9.9 or 15 HP OUTBOARD FUEL CONSUMTION QUESTION

9.9 or 15 HP OUTBOARD FUEL CONSUMTION QUESTION

Post by olde.. » Sun, 17 Aug 1997 04:00:00


   Today I shopped dealers on these motors, both 2 stroke AND 4 stroke.
My probable use is with a 10 foot rib inflatable. Every salesman says i
will NOT go thru even a single 6 gallon tank of gas in a full 6 hours of
non stop running with either the 2 OR 4 stroke motor. I hate to be a
doubter.....but PLEASE , someone tell me the truth on what to expect.
The last time I heard this kind of pitch, I ended up with a jet ski that
cost me 60 plus bucks a day for gas on Easy riding.
    Also, I was told the 4 stroke honda AND Evenrude were still too new
to estimate maintenance costs and engine longevity compared to 2
strokes. Was told ny "some" that the 4 strokes are MUCH slower top end
speed wise also. Anyone know of a book I can buy so I don't have to ask
dumb questions?          Thanks! Mike

 
 
 

9.9 or 15 HP OUTBOARD FUEL CONSUMTION QUESTION

Post by Start Your Engines In » Mon, 18 Aug 1997 04:00:00

Quote:

>   Today I shopped dealers on these motors, both 2 stroke AND 4
stroke.
>My probable use is with a 10 foot rib inflatable. Every salesman
says i
>will NOT go thru even a single 6 gallon tank of gas in a full 6
hours of
>non stop running with either the 2 OR 4 stroke motor. I hate to be a
>doubter.....but PLEASE , someone tell me the truth on what to
expect.
>The last time I heard this kind of pitch, I ended up with a jet ski
that
>cost me 60 plus bucks a day for gas on Easy riding.
>    Also, I was told the 4 stroke honda AND Evenrude were still too
new
>to estimate maintenance costs and engine longevity compared to 2
>strokes. Was told ny "some" that the 4 strokes are MUCH slower top
end
>speed wise also. Anyone know of a book I can buy so I don't have to
ask
>dumb questions?          Thanks! Mike

I had a 9.9 Johnson 2 stroke long shaft power a 22 ft. O'Day
sailboat, and it would burn a 6 U.S gallon tank in about 6 hours at
full cruising speed, which was a little under full throttle because
on this boat there was very little increase in speed at full
throttle. Keep in mind that this was an older engine, circa 1980, the
newer ones will probably be more economical.  I now have a 9.9 hp.
Mercury 4 stroke, 1995 model with low hours on it. (It currently has
30 hours use). Pushing a 20 ft Fiberglass cabin cruiser at about 6
knots it will burn up a 3 U.S gallon tank in about 4 hours. Throttle
setting was wide open for this test after the engine had 10 hours on
it. One thing to consider if you are going to use it on an inflatable
is whether or not you will be physically carrying the motor around
very much, because the 4 stroke is about 25% heavier. Also, if you
are going to be transporting it in the trunk or store it in the
horizontal position, the 2 stroke is much more forgiving, in that
there is no oil to leak out no matter which way you lay it down. The
4 stroke is usually more fussy about how it is stored, and will
punish you with a mess of oil on occassion if it is not positioned
properly. I always store mine in the vertical position for this
reason, and also because I worry about oil possibly getting into the
combustion chamber while stored horizontally. I'm sure the
manufacturers have taken steps in the design to prevent this, but if
it were to happen it could result in bent connecting rods on start up
when the piston locks hydraulically near the top of the compression
stroke. These engines are new enough that I haven't personally heard
of this happening yet, but I have heard of several cases of it
happening to automotive and industrial engines that have been upset
for short periods of time.

