Look, preload is a coil spring suspension term. It's how much the springs are loaded when they're installed. Like YR's earlier example, you have a "free height" and an installed height, just like a valve spring right? The preload is the load induced by compressing the spring to its installed height. How much preload is placed on the spring actually changes how the spring behaves in the suspension. It's even easier to understand with a coilover, you can adjust a collar on the coilover to shorten the spring and load it irrespective of the cars weight being on the spring. By changing the installed height you change the properties of how the spring reacts. Just like shimming a set of valve springs.
That doesn't happen with a torsion bar suspension, plain and simple. Can you load the torsion bar before the weight of the car is placed on it? Sure. You turn the adjusters so that the suspension is loading against the bump stops when the suspension is fully extended. But as soon as you place the weight of the car on the springs, that adjustment just becomes a ride height adjustment. There's no change in how the torsion bar reacts, you haven't changed any of it's operating properties.
The torsion bar adjuster loads the torsion bar in exactly the same way as the weight of the car does, and the weight of the car overrides that adjustment. There's no separate preload adjustment that changes the behavior of the torsion bar.
You are not creating potential energy any differently with different sized torsion bars. Bonnetron already explained this better than I did.
I don't expect you to change your mind though, because as you already said you've been suspicious of anyone that's ever tried to teach you anything. Fact is those books and teachers have more knowledge than you ever will, because you're unwilling to learn.
