FORUM RULES UPDATED - The forum rules have been updated to continue to provide a friendly and safe environment for our member community. Please take a moment to review the updated rules and our terms of use and privacy policy. Click here for Forum Rules which has links to the 'terms of use' and 'privacy policy'.
I have a volvo 5.7OSI petrol engine with composite drive and duoprop. I believe the year of make is 2006, I bought the package new in 2007.
The problem I have is a lack of speed of late, usually I achieve 20- 21knts at 3200rpm, now I am getting 17-18 knts at same RPM. I can still achieve approx...