Originally Posted by
SlickHolden
Wrong!.. And maybe you should read me before quoting me with your gospel..
I said a truck with no load will and bloody hell they do move very fast indeed with out loads, People get behind them and think this truck without a load will hold me up, Wrong it will power away with ease it surprises them not me, Now tell me is this 300hp or 200 hp engine going to make a 3000+kg truck semi move that fast?.
Trucks don't have a whole heap of gears to keep in the pulling range for nothing, They have them gears to keep in the torque range, Because that is what pulls them and there loads.. Truck drivers don't rev there engines they change early to keep the torque area to keep them moving forward faster and faster, There little power won't do the pulling it's the 600-700+Nm torque that does it.
I know this because my mate drives B-Doubles for a living, My uncle drove them all his life and my grandfather also..
I mean doesn't it in anyway question your theory or are you to blind and always right to actually question yourself?
If a cars engine was installed into a Truck, Say a Holden Commodore SS 5.7lt LS1.. 2001 version was 299Hp 465Nm.. Will that engine pull a truck and it's load?. Same power but is let down by torque.
Even if not possible to fit think about it.
First, for me quick acceleration is <6 sec. to 100km/h. So even the 500+ hp trucks without the extra sleeper cabin and without a trailer struggle to get anywhere near that.
So to answer your first question yes 300hp is more than enough to achieve the acceleration rates that 3 ton+ trucks can do. Do you realise how much power 300hp is? (roughly 226200 Joules per sec. !!!)
Trucks have alot of gears because they have a really short operating range (maybe 3000rpm) so they can't make big jumps in ratio like a car does.
How does it question the theory (it isn't mine) that power over speed is what gets you going? When I plug the numbers into the math they work.
To answer you second question: It doesn't matter what peak torque the engine makes if the peak power is the same then they have the ability to do the same amount of work.
Originally Posted by
Slicks
You expect me to believe that a 19 year old kid has driven cars that cost more than his life? Well if you have I can see where you get this "idea" of power moving the cars. With the turbo cars the turbo lag creates that illusion, and most of the other are pretty peaky (making more torque in the higher RPMs).
Like I said before, go drive a V6/V8 truck and come back to talk to us.
Of the turbo cars only the 944 had noticable lag... Did you miss the part where I said I have driven a corvette stingray... that would be a 1968 one with a L88 in it. Not exactly a "peaky" engine. Even that one didn't accelerate on the torque curve.
Originally Posted by
Slicks
The torque curves for each gear (yeah, gears multiply torque remeber?) matches *EXACTLY* to the G-forces... Care to explain?
And once again, IF hp trully did move the car, the graph of G-forces would look like the hp curve right?
They don't match! look at them they don't touch, the shapes are different and you have cut the thrust graph to fit as best you could. HP doesn't accelerate the car on it's own it is highly dependant on velocity. I have explained why several times I have shown the math which is standard text book stuff.
Originally Posted by
Slicks
How do you derive torque from power, when power is just a calculation of torque? If you know the power, then you already knew the torque before hand.
Quite easily torque is equal to power divided by speed. If you know the power then it is not always the case that you know the torque (maybe the computer didn't tell you at the time), but you can certainly figure it out.
Originally Posted by
Slicks
Uhhh, I dont know what "trucks" you've been around, but the ones here rev to 5000-6000RPMs... Like my moms blazer that I mentioned, it revs to 5500RPMs, making peak power at 4400RPMS, but pulls the hardest around 2000-3000RPMs, where its making very little power, but a good deal of torque.
By Trucks I mean tractor trailers, 18 wheelers, Semis, that sort of thing. You will be hard pressed to find a diesel (anywhere) that redlines at 6000rpm. the highest I have heard is 5500rpm.
By the way here is a quote from the website you posted:
Originally Posted by
www.welltall.com
A further understanding of the relationship between Power and Torque reveals that the shift point calculations can be greatly simplified by looking at the Power curve.
