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Old 6th February 2006, 17:38   #31
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Quote:
You have 2 engines --- truck and F1.. both same power (but obviously different torque.)
You put the F1 engine in a truck ... and change gear ratio's to compensate for the higher rpm. (Assume weight remains same).... I think it'll pull the same amount of load.
Yes, it is possible. But the F1 engine has to rev very high to pull that load. So, just once it will pull the load from Kashmir to Kanyakumari. And then its life will come to an end!
That's why truck/bus engines are designed to develop high torque in low RPM, so that they can last long....
This exact question has been answered in www.howstuffworks.com (please search for exact page)
You can also get more info here
http://www.team-bhp.com/forum/techni...-movement.html (Physics behind car's movement)
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Old 6th February 2006, 17:44   #32
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Quote:
Originally Posted by sbasak
Kashmir to Kanyakumari. And then its life will come to an end!
absolutely...

Quote:
Originally Posted by dceite
I think what Abhibh meant was both the cars are EXACTLY equivalent EXCEPT power@rpm figure. For one its 100PS@5000 rpm, for other its 100PS@6000RPM.
2 engines.. having same power at different rpms have to have different torques... at most you can say they can have similar looking curves but figures would be different.
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Old 6th February 2006, 17:50   #33
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Quote:
Originally Posted by SLK
2 engines.. having same power at different rpms have to have different torques... at most you can say they can have similar looking curves but figures would be different.
egggg-jactly what I was trying to put across .. without defining the torque curves, it is impossible to answer the question.
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Old 7th February 2006, 16:34   #34
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Would depend on the engine in question as well, like how quickly it can rev up. But ultimatly total power is what maters, it's a little complicated but google can give calculators to "convert" torque to horsepower.

Case in point: the US BMW M3 and an evo8 have almost the same power/weight ratio but the M3 still picks up faster.
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Old 8th February 2006, 00:34   #35
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well everyone keeps talkin about the part throttle responses of the ford ikon 1.6.....even though it has less power compared to a palio/petra 1.6.91 bhp of the ikon compared to 100bhp of the palio/petra both producing it at an equivalent 5500 rpm.but where the ikon scores in initial acceleration is its torque.it produces 13.3kgm@2500rpm whereas the palio/petra produces 14kgm@4250pm.0-100 figures of both the cars will nearly be identical,roll on figures of the ikon will be better,top speed of the petra will be higher.i hope im right.expert members please comment.
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Old 10th February 2006, 01:07   #36
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[quote]I have a simple question regarding Performance of a CAR:
If there are 2 cars like Ford ikon 1.6. Now out of these 2 cars 1 is 100PS@6000RPM and other is 100PS@5000 RPM. Now i want to
know which car will out perform?? I mean the one with 6000 RPM will be better in terms of pickup, top speed etc. or the one
with 5000 RPM is better ??./[unquote]


Well the simple question is not so simple to answer. We have to know the torque-rpm curve or bhp-rpm curve. Also gear ratios, as mentioned in any posts is also required.

Let us assume that both vehicles have same gear box. Also we assume the torque or bhp rpm curve has a similar pattern that is initially they rises in a same ratio, remains nearly constant in the midrange in the same ratio and then top end curve is again in the same ratio. That means, that for each rpm, the torque of the engine doing 5000 rpm would be higher than the torque produced by higher revving engine (simple arithmetic -> torque=bhp/rpm and engine with lower rpm means higher torque as bhp is constant). Say the engines will develop around 60 bhp at midpoint of their operation that is it will 60ps @ 2500 rpm and 60ps @ 3000rpm. You can see that the torque is higher for engine with lower rpm.


Now when both the cars are going to start from ZERO, then the car with lower revving engine will pull out faster but it will hit the redline also first. Which means that you have to shift earlier while other continues to enjoy the lower gear advantage for another 1000 rpm. So in the end, they will remain almost same.


Now we assume that both are cruising at same speed and both are doing around say 2000 rpm. Now when floor the pedal, the car with lower rpm engine has got the torque advantage and hence will accelerate faster than the car with the higher rpm engine. Thus the in gear acceleration for the lower revving engine and hence its drivability will be better. Similarly the top speed of the lower revving engine may be better.


Now we assume that they have different gear box such that they have same speed at their max rpm in any gear as long as the power is available (say both are doing 120 km/hr at their peak rpm - first one at 5000 and second one at 6000 - in third gear). Under such conditions, the entire characteristics, e.g. 0-60, in gear acc and top speed will remain almost same.
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Old 9th August 2006, 19:59   #37
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Hi all,
I know this is a very old thread... But just to get my doubts clarified....

I heard a friend of mine saying that putting Petes performance kit on the car would increase its torque... how far is this true?...
how would Petes kit help in increasing the torque?....

Also how would you measure the torque? (what methodolgy is used?)

My friend also said that higher torque means... you can shift gears at lower speeds? is it true?

regards,
ant.
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Old 9th August 2006, 20:54   #38
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Quote:
I heard a friend of mine saying that putting Petes performance kit on the car would increase its torque... how far is this true?...
Some members are already using Petes Tuning Box.
You can check out the Review here.
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Old 16th August 2006, 12:49   #39
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Quote:
Originally Posted by Shan2nu
Torque and power are very much related. The amount of power an engine produces at a certain rpm depends on the amount of torque produced at that rpm.

