Welcome Guest - Sign Up today
Welcome Guest - Sign Up today

Announcement

Collapse

Private Messages

We are aware of a current issue where your messages screen does not properly load and we are working on a fix.

In the interim, you can access you messages by navigating to this link: https://forums.iboats.com/privatemessage/notification

Apologies for the inconvenience.
See more
See less

1984 mercury 90 hp manufacturer recommendation for prop

Collapse
X
  • Filter
  • Time
  • Show
Clear All
new posts

  • 1984 mercury 90 hp manufacturer recommendation for prop

    does anyone know what mercury recommends for a 1984 90 hp two stroke?

  • #2
    You can find out here. Just select a comparable newer engine.
    https://www.mercurymarine.com/en/us/...or/#!/step-one

    Comment


    • #3
      Inline six right? What size, type and weight boat is it going to be installed on?

      Comment


      • #4
        Originally posted by Blystone View Post
        does anyone know what mercury recommends for a 1984 90 hp two stroke?
        The right prop for that engine will depend totally on what kind of boat the engine is installed on. In other words, if that engine is on a pontoon boat, it will use a totally different prop if used on a runabout.

        Comment


        • #5
          WOT range for that engine is 4500 - 5000. Engine makes its best power between 4700 - 4800 rpm Above 5000 rpm the power falls off rapidly due to small intake and exhaust ports and fewer reed valves than higher hp inline 6s. Great stump pulling bottom end though.

          Comment


          • #6
            Originally posted by WesNewell View Post
            You can find out here. Just select a comparable newer engine.
            https://www.mercurymarine.com/en/us/...or/#!/step-one
            The newer engines have different RPM ranges and often different gear ratios, and since this selector doesn't go back to the era of the old inline 6s, any recommendation will most likely be incorrect

            Comment


            • #7
              Well, without info on the boat he's going to use it on, it's his best bet for something close to accurate since he'll have to provide that info for the prop selector.

              Comment


              • #8
                a 17” prop would work on 15 - 16 ft boats, a 15” on 17 - 18 ft. That’s based on 40 yrs propping those engines

                Comment


                • #9
                  thank you to everyone who responded to my inquiry. sorry its a very very delayed response however my boat is a 17 foot fiberglass open bow 1987 monark 171 o/b

                  Comment


                  • #10
                    Gear ratio is 2::1. Prop is likely 15" Pitch, although final choice is by trial and error.

                    Comment


                    • #11
                      Sign up today
                      Do you know the dry weight of your boat? Under 1000# with 90 hp I'd try a 17-19p prop.

                      Comment

                      Working...
                      X