merc 1150 (6 cyl) vs mariner 80(3cyl)

[phatmanmike]

as many of you fella's and fellete's know, i have a huge gas guzzling mercury 1150 tower of power that gets about 2 mpg. even less at WOT.<br /><br />im selling her to some other fella who dont care bout no stinking gas milage ! besides, its too big for my boat, which is rated for 65hp .<br /><br />i am purchasing a 1989/1990 mariner 80hp 3 cylinder with internal tilt/trim and SS 17p prop with controls. <br /><br />since the mariner 75 has 3 holes sucking gas as opposed to my big sixer, anybody have any ideas what i should expect as MPG differences. we do lots of long range cruising, 30, 40 and more miles ata time.<br /><br />i had a 3 cylinder 65 suzuki that got over 6 miles per gallon on the same boat.<br /><br />my buddy has a 70 hp 3cylinder johnson and gets 6 mpg on almost identical boat.<br /><br />also, since the merc was 1976 and the mariner 1990, does that mean that the hp difference wont be AS much since one was prop shaft and one was crankshaft rated. im just curious<br /><br />any ideas or suggestions welcome

 

[Bob Kimber]

Re: merc 1150 (6 cyl) vs mariner 80(3cyl)

Hi Mike,<br /> I replaced my 79 model 90hp inline six with a new 3cyl 90hp 2000 model Merc, it is the same capacity as the 80 you are thinking of, which then became the 75hp. In my case there was a considerable improvement in speed and fuel consumption, some of the comparisons.<br /><br />Old 90hp 6cyl<br /> 23mph @ 4200rpm <br /> 33mph @ 5000rpm (WOT)<br />average fuel use to my most commonly used fishing spot (30 miles round trip) at between 4200 - 4800 rpm depending on sea conditions varied between 6.5 to 8 imperial gallons ( 29 to 36 litres)<br /><br />new 90hp 3cyl<br /> 28mph @ 4200rpm<br /> 39mph @ 5350rpm (WOT)<br />average fuel use for same trip is now 4 to 4.5 imp gallons (18 to 20.75 litres) which puts it into the 6 mpg range<br /><br /><br />The power difference is very apparent I had to go from the old 15" pitch prop to new 17" pitch prop to keep WOT down to recommended rpm range, speed verified by gps has increased by about 6mph both at cruise and WOT, this is on a fairly heavy 17ft deep V half cabin f/glass boat with a 3/4 length bimini top which weighs about 2600lbs with fuel, gear and 2 adults.<br /><br />Bob

 

[phatmanmike]

Re: merc 1150 (6 cyl) vs mariner 80(3cyl)

bob, thank you. you couldnt have been more helpfull !!!!!!