re powering, fuel economy question

[ozzycat]

Hello,I have an 18 foot half cabin,carribean[,a fairly heavy boat].I recently blew up the motor, and I am now going to re power with a 130 150 or 175 HP 2 stroke carberator engine.At speeds around 27 knots which one of these would give the best fuel economy.Does anyone have experience with this?Some people have said the larger motors dont have to work as hard and dont suck as much gas is this true?

 

[tashasdaddy]

Re: re powering, fuel economy question

what is your boats rated hp? a 175 running at 3/4 throttle, is going to be better than a 150 at full throttle. it's a boat what' fuel economy? you also get better economy if you got to wide open and then throttle back. the way most are set up is the timing stay higher this way, and the fuel is cut. or something like that.

 

[ozzycat]

Re: re powering, fuel economy question

my boat is rated 165 I think but I am going to put a pod on to take the motor back and reinforce the transom.Thanks for the reply

 

[tashasdaddy]

Re: re powering, fuel economy question

besure to watch the engine height when you set back, not sure but i believe you raise the engine 1/2 inch for each 12 inches of set back. someone else will have to chime in on that.

 

[DJ]

Re: re powering, fuel economy question

Buy the most horsepower you can afford. Just because you have it, doesn't mean you use it all.

4-strokes are heavy. They are good on fuel but the weight penalty is substantial.

The new DFI 2-strokes are lighter and very efficient. When I repower, it will be a Bombi-(Johnson/Evinrude)etec.

 

[Silvertip]

Re: re powering, fuel economy question

The three engines you list will burn roughly 13, 15, and 17.5 gallons/hour respectively at wide open throttle. They will burn somewhere around 2/3 of those numbers in the 4000 RPM range. That means the 175 loafing will burn about the same as the smaller engines running wide open.