Do you talk power or drive torque?

[HDi fun]

It's not 5252rpm. It's just 5252. It's a ratio and has no units.

Power, whether measured in kW or bhp is a function of rotations per unit of time and torque which is a coupling force rotating about a common centre.

[Zwaf]

I see lot of people can find Wikipedia. Like HDI fun said, it's a ratio not an unit. I don't doubt in equations posted here, just saying it is not obligatory that engine torque must drop above 5252 RPM, or engine torque MUST be hold its value untill 5252 RPM.
I know my english is not at best, but I'm sure it it understandable enough for those willing to read.
Say mr Watt hello for me when you see him!


For example, in which point crosses F1 engine? In which point crosses WRC engine?
WRC got about 300 HP and (reportedly) about 600-700 Nm of torque. Let's say it is 600 Nm ('tough i believe it is more). Crossed at 5252 RPM that brings us to about 450 HP (I rounded the number). Is it way more then 300 HP?

For the end, I think that is enough to make an point here and after this point thread will become "windmill chase case".
Like said before, I'm to old for chasing windmills, and to young to let common sence go away from me.

Roger and out!

[HDi fun]

The equations are all correct, without question.

[SLEEPER]

Originally Posted by Zwaf

I see lot of people can find Wikipedia. Like HDI fun said, it's a ratio not an unit. I don't doubt in equations posted here, just saying it is not obligatory that engine torque must drop above 5252 RPM, or engine torque MUST be hold its value untill 5252 RPM.
I know my english is not at best, but I'm sure it it understandable enough for those willing to read.
Say mr Watt hello for me when you see him!


For example, in which point crosses F1 engine? In which point crosses WRC engine?
WRC got about 300 HP and (reportedly) about 600-700 Nm of torque. Let's say it is 600 Nm ('tough i believe it is more). Crossed at 5252 RPM that brings us to about 450 HP (I rounded the number). Is it way more then 300 HP?

For the end, I think that is enough to make an point here and after this point thread will become "windmill chase case".
Like said before, I'm to old for chasing windmills, and to young to let common sence go away from me.

Roger and out!

.-No No Please the explanations again

Forget the numbers - as in the actual bhp/torque values thwey are not rellevant in themselves to the crossing point.

The fact is that the two will cross at that figure and that fact has no baring on how fast or slow the increase is before or after or on how high or how low the figures are before or after.

The crossing is ( for the nth time ) a consequence of the formula nothing more ......................................but it is a fact.

[HDi fun]

All these formulae are used for is to calculate engine power (the rate at which work is done) from measured torque and measured RPM.

5252 only arises as a result of it being the compaction of a whole bunch of conversion formulae.

Go and play around with the arithmetic. Take out the numbers and just work algebraically with the units alone.

There's no significance of curves crossing when one unit is power measured in bhp and the other is torque measured in lbft. It's arbitrary.

[Zwaf]

Well, Sleeper,
That was egsactly my point!

We must be aware that whatever meassure unit we use that is just an amount of something we choose to use. Nature (or physic laws) does behave by almost* strict rules. People where forced to derivate meassuring units, and most of them are product of fiction. So in various parts of time and various parts of planet people have had developed various units. So we can see that 1 HP is given at various RPM depending on fact we use Kilograms or Ounces or...you name it - don't know english words for all mass or weight** units. Thing could be even more further then famous 5252 caracter if we decide to use any of numberous power meassure units. We even got american horse power versus "plain" horse power...
So, in mathematical expression with choosen units 1 HP will be reached at 5252 RPM, but egsact same amount of power can be reached anywhere in RPM if we use some of weight** units.


So, finally we agree that it is not benefitial to cross max torque with power line in anny determined point in revs when constructing an internal combustion engine.
Glad we understand each other after first posts in this "saga".

Now we can go to virtual pint of beer and chat about weather. :cheers:

*Why almost? Ask mr. Bor.
** I do think it is avoidable to strugle my english with mass-weight difference explaination.




EDIT: I started to write before HDI fun posted... You see by time difference how demanding to me is to speak technical in foreign language!

[SLEEPER]

We will put your translation skills as the reason for any misunderstanding then ......possibly thats what happens if you cut and paste in a second language.

[Zwaf]

Thank you for your kindness, Sleeper!

Next time HDI fun and myself shall translate wisselly.

[Jakeymd]

the lines will only cross at 5252rpm if power is measured in hp and torque is measured in lbft. think that might be where some confusion is.

[Zwaf]

Mr Watt gave us explanation how to determine 1 HP.... and that is all. That is not recomendation where to cross your max torque with power line in dyno chart nor does it mean that otherwise your engine will not runing fine.

Manufacturers crosses their torque and power lines wherever they find apropriate having in mind purposse and technical abillity of given engine.

For eg., my stock engine got max torque at only 1900 rpm (240 Nm) and max power at 4000 RPM (100 HP).
If I can make my engine hold max torque until 5252 revs at that moment that engine will make an output of 180 hp.
You see, a lot of 1,9 TDI makes even more output, but not as high as 5252 RPM!

Some constructors believe that ideal power distribution should look as follows:
Reach desired (or possible) torque as soon as possible and hold that value untill your engine reach desired (or possible) HP. After that point you decrease torque and hold max power trough revs as high as possible.

I will not be as rude as my oponents and say that they who can not understand that got no common sence, nor I will bite that translation demagogia after point is made.
Confusion is made because interpretation of correct formulaes in way that nature think and behave in imperial unit sistem. No, nature is behaving by nature laws and we made all of the units to explain processes to ourselfs. This is how numbers like 5252 or 9549 or 7024 apears.