I have a Volvo 31A series diesel in my 20' center console fishing boat. Reportedly, the A-series has a 16.5:1.0 compression ratio. The B-series and later had 17.6:1.0 compression ratios. The factory specs report the same hp output, but all the boaters conclude that the latter series engines have a bit more horsepower due to the additional compression. Does compression ratio affect hp output in a diesel as it does in a gasser? Or is it more a function of turbo boost?