Recall the formula P=Fv. Moving around the terms, you get a=P/(mv). This means that given the velocity of the car, the mass of the car and the power transmitted from the engine to the tires, the acceleration can be calculated from a=P/(mv). This means that the higher the car velocity is, the less acceleration you can expect.
Note that the power curve of a car can be obtained by P=2πΓ(ω)ω. If we take our Skyline's torque curve after the peak torque, we can obtain a power curve like P=2πω(-2.568ω+580.32). If you plot this power curve, then you know that it peaks at a certain point and then falls all the way from there. (Officially the peak power point is at 6800RPM but our peak based on our simplified torque curve most likely won't yield the same power curve and hence the same peak power point.)
From the power curve, we know that if we want to maximize the acceleration of the car, we don't need to up shift before the peak power point. This is because if we shift up, we get lower RPM and hence less power from the engine. Note that the velocity of a car before and after the shift remains the same. However, the acceleration of the car is greatly reduced because power is smaller at lower engine speed.
It is easy to see that to maximize acceleration, we need to keep the power from dropping. That means we should shift when we are after the power peak and if we don't shift at the next instant, we will find that we get less power from the engin by avoiding the up shift. That happens when we get the same power from the engine when we shift up. Suppose P is the power at the optimal shift point. By solving the quadratic equation: 2π(-2.568ω2+580.32ω)-P=0, the roots we obtain are the optimal shift point (ω) and the engine speed at the next gear after the shift (ωgk+1/gk). Note that the sum of the roots equals the negation of the second term divided by the first term, so we have the following equality:
gk+1 2π(580.32)
ω + ----- ω = − ---------------
gk 2π(-2.568)
Solve for ω, we get exactly the same equation we have in our previous discussion.
580.32
ω = ------------------------
2.568(1 + gk+1/gk)
Thanks for proof of the theory
Also about the Tesla website. They are not giving any specific information, they simply say "constant acceleration to 6000rpm" but seeing as it is just commercial text that could mean strong, roughly uniform acceleration to 6000rpm. Anyways it is a mute point because you will notice that to achieve a constant rate of acceleration (according to the laws of physics) the power needs to increase with speed. In the tesla car it does just that, increasing at a linear rate with speed. Unfortunately this won't lead to constant acceleration (as power required goes up exponentially not linearly). To validate the result an actual test needs to take place.
Originally Posted by
Cyco
If you are as tall as you claim this is bullshit and you know it - you just wont fit in these highlighted cars, and you will really struggling to get in the Murci.
Really so you can tell me exactly how long my neck and back are? Yes head room and leg room is tight (oddly still comfortable in the mini) but not impossible. Still a comic thing, seeing me getting into and outof those cars.
Originally Posted by
Cyco
The equation ignores how much grip the vehicle has, just a minor factor in acceleration last I checked......
No it doesn't running resistence has a term for grip included.
Originally Posted by
Cyco
It also shows that it is a equation for motive FORCE. Forces are measured in NEWTONS, like torque. You have fraudulently tried to pretend this is equivalent to power in this case, whist arguing that that are completely separate elsewhere.
No I haven't I have shown that motive force is derived from (not equivalent to) power. It is also obvious that torque is not equivalent to motive force.
Originally Posted by
Cyco
Good scientists look to try to prove themselves wrong, charlatans who try and get kudos are the only ones who try and prove themselves right - and end up looking very foolish when they get found out.
If you are stupid/naive enough to believe every theory thought up is perfect and holds to scrutiny then I'm very glad I'll never have to use anything you design.
When you think up a theory you then try to check if it actually works, if it works in the experiment you made then you check the other variables that were not checked in the original experiment. If everything stands up then there is no reason to change your theory. You change theories when you hit problems that give results that don't agree with the theory. I do not think that every theory is perfect, I believe that theories that have been tested to exhaustion testing all variables involved will in the end stand the test of time. Theories that have proven themselves become laws. I believe Laws to be perfect and more than able to hold up to close scrutiny.
Power, whether measured as HP, PS, or KW is what accelerates cars and gets it up to top speed. Power also determines how far you take a wall when you hit it
Engine torque is an illusion.