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Fuel Consumption

1054 Views 4 Replies 5 Participants Last post by  hammer
Would appreciate some input on fuel consumption. This is my second year owning a boat. 30' 1987 Sea Ray Weekender with twin inboard Merc 350 with 4 barrel carbs. I'm not a speed demon but seems I used a lot of fuel last summer cruising from JB. My question is about what RPM do the carbs go from two to four barrels and really start sucking fuel. I usually cruise at 20 to 25 MPH but sometimes kick it up. With fuel up big time I would like to know at what RPM I'm throwing $$$ out the window.Thanks--

"Another Thousand"
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Most marine engines are tuned so that they get their best mpg around 3000 to 3500rpm. Any more than that and you're gonna open up those secondaries on those carbs and spend more $$ at the pump.
total horsepower divided by 24 will give you a pretty good "WAG" on gals per hour
Pretty much all modern carbuerators operate on a as needed basis. It's not about the RPM, it's about the load. The more load put on an engine, the more carbueration it needs. With no load, most secondarys would never open. So what that probably translates into is it depends on your cargo, people included. Most likly, you shold be able to stay out of the secondarys if you stick to 2800-3200.
Yeah, give me your beer to take out for you to lighten your 'load'. I have fuel injection.
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