Hello, my name is Mike and I can help you with this.
Unfortunately, there is no way to associate this failure with any type of factory defect. A factory defect would have to show itself while the vehicle is under factory warranty.
At this point, if you have no extended warranty coverage, your best hope would be to convince Porsche customer service that you are in need of some "good customer" assistance. Depending on the information you give them, you may be able to work out something to help you.
At some point, though...every manufacturer has to end it's warranty coverage completely. The Porsche has a 50,000mi 48 month warranty. I'm sure you understand that you are well beyond this coverage in both miles and time. However, generally engines and transmissions are 2 things that are worth asking for help on because they can affect the reputation of the manufacturer.
Another thing to keep in mind is that dealers make less money when they fix a car under warranty. Many dealers have some discretion to help beyond the end of the official warranty, but they don't want to make less money. They want to replace the engine at full retail price. This is why I direct you to the Porsche cutomer service to bypass the dealer.
I know that you were hoping for information that would be more helpful to your cause, however all I can offer is my experience with how these things generally end up.
Thank you,
Mike
ASE Certified Technician
20 years experience, all makes and models.