 Horsepower vs. Displacement
On Wed, 23 Apr 2008 02:51:11 -0700 (PDT), in message
<6bd8f565-9a51-463d-8947-d4dc83566add@26g2000hsk..com>
Jay <jay-smith-1935@excite.com> wrote:
>Often, one will see two outboard motors with the same rated horsepower
>yet one may have 25% greater engine displacement (i.e. 68cc vs. 85cc)
>yet both will be rated 2.5 hp.
>
>(1) How does the smaller displacement motor achieve the same
>horsepower rating as the one with a greater displacement?
That's a much more complicated question than can be dealt with in a
brief post. One simple answer is that it might run at a higher speed.
>(2) What's the bottom line advantage, if any, to the outboard that has
>the same horsepower rating yet has a greater cc displacement?
I don't think it is possible to answer that question in general
without comparing specific engines for specific applications. Try
treating the engine more like a black box:
What does it cost to buy?
What does it cost to run?
Will it run on the low octane fuel easily available?
What are the reported characteristics of reliability and durability,
or alternately the reputation of the manufacturer?
I have written papers on engine performance, yet those were the
questions I asked myself for my most recent small outboard purchase.
Ryk
>
>Sorry if these two questions seem rather elementary to some but I'm
>new to the outboard motor scene and figure the only thing to do if
>you're not certain of something is to ask the experts.
>
>Thanx.
>
>-Jay
>
>
>ANSWERS:
>
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