H/P Torque Comparrison question

[McRat]

"Yet the brochures for all the diesel pickups scream, MORE TORQUE!!!!  Really    Exactly what good is 605ftlb at 1600 if it only occurs on a dyno?"

It makes a huge difference when you are towing your trailer uphill.

Regards, Neil  Tucson, AZ

It won't tow uphill at 1600.  I have 4 Duramaxes, a 3500HD, a 2500HD, our race truck, and a Kodiak 5500.  All different years.  Both 5 and 6 speed Allisons.

None will go uphill laden at 1600.  Not enough muscle down there.  Big torque, crappy HP.

Yes, they will cruise at 1600 on level ground at partial throttle, but they won't go up a grade heavy.

They tend to like 2000-2500 rpm when heavy on a grade.

[Jon]

Made no more hp and no more torque but went faster top speed, your rear end gearing is up the creek.
Made no more hp and no more torque but accelerated faster, you came into the next gear after a shift at a better hp/torque point.

It's a maths thing.
jon

[McRat]

Made no more hp and no more torque but went faster top speed, your rear end gearing is up the creek.
Made no more hp and no more torque but accelerated faster, you came into the next gear after a shift at a better hp/torque point.

It's a maths thing.
jon

Actually, by shifting on the downhill HP slope, I reduce the average torque used while racing.  By 5252, the torque curve is dropping quick.

So more average engine torque during a 1/4 mile run runs slower.  More average HP runs faster.

[dw230]

And how does all this answer the OP's original question?

DW

[McRat]

And how does all this answer the OP's original question?

DW

Cliff Notes:

It's the area under the curve, not the engine design or torque numbers.  Peak HP numbers aren't the answer unless you can always run at that rpm.

[tortoise]

And how does all this answer the OP's original question?

HP is HP, and Torque is torque . . . Is this true?

Yes

[dw230]

So, bottom line is: HP is HP, TQ is TQ. Engine design(in our limited field of view) does not count.

Close the thread!

DW

[rgn]

From the link on the other page:

POWER (the rate of doing WORK) is dependent on TORQUE and RPM.
TORQUE and RPM are the MEASURED quantities of engine output.
POWER is CALCULATED from torque and RPM, by the following equation

HP = Torque x RPM ÷ 5252

[Graham in Aus]

Interestingly, reading to the bottom of the article:

Note that at 5252 RPM, torque and HP are equal. At any RPM below 5252, the value of torque is greater than the value of HP; Above 5252 RPM, the value of torque is less than the value of HP.

I think I read this somewhere else and struggled to get my head around it! 

[hotrod]

Yes that is correct, which is why this debate is always so useless.

Torque and hp are always directly tied to each other by the formula, you cannot increase horsepower at a given rpm without also increasing torque at that rpm.

The only reason torque and rpm are the measured values is because it happens to be convenient to measure those two values. You could just as well use other methods to determine hp and then compute torque.

If you remember your grade school instruction about how James Watt developed the concept of horse power to rate steam engines, he was not measuring the "horses's torque", he was measuring the work they did in specific period of time and that became the definition of a horse power.

1 hp = 33,000 ft/lbs per minute, or 550 ft/lbs per second

Larry

[WOODY@DDLLC]

Torque is the ABILITY to do work! Curling the beer can to your lips! 

HP is the AMOUNT of work in a given time!
The number of times you curl the beer can to your lips in a minute! 

No wait, isn't that GPM?   

Now where did I put that beer ..................

[tortoise]

Note that at 5252 RPM, torque and HP are equal. At any RPM below 5252, the value of torque is greater than the value of HP; Above 5252 RPM, the value of torque is less than the value of HP.

I would have thought that in Australia, one would say that at any RPM below 9550, the value of torque in n-M is greater than the value of power in kW; above 9550 RPM, the value of torque is less than the value of power.

[SPARKY]

Remember you can multiply torque with gears-- but without the Rs you will not be able to do it at the speed you might like  my PG/GV 2 speed glidewith GV od  only works because I can only hook up  so much and the BBC has a fair amt of TQ and it put me in the best part of my curve for my  hard pull I would love to have a trans that has  about 6 speeds that  was not a bang shiffter  2.5, 1.50, 1.25, 1.10, 1.00 .95

that with a 1.5 and a 1.0 rear axle  that  dream woorld

[Dean Los Angeles]

Horsepower . . . torque . . .  Give me BMEP any day.
Brake Mean Effective Pressure
http://www.epi-eng.com/piston_engine_technology/bmep_performance_yardstick.htm

It all starts here. How much pressure can you develop in the cylinder?.
The article states that the NASCAR cup guy are getting 211 PSI.
Top fuel is getting 652 psi. Top fuel is pretty close to nirvana. Produce as much heat as you can and retain as much as possible.

You wusses are cooling the engine with water to keep it from melting and throwing away all of that precious heat.

There are 100 questions about better octane fuel and nobody asking how much heat that fuel produces.

Once you have done all of the expensive flow bench testing and the intake and valves are as perfect as possible, you run it on the dyno to see where that torque curve ends up and then select gear ratios to match.
You do don't you?

[Jon]

Horsepower . . . torque . . .  Give me BMEP any day.
Brake Mean Effective Pressure

How much pressure can you develop in the cylinder?.

You wusses are cooling the engine with water to keep it from melting and throwing away all of that precious heat.

BMEP is a calculated number based on torque and displacement that is handy for comparing performance of different displacement engines, much the same as using max torque divided by cubic inches.

It isn't a measure of the pressure produced in the combustion chamber.


Being a wuss I would like to learn how I can capture the energy that I have been wasting into the cooling system, it would save me a heap of trouble.
Could you share the knowledge please?

I'm not being a smarta$$, I want to learn something here.


Cheers
jon