When did Merc change the point at which HP is measured?

[MercFan]

Sorry for the repost. I know I saw this in a thread somewhere, but the search engine doesn't find anything Even tried a simple search for Clams, and it only returns like 3 threads.<br /><br />But the question is... I read that Merc changed their point at which the measure hp. When was this? And from where to where did this "point of measurement" move?

 

[boatdoc]

Re: When did Merc change the point at which HP is measured?

seems like it was early 80's,.measurement point moved from powerhead output to a rating at the prop

 

[Clams Canino]

Re: When did Merc change the point at which HP is measured?

Yes...<br /><br />Rating went from crankshaft to propshaft in or around 1982 (they didn't do all models at once).<br /><br />In the case of the inlines the 140 became the 115 and the 115 became the 90. This indicates to me that they were playing with "rough" figures as the two latter ratings are quite conservative.<br /><br />-W

 

[MercFan]

Re: When did Merc change the point at which HP is measured?

Thanx guys!<br /><br />So assuming you have a Merc outboard of 1980 140hp, and you want to replace it with a "new" motor you will only need to buy a 1988 115hp?<br /><br />And other manufacturers? Where do they measure? Mariner, Yamaha, Evinrude etc?

 

[phatmanmike]

Re: When did Merc change the point at which HP is measured?

all outboards had to have prop ratings by 1986. so technically, a 1988 150v6 would have more balls than say, a 1982 150v6. kinda-ish

 

[jimmbo]

Re: When did Merc change the point at which HP is measured?

In 1981 merc had a 225, 200, 175, and 150 V6s. in 1982 they had only a 200 and 150 which were touted as being more powerful. Later years reintroduced a new 175 and a 135. The early 150 and 175 were the same displacement(122 cuin) and the 200 and 225 were 142 in. blocks. The later 150 and 135 were the small small block while the 175 and 200 were the 142 in. blocks. <br />Looks like a decal switch overall