Increasing Small Outboard Power
 

I have a 1996 Mercury 3.3 HP 2 stroke outboard that does a decent job.
Recently, I ran aground and chewed up the prop. I need to replace it
but here's where the question popped up. Is there a way to increase
the speed/power of this motor with a different prop (or any other
means)?

I see that there's an optional Black Max prop for this outboard but I
don't know if it make any difference except in price.

Is there anyway (prop, fuel, plug or anything else) to increase the
power and speed from this outboard without having to buy a higher
horsepower outboard?

I'm hoping that there's a way without damaging the outboard. Any
experience or suggesting would be greatly appreciated!

You really need to know what your current rpms are. For more speed you want
to prop about 400 rpms below max rpms.
An increase in pitch of the prop by no more than 2" will probably give you
that but you really need to know your current rpms to be sure.

Other than that, you can increase power by making engine mods such as
shaving the head to increase compression. This will require a change to the
carb jetting and also require you to run 93 octane fuel. It will make a
difference but for the cost - I would sell your engine and purchase a 5 hp
or whatever you can use instead.


--
Tony
My Boats and Cars
http://t.thomas.home.mchsi.com
"Louis" wrote in message
om...
I have a 1996 Mercury 3.3 HP 2 stroke outboard that does a decent job.
Recently, I ran aground and chewed up the prop. I need to replace it
but here's where the question popped up. Is there a way to increase
the speed/power of this motor with a different prop (or any other
means)?

I see that there's an optional Black Max prop for this outboard but I
don't know if it make any difference except in price.

Is there anyway (prop, fuel, plug or anything else) to increase the
power and speed from this outboard without having to buy a higher
horsepower outboard?

I'm hoping that there's a way without damaging the outboard. Any
experience or suggesting would be greatly appreciated!

On 17 Oct 2004 11:32:57 -0700, (Louis) wrote:

I have a 1996 Mercury 3.3 HP 2 stroke outboard that does a decent job.
Recently, I ran aground and chewed up the prop. I need to replace it
but here's where the question popped up. Is there a way to increase
the speed/power of this motor with a different prop (or any other
means)?

I see that there's an optional Black Max prop for this outboard but I
don't know if it make any difference except in price.

Is there anyway (prop, fuel, plug or anything else) to increase the
power and speed from this outboard without having to buy a higher
horsepower outboard?

I'm hoping that there's a way without damaging the outboard. Any
experience or suggesting would be greatly appreciated!

I wouldn't do much more than a compression test on a motor like this
and replace the rings/reed valve etc. if needed. It's possible to get
more power, but reliability, idling and so on suffers and more stress
is put on bearings and the like.

Things like de-gunking the exhaust (critical in 2 strokes) and
polishing the ports and head a safe improvements, upping the
compression ratio requires jetting and timing corrections, which if
not done correctly, can leave you worse off than before.

Louis wrote:

[...]
I'm hoping that there's a way without damaging the outboard. Any
experience or suggesting would be greatly appreciated!

Since you already need to replace the prop, you could look for a prop with
a different pitch (as size is usually restricted) the pich/diameter of a
prop is like a transmission ratio. You can increase the pitch, but that
would be the same effect as selecting a higher gear in your car (if you
drive a manual stick that is): it has more effect if you have a higher
speed.
If you have a heavy-ish boat and dont care about reaching topspeed, you
could go for a lower pitch/bigger diam. This will increase the amount of
power you can transfer to the water, as with a lower speed, the engine is
making more rpms.
if you have a (very) light boat, you could opt for a higher pitch.
You need to get on the plane with your boat to exceed hull speed, so
probably that is not feasible.
If you want to increase the power your boat is delivering: let it make
more rpm. Horsepower is a product of torque and rpm, so increasing the rpms
will get you more horsepower. maybe you will even reach the advertized 3.3
Hp, as that is usually rated at unsustainable rpms.

--
vriendelijke groeten/kind regards,

Jelle

begin upgradeyouroutboard-3.5.exe

On Wed, 20 Oct 2004 11:43:15 +0200, Jelle
wrote:

if you have a (very) light boat, you could opt for a higher pitch.
You need to get on the plane with your boat to exceed hull speed, so
probably that is not feasible.

===================================

It is just about impossible to get a boat, any boat, on plane with a 3
hp motor. 5 hp is about the minimum required for 1 person on a light
weight boat, 7 or 8 hp is better. Hot rodding a 3 hp up to a 5 is
not realistic.

--
Bill
Chesapeake, Va


"Wayne.B" wrote in message
...
On Wed, 20 Oct 2004 11:43:15 +0200, Jelle
wrote:

if you have a (very) light boat, you could opt for a higher pitch.
You need to get on the plane with your boat to exceed hull speed, so
probably that is not feasible.

===================================

It is just about impossible to get a boat, any boat, on plane with a 3
hp motor. 5 hp is about the minimum required for 1 person on a light
weight boat, 7 or 8 hp is better. Hot rodding a 3 hp up to a 5 is
not realistic.


I have been considering getting rid of my doel type fin and installing a set
of Smart Tabs. During my research on them I ran across an article where
someone installed them on a 10' Zodiac with a 3hp motor. It would plane!
Even the manufacturer was amazed.

On Wed, 20 Oct 2004 18:49:30 -0400, "IBNFSHN" wrote:

I have been considering getting rid of my doel type fin and installing a set
of Smart Tabs. During my research on them I ran across an article where
someone installed them on a 10' Zodiac with a 3hp motor. It would plane!
Even the manufacturer was amazed.

==========================================

I'd be amazed also. Was anyone onboard at the time or was it running
on remote control?

Maybe with an 80 pound driver :-)

as a 16 year old kid, I was able to make a 10 foot boat plane on 5 hp, but I
had to lay on the bow for nearly a half mile to get it up there. I can't
imagine an adult doing it with 3hp, or 3 hp either.

I have been considering getting rid of my doel type fin and installing a set
of Smart Tabs. During my research on them I ran across an article where
someone installed them on a 10' Zodiac with a 3hp motor. It would plane!
Even the manufacturer was amazed.

==========================================

I'd be amazed also. Was anyone onboard at the time or was it running
on remote control?

Maybe with an 80 pound driver :-)