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32off

Need help with engine replacement

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32off

I have an 04 sunsetter with the 340 monsoon.  I have to replace the motor and was looking at the 383 crate engine. Has anyone had to do this before? Indmar will not help you with a boat that is over a few years old....I know I will have to reprogram the computer but the cost difference between the two is not so bad that I would not go for the 50 lbs of TQ and 100 HP with the 383 vs the 350 HO.  I am in discussions with comp cams regarding the camshaft but I am weary of running into some demons.

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oldjeep
2 hours ago, 32off said:

I have an 04 sunsetter with the 340 monsoon.  I have to replace the motor and was looking at the 383 crate engine. Has anyone had to do this before? Indmar will not help you with a boat that is over a few years old....I know I will have to reprogram the computer but the cost difference between the two is not so bad that I would not go for the 50 lbs of TQ and 100 HP with the 383 vs the 350 HO.  I am in discussions with comp cams regarding the camshaft but I am weary of running into some demons.

You're buying a bobtail 383?  Or just a long block?  If just a long block are you planning on the new intake manifold you need (among other things?)  You can't just toss the intake and throttle body on from your 340 and expect to make much extra power.  Even the 340 and 350 monsoon use different intakes on the same (ish) 5.7 base engine

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32off

I was under the assumption that vortec head is vortec head....Is there something different??

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96Response

Stay with what you have. Unless your going to have the Comp. Flashed with all new programs, you wont have any additional power and possibly have less. All the fuel and ignition is controlled buy that. Playing with props will give you more bang for your buck than getting involved in issues like Comp. programs. Just my .02 cents. Keep in mind that a fresh engine with appropriate tune will be a big difference from what you get use to as the engine you are replacing was worn out anyway. 

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mackie12

I have never done it nor probably never will. However, would love to have an additional 100 Hp and 50 Tq in my response, so I say go for it!

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Woodski

@32off:  The answer is yes, a few on this site have done engine upgrades of various levels / types.  Search the forum and you will find a few threads, @Michigan boarder did a 383 carbed build.  I did a 100 hp upgrade and yes, it is lots of fun.  Also, find the 'lets talk MEFI' thread, that will help you on the programmer side.  As for cams, a ZZ4 cam is very nice, that is what I installed with a pair of fast burn heads.  If you can't alter the calibration in the ECU, one option would be to change injector size to get the additional fuel flow.

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32off

Thanks everyone for the input. I really wish Indmar was more customer friendly. I mean, they make a product that is still very usable after 20+ years so why not support it....Oh, the old corporate greed problem...

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32off

I found at least two companies that can reprogram my MEFI 4. OBD diagnostics and Jet Performance does them too. Its a bit pricey but OBD stands behind their programs so if it is too rich or lean the will re-do the program until it is right. 

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MadMan

I did something similar to my boat with '00 5.7 Monsoon.  I basically built a 383 Monsoon.  It has the same heads, intake, cam etc. as a Monsoon with a 3.75" stroke crank.  I did it this way, not for more horsepower, but to move the power down to a lower RPM, suitable for a towboat.  The MEFI 3 was way to rich, so didn't even bother re-flashing it.  Been happy with it, running strong for 5 years.

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