I'm wondering what are good price/performance modifications for this motor
(1997, in an inboard ski boat). Specifically, what modifications that would
commonly find on street of off road vehicles, such as heads, cam, MPFI kit,
intake manifold, supercharger, etc, would not work or not work well on a
marine engine application? Obviously exhaust is one of them.

Secondly, how will the existing fuel system cope with additional horsepower,
or is an aftermarket open loop MPFI system one of the required
modifications?

The boat has enough low end for my purposes, so I'd like to bump the power
range to 2000-6000rpm and get another 5-10MPH (70-100 hp?) out of the boat.
(Let's assume it is or will be prop'ed appropriately)

My background is in street and off-road, so any marine application advice is
appreciated.

Thanks in advance.

Buy, borrow, or steal the book "Small Block Chevy Marine Performance" by the
GOD of GM marine engines Dennis Moore.
Read it cover to cover and it will answer all your questions.
Amazon, eBay, or www.mooreperformance.org
Dennis has forgotten more than anyone else will ever know about GM based
marine engines.

"no one" wrote in message
...
I'm wondering what are good price/performance modifications for this motor
(1997, in an inboard ski boat). Specifically, what modifications that
would
commonly find on street of off road vehicles, such as heads, cam, MPFI
kit,
intake manifold, supercharger, etc, would not work or not work well on a
marine engine application? Obviously exhaust is one of them.

Secondly, how will the existing fuel system cope with additional
horsepower,
or is an aftermarket open loop MPFI system one of the required
modifications?

The boat has enough low end for my purposes, so I'd like to bump the power
range to 2000-6000rpm and get another 5-10MPH (70-100 hp?) out of the
boat.
(Let's assume it is or will be prop'ed appropriately)

My background is in street and off-road, so any marine application advice
is
appreciated.

Thanks in advance.

If I recall correctly, the '97 was pre-vortec (at least the marine engines).
If so, you definitely want vortec for hole shot.
Dave

"bomar" wrote in message
...
Buy, borrow, or steal the book "Small Block Chevy Marine Performance" by
the
GOD of GM marine engines Dennis Moore.
Read it cover to cover and it will answer all your questions.
Amazon, eBay, or www.mooreperformance.org
Dennis has forgotten more than anyone else will ever know about GM based
marine engines.

"no one" wrote in message
...
I'm wondering what are good price/performance modifications for this
motor
(1997, in an inboard ski boat). Specifically, what modifications that
would
commonly find on street of off road vehicles, such as heads, cam, MPFI
kit,
intake manifold, supercharger, etc, would not work or not work well on a
marine engine application? Obviously exhaust is one of them.

Secondly, how will the existing fuel system cope with additional
horsepower,
or is an aftermarket open loop MPFI system one of the required
modifications?

The boat has enough low end for my purposes, so I'd like to bump the
power
range to 2000-6000rpm and get another 5-10MPH (70-100 hp?) out of the
boat.
(Let's assume it is or will be prop'ed appropriately)

My background is in street and off-road, so any marine application
advice
is
appreciated.

Thanks in advance.

I called summit, they didn't stock anything called vortec...

Vortec is a word GM used to describe a swirling of the intake gasses in the
cylinder and combustion chamber - what specifically are you talking about?

"Dave" wrote in message
. com...
If I recall correctly, the '97 was pre-vortec (at least the marine
engines).
If so, you definitely want vortec for hole shot.
Dave

"bomar" wrote in message
...
Buy, borrow, or steal the book "Small Block Chevy Marine Performance" by
the
GOD of GM marine engines Dennis Moore.
Read it cover to cover and it will answer all your questions.
Amazon, eBay, or www.mooreperformance.org
Dennis has forgotten more than anyone else will ever know about GM based
marine engines.

"no one" wrote in message
...
I'm wondering what are good price/performance modifications for this
motor
(1997, in an inboard ski boat). Specifically, what modifications that
would
commonly find on street of off road vehicles, such as heads, cam, MPFI
kit,
intake manifold, supercharger, etc, would not work or not work well on
a
marine engine application? Obviously exhaust is one of them.

Secondly, how will the existing fuel system cope with additional
horsepower,
or is an aftermarket open loop MPFI system one of the required
modifications?

The boat has enough low end for my purposes, so I'd like to bump the
power
range to 2000-6000rpm and get another 5-10MPH (70-100 hp?) out of the
boat.
(Let's assume it is or will be prop'ed appropriately)

My background is in street and off-road, so any marine application
advice
is
appreciated.

Thanks in advance.

On Tue, 27 Jan 2004 18:30:58 -0800, "no one"
wrote:

I called summit, they didn't stock anything called vortec...