Jamie Bracht

 
 
 

9.9 or 15 HP OUTBOARD FUEL CONSUMTION QUESTION

Post by James W. Hebe » Tue, 19 Aug 1997 04:00:00



Quote:
> One thing to consider if you are going to use it on an inflatable
> is whether or not you will be physically carrying the motor around
> very much, because the 4 stroke is about 25% heavier. Also, if you
> are going to be transporting it in the trunk or store it in the
> horizontal position, the 2 stroke is much more forgiving, in that
> there is no oil to leak out no matter which way you lay it down. The
> 4 stroke is usually more fussy about how it is stored, and will
> punish you with a mess of oil on occassion if it is not positioned
> properly. I always store mine in the vertical position for this
> reason, and also because I worry about oil possibly getting into the
> combustion chamber while stored horizontally. I'm sure the
> manufacturers have taken steps in the design to prevent this, but if
> it were to happen it could result in bent connecting rods on start up
> when the piston locks hydraulically near the top of the compression
> stroke. These engines are new enough that I haven't personally heard
> of this happening yet, but I have heard of several cases of it
> happening to automotive and industrial engines that have been upset
> for short periods of time.

This is an interesting observation! I had not thought about that
aspect of the 4-stoke outboard.

My 2-stroke Force Five is also touchy about how it stores.
It will leak fuel from the carburetor in certain positions,
even if the fuel has been allowed to run out before unloading
the engine from the transom. There seems to always be a little
bit left to leak if you don't set the motor down properly.

----------------------------------------
Jim Hebert, K8SS            SAILORS
Beverly Hills, MI            visit

----------------------------------------

 
 
 

9.9 or 15 HP OUTBOARD FUEL CONSUMTION QUESTION

Post by Gregory E. Si » Fri, 22 Aug 1997 04:00:00

H'lo Mike,

I've been running a '96 Honda 4 stk 15 hp on a 10ft  Storm (Achilles)
for the last couple of seasons so this should be valid for your info.

Quote:
>   Today I shopped dealers on these motors, both 2 stroke AND 4 stroke.
>My probable use is with a 10 foot rib inflatable. Every salesman says i
>will NOT go thru even a single 6 gallon tank of gas in a full 6 hours of
>non stop running with either the 2 OR 4 stroke motor. I hate to be a
>doubter.....but PLEASE , someone tell me the truth on what to expect.
>The last time I heard this kind of pitch, I ended up with a jet ski that
>cost me 60 plus bucks a day for gas on Easy riding.

I run mine up a local river (18-20 miles) using the 9.5" prop.
Duration of trip has averaged 55 minutes wide open throttle,  with
loads ranging from 300 to 500 lbs.   I burn around 1 imperial gallon
(maybe slightly more under heavier loads),  and always have enough to
get home with a total of 2 gallons.   I have done the same trip
several dozen times with fairly consistent results.   It would be a
safe estimate that this engine burns 1 gallon (imp) per hour WOT and
considerably less at lower settings.

Quote:
>    Also, I was told the 4 stroke honda AND Evenrude were still too new
>to estimate maintenance costs and engine longevity compared to 2
>strokes.

Honda's been building 4 stroke outboards for a very long time... it is
the rest of the manufacturers that are recently getting on board.
(does honda even make a 2 stroke anything?)   I've always been
impressed by the ones I've seen... they never die if basically cared
for.   I've heard independant mechanics quote 10,000 hrs to be
expected from a good 4 stroke.

Was told ny "some" that the 4 strokes are MUCH slower top end

Quote:
>speed wise also.

Much slower?... naah,  but probably not as snappy.  (I fixed that with
an 8" prop for funnin' around).   Better fuel economy at the majority
of throttle settings,  quieter,  cleaner,  no mixing gas,  10-15lbs
heavier.  

One word of caution... my inflatable is 65 lbs,  inflatable floor and
keel (no boards).   Of course I HAD to find out what it'd do with just
me in it so on a calm day,  close to shore and taking reasonable
precautions I carefully and gradually opened it up.   To keep it
short,  with my weight very forward and on the port pontoon I managed
to top it out at a very good clip but only for a few seconds before it
instantly snap rolled clockwise.   I'd caught it the first time (thus
shifting to port) but managed to roll 180 deg. lifting all my weight
with it quick enough to beat my reflexes the second time.  

Therefore,  be careful with light loads and high throttle settings.
It was an expensive thrill the first time,  but I'm plenty content
with 2 ***s (and very stable) right up to speed.   Check out the
price of engine hoods... they don't float but my new one does now.

Greg.