Does anyone have a 2003 Rinker 270 FV with a 383 Mag MPi or larger?
jmichels
Member Posts: 311 ✭✭
I am looking to repower in the near future. Love the boat just want a bit more power to get me in mid 40s comfortable or even 50. I know the 383 mag mpi is a drop in for the B3 has anyone gone larger? what fits and works? Currently I have a 350 Mag MPI Horizon. Thanks!
Answers
there are plenty of mercruiser engines that aftermarket builders or shade tree mechanics have stroked and bored to 383, but they didn't 'start' life as such... they usually started life as a 350 or 305...
depending on family of block, they have to be notched for connecting rod clearance- would you rather a machine shop do that or some fella with a dremmel? When you get into the realm of stroked engines, you are usually into the realm of folks who haven't thoroughly R&D's the platform.
383's and 408's are the exception, do a degree, as they've been done a long time and have almost become a standard...
PC BYC, Holland, MI
2007 280 Rinker Express 6.2L B3
https://www.mercurymarine.com/en/us/engines/inboard-and-sterndrive/remanufacturing/plus-series-bravo-sterndrives/
I guess my question is will the computer adjust and add fuel and timing if the engine calls for it or does it have set parameters and maximum values its programmed to do? Reason I ask because its very easy and affordable to pull my current 350 mag and have a machine shop , rebuild it into a nice stout 383 stroker. But if computer wont give it the extra fuel, timing etc it can take then its useless....
yes... and no... no and yes... and maybe...
your computer trims for a known displacement but it varies across the temperature and MAP/MAF spectrum. It's rich at cold start up, and because that's when it's a really really bad time for a pre-det... rich is actually harder to ignite than lean, and therefor it is less likely to ignite under pressure, but requires spark...
it's expressed in terms of duty cycle or sometimes called pulse width of the injector, and is a control of the PCM/ECU and how long the injector gate stays open. and when. mostly, how long it's open, though.
your engines PCM/ECU is capable of trimming for the added displacement, but so long as it thinks it's displaced less, it will only provide the fuel for that displacement... so yes and no... it doesn't have o2 sensors to sniff the exhaust and trim accordingly, but it will still run albeit lean... so no and yes... it can be adjusted, but requires a PCM flash- which to my knowledge (calling all experts, Al, namely) there is no way for us to do it... So.. maybe...
but here is the thing...
you have a known fuel pressure at the rail that is closely regulated to 45psi. You have specific injectors that deliver a precise volume of fuel to each cylinder. I'm thinking they are around 26# injectors, but I don't know that for sure... they may be 24# with a wider pulse width/duty cycle, or they may be 28# w/ shorter duty cycle/pulse width... but within this 'game' is your salvation...
using 24# injectors as a rule (which I've already said I don't know what yours are), they should deliver somewhere close to the range of 248cc to 258cc per minute. that is their capability @ 45psi.... you need more fuel... so.. look past the pound (#) rating of the injectors and get into the specific delivery in cc's per minute. Your pressure isn't going to change... you can't flash the computer (easily or economically)... but you can increase the size of the injector to somewhere in the 25~26# range (or better said in the 260ish cc per minute to 280ish cc per minute)...
so... go find some injectors that work for your application... you'll be bound by several things- one is ohms, the resistance has to match, another- is stack height and diameter... another is maintaining the spray characteristics while effectively increasing the diameter of the hole(s) the fuel squirts from... likely only backseated to ohms is connectors- EV1 or EV6? you can buy adapters to interchange these, but most folks have bad luck with these as they sometimes alter (increase) the resistance (ohms).
Bruce at FiveOmotorsports will hook you right up... or, look for a chart that compares weight (in pounds) to cc's delivered and to stoich @ x cubic inch displacement under known atmosphere and operating temperature...
my guts tell me you'll be jumping up a single #(pound), but you're going to want to select a 'light' pound, or one that falls on the shy side of the cc scale... this is where an expert like Bruce can help... the straight up best injector person I've ever met on this subject is a fella named Sean, but known as 'hemifever', and he may help you out too... google for him and you'll find his email...
remember one thing, though- you'll want to err on the side of caution, and run a little rich rather than lean.. if your current injectors are on the heavy side (in cc's) of a # rating, you may want light side rated #'s TWO #'s higher....
follow?
What about the "383 MAG bravo 4V"? 350HP, 429ft/lb. 370HP 456ft/lb with the same manifolds that came on the "Scorpion" 383 from Mercury. More torque than carb 502. Light weight compared to a BB.
https://www.mercurymarine.com/en/us/engines/inboard-and-sterndrive/remanufacturing/plus-series-bravo-sterndrives/
Are the small blocks not good for high load/mid RPM use? -=Mike G.
2014 Rinker 260EC