Vortec is a word GM used to describe a swirling of the intake gasses in the
cylinder and combustion chamber - what specifically are you talking about?
The name "Vortec" originated in the 1986 4.3L V-6 engine that used
"vortex technology" to create a vortex inside the combustion chamber.
GM Powertrain engineers incorporated this phenomenon into their
engines to achieve a better air-to-fuel mixture in the combustion
process. The result is what has now developed into Vortec engines --
engines that are designed to deliver plenty of horsepower without
sacrificing fuel efficiency. While the technology has evolved over
time, the design philosophy remains the same. Vortec engines deliver
both power and efficiency, all in a low-maintenance, durable package.

Yes, you found the website too. I'm looking for good price performance
mods, not a marketing term.

Anyway, I found out some interesting stuff about MPFI from edlebrock I
should share.

Well, the local FI expert at edlebrock seems to think that since marine
manifolds have dry areas, it's completely feasible (and has been done to
extrodinary success) to place aftermarket MPFI systems on marine engines in
a closed loop configuration - you simply sleeve the waterjacket with a
larger hole down to the manifold itself and drill/tap a smaller hole for the
sensor. An absolutely brilliant solution - Having a sensor looking at only
one side of the motor is a compromise, but only a liability if it's out of
tune in the first place, in which case the sensor's not gonna work or last
in anycase.

Now I got a lot of flak a couple months ago about using O2 sensors in marine
applications ( a statement was made that O2 sensors are only valuable for
emissions and catalyst health - which I personally do not agree with but am
not in a position to argue)

Comments on closed loop aftermarket MPFI marine applications???

"Tom Ruta" wrote in message
...
On Tue, 27 Jan 2004 18:30:58 -0800, "no one"
wrote:

I called summit, they didn't stock anything called vortec...

Vortec is a word GM used to describe a swirling of the intake gasses in
the
cylinder and combustion chamber - what specifically are you talking
about?
The name "Vortec" originated in the 1986 4.3L V-6 engine that used
"vortex technology" to create a vortex inside the combustion chamber.
GM Powertrain engineers incorporated this phenomenon into their
engines to achieve a better air-to-fuel mixture in the combustion
process. The result is what has now developed into Vortec engines --
engines that are designed to deliver plenty of horsepower without
sacrificing fuel efficiency. While the technology has evolved over
time, the design philosophy remains the same. Vortec engines deliver
both power and efficiency, all in a low-maintenance, durable package.

"no one" wrote in message ...
I called summit, they didn't stock anything called vortec...

Vortec is a word GM used to describe a swirling of the intake gasses in the
cylinder and combustion chamber - what specifically are you talking about?

"Dave" wrote in message
snip

Just in case you are still interested, these heads are on the Summit
website under:

Engines & components/Cylinder heads and accessories/ GM Performance
Vortec Heads

$259 each with valve and springs.


I'll agree with the others it will take a LOT more power to increase
speed 10mph. A buddy of mine wanted his stock 454 powered 24ft Baja to
go faster. Basically he had to double the power to increase top speed
by 12mph.

"David McNally" wrote in message
om...
I'll agree with the others it will take a LOT more power to increase
speed 10mph. A buddy of mine wanted his stock 454 powered 24ft Baja to
go faster. Basically he had to double the power to increase top speed
by 12mph.

You have got it. PLUS onthat Baja, it can be trimmed out of the water.
An inboard can't. Its taking me 200+ more HP to gain 12-15 mph on my
Formula.

"bomar" wrote in message
...
Buy, borrow, or steal the book "Small Block Chevy Marine Performance" by
the
GOD of GM marine engines Dennis Moore.
Read it cover to cover and it will answer all your questions.
Amazon, eBay, or www.mooreperformance.org
Dennis has forgotten more than anyone else will ever know about GM based
marine engines.


Dennis is an excellent STOCK Mercruiser mechanic. PERIOD. He is 10 years
behind the times whenit comes to anything high performance.

"no one" wrote in message
...
I'm wondering what are good price/performance modifications for this
motor
(1997, in an inboard ski boat). Specifically, what modifications that
would
commonly find on street of off road vehicles, such as heads, cam, MPFI
kit,
intake manifold, supercharger, etc, would not work or not work well on a
marine engine application? Obviously exhaust is one of them.


What ever you do to it, is never going to justify the expense. Its a Ski
Boat. Their hulls will only go so fast.


Secondly, how will the existing fuel system cope with additional
horsepower,
or is an aftermarket open loop MPFI system one of the required
modifications?


It won't! you are going to be reprogramming computers, and maybe changing
injectors and increasing fuel pressure.


The boat has enough low end for my purposes, so I'd like to bump the
power
range to 2000-6000rpm and get another 5-10MPH (70-100 hp?) out of the
boat.
(Let's assume it is or will be prop'ed appropriately)


100 HP in a ski boat hull is probably not going to gain you 10 mph. Check
out what speeds are run with a 320 HP engine and then a 400 HP engine.
Its only a couple MPH. To gain 100 HP on a SB Chevy, you are going to
have to change the cam, change and/or port the heads, reprogram the
computer, change the exhaust, and change the fuel system. You are
talking thousands of $$$ here, and when you are done, its gonna be a lousy
ski boat.