The "blueprinting & balancing" refers to the new aftermarket internals added to a newly rebuilt engine block. "New" blueprints are created from exacting measurements of the parts as they are assembled. This verifies an accurate rebuild.

The balancing refers to the rotating assembly (pistons, rods, crankshaft) where any part not balanced can lead to premature wear on the bearings, or worse, failure of the part at high revs or high torque.

For example, our v8 engines have eight pistons. To balance them the pistons and rods are assembled as if ready to install, then each assembly is accurately weighed, then the lightest assembly is set aside and the other seven have material removed to "balance" them to the weight of the lightest one (set aside).

 

My point is that there is no other way to build a motor properly. The terms are near meaningless as applies to a crate motor or a new motor in a vehicle. They are _ALL_ done this way unless you buy something from a half assed shade tree mechanic.

 

So what exactly does "port and polished" mean?
In Grand Terismo that is one of the options for upgrading your car, you can port and polish and balance and blueprint your engine.

 

That is legitimate milling work done to your heads (typically increasing the diameter of exhaust ports and polishing the surfaces to reduce turbulence and resistance). Some heads are pretty well done form the factory and would net a negligible gain for the cost (looking at my N/A Porsche), and others are really worth it.

 

Like he said, typically done to the exhaust ports.

Typical first step is to apply the exhaust gasket to the heads and then scribe the edge of gasket's opening around each port. You then grind and wallow out the port to "gasket match" the port. Then this larger port opening is ground into the head around the valves.Care has to be taken not to oversize the port area, as this can reduce the velocity of the exhaust fumes, and negate the benefits of the gasket matching. Oversizing can also grind into the heads coolant ports and cause a leak.

Some engines also respond well to intake porting of the heads, as well. Serious builders will also port and polish the intake manifold runners, as well as any imrc plates, if any (the Rover\Buick 215 does not have imrc plates).