1998 Mercury 150efi Offshore Ideal RPMs?

trayscool · #1 November 3rd, 2008, 05:00 PM

I have a 1998 Mercury 150efi offshore on my 21' Striper Cuddy. The motor runs perfect, idles perfect, and starts just like a car everytime. It has plenty of power for my boat. I was wondering what the ideal RPMs are to run this motor. On my most recent trip I ran it at 3500rpms and I was going about 25mph. It seems to run best from 3000-4000 but hesitates below 3000rpms. What will give me the best performance and mpg for this motor? Im not concerned with speed, only getting the best mileage and longevity from the motor. thanks in advance

hamit59 · #2 November 3rd, 2008, 07:17 PM

The book said it should have wot @5000-6000. Your setup could have a lot to do with your boat and water conditions as for fuel mileage. My best advice
is to check your fuel mileage on a few runs starting at 3000 rpms as long as your on plane and go up from there on each run. My thinking is after you get on plane you have to choose what speed you want to maintain it is normal the faster you go the more fuel you'll use. Every boat is diff and there is no way any one can tell you for sure what is best for every boat.

Many of the marine Gps have the flow meters so you can see what the speed and fuel flow is and it will tell you what your mpg is.

trayscool · #3 November 3rd, 2008, 08:30 PM

thanks for the reply. when we did a sea trial we had the boat going about 50mph at WOT 6K rpms for about 15 seconds. i know that the motor will eat more gas at a lower rpm until it hits prime, i just want to find out what ideal rpms are for this motor

trayscool · #4 November 3rd, 2008, 08:34 PM

I just pulled this off the mercury website for a brand new 2 stroke 150efi and this seems to be the ideal performace MPG wise. EDIT this is for a 21' center console fishing boat

RPM-4000
speed-28.4
gallons per hour-12.5
mpg-2.3

does this sound about right?

trayscool · #5 November 6th, 2008, 12:38 PM

anyone?

Paul DuLaney · #6 November 8th, 2008, 09:15 AM

I have a 2004 150EFI on a 2001 Taho Q3 ski/fish and it seems to do the best around 3500 rpm as far as fuel burn. Now I realize my boat is a lot lighter than yours, so you need more rpm to hold on plane than I do.A friend of mine has a 21 foot SeaSwirl striper duel console with a Honda 225 and he loves it.