Does anyone know what the correct/good compression ratio is for an 1987 turbo at 2175 CPM. This is a dealer installed engine with 38, 000 miles. The car does not idle very well and sometimes dies with A/C on, otherwise starts and runs good.

 

Sounds like you have a dirty/faulty BAC valve or connection.

 

minimum compression for a 13b at sea level is 85 psi, the max you could ever get is 125 or so.
The compression ratio for that car is 8.5:1, although knowing that won't really help you.