I am having devil of a time with soft bodies in V8.XXX. I start with triangulated polygonal mesh (a geodesic sphere), then source it in POP as SoftBody. Setup a collision between it and a polyplane, with a little bounce.
However nomatter how I set the Spring, the result is the same. Upon collision the same thing happens. The soft body does not keep its ‘volume’, and the point go into space really far. Changing the spring options has no effect

A more simple example is as follows
In SOP
Sphere SOP with Group SOP (group name Pin_Group)

In POP
SoftBodyPOP referencing the Sphere SOP with Fixed Point referencing the Pin_Group
The ForcePOP is appended with -9.8 in Y to simulate gravity.
Now without any other POPs the POPnet is doing strange things. First is that the point on the softbody go wild and shoot off into space.
If Spring constant is low (10) the softbody just stretches into superlong shape. With high Spring COnstant, the point randomly shoot off into space.
Regardless of Spring constnant and initial tention, upon bounce (with low Gains of about .1) the point bounce off into space, and seem to gain energy upon bounce. Which is unlike normal POP particles.

So how do we get ‘normal’ soft bodies, such as jello.

I can't get information from help files on this.
What is the relationship betweem Spring Constant and Initial Tentsion.

A soft body is a spring system. So in general, it makes absolutely no guarentees about volume. All it does is create a spring for each edge in the geometry. Since you have no springs between the points of your sphere, there is nothing to prevent collapsing of the points as the springs contract.

In the past, others have coped with this by applying the softbody to a Lattice deformation of the geometry instead. For the Bound SOP input of it, make sure to turn on Enforcement Bars. This adds edges (in effect springs) for the SoftBody so that it prevents collapsing. So you apply the SoftBody to the Bound SOP to drive the deformation of your actual geometry. I believe there was a 3D Buzz Houdini VTM that covered this. There's also an example of this in the online help of the Spring SOP (which is an older, more primitive version of the SoftBody POP).

Having said that, in Houdini 8, there is a new method that does this in DOPs called the POP Shape Match DOP. The help for this DOP also has an example that you can load and try.