Mercury 1988 115 HP bore/stroke

[Gerald McDonah]

Ok, I know there is a lot of smart people out there so give me real info. A Mercury 115 hp in 1988 had the same bore/stroke, as did the 1981 140 hp, they both have (A) series carbs, some jetting difference, reed stop openings are the same. So what made a 140 a 140 and a 115 a 115, or are they just decaled different.

 

[achris]

Re: Mercury 1988 115 HP bore/stroke

Hi GMC<br /><br />Welcome to iBoats.<br /><br />Slightly different porting in the block, 'power ports' in the piston skirts and they are different sized carbs.<br /><br />Chris.........

 

[Clams Canino]

Re: Mercury 1988 115 HP bore/stroke

Corrections <br /><br />The main difference is "propshaft ratings".<br /><br />The 1982 115 was virtually identical to the 1981 140 except that the power is rated at the propshaft instead of the crank.<br /><br />Both have power ported pistons, same bore and stroke, low-dome pistons, and same carb diamater.<br /><br /> There is one notable difference, the 140 uses reed blocks with ten petals per side. The propshaft rated 115 uses reed blocks with 8 petals on the odd numbered cylinders and 10 on the even numbered cylinders.<br /><br />On a dyno a 140 makes an easy 140 at the crankshaft. The propshaft rated 115 makes about 130-135 at the crankshaft. This impacts top end speed slightly but they have pretty much the same hole shot and operating characteristics.<br /><br />-W

 

[achris]

Re: Mercury 1988 115 HP bore/stroke

Sorry, didn't see the different years, I was assuming the same years.<br /><br />I'll just go off and hide again. <br /><br /><br />Chris.........

 

[Gerald McDonah]

Re: Mercury 1988 115 HP bore/stroke

So after reading that my 115 HP mercury is basicly the same engine as the older 140 hp except for the reeds, which give it the capability to breath a little more. I would like to get a little more HP in the future. I understand that I should not buy a 150 HP engine that is older than an early 1980 or it realy wouldn't be putting out much more. I also had heard a rumor that in the late 1980's Mercury put out a 150 HP v6 tha was for the bass boats of there time that put out close to 175 hp, any truth. And how do I get more HP out of my L6 Mercury, If I pain the head and jet up the carbs, will the reeds have the capabilty to let it make more hp, or is it a fruital waste of time and money. Thanks again guys for all your info.

 

[achris]

Re: Mercury 1988 115 HP bore/stroke

Sorry GMC, no head to plane on these engines. And yes, the EFI V6 150 was dyno-ed at 198hp.<br /><br />Chris......

 

[Clams Canino]

Re: Mercury 1988 115 HP bore/stroke

Originally posted by gmc62955:<br /> So after reading that my 115 HP mercury is basicly the same engine as the older 140 hp except for the reeds, which give it the capability to breath a little more. I would like to get a little more HP in the future. I understand that I should not buy a 150 HP engine that is older than an early 1980 or it realy wouldn't be putting out much more. I also had heard a rumor that in the late 1980's Mercury put out a 150 HP v6 tha was for the bass boats of there time that put out close to 175 hp, any truth. And how do I get more HP out of my L6 Mercury, If I pain the head and jet up the carbs, will the reeds have the capabilty to let it make more hp, or is it a fruital waste of time and money. Thanks again guys for all your info.

You could change the reed blocks to the 10/10 type and pick up a few HP. Nothing that would translate to much more MPH on the boat though.<br /><br />-W