[quote]Bill Roberts wrote:
[quote]pat wrote:
[quote]Alpha F wrote:
[quote]pat wrote:
[quote]Alpha F wrote:
I meant to post this picture on my post above.
Ferrari Dino[/quote]
It’s amazing, not more than 10 years ago nobody wanted these cars. You could pick one up for $30,000. Now they are going $300,000. Same with muscle cars. Damn collectors, they priced all these cars way out the range of us regular folk and now we can’t touch’em.[/quote]
Yes, my husband told me that and I said to him: why didn’t you buy it when it was so cheap!
The Dino is beautiful.
By the way, my husband said that the way you talked about torque ( on the BMW above ) was “the intelligent way to talk about torque”.
He says that talking about torque without the RPM value is meaningless.
[/quote]
I like your husband. Actually, torque is the real number that can be gleaned directly from the motor, horse power is actually a calculated value.[/quote]
Almost everything though is measured with calculation in the measurement. For example, whether measuring torque or horsepower, a Superflow dynamometer uses the computer to provide numeric values. Even if doing something quite simple such as weighing an object, ordinarily these days calculation is done: for example, the scale may take a voltage that results from the weight on the device and calculate a weight from that.
So, calculation being involved really is quite ordinary.
On top of this, at least when measuring rear wheel values, absolutely a dynamometer knows nothing of the crankshaft torque. That’s totally a calculated value, requiring input as to what the engine rpm is, which cannot be measured at the rear wheel.
Even when measuring at the crankshaft, with an inertial dyno such as many Dynojets actually power is being measured at least as directly as torque is, and if anything torque is the “more calculated” value. Measurement of acceleration of the drum in a unit time is measurement of work performed in unit time: or in other words, it’s measurement of power. If the engine rpm is known then torque can be and is calculated from the work performed.
With hydraulic dynos, a Dynapack for example directly measures fluid horsepower, while others measure a strain force which is torque at the point measured, but again if it’s not the crankshaft, then an input is required to calculate crankshaft torque. Same for eddy current.
Which brings to the main thing: the function of an engine is to deliver power, not simply twisting force in and of itself without regard to rotational speed. And when giving regard to rotational speed, then what we have is power, not torque alone.
Torque in itself will do nothing for anyone with regard to a vehicle. 1000 ft lb of torque from an engine that does not turn, or turns at a lower rpm than useful given the gearing or which requires an excessively short gearing, is of very little value. Because we use transmissions the rear wheels and accelerative force do not “know” what the crankshaft speed is. All it “knows” is the torque at the rear wheel at the rear wheel speed, which is horsepower.
Thought experiment: If a given car manufacturer came out with a new engine where at all points it had double the torque while turning only half the rpm and therefore had exactly the same hp curve once taking the numbers off of the rpm scales, wouldn’t it require gearing twice as short for the most equal comparison? What benefit would anyone get from having “twice the torque”?
Or what if I modified an engine where to give it internal 2:1 gearing that turned a second shaft, which appeared to be the crankshaft output and I called it that? Now it would have “twice the torque” but would it be the slightest bit better? If putting credence into “torque values” over horsepower one would, wrongly, think yes. Whereas on looking at the hp curves that would be identical other than having different rpm values associated with each point on the curve, one would correctly conclude the engines were equivalent in ability to accelerate the vehicle or pull a load, other than requiring different transmisssion gearing.
So which view (hp or torque) would be the useful one?
However, one can expect that the truck owner with the 200 hp engine which turns lower rpm and has shorter gearing and less rear wheel torque at any given road speed will tout his crankshaft torque figures and claim superiority to a 300 hp engine with an equally broad hp (also equally broad) torque curve! For his purpose of feeling good about his engine, I suppose the torque view is the more useful! But for example, in any racing context, if anyone suggested that torque, regardless of rpm, was what they should be aiming for instead of horsepower, that would not be useful.
Crankshaft torque at low revs is (unless it’s enormous torque) low power and does little. The horsepower curve tells what the acceleration or pulling potential is: the torque curve does not, unless knowing the rpm, which actually means knowing the hp.
In any case, when having the hp curve, one has all the information needed even if not having engine rpm: but if having a crankshaft torque curve but no associated rpm values, one knows little to nothing about the engine’s ability to accelerate or pull a load.
It’s entirely useful to discuss the broadness of a torque curve, as you did and so I mentioned to Alpha F (since she had heard me going on about the torque subject, probably a number of times, and she was talking about your post and this thread) that your discussion of it is the way that makes sense. Unlike where people go on about torque in and of itself, often for engines without remarkably much power, without reference to being across a range of rpm or with reference to rpm in any way.
Of course it’s rare for there to be any converts from the church of torque to the science of hp and I have no such intent 
I might someday go for a 928 again. When in college I had an old '83 but eventually the repairs needed exceeded what the cars were going for. A more recent one with say an LS7 crate engine could be quite good:
[/quote]
That also speaks to why electric motors, while having instant torque, suck at accelerating. And I hate electric motors with a passion.
And yes, if you are chasing speed and performance, horse power is the number you want. Torque is about moving load. That’s why diesel engines have high torque and low HP. It about moving load, not hauling ass.
You sure you wouldn’t want an air cooled 911?
Somebody around here was selling an '83 928 for 5 grand. It was tempting, but I knew that bitch would be a money and time pit and I don’t have enough of either. It was tempting. They seemed in serviceable condition.
