well try to look at it this way. Cars are terrible investments. Some people will tell you they aren't investments but I call hog wash on that because ANYTHING that you put your earned income on that can be later be sold is an investment...just because its a bad investment (in terms of appreciation) doesn't mean it isn't an investment of your money. That being said what value does it have for you (fun, enjoyment, quality of life improvement, bla bla)? What would you need to spend now in order to gain an equal amount of satisfaction?
I ask this question because if I sold my very well maintained Boxster S right now I wouldn't have enough money at the end of the transaction to have comparable value. I'd have to spend MORE. and I'm not really sure the extra expense would translate into significantly more enjoyment--the car is that good in my opinion.
I'd have to go into another category: sports coupe, GT, track toy, etc. to get more enjoyment...that means more money.
But in your situation if you were to replace the engine you would 1-get the car on the road again and have the utility 2-have a functional car you could sell and recoupe the cost of the fix...you're taking a bath on the previous value of the car, but again a car is a depreciating investment anyway. I just put in $6K on major maintenance and repairs (IMS upgrade included). I'm not getting that money back...money pits!
How much is the RUF upgrade?
