repowering 2006 Chaparral volvo 5.7 with stroker.

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wellcraftpower

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I want to rebuild my 5.7 in a chaparral 2006 256 ssi .. It does not have exhaust in transom. All in lower unit. I want to do a stroker engine for torque low compression with a comp can extreme. they have the bigger one they recommend but not sure if this boat can handle it without causing water inversion. someone has to know of a good combination for the vortec 350 . I would change the springs and do the work needed. And is it possible to program the computer to except these changes. thanks for any help if someone here can answer this. . Just looking to rebuild my motor so it has a little more power and is reliable.
 
alldodge

alldodge

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Just noticed this is a VP. At marineengines site I was thinking it was a Merc.
Same things go with the ECM reflash but even more so with VP, probably won't be able to.

Hey @Scott Danforth your thoughts

You won't need to go thru hull unless you just want to, or might be if go radical with the cam. The easiest way is to get a new rotating assembly and cam and then put a carb on it
 
Scott Danforth

Scott Danforth

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Reversion is a function of cam profile, compression ratio, ignition timing, and exhaust design.

Check with MEFI Bob on the ECM if he can reprogram your ECM before you do any engine work

I personally would ditch the EFI on the SBC if building a stroker

If building an SBC stroker, I would go AFR heads, keep the compression ratio at about 9.4-8.6, LCQ style pistons, 268 degrees roller cam, heat exchanger, tall intake, carb spacer
 
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wellcraftpower

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alldodge said:
Just noticed this is a VP. At marineengines site I was thinking it was a Merc.
Same things go with the ECM reflash but even more so with VP, probably won't be able to.

Hey @Scott Danforth your thoughts

You won't need to go thru hull unless you just want to, or might be if go radical with the cam. The easiest way is to get a new rotating assembly and cam and then put a carb on it
Click to expand...
I dont want to go through hall.
 
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wellcraftpower

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alldodge said:
Just noticed this is a VP. At marineengines site I was thinking it was a Merc.
Same things go with the ECM reflash but even more so with VP, probably won't be able to.

Hey @Scott Danforth your thoughts

You won't need to go thru hull unless you just want to, or might be if go radical with the cam. The easiest way is to get a new rotating assembly and cam and then put a carb on it
Click to expand...
It is Volvo Penta. And i have been thinking carb. Looking at a edelbrock system that get good reviews.
 
Scott Danforth

Scott Danforth

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For decades, Volvo Penta used Holley vs Edelbrock/ Rochester
 
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wellcraftpower

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Thanks for all the reply's. i really don't want to ditch EFI but if i have to so be it. I want to use the Vortec heads just rebuild them . Cam doesn't need to be huge. mild . Okay maybe just under huge. What's involved in ditching the EFI .
 
Scott Danforth

Scott Danforth

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wellcraftpower said:
I wish there was someone that knew a good combination for the parts. Every 5.7 350 should be the same. maybe a little different. but not much.
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the small block chevrolet has gone thru 6 minor generation changes in the 70+ years its been around. just the 350 (5.7) has been around for 5 of them. With power from 130hp to 600 hp naturally aspirated....they are not all the same.

building a marine motor is also not the same as a truck or a car or an airboat or a trash pump or a genset or a bus. so you have to first identify what you want to do. very specificially, what you want to do.

because if you said, I want to build a 330hp/410 ft-lb motor for a 24 ft boat is different than a 350hp/450 ft lb motor for a 26 ft pocket cruiser. which is different than a 500hp, 400 ft lb motor for a jet boat

once you pick a direction, do no worry about money..... because building a marine motor costs what it costs. the price of building a small block motor in the past 5 years has doubled.

not sure why you want to be rebuilding such a new low-hour boat motor, however you have your reasons

so, very specifically

what Chap do you have?
what drive? Ratio? prop(s)
what is the true wetted weight?
what is the issue you perceive you have?
what is it that you want to do?
in post #1 you state:
wellcraftpower said:
I want to rebuild my 5.7 in a chaparral 2006 256 ssi .. .... Just looking to rebuild my motor so it has a little more power and is reliable.
Click to expand...
define what you want for a "little more power" and what issues you have had that you think your current motor is not reliable
 
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