I currently have a 1988 242 LS with a 454 which was rebuilt and putting out around 430hp to the crank (confirmed on dyno). I am currently running a pretty beat up 21p Mirage which does perform well, however, being it came with the boat and was dinged up I purchased a new 21p Mirage Plus per many suggestions. This week I had an issue all day where the prop would start going well onto plane and right around 3200 RPM the prop would let go the RPMs would shoot to 4200 RPM and with a ton of work would come back down to normal levels. The prop was also imposible to go any slower than 30 MPH on plane. Has anyone experianced this issue? I had the same thing happened with a test four blade Bravo. One extra thing to note is my current 21p Mirage is a solid hub and all the other props have been the plasitc hub if that makes a difference.

Thanks for the help.

Jed

No ideas?

Maybe your engine coupler is bad and spinning under heavyier load. Is your drive all the way down (trimmed in)?

I thought the coupler but I have no rubber smell and it seems to be good with the other prop. This is with the drive all the way in and tabs down to help with the slower speed and no luck.

Do the new props you are trying have the vent plugs in them? Are you through prop exhaust?

Props do not have vent holes as an option and the exhaust is above the water line.

Is it possible going from a 21P to and 21P Plus could be causing this problem. Same with the 22 Bravo one I tested.

Should I try a simple 21P non plus or a 19P Plus? What is everyone else experiancing out there?

I would think a 23 would be better with that power

Call bblades

The 21 plus and bravo 22 should actually bite better than the regular mirage 21. The boat shouldn't have problems planing with any of those props. Definetly a strange problem

I agree extrememly odd. It grips well and then as soon as the bow begins the level off the RPMs fly up and stop and with alot of trim and tab play the RPMs will slowly come down. The old dinged up 21p bites all the time everytime through the whole RPM range at all spreads and any trim within the limit switch.

It just seems so odd to be happening with all different props. Besides being different blades, cups, and pitches all the test ones have the plastic hub insert versus a solid metal one. Would that make a difference?

Oreo,

on my 88 with stock 365mag motor I spun a 21 mirage plus, just wanted to put it out there, sounds as if something else is going on thou