Ok.
.
.I maybe way out of my depth here but here goes:
If you take two pieces of material of an arbitrary thickness and clamp these together with a standard bolt and nut
- where are the maximum forces at work?
With a bolt and nut I think the maximum force is directly underneath the head of the bolt and underneath the nut.
Now.
.when applying such loads it's a good idea to spread the stress over a large area.
.
.
.
.eg.
100 pounds of pressure on 1 square inch is more stress that 100 pounds of pressure on 10 square inches.
.but how can we spread the force when clamping parts? Well if I have threads in the parts then the force will be spread over the surface area of the threads which is a multiple of the area underneath the bolt/nut.
The problem is I can only screw into one piece of material.
.I can't screw into both and still generate a clamping force.
So.
.
.
.In modern engines the clamp load is distributed in the block via the threads and concentrated in the head under the bolt/nut.
Now taking the drag racer as an example: if I bore all the way through and thread a nut on the other end I haven't won much.
.
.The load is now directly underneath the head of the bolt and underneath the bolt at the other end.
.
.
If I instead
use a girdle that uses
'n' bolts to press some kind of frame onto the head and at the same time press a frame against the bottom of the block, then I have a real gain in structural integrity.
On a side not you cannot bore a gen2/gen3 through completely.
I'm pretty sure the threads for the bolt for cylinder 4 intake side ate outside of the normal block.
There are not enough hard facts and certainly nothing statistically relevant to say the naked block or head of any one gen is intrinsically better than the other.
tested up to 750bhp and 50psi of boost or some equally ridiculous claims!! I have read of nobody at all running sleeves with any success.
