242LS prop results and suggestions needed.
 

Just put a 350 MagMPI in my 1986 242. Running a alpha one 1.5 gr. I can spin it up to about 4,300 @43mph with a SS 3-blade 19” pitch.

i was going to try my 21” pitch Mirage plus but figured if I couldn’t spin the 19” past 4,300 it would be useless.

any suggestions on what I could try to get the RPM up a little. Boat runs fine otherwise, gets on plane fine. Just looking for suggestions. Maybe someone tried something that worked good.

Try stepping down to a 17. The max rpm on that engine is 4800 correct?

4800-5000 I believe.

I believe 17 will work for you.

I’ll try to hunt down a 17. Are the mirage plus props ok? Like I said I have a 21. Great looking prop but don’t think it will work for me.

I personally do not care for them. Some do, some dont. A bravo or revolution will perform better on a 242 in my experience. I dont believe they go down that small though.

any suggestions in a 17 pitch?

Are you sure the engine is healthy, compression and leak-down testing, etc?

He said it was new in his other posts. Remember it is a small block 350 mag so it should be 300hp or so. Thats less than the 454 that came in the boat, also the sb vs bb torque issue here.

.030 over sb. Everything is new. I know it's not a BB and don't expect it to act like one. (Or identify as one) I guess just seeing if someone had anything close or prop suggestions.

i would say 43 mph with that setup is good.

I agree 43 is a good number for that set up. But at 4300 rpm she isnt at full potential. I would go with a 17p and try to get it closer to the 4800 goal. I imagine a 17 will yield 4500-4600rpm. However I don't know of a 17p 4 blade that is built like a bravo or revo.

Would going to a 17 pitch prop and spinning it faster really do anything? Like I said, it gets on plane great and cruises fine. If I get the same results but spin it faster do I really gain anything?

I think the 17p mirage is going to work best for you with the torque limitations and weight you are dealing with. The 330 BB boats had a 19 mirage. See if you can pick up a used 17 and give it a whirl.