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Deleted User YDKXO
Guest
12kg each side isn't going to make much difference to performance and economy on a 12000kg boat /forums/images/graemlins/smile.gif
I'm sure it's much more than a turbos and injectors swap but it's got to be worth checking with Volvo
The figures you and Mapism have quoted are specific fuel consumption figures and constitute an average over the full power demand curve. Unfortunately, a propellor cannot absorb the full power from the engine at all rpm. In fact it can only accept full power at one particular rpm and that particular rpm is usually max rpm ie 2800rpm with these engines. Some engine manufacturers do produce what's called prop demand fuel curves but these are based on a mathematical formula rather than reality and are only accurate for displacement boats not planing boats like the P42. The only way you can compare the fuel consumption of a P42 with either engine is to stick 2 boats, one with the 63L's and the other with 63P's side by side under the same load and atmospheric conditions and measure their relative fuel consumptions at various rpm/speeds
Having done all that, I doubt you'll find much difference! IMHO any difference in fuel consumption would not be a deciding factor between one or other engine
I'm sure it's much more than a turbos and injectors swap but it's got to be worth checking with Volvo
The figures you and Mapism have quoted are specific fuel consumption figures and constitute an average over the full power demand curve. Unfortunately, a propellor cannot absorb the full power from the engine at all rpm. In fact it can only accept full power at one particular rpm and that particular rpm is usually max rpm ie 2800rpm with these engines. Some engine manufacturers do produce what's called prop demand fuel curves but these are based on a mathematical formula rather than reality and are only accurate for displacement boats not planing boats like the P42. The only way you can compare the fuel consumption of a P42 with either engine is to stick 2 boats, one with the 63L's and the other with 63P's side by side under the same load and atmospheric conditions and measure their relative fuel consumptions at various rpm/speeds
Having done all that, I doubt you'll find much difference! IMHO any difference in fuel consumption would not be a deciding factor between one or other engine