For EG: the Vtec produces 132nm at 4700rpm. Now to calculate the power we will have to convert nm to lb ft which comes to 97.34 lb ft.

Now using the formula (bhp = torque * rpm/5252) we get 97.34 * 4700 /5252 = 87.10 bhp.

So the Vtec produces 87.10 bhp at 4700 rpm.

IMO the ideal torque curve would be if an engine were to produce max torque as low as 2000 rpm and keep it there for as long as possible.

If the Vtec engine was to keep that max torque of 97.34 lb ft beyond 4700 rpm, the engine would have produced 106 bhp at 5719.25 rpm and would have gone all the way to 126.03 bhp at 6800 rpm.

So the power of an engine depends on how much torque is produced at different engine speeds.

Diesel engines produce more torque mainly due to the high compression ratios the engines run on and the fact that they have a smaller bore and a longer stroke.

Actually it isn't that complicated but does take a lot of time before you start understanding it. When i started off with this, i was as confused as you are but when as i kept reading and discussing this with others, i've got a basic idea of what it's all about. *

Regards...
Shan2nu
Shan2nu, If when the max torque is produced at the max rpm in a city vtec, it genereated 87horses then how is the 106hp figured arrived at?

simplying it
if 132nm at 4700rpm converts to 87.10hp, then how does the car reach 106hp, coz a car cannot exceed its torque?

and I also read here on the link below that it implies that torque and bhp meet at 5252rpm which is not true.

http://www.nsxprime.com/FAQ/Miscella...queHPSpeed.htm

Last edited by devarshi84 : 16th August 2006 at 13:06.
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Old 16th August 2006, 13:20   #40
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Quote:
Shan2nu, If when the max torque is produced at the max rpm in a city vtec, it genereated 87horses then how is the 106hp figured arrived at?

simplying it
if 132nm at 4700rpm converts to 87.10hp, then how does the car reach 106hp, coz a car cannot exceed its torque?
Thats bcoz "Bhp" is the result of "Torque" and "Engine Speed/RPM". Max power is produced when these 2 factors produce the best combined result.

At 4700, the torque is at it's max but the rpm isn't high enuf. At 6800, the torque maybe less but the combination of torque and rpm is stronger than at 4700.

If you were to look at the torque curve, the formula (torque * rpm) / 5252 would produce it's best result (Bhp) at 6800 rpm and thats where max power is said to be produced.

Shan2nu
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Old 16th August 2006, 13:29   #41
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Quote:
and I also read here on the link below that it implies that torque and bhp meet at 5252rpm which is not true.
That bcoz you're considering the wrong units. This is possible only if power is measured in "bhp" and torque is measured in "lbft". It doesn't work with "nm" or "kgm".

Shan2nu

Last edited by Shan2nu : 16th August 2006 at 13:30.
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Old 16th August 2006, 13:32   #42
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ok lets take the example you gave here.

you said that at 132nm torque produced at 4300 Rpm A honda city vtec will make 87hp, but honda makes 106hp. correct? so why the difference?
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Old 16th August 2006, 13:37   #43
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Quote:
you said that at 132nm torque produced at 4300 Rpm A honda city vtec will make 87hp, but honda makes 106hp. correct? so why the difference?
It's 132nm@4700.

Honda never claimed 106bhp@4700, they said it produced 106bhp@6800.

Thats why the diff.

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Old 16th August 2006, 13:44   #44
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I am trying to understand this. lets start afresh.

car in question honda civic

Max Torque is 126 lb.ft produced at 4300 RPM
Max Power is 130.19 hp (132PS) produced at 6300 RPM

so at 126lb.ft of torque produced at 4300RPM by the engine, bhp should be

126 x 4300/5252 = 103.16hp

AND honda claims 130.19 hp (132ps) for the civic at 6300rpm

so
126 x 6300/5252 = 151.xx

shouldnt that be 130.19 instead of 151.xx??


Your post I quoted above talks about 126horses for the city vtec at 6800 rpm, How did you arrive at 106hp at 5719RPM? Is there some relationship? coz As you said Honda claims 106hp at 6800 rpm?

Last edited by devarshi84 : 16th August 2006 at 13:48.
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Old 16th August 2006, 14:02   #45
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Quote:
Your post I quoted above talks about 126horses for the city vtec at 6800 rpm, How did you arrive at 106hp at 5719RPM? Is there some relationship? coz As you said Honda claims 106hp at 6800 rpm?
Lemme clear this first. What i was trying to say was that "if" the Vtec engine could sustain 132nm from 4700 - 6800 rpm, the car would have produced 126bhp@6800. But, facts are facts. The engine does not produce 132nm@6800. It produces 81lbft (110nm).

Quote:
car in question honda civic

Max Torque is 126 lb.ft produced at 4300 RPM
Max Power is 130.19 hp (132PS) produced at 6300 RPM

so at 126lb.ft of torque produced at 4300RPM by the engine, bhp should be

126 x 4300/5252 = 103.16hp

AND honda claims 130.19 hp (132ps) for the civic at 6300rpm

so
126 x 6300/5252 = 151.xx

shouldnt that be 130.19 instead of 151.xx??
The same rule applies, in this case. The engine does not produce 126lbft@6300. It produces 108lbft, so the power is 130 and not 151.

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