chollyjohn
Regular Contributor
Some may know in this Forum I
Some may know in this Forum I have been searching for a boat. 270DA by Sea Ray. The original engine was a 7.4L (330) HP with Bravo II outdrive. Recommended prop is 17.75 x 21. The engine is now changed to a 7.4LMPI (365HP) and same outdrive being used. Outdrive ration is 2:00:1. 7.4L std has max RPM of 4600 while the Magnum can run at top of 5000RPM. My question is how can you calculate for just the HP difference so as NOT to overrev. One way is to buy several props; but costly. Any comments anyone?
Some may know in this Forum I have been searching for a boat. 270DA by Sea Ray. The original engine was a 7.4L (330) HP with Bravo II outdrive. Recommended prop is 17.75 x 21. The engine is now changed to a 7.4LMPI (365HP) and same outdrive being used. Outdrive ration is 2:00:1. 7.4L std has max RPM of 4600 while the Magnum can run at top of 5000RPM. My question is how can you calculate for just the HP difference so as NOT to overrev. One way is to buy several props; but costly. Any comments anyone?