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[Nikoror]

Maybe a more theoretical approach will make things clearer (or even more confusing )

From physics we know that:
Power=for a rotational system=torque*angular velocity
Let's plug in now:
Power is in W, Torque in Nm, Angular velocity in rad/sec
rpm=revs/min=2pi radians/min=2pi/60 radians/sec
So power(in kW)=(Torque*rpm*2pi/60)/1000=(Torque*rpm*0.1047)/1000 (or Torque*rpm/9550, so it is easy to see that when kW and Nm are used the two graphs will intersect at 9550 (when rpm=denominator).
To get the same in Hp we know that there are 746W in a hp or .746kW, so Power(Hp)=Torque*rpm/7126 (now the two graphs intersect at 7126 Rpm.
Finally, in imperial units:
1Nm=.738 lb-ft, so we get Hp=Torque*rpm/5258 ->so now the graphs will intersect at 5258 (5252 if you do the math more precisely). That's it.
And also as we all know dynometers measure torque and rpm and then "calculate" hp which is often a topic for discussions and comments about which dyno is more accurate and if the owners don't "manipulate" the dyno to give greater/lesser numbers based on the occasion.

I'll call about the water injection

[Greg Gordon]

I understand all that perfectly well. I know the amount and the 75% number will change with a different system of measuring. That doesn't matter. If 300lb/ft of torque will break the transaxle the same amount of force will still break it no matter what unit of measurement you use. By using a different unit of measurement you can get the lines to cross at a different place and the percentage value to change, but that's just doesn't invalidate my point.

We are loosing sight of my original point. If the motor makes 400hp at 6000rpm it will a peak torque of at least 300lb/ft (75% of 300) use what ever unit of measurement you want, it's still enough to break the transaxle.

I am still waiting for that dyno sheet that can prove otherwise...

[Nikoror]

An engine with 400hp at 6000rpm will have exactly 400*5252/6000=350lb-ft at 6000rpm, which means for a boosted engine it will have even more below 6000 with a peak at around 4000 rpm and probably around 400 lb-ft.

I think the only thing that people are saying is that you can have huge torque without huge horsepower on a boosted engine (a lot of torque at low rpm) and then a great decrease as rpm increases. This way things still will break because of the torque, but the horsepower will be far from 400. Of course if horsepower is fixed at 400@6000 rpm there is no way of not having 350ft-lb of torque at the same rpm and for an engine that was built for a 6000rpm redline no way of not having more torque at some lower rpm

[Greg Gordon]

OK! Now we are on the same page and even on the same paragraph.

You can have huge torque without a lot of horsepower on a boosted engine. I didn't say you can't do that.

What you can't do is have huge horsepower without a lot of torque on a 6000rpm engine, and that's the incorrect assumption some others were making. Remember this conversation started when it was suggested that it's torque not horsepower that breaks the transaxle. Then I said it's a moot point because when you raise horsepower on a 6000rpm engine torque will be increasing as well. That's the point where people started to get confused. While you can have huge torque with little horsepower, the converse is NOT true on a 6000rpm motor.

I think we are all clear now. These little diversions are fun. I will be looking forward to your call on water injection. I will try and get my supplier to hook you guys up if you plan to go that route.

[Mats]

An engine with 400hp at 6000rpm will have exactly 400*5252/6000=350lb-ft at 6000rpm, which means for a boosted engine it will have even more below 6000 with a peak at around 4000 rpm and probably around 400 lb-ft.

I think the only thing that people are saying is that you can have huge torque without huge horsepower on a boosted engine (a lot of torque at low rpm) and then a great decrease as rpm increases. This way things still will break because of the torque, but the horsepower will be far from 400. Of course if horsepower is fixed at 400@6000 rpm there is no way of not having 350ft-lb of torque at the same rpm and for an engine that was built for a 6000rpm redline no way of not having more torque at some lower rpm

Thank you, that is pretty much exactly what I was trying to say.

[Greg Gordon]

Mats, don't you ever sleep?

[Nikoror]

don't u
it's actually 8-10a.m. in europe now

[Mats]

Hehe, exactly. 9:41 when typing this.
What are you, 6 hours behind (Detroit is anyway)?

But no, I never sleep, not really. One eye open, always searching...

[Greg Gordon]

I work nights and sleep days every other week. That's the normal life of a freight pilot. This makes it seem as if I post around the clock.

[x-rad]

I'm in Detroit and i'm sleeping most of the time....good thoughts above, can someone convert it all to N/m for me to understand better???

[Greg Gordon]

I don't want to convert all the numbers to NM or whatever. If you really want that information there are plenty of internet calculators to do it for you.

Don't get lost in the numbers, just think of it this way. A 6000 rpm motor with a lot of horsepower will have a lot of torque. Motors that have huge horsepower numbers and relatively low torque numbers have high red lines and peak horsepower at very high rpm.

[Barry]

Aaaahhh*yawn* mmmmmm*stretch*...*fart*early morning smile ...

I just woke up...wazzup ??