yardpro

LOL.....
Mark and i are having a back and forth pm about whether torque or rpm is a more important....
we keep going around and around in circles...

SOOOO he resurrected this thread as i got him all worked up about it....


Sorry guys,,,,lol

Dave928S

This thread is KIBORTED!

Tazzieman

Exactly what Alan de Cadenet was trying to explain

mark kibort

Yes, Awesome!!

Ha ha .. good discussion off line.. but, you are still hung up a few things that don't lead to a fair comparison of HP and torque . (in our offline conversations) . I gave the tesla HP curve to help understand that its HP curve is not much different than a gas engine in reality..... its better because its wider, and starts out at 0. but, it really needs a gearbox as well to be optimized and compete completely with a gas car.

Remember, HP is made up of torque and RPM. power, made from, or determined by, force and velocity, or rate of change of KE. Quite simply, it just contains more information than engine torque alone. Now, if we are talking rear wheel torque figures, I agree, that's all you need as well. but since many of us don't want to do through the calculations of thrust graphs and gear ratios, tire diameters, etc, using HP is just easier to use when trying to compare two cars with different engine torque values.

Again, I always fall back to my example of a 500hp Porsche vs 500hp viper, one with 250ftlbs and the other 500ftlbs of torque. given the same shape and useable range of RPM in the max HP range, they both will accelerate at any vehicle speed, at exactly the same rate. (and if they are not the same shape, closer ratio gears can assure that the Porsche is always in it the same Max Hp range. the gear box just optimizes the HP you have.
It's all about HP-seconds. He who uses the most HP -seconds in a race, wins! HP-seconds, is 746 Joules, or 746watt-seconds. It's a unit measure of work....

RFJ

HUM could you REPEAT that I'm a little hard of hearing??!!

mark kibort

It's been 4 years...... Did I already say that?

SMTCapeCod

Hopefully, your views on oil are well sorted and not in need of dicussion/validation.
;-)

Magnus Rostadmo

Gentlemen !

I think this video sums up this matter in a wonderful way -

Video for steam engine full pull▶ 2:06
18. aug. 2014 - Lastet opp av Rob Gill
110HP Case Steam Tractor Pull Pinckneyville Illinois August 15 2014 www.youtube.com/watch?v=EVxByLO_6cA

This steam engine throws a full pull without a slightest hesitation, but as you see in its own slow pace. This engine, if it had more HP, it could;

a) Make more torq and pull an even greater weight at the same slow pace without stalling -----or-----
b) Pull the same weight, but Accelerating it to a greater speed !

Torq does not accelerate a car -- HP "transformed" to "rotating torq" does. The greater the HP the more "rotating torq" you can make.
Torq does not accelerate anything without movement-- add movement and you will do work - as in HP- the more movement - as in revs - and you will get more acceleration.

mark kibort

one of the things that give folks the "ah ha" moment, is when you tell them that HP (or power) is the "rate of doing work". But you have to explain it in a way that, connects "rate" with acceleration. so you have work which is a force over a distance. (and torque is just a rotational force). THEN you do that "work" really fast (like accelerating your car from any speed to any final speed), it requires more power. more power = faster rate of doing work.
power or in the car world, HP... is the potential of that vehicle to accelerate at from and to any particular speed. engine torque is meaningless without knowing a few other factors, but rear wheel torque is equivalent to power made at any vehicle speed.

Think of power just containing more information than "engine torque"
what has more information than power? a unit measure of work.... that would be the HP-Second. (or watt-second which is a Joule, which is the unit that Kinetic energy is measured ) It's how a rolling dyno measures HP. the faster the rate of change of KE, the more HP. sure force at the drums is what causes the rotation, but its at the wheels, after , and through the gear box . So, power, or rate of change of KE, is the most straightforward way to compare performance of two different vehicles or determine performance at any vehicle speed.

As a note, your last statement needs a little massaging. You cant have a force without movement. Think of taking off a lug nut. you have a force acting on the wrench..... but the lugnut is fighting back with an equal force, so , there is no net force. no force, no movement... If you get a movement, you will get a net force to create that movement. This is because F=ma.

porschedog

I like speedtoys explanation best

One of my co-workers is using E85 in his non-flexfuel Subaru rally car for more torque. He is 24 years old so he knows everything.

rnixon

Not again. My explanation.

mark kibort

SMTCapeCod

This would be a stellar Intelligence Squared (style) debate,
via web or live at some 928 event...probably a few hours after dinner.

( http://intelligencesquaredus.org/about )

mark kibort

Ha ha.. yes, it would.

rnixon

I'm fairly sure that no one from the Oxford Union wrote that