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BLACKBOX
02-02-2014, 05:34 PM
Got 57 GPS today, first time out in 3 months (I am due for a tune-up). Have 21P Vengeance Prop. Tried the Mercury Prop Guide, which says for my setup to look at the 23P Laser II or Revolution 4, which might bring me over 60. Any thoughts? I have 4.3 MPI 1.62 ratio Alpha, WOT is 5000 (w/diverters engaged). My boat cruises beautifully at 3500 rpm, 45 mph, so don't want to jeopardize that handling...

Ghost
02-02-2014, 05:37 PM
What's the prescribed max rpm range for the motor?

BLACKBOX
02-02-2014, 07:42 PM
4900, which is what WOT is with thru-prop. For some reason, the engine runs at nearly 5000 with through-hulls engaged...

Just Say N20
02-02-2014, 09:39 PM
For what it's is worth, my experience with 16s would suggest that 57 with the 4.3 is pretty darn impressive. It sounds like you have just about the perfect set up. You might find a prop to give you a little more top end, but it will cost you everywhere else. And you have a great cruising rpm/mph relationship.

As a guy who has spent a good deal of time and money searching for that last elusive few mph, I feel your pain. Enjoy what you have. :)

Conquistador_del_mar
02-03-2014, 01:06 PM
Got 57 GPS today, first time out in 3 months (I am due for a tune-up). Have 21P Vengeance Prop. Tried the Mercury Prop Guide, which says for my setup to look at the 23P Laser II or Revolution 4, which might bring me over 60. Any thoughts? I have 4.3 MPI 1.62 ratio Alpha, WOT is 5000 (w/diverters engaged). My boat cruises beautifully at 3500 rpm, 45 mph, so don't want to jeopardize that handling...

Since the Vengeance is a 3 blade prop and the handling seems so good, you might have a difficult time finding a better speed prop. If you are willing to experiment, I would highly recommend trying a Rev 4 which will definitely get you a great cruise speed and the handling is also wonderful. My two cents, Bill

BLACKBOX
02-03-2014, 09:39 PM
Thanks for the input! I did hit 58 GPS over the summer, so it sounds like I've got it pretty good, then, from what I'm hearing. The 4 blade sounds intriguing, though!