Horse Power Rating

[churchk5]

Hi,<br />I am new to boating and was just wondering how hp ratings are developed. I have a Johnson CD-11 that is claimed to be 5.5 horse but have found that it is actualy more powerful than a newer Mercury 8 horse. Were hp ratings calculated differently back in 1954?<br /><br />Church

 

[catfish1]

Re: Horse Power Rating

no, the 1954 5.5hp does not have more hp than a newer 8hp merc! in 1954 the hp was rated at the powerhead, now they are rated at the prop shaft. so the 1954 5.5 hp is only putting about 5hp to the propshaft, there is a 10% reduction from powerhead to the propshaft.

 

[JB]

Re: Horse Power Rating

Howdy, Church.<br /><br />I don't know how you "found that" it is more powerful than a Merc 8hp, unless the Merc is really sick.<br /><br />In 1954, outboard engines were rated at the flywheel. Since the mid-80s all outboards are rated at the prop.<br /><br />By current rating, your engine is somewhere between 4 and 4.5hp.

 

[DJ]

Re: Horse Power Rating

The one thing missing here is that outboard makers in the fities tended to lie about the actual outboard hp. <br /><br />Merc. (Keikaefer) was famous for that.