Ideas for increasing power in a pair of Merc 454 L29s
#21
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Do I have a costly story for you.
My wife and I purchased a 2000 330SS in 2004 with the 7.4 efi engines. After a few years I felt I should go faster. Part of the problem is I feel the walk through windshield is safer for my wife that doesn't want to swim. This is another story. We want a walk through transom. In other words the layout is as good as I can find for the money.
When we purchased the boat there was a pair of bravo 1 drives available that I purchased and had installed. On the best day the boat wend about 51 mph.
The next thing is we rebuilt the 454's into 489's. This brought the boat to about 58 mph. This proved to be less expensive than 525's however nowhere near as mush power.
I had the 22 pitch props lab finished. This brought the boat up to about 58 on the GPS. I know but when the drives are lifted they no longer start cavitating.
The next thing was the above water exhaust. This gave us another 25 rpm or almost 59. Sound great.
I ground off some of the 3/8" hook on the bottom. This got us to about 59.5
I have installed CMI heders last year. Still not 60.
I talked to some other comrades and I am thinking about shorter drives. One recommended drive extensions.
You can really spend money if you try just a little bit.
My wife and I purchased a 2000 330SS in 2004 with the 7.4 efi engines. After a few years I felt I should go faster. Part of the problem is I feel the walk through windshield is safer for my wife that doesn't want to swim. This is another story. We want a walk through transom. In other words the layout is as good as I can find for the money.
When we purchased the boat there was a pair of bravo 1 drives available that I purchased and had installed. On the best day the boat wend about 51 mph.
The next thing is we rebuilt the 454's into 489's. This brought the boat to about 58 mph. This proved to be less expensive than 525's however nowhere near as mush power.
I had the 22 pitch props lab finished. This brought the boat up to about 58 on the GPS. I know but when the drives are lifted they no longer start cavitating.
The next thing was the above water exhaust. This gave us another 25 rpm or almost 59. Sound great.
I ground off some of the 3/8" hook on the bottom. This got us to about 59.5
I have installed CMI heders last year. Still not 60.
I talked to some other comrades and I am thinking about shorter drives. One recommended drive extensions.
You can really spend money if you try just a little bit.
#22
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Update: assuming the drives didn't get changed during the rebuild, they should both be 2:1 drive ratio.
Also, a seemingly dumb question, but since I don't bring the boat out of the water I don't know... For the trim tabs, when I press up on the switches should it move the tabs up or the bow up? I need to figure out how to fully retract them.
Also, a seemingly dumb question, but since I don't bring the boat out of the water I don't know... For the trim tabs, when I press up on the switches should it move the tabs up or the bow up? I need to figure out how to fully retract them.