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looking to convert my 5.7 to a 383 stroker

duanemosley

New member
title says it all, i have a 2006 rinker 250 ec 6450 lbs dry weight that came factory with a 280hp 5.7 osi-ef volvo penta, xdp DP with 1:95.1 gear set and F-3 blades. the 5.7 did ok with 2 people but once i filled the fuel tank it was kind of sluggish. if i had a few people on board, a few of my guests would have to walk to the cabin in order to get on plain, that is with drive and trim tabs fully down. well the 5.7 spun #1 rod bearing with 486 hours. i am looking to convert my 5.7 to a 383 stroker. i would like to build my own vs buying a mass produced engine. it's hard to trust what your getting when you buy mass produced. i am not looking to go all radical but would definitely like a power boost in ft-lb as well as HP. i want an engine that is going to go as well as last. i have been doing hours and hours of reading and most of the threads are old so instead of posting on one of them, i wanted to start a new thread.

has anyone converted their 5.7 to a 6.3 with the volvo penta ECM? if so who reprogrammed your ecm for proper A/F mixture?

i would like to stay around 9:1.1 up to 9:5.1. i would like to stay in the 89-90 octane rating with my fuel.

possible cam choice #1
http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=201&sb=2

cam option #2
http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=202&sb=2

what piston profile are people using with the 64cc vortec heads to get the proper Quench effect? i have purchased my felpro marine head gasket set but can't seem to find the compressed thickness dimensions.

is it better to piece together the necessary parts in order to get the proper pistons or does someone offer the correct kit?


any and all help will be appreciated.

thanks

duane
 
Being that I'm in the middle of converting 2 2006 Vortec 350's to 383/6.3 engines I can tell you what I'm doing. Up in the Mercruiser forum (http://www.marineengine.com/boat-forum/showthread.php?434197-Twin-350-s-to-twin-383-s) is my post and related answers, mostly good stuff, especially the stuff from RicardoMarine. I'm using forged Wiseco pistons from Skip White Performance off eBay. They'll give my 64cc Vortec heads about 9.2 at 0 deck height. Wiseco piston.jpgWiseco 1.jpg

My goal was to build a quench effect engine and using a .040 compressed head gasket I'll have 9.15 compression and WOT will be 4800, using stock marine roller cam BUT with 1.6 roller rocker for an increase in valve lift. Your cam #1 choice looks pretty good although the stock GM roller cam that is in your engine is tough to beat.
 
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