- Joined
- Mar 3, 2006
- RO Number
- 20406
- Messages
- 1,584
Hey guys. Any Volvo Penta duoprop experts here? I've got a 1987 AQ271A (GM 350) with a VP DP290 duoprop. The boat (87 Sunray Mirage, 25ft, approx 4500 lbs loaded, fuel and water)got it pretty much as a wreck and I've been rebuilding it gradually over the last 3 years.
Problem is with performance. I have to go full down on the trim tabs and nurse it to get it to come out of the hole. It'll rev to about 2900 and its like hitting a wall. WOT is only 4000 but book says it should be 4400. I've rebuilt the entire fuel and ignition system as well as the entire top end of the engine.
My intuition is telling me I've overpropped. The current set is B6. I have no idea what the pitch or diameter of the individual props are. What I was wondering is approx. how many RPM would I pick up by taking some pitch out? The Volvo Penta info I have doesn't give me any ideas. I can only afford to buy one set of screws this year and need to make an educated decision on getting B4's or B5's. I'm guessing but by going down a set I'm taking about 2" of pitch off the set. My experience with Mercruiser props tells me I'll pick up about 100 RPM per inch of prop I take out.
Any help you VP guys could offer would be greatly appreciated.
Problem is with performance. I have to go full down on the trim tabs and nurse it to get it to come out of the hole. It'll rev to about 2900 and its like hitting a wall. WOT is only 4000 but book says it should be 4400. I've rebuilt the entire fuel and ignition system as well as the entire top end of the engine.
My intuition is telling me I've overpropped. The current set is B6. I have no idea what the pitch or diameter of the individual props are. What I was wondering is approx. how many RPM would I pick up by taking some pitch out? The Volvo Penta info I have doesn't give me any ideas. I can only afford to buy one set of screws this year and need to make an educated decision on getting B4's or B5's. I'm guessing but by going down a set I'm taking about 2" of pitch off the set. My experience with Mercruiser props tells me I'll pick up about 100 RPM per inch of prop I take out.
Any help you VP guys could offer would be greatly appreciated.