Winnipesaukee Forum - View Single Post

BroadHopper · 07-23-2009, 10:46 PM

I have an '88 F-223 LS with the original 454 Mercruiser turning a Mirage II 25' prop. The best I can do is 10 GPH and the worst I have seen is 20 GPH. I measure this by dividing the number of gallons used by the hours clocked on the hour meter. I don't have an accurate speedometer.

To maintain 10 GPH. I will go on plane at 3K rpm and throttle back to minimum planing speed at 2200 rpm. If I had a gph meter, I can probably do better.

20 GPH is at WOT at 4500 rpm. Which is 65+ mph. With an 80 gallon tank, that is 4 hours between fill ups.

From what I read in magazines and browsing on the internet, the most accurate way of gathering MPG is with a GPS speedometer. There are GPS speedometers on the market that can calculate MPG and GPH. Expensive. I wonder what the forum members are using for instruments.

07-23-2009, 10:46 PM	#11
BroadHopper Senior Member Join Date: Oct 2004 Location: Laconia NH Posts: 5,576 Thanks: 3,216 Thanked 1,103 Times in 794 Posts	Interesting I have an '88 F-223 LS with the original 454 Mercruiser turning a Mirage II 25' prop. The best I can do is 10 GPH and the worst I have seen is 20 GPH. I measure this by dividing the number of gallons used by the hours clocked on the hour meter. I don't have an accurate speedometer. To maintain 10 GPH. I will go on plane at 3K rpm and throttle back to minimum planing speed at 2200 rpm. If I had a gph meter, I can probably do better. 20 GPH is at WOT at 4500 rpm. Which is 65+ mph. With an 80 gallon tank, that is 4 hours between fill ups. From what I read in magazines and browsing on the internet, the most accurate way of gathering MPG is with a GPS speedometer. There are GPS speedometers on the market that can calculate MPG and GPH. Expensive. I wonder what the forum members are using for instruments. __________________ Someday may never be an actual day.