2800 SCR Repower

[hobknobwa]

Hi All, have a little tired 2000 2800 SCR with a single 7.4 Only goes 35 mpg, and gets at best, ( confirmed with a fuel management system ) 1.4 mpg on a good day with a tail wind. I need to repower. Anyone know how fast this hull can go? I am thinking of a single 8.1 MPI. My leg is only two years old, and was a new Bravo III Seacore. Another option is a rebuilt 7.4 ( 375 hp 500 ftpds torque ) I purchased a year ago from US Engines in Seattle. I am told it will crank out the power, but my mechanic seems skeptical due to the MPI of the original 7.4 being limited?

Any thoughts.

Thanks Adrian

[pascavone]

i have the same boat at can crank up to 37 mph with the slack.....

point is what the hurry?

the twin 4.3 give the same performance.

if i re engined, I think about the mag 8.1, which is a board over 7.4.... then you need larger props to get the use of it.

if your read many post in here, most of these cruizer top out at 35 to 40.... longer, more weight, more engines.... still 35mph.

would be easier to buy something else them mess with the laws of physics....

[shrew]

Speed is going to be dictated by the gearing of the drive and the pitch of the prop, not the HP in the engine. I upgraded from the 7.4 to an 8.1. 35 MPH is pretty fast for that boat. My typical cruising speed is around 25kts at 3700-3800 rpms. If you're looking to cruise at 35mph or higher, you have the wrong type of boat. It doesn't matter if this is a Maxum or a Searay, express cruisers aren't really intended to be run like that. IMHO.

[pascavone]

i'm not shy, i run 4800 to 5000 rpm, for short bursts.... but 26 to 30 is fine on flat water.