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#1
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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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