Originally Posted by Jeremy5848

615, 616, and 617 engines have compression 21.5:1
601, 602, 603 engines have compression 22:1

regardless of NA or turbo.

There is no compression difference between, for example 617.912 (NA, 88 HP) and 617.952 (Turbo, 125 HP), according to the Technical Data manual referenced in my earlier post.