Am I propped up right?

crownlyfe

Cadet
Joined
Jul 27, 2015
Messages
8
Stainless Steel quicksilver mirage prop 23P, reaches around ~44-46 MPH with 3-4 people and some gear on the boat like cooler,beach chairs,tube,lifejackets etc.
5.7L alpha 1 on a 3100lb dry weight boat. For some reason I feel like I should be able to hit maybe 50?
 

Maclin

Admiral
Joined
May 27, 2007
Messages
6,761
What RPM at top speed? Is speed by GPS or speedo? What size and type of boat?
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
28,267
50MPH takes a whole lot of power, and production boats are generally powered to hit 40-45MPH, at most. Check your GPS speed and report back on RPM, as well. I will be surprised (but not shocked) if you get to 50MPH with that powerplant.
 

Faztbullet

Supreme Mariner
Joined
Mar 2, 2008
Messages
15,931
Carb, EFI or MPI??? The same boat with the 350EFI and the large Bravo outdrive will run 50+mph. Try tapping the trailer button at WOT to raise the drive as it may not be getting full trim.
 

crownlyfe

Cadet
Joined
Jul 27, 2015
Messages
8
it's carb engine just went out to test 4050 Rpm 45mph is Throttle all the way down 4 ppl some gear full tank of gas, 32-35 mph around 3100 rpm, decent prop or should I look into something else
 

Faztbullet

Supreme Mariner
Joined
Mar 2, 2008
Messages
15,931
21 pitch 4 blade will help..did you try try tapping the trailer button?
 
G

Guest

Guest
You should first start by determining what your engines WOT operating RPM is.
You have a 5.7 GM V-8 that whose WOT range is between 4500 to 4800 RPM. (confirm what yours is exactly with a Merc dealer)
The propeller you consider should not exceed the maximum rpm range at WOT.
If you're only turning 4000rpm, you need to drop the pitch to get the revs up.
As a general rule - a 2 inch reduction in pitch will increase the RPMs by 200
Good Luck
 
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