When did Mercury start rating motors at the prop?

[mgsolakis]

When did Mercury start to rate motors at the prop?

 

[tazrig]

Re: When did Mercury start rating motors at the prop?

With their I/O's I believe it was in the mid 90's Outboards should be the same i would think.

 

[wired247]

Re: When did Mercury start rating motors at the prop?

1982 on the V6's. Inlines got the treatment in '87 I believe.

 

[mgsolakis]

Re: When did Mercury start rating motors at the prop?

Does that mean that a Mercury 3 cyl built in 1986 would be rated at the powerhead and thus be 10-20 % less powerful? I've seen them at 90 hp, 80 hp and 70 hp? Was that changes of the ratings of changes of the actual hp based on modifications that Mercury made to the motor?

 

[Bob_VT]

Re: When did Mercury start rating motors at the prop?

By 1986 the Merc was prop rated. Different HP motors using the same design had carburetor changes in the throats and jets, the bloch had porting changes and the exhaust sections had slight differences in some.

The motor was designed and built to optimum specs and there is really not much you can do without major machine work. Merc was also infamous for "underrating" the advertised HP for years going back to the 1950's

 

[Dukedog]

Re: When did Mercury start rating motors at the prop?

Changed when tha first generation block went away..........(V6)

 

[mgsolakis]

Re: When did Mercury start rating motors at the prop?

Ok thanks, I am looking into getting a 1986 3 cyl 90 hp. I'm currently running a 75' 75 hp Evinrude Hustler. It's a good motor but I find it really lags with more than 1 person in the boat. I think it would be better on a lighter hull. My boat is a 1300 lbs and I think the Mercury 90 will be a better fit if it's not too heavy. Anyone know what the weight difference would be off hand?

 

[mixerjv]

Re: When did Mercury start rating motors at the prop?

The '86 90hp Merc was a tower of power 6 cylinder. 290 lbs.

The 75hp was a 4 cylinder was 265 lbs.

The 60hp 3 cyl, which I happen to have ('87), is 190 lbs. As mentioned before, it was a 70HP before the change to propshaft hp.

Weight data can be had at nadaguides.com - select boats- select outboard icon and go from there. '79 and later. Don't know about the 'rude.

 

[mgsolakis]

Re: When did Mercury start rating motors at the prop?

Thanks for the reply, perhaps it's an 87' it is a 3cyl, Mariner by name and has the serial number A721455.

 

[Fun Times]

Re: When did Mercury start rating motors at the prop?

Thanks for the reply, perhaps it's an 87' it is a 3cyl, Mariner by name and has the serial number A721455.

MARINER -ELO ( 90 H.P. (1987) Serial No: 0A721455 Model No: 7090717 (3 cylinder)


You'll be able to find a lot of detailed information in here about the changes,
Classic Whaler: Boston Whaler: Reference: ICOMIA Engine Horsepower Standards

 

[Texasmark]

Re: When did Mercury start rating motors at the prop?

It's prop rated. I have a 90 also and once had a late '70's or early '80's vintage 4 cyl 85 that was powerhead rated...the year(s) the decal was silver, red, and blue and at the rear of the engine it went from horiz to vert, like the logo on the side of Ranger boats. Big difference in the performance of the two engines.

Mark