes to rotational propulsion. Car engines derive their power essentially through rotation therefore we rate engines (and electrical motors) based on their Torque, not Force.

The formula is then T = I*alpha where
T = Torque
I = moment of inertia (i.e. the tendency of a stationary shaft to resist rotation)\
alpha = angular acceleration

Therefore, it is clear to see that for a given moment of inertia, the higher the Torque to higher the angular acceleration. Makes sense so far? higher angular acceleration means higher straight line acceleration at the wheels.

Hope you find this useful, I am running short of time. Let's save the discussion of Power for another day lol. Cheers!

This post has been edited by onlyforthecars: Dec 7 2009, 06:42 PM

1. Not necessarily. For engines, horsepower is actually derived from torque. It is given by the formula HP=Torque x RPM/5252. Thats why you have diesel engines which can pull heavy weights but dont have high top speed, because they operate at low rpms. Try driving a diesel powered vehicle (eg pickup truck). You will find they have much better low speed acceleration compared to petrol powered vehicles.

2. It is neither very advantageous to have a higher rpm peak torque or a lower rpm one (although for city driving, a low peak, wide torque curve is preferable due to the low speeds involved). What is better is to have a flat torque curve. This means torque is available for a wider range of rpm, i.e your pulling power is spread over more rpm. This is especially noticeable in certain cars having a narrow range, where you have to shift the gears often to keep accelerating.

3. An engine is most efficient at peak torque. At this point, you are getting the most power from your engine compared to fuel being consumed. Your statement that a car running at low rpm would consume less fuel is misleading. Assume 3 identical cars heading to the same destination. 1 fella drives at a very low speed (60kmh=2000rpm), the 2nd guy drives at the speed that matches peak torque (120kmh=4000rpm) while the 3rd guy drives flat out (160kmh=6000rpm). When compared, most likely the 2nd guy will get the best fuel consumption, because he keeps his engine running closest to peak torque. But even this analysis is still subjective, i'm just giving a best case scenario. It would be best to test each car individually to find the point where it gives best FC, but chances are high this will be somewhere near peak torque when at constant speed.

sporty way? there's nothing sporty about the campro... just because it is a small & inferior engine it has to be rev higher..

ermm.. good comparison, but not nessesary... no1 could be having better fc... 2x the rpm doesnt mean 2x d fc..

tl:dr @onlyforthecars.

city driving + carrying loads = torque rules.
high speed blast = bhp rules
genting = torque rules

geddit?

You're being rather unfair to the campro, as i mentioned...it has a lousy torque curve for a engine suitable for city driving. Iinm, it has a slightly higher than average maximum HP for 1.6L class and from what I've seen, its quite good on the highway.
I don't think u understood my analogy. I in fact said that car number 2 (at 4000rpm which is nearest peak torque) would probably get the best FC, simply on the assumption that at peak torque, you get the best power for fuel consumed.

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Added on December 7, 2009, 8:44 pmAgreed. The simplest non-technical explanation anyone can give

This post has been edited by joe_star: Dec 7 2009, 08:44 PM

i think u got me wrong.. wut i meant was tht the torque peak much later at the band.. not earlier like 4g18. btw.. all NA cars need to rev higher to draw out the power.. im not a car idiot..