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del cecchi
 
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Default Selecting HP for given hull (outboard)


"Clams Canino" wrote in message
. net...
"del cecchi" wrote in message news:NTKfb.139

The bigger motor won't burn less gas at the same speed fer sure.
Maybe not much more, but not less.



Bzzzzzzt.

Anyone who reads this NG can tell you that I had FOUR different motors

on
the back of my (dearly departed) Four Winns last year.

76ci 80hp - 89ci 100hp - 99ci 115hp - 99ci130hp (crankshaft ratings

to keep
this simple)
All tested with a 14, 15, and 17 pitch stainless props.

I can tell you *unequivicably* that in the case of 2-stoke outboards,

output
is governed by two factors - spark advance and throttle openings.

If you have to run a 100hp with spark at max advance and the throttle

body
3/4 open to achieve a speed of 25 mph but you can take a 130 and do

the same
thing at max advance with the throttle body just cracked a bit - guess

which
motor will deliver better mileage??

And that's not even accounting for the propping up you can do with

more HP.

I'm sorry, but that sentance could not be *more* wrong.

If I ever wanna help this world deplete it's gas supply - I'll start

by
putting the 80hp (I kept it) on the PM-II and pulling tubers all day -

OK?


-W


My guess would have been the 100. That is the way it works for 4 stroke
motors in cars, and if one believes the fuel consumption curves in
magazine tests of outboards, it would appear to be the same for
outboards based on a little extrapolation.

However experience trumps extrapolation. It certainly seems true that
WOT blows the fuel economy.

del