montana73 wrote:
I guess I'm a bit disappointed after seeing everyone's posts. I have a 1999 Sundowner 245 with the 7.4L Volvo Gi and DP stainless props. I had F6's when I bought it, but I live around 5200 ft and often boat on lakes at 6000 or 6500 ft. Top end with F6's was 48 mph. Switched to F5 to get out of water faster. Dropped to 42. Still only run at 4k rpms. Just last weekend, I switched to F4's (stainless as well) and pop out of the water great (perfect for skiing even with 6-8 people in the boat. However, I can hardly break 38 with 1/4 tank of gas and by myself. Still sitting at 4k rmp, which I think I should be running faster. It's kind of weird because my first run out, I popped right out and broke 44 mph and sitting around 4300 rmp. I slowed down and tried again (and again, and again) and could never break 38 mph on glass water and perfect trip. I know I'm at high altitude, but seems like I should be running a lot faster. I believe I have 1.78 gear ratio too. Not sure, because it's hard to read tag on outdrive. Any thoughts? It's almost like the engine was governed at 4000 mph. Dealer in Pueblo said it should run up to 4800 rpm with no problem. Thanks, Russ
You didn't mention trim...if your not trimming the drive constantly, trying to get maximum performance, you leaving some MPH on the table. My boat for instance will only run about 38 MPH @ ~4000 RPM trimmed all the way down. Trimmed to the max WFO at 5800rpm I can get to 52-53 MPH under perfect conditions. Also glass water is not the fastest water, fast water has a little chop on it.