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no one
 
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Default 350 Magnum EFI (TBI) Performance Improvements

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.




  #2   Report Post  
bomar
 
Posts: n/a
Default 350 Magnum EFI (TBI) Performance Improvements

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.






  #3   Report Post  
Dave
 
Posts: n/a
Default 350 Magnum EFI (TBI) Performance Improvements

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.









  #4   Report Post  
no one
 
Posts: n/a
Default 350 Magnum EFI (TBI) Performance Improvements

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.











  #5   Report Post  
Tom Ruta
 
Posts: n/a
Default 350 Magnum EFI (TBI) Performance Improvements

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.







  #6   Report Post  
no one
 
Posts: n/a
Default 350 Magnum EFI (TBI) Performance Improvements

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.







  #7   Report Post  
Tom Ruta
 
Posts: n/a
Default 350 Magnum EFI (TBI) Performance Improvements

On Tue, 27 Jan 2004 18:57:26 -0800, "no one"
wrote:

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


You are crazy to think that adding 10 mph to the top end is (a) wise
or (b) economical. these are semi-displacement hulls and the vast
majority will be squirrely above 50. Maybe with some trim tabs.
Look at Malibu's Corvette for instance.

....
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)


There are marine O2 sensors. Take to the marine speed shops like Dana
or AZ Speed and Marine.


  #8   Report Post  
David McNally
 
Posts: n/a
Default 350 Magnum EFI (TBI) Performance Improvements

"no one" wrote in message ...
Yes, you found the website too. I'm looking for good price performance
mods, not a marketing term.


The center-bolt cylinder heads on GM V8's have a large wall in the
intake port. It is easily visible with the intake manifold removed.
This wall improved low end torque and emissions but is a huge
restriction at higher RPM's. The new "Vortec" engines have performance
heads without the intake restrictions and a heart shaped combustion
chamber. I don't know if your motor has Vortec heads or not. I'm
pretty sure the Mercruiser Scorpion engines did. These heads are very
affordable and can make a significant performance improvement. Beware
though, the Vortec intake port is slim and tall and doesn't match up
well to intake manifolds not designed for them.


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???


Why? What purpose would closed-loop serve?? The computer knows how
much air is entering the engine (displacement x RPM x throttle
openning x temp) it can easily be programmed to supply the correct
amount of fuel without post combustion feedback. The feedback is
neccessary only to trim the fuel to improve catalytic converter
effectiveness. I'll admit some racers are experimenting with wide band
02's but I question why they are neccessary.


"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.





  #9   Report Post  
lifespeed
 
Posts: n/a
Default 350 Magnum EFI (TBI) Performance Improvements

"no one" wrote in message ...
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???


You can do aftermarket SEFI, closed loop with O2 and other cool things
too. Costs money and effort, but it does work, and work well.

Vortec heads produce good low speed torque, but aren't suitable for
high-perf applications where more than 300 - 320 HP is needed.

The trouble is you're talking about a ski boat hull, so adding power
doesn't make much sense. If you like watersking AND going fast there
are alot of boats that would make you happier than a center-engine ski
boat. A Ski Boat does not have to be a flat-bottomed 45 mph inboard.

Lifespeed
  #10   Report Post  
Doug Meredith
 
Posts: n/a
Default 350 Magnum EFI (TBI) Performance Improvements


"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.


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