350 Magnum MPI, RPM at WOT
 

We purchased a 2004 Sea Ray Sundeck 240 at the end of last season and just
put it back in the water last weekend. We were pretty easy on it last year
and just got enough hours on the engine to get through the 20 hour break-in
period.

Now, we are pushing the boat a bit harder and the RPM at full throttle
seems too high to me. Our previous boat was a 1990 with the 5.7L 260 hp
engine, so I am not sure if things have changed.

This engine is the 350 Magnum MPI with Bravo III drive producing 300 hp. At
full throttle, the engine is turning 5200 rpm and the speed is not that
great. Also, compared to my previous boats, the RPM vs. speed is quite
different. The older boats had a very close correlation between the RPM and
speed with 3000 RPM being very close to 30 MPH. This boat, the RPM is much
higher than the speed, probably 1000 RPM higher than the speed.

Do you think the boat is mis-propped?

I am going in soon for a steering cable problem and wanted to get some
opinions on this issue too.

Thanks,
Dave

You should be doing 50+ MPH. Hopefully the selling dealer will get it
propped right for you at no charge.
JIMinFL
"David Patnaude" wrote in message
...
We purchased a 2004 Sea Ray Sundeck 240 at the end of last season and just
put it back in the water last weekend. We were pretty easy on it last year
and just got enough hours on the engine to get through the 20 hour
break-in
period.

Now, we are pushing the boat a bit harder and the RPM at full throttle
seems too high to me. Our previous boat was a 1990 with the 5.7L 260 hp
engine, so I am not sure if things have changed.

This engine is the 350 Magnum MPI with Bravo III drive producing 300 hp.
At
full throttle, the engine is turning 5200 rpm and the speed is not that
great. Also, compared to my previous boats, the RPM vs. speed is quite
different. The older boats had a very close correlation between the RPM
and
speed with 3000 RPM being very close to 30 MPH. This boat, the RPM is much
higher than the speed, probably 1000 RPM higher than the speed.

Do you think the boat is mis-propped?

I am going in soon for a steering cable problem and wanted to get some
opinions on this issue too.

Thanks,
Dave

Do you think the boat is mis-propped?

I am going in soon for a steering cable problem and wanted to get some
opinions on this issue too.

Thanks,
Dave


I agree that it sounds very under propped. I bet it has great holeshot
torque, and the extra ponies really help that. Get a prop with more
pitch and bring those rpm's down some. 5200 is buzzing for a 350 motor,
and bearing life will be greatly reduced.

The owners manual or a tag on the engine should state the WOT RPM. Check it
out and post back here!


"David Patnaude" wrote in message
...
We purchased a 2004 Sea Ray Sundeck 240 at the end of last season and just
put it back in the water last weekend. We were pretty easy on it last year
and just got enough hours on the engine to get through the 20 hour
break-in
period.

Now, we are pushing the boat a bit harder and the RPM at full throttle
seems too high to me. Our previous boat was a 1990 with the 5.7L 260 hp
engine, so I am not sure if things have changed.

This engine is the 350 Magnum MPI with Bravo III drive producing 300 hp.
At
full throttle, the engine is turning 5200 rpm and the speed is not that
great. Also, compared to my previous boats, the RPM vs. speed is quite
different. The older boats had a very close correlation between the RPM
and
speed with 3000 RPM being very close to 30 MPH. This boat, the RPM is much
higher than the speed, probably 1000 RPM higher than the speed.

Do you think the boat is mis-propped?

I am going in soon for a steering cable problem and wanted to get some
opinions on this issue too.

Thanks,
Dave

I have an '04 270hp VolvoPenta 5.0 on a 21.5' FourWinns Funship (4200 lb
boat) w/ 19" prop... turns 5000 rpm at WOT and gets to 51 mph with a
medium load... exactly matches what the dealer and manuals say it
should. I cruise at about 27-28 mph at 3000 rpm.

You dont say what speed you see at WOT. I'd suggest trying the next
higher pitch prop, should drop your R's by about 150-200 and maybe add a
couple mph.
....cb


David Patnaude wrote:
We purchased a 2004 Sea Ray Sundeck 240 at the end of last season and just
put it back in the water last weekend. We were pretty easy on it last year
and just got enough hours on the engine to get through the 20 hour break-in
period.

Now, we are pushing the boat a bit harder and the RPM at full throttle
seems too high to me. Our previous boat was a 1990 with the 5.7L 260 hp
engine, so I am not sure if things have changed.

This engine is the 350 Magnum MPI with Bravo III drive producing 300 hp. At
full throttle, the engine is turning 5200 rpm and the speed is not that
great. Also, compared to my previous boats, the RPM vs. speed is quite
different. The older boats had a very close correlation between the RPM and
speed with 3000 RPM being very close to 30 MPH. This boat, the RPM is much
higher than the speed, probably 1000 RPM higher than the speed.

Do you think the boat is mis-propped?

I am going in soon for a steering cable problem and wanted to get some
opinions on this issue too.

Thanks,
Dave

On 3 Jun 2005 13:15:55 GMT, David Patnaude
wrote:

We purchased a 2004 Sea Ray Sundeck 240 at the end of last season

I used to race six of these on the Hudson river.

But I now have a 36' Zimmerman, and a very long driveway.

Me and the wife
http://pg.photos.yahoo.com/ph/harkra...bum?.dir=/1323

cb wrote in
:

I have an '04 270hp VolvoPenta 5.0 on a 21.5' FourWinns Funship (4200
lb boat) w/ 19" prop... turns 5000 rpm at WOT and gets to 51 mph with
a medium load... exactly matches what the dealer and manuals say it
should. I cruise at about 27-28 mph at 3000 rpm.

You dont say what speed you see at WOT. I'd suggest trying the next
higher pitch prop, should drop your R's by about 150-200 and maybe add
a couple mph.
...cb


I would say that the speed is a bit low too. Low 40's was the top speed.

"Woodchuck" wrote in
:

The owners manual or a tag on the engine should state the WOT RPM.
Check it out and post back here!




I didn't get to check on the engine itself, but at the Mercruiser website,
WOT for this engine is listed as 4800-5200 RPM.

I guess they went for the low end torque instead of the top speed.