Max speed at what RPM and is 350MAG mpi maxing out at 4000rpm's?

[lexmartens]

On Mercruiser website it says the 350 MAG mpi has his operating range ending around 5000 rpm's.
Yesterday i was boating and noticed that my boat reaches about 50 mph and than holds that speed and does not go any faster. The Rpm's are around 4000 and i give it full throttle... I have a 3 blade mirage and a 1998 Maxum 2100SC. Sterndrive Alpha one. Is this normal or should it be able to go faster and reach more rpm's. Trimming has hardly any effect on the RPM's and the speed increase very very little. I think I noticed while doing the "Max speed" i feel and hear the engine cutting or holding a little back in short, small noticeable shock's at this 4000 rpm's.

-Is this the Maximum speed of this combination?
-Should a worry something is not ok?
-Could it have to do with the fuel that it does not get enough at higher rpm's?

thanx

 

[mkast]

Re: Max speed at what RPM and is 350MAG mpi maxing out at 4000rpm's?

Tune up?
Propeller?
Load on board?
Or, all of the above.

 

[Don S]

Re: Max speed at what RPM and is 350MAG mpi maxing out at 4000rpm's?

On Mercruiser website it says the 350 MAG mpi has his operating range ending around 5000 rpm's.

You aren't looking at the new engines rpm range and comparing it to your engine are you? You shouldn't be. A 1998 350 Mag has a WOT range of 4400 to 4800. Being a 98 boat, has it always run at this rpm?
Before you start changing anything, verify your tachometer is correct.

 

[lexmartens]

Re: Max speed at what RPM and is 350MAG mpi maxing out at 4000rpm's?

Sorry, had to mention the engine is a 2007 produced and fixed in the boat in 2008.

 

[emilsr]

Re: Max speed at what RPM and is 350MAG mpi maxing out at 4000rpm's?

Get it to a Merc mechanic and have it scanned. That "cutting out" you're hearing/feeling may be the ECM in a soft guardian mode....reducing power and rpm. Normally you'd get an alarm, but since the engine was retrofitted into an older boat all that may not be hooked up.

It could be something else like fuel flow or an incorrect prop, but I'd check the engine's 'puter for error codes before you start throwing money at it.

 

[Tail_Gunner]

Re: Max speed at what RPM and is 350MAG mpi maxing out at 4000rpm's?

You aren't looking at the new engines rpm range and comparing it to your engine are you? You shouldn't be. A 1998 350 Mag has a WOT range of 4400 to 4800. Being a 98 boat, has it always run at this rpm?
Before you start changing anything, verify your tachometer is correct.

As above...That intermitent cut out your hearing is more than probably the electronic rev limiter...meaning your motoring is probably hitting 5000 rpm...and for a nano second you get a ign interupt going on. Check the tach gauge on the back there is a switch for 4-6-8 it should be on 8. From there find a indepedent gauge to verify the boat gauge from 800 to 5000...Umm dont spend to much time at 5000.

Boat tachs are rugged and pretty...but notorious for being inaccurate.

 

[Pulse8]

Re: Max speed at what RPM and is 350MAG mpi maxing out at 4000rpm's?

As above...That intermitent cut out your hearing is more than probably the electronic rev limiter...meaning your motoring is probably hitting 5000 rpm...and for a nano second you get a ign interupt going on. Check the tach gauge on the back there is a switch for 4-6-8 it should be on 8. From there find a indepedent gauge to verify the boat gauge from 800 to 5000...Umm dont spend to much time at 5000.

Boat tachs are rugged and pretty...but notorious for being inaccurate.

Still It would be nice to know the pitch of your prop? and speed is 50mph?
But as they say above the stock gauges aren't the best and can give another read out.
I like to help you if were in Brabant and scan it for you.