Trying to get the best speed out of my 350 MAG MPI/ 21P Mirage Plus Prop

[jserr68594]

I have a 2006 StarCraft Nexstar 19' boat that weighs in at 2100 w/o engine dry. It has a 350 MAG MPI 300 HP Engine and a Bravo 1 outdrive.

I currently am running a Mirage Plus 21 Pitch prop. The boat goes 58 MPH @ 4750 RPMs with just me on board. My WOT range is 4800-5200 RPM.

Am I lugging the engine at this RPM? Would I gain performance by having my prop "labbed" or changing pitch? Are there better props out there? I would like to see 60 MPH if possible. Any suggestions? I wish there were easy upgrades for the MPI engine, but I think it is maxed out w/o internal engine work.

Any help is appreciated!!

 

[Tail_Gunner]

Re: Trying to get the best speed out of my 350 MAG MPI/ 21P Mirage Plus Prop

I have a 2006 StarCraft Nexstar 19' boat that weighs in at 2100 w/o engine dry. It has a 350 MAG MPI 300 HP Engine and a Bravo 1 outdrive.

I currently am running a Mirage Plus 21 Pitch prop. The boat goes 58 MPH @ 4750 RPMs with just me on board. My WOT range is 4800-5200 RPM.

Am I lugging the engine at this RPM? Would I gain performance by having my prop "labbed" or changing pitch? Are there better props out there? I would like to see 60 MPH if possible. Any suggestions? I wish there were easy upgrades for the MPI engine, but I think it is maxed out w/o internal engine work.

Any help is appreciated!!

Your slip is 8% if the drive ratio is 1.5 that is at the end of the game....

I guess having your prop labbed would be the choice about 4-600...Google BB Blades

If the engine does not have vortec heads you could do a short block build up... cam.. spring's.. upgrade and that would get you there....There's a thread on a small block build.in the I/O forums going on now its about a 1800 upgrade a 350 gains about 75-100 hp

 

[jestor68]

Re: Trying to get the best speed out of my 350 MAG MPI/ 21P Mirage Plus Prop

Based on your current performance, the Mercury prop selector says to use a 19 pitch in a Mirage prop with either a 1.36 or 1.5 gear ratio.

IMO, your problem is you are using the wrong prop design. You should be using a Laser or Enertia in a 21 pitch. These smaller diameter props will generate more rpm and speed than the larger diameter Mirage on your runabout.

 

[jserr68594]

Re: Trying to get the best speed out of my 350 MAG MPI/ 21P Mirage Plus Prop

I think you are correct on the prop design. I'd love to find a used Enertia 21P. How do you think a laser II 21P would work?

 

[Tail_Gunner]

Re: Trying to get the best speed out of my 350 MAG MPI/ 21P Mirage Plus Prop

Jestor was spot on on the enertia good catch there..it could get you a 3-400 rpm gain. The laser i believe is a bit off...it's a light boat prop both a opinion and practical experience....but you really never know until you give it a go.