FeLizDream
Active Member
- Jun 28, 2015
- 253
- Boat Info
- 2001 Sea Ray 400 Sedan Bridge, with engine synchronizer.
- Engines
- Cummins 6cta 450 HP, prop 22 Lx 22" L cup.
Talking about Props, ( My props are 4 blade Nibral 22" x 23" l cup) at full load I was making 2,500 to 2,600 rpm depending on sea conditions, i' d like my engines be happy and last a long time , so I decided to drop the pitch 1" to get 100 more rpm and applied PropSpeed. Mi props now are 22' x 22" and I can reach easy 2,700 to 2,750 rpm at WOT fully loaded with full gas, 1/2" tank of water and 4 adults. SBMAR recommends 2,750 rpm for Cummins 450 diamonds.
In my last trip to Venice Beach, Fl from Marco Island, i tested the boat cruising at 23.2 mph and 2200 rpm with front winds and front waves, i lost like 1 mph or 2 mph in speed but i feel my engines are running smoothly and happy.
see Article by Tony Athens SBMAR about this engines:
" The Solution for a Long Engine Life
Look at the fuel & load curves below… If you are loading the engine above the 450 Diamond curve in the “cruise RPM zone”, then IMO, you are at serious risk. They key is to just think of your 480CE engine as a 450 Diamond, prop it to stay at or below that load curve, especially in the “cruise zone” and you have done it right. Damage has occurred in the past as to over stressing the valves, etc., cannot be undone, but at least from here forward, you have done all you can do…
Here’s the bottom line: If you cannot get your load close to the 450 Diamonds curve and be happy with the performance, then you have what we call, “too much boat and not enough engine” And lastly, think about where all of the wear and tear takes place on these engine – It’s not at WOT, it’s at CRUISE!
In my last trip to Venice Beach, Fl from Marco Island, i tested the boat cruising at 23.2 mph and 2200 rpm with front winds and front waves, i lost like 1 mph or 2 mph in speed but i feel my engines are running smoothly and happy.
see Article by Tony Athens SBMAR about this engines:
" The Solution for a Long Engine Life
Look at the fuel & load curves below… If you are loading the engine above the 450 Diamond curve in the “cruise RPM zone”, then IMO, you are at serious risk. They key is to just think of your 480CE engine as a 450 Diamond, prop it to stay at or below that load curve, especially in the “cruise zone” and you have done it right. Damage has occurred in the past as to over stressing the valves, etc., cannot be undone, but at least from here forward, you have done all you can do…
Here’s the bottom line: If you cannot get your load close to the 450 Diamonds curve and be happy with the performance, then you have what we call, “too much boat and not enough engine” And lastly, think about where all of the wear and tear takes place on these engine – It’s not at WOT, it’s at CRUISE!
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