OMC to rate H.P. At Prop

[Naiscoot]

What year did OMC begin rating horsepower at the prop instead of the power head? Was this an industry wide change or did it vary between makers. Thanks, Naiscoot<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /><o:p></o:p>

[Riverratt]

They changed the V6 starting in 1986 but not sure about the others.

[Naiscoot]

I wonder how much actual horsepower was really lost. I have been told around 10 % but that could be vary depending on the shaft length. Thanks, Naiscoot

[hsbob]

140 hp became 115 , 115 to 90. all v-4.

[Naiscoot]

Well that is more than I thought. Do you think this percentage applied to all models or to all makers? I have been told that the older Mercury's lost about 10% at the prop. So a 150 would actually produce 135 at the prop. But if OMC were around 19% (140=115) a 150 would work out to be around 120. As long as I can remember Mercury was known for performance and most Ski and Speedboats had Mercs. I wonder if this was one reason why? Like the old muscle cars when Mopar's just seemed to squeeze out a few more ponies than the rest. Thanks,<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /><o:p></o:p>
Naiscoot.<o:p></o:p>

[Naiscoot]

Well that is more than I thought. Do you think this percentage applied to all models or to all makers? I have been told that the older Mercury's lost about 10% at the prop. So a 150 would actually produce 135 at the prop. But if OMC were around 19% (140=115) a 150 would work out to be around 120. As long as I can remember Mercury was known for performance and most Ski and Speedboats had Mercs. I wonder if this was one reason why? Like the old muscle cars when Mopar's just seemed to squeeze out a few more ponies than the rest. Thanks,<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /><o:p></o:p>
Naiscoot.<o:p></o:p>

[warrior74z]

What year did OMC begin rating horsepower at the prop instead of the power head? Was this an industry wide change or did it vary between makers. Thanks, Naiscootffice:office" /><O:p></O:p>
First year the Mercs were rated at the propshaft was 1983.

[terry taylor]

I think at that point in time changing stickers was easiest way to change HP. at the prop.I also think for example 140 to 115 you would be getting a bonus a very strong 115 if you know what I mean. A nother example OMC. V configeration 99.9 cubic inch large pistons were very torquie port size and timing along with carb. size dictated HP. There was much ado between MFG,s at that time and competition whitch benifited the consumer . The engine potentcy was often measured by [ how many skiers can that thing pull at one time] low end power was desired by many for that reason while high RPM performance was preferred by others. quite often this figered in to a persons purchase THANKS.