vortech5.7? do`s,dont`s need`s and dont need`s

[scon]

ok i currently have a sbc 305 in my boat and was having problems with its performance....well over the past week with alot of help from iboats i got this thing running the best it ever has i turned 54mph by gps and was turning 4500 rpm give or take(going by the dash) u know the old saying"they run best before the go".....well its true.shortly after my top speed run it started knocking and is getting worse........ question is...i was thinking of going with a fuel injected 5.7l vortech.now as new as i am to boating tech i have a few ?`s
1..since i need the computer and subharness ill also need o2 sensors..without them the computer will stay in closed loop n make it run rich.there for not performing correctly...what do i do there?
2..the fuel pressure is not going to be enough since there isa cardhere now and the vortech is going to require 60 +psi....whats recommended there? aftermaket inline pump?
3..on obd computers is there a way to attach the serial port for scan tools so if this project works and i start having trouble later i can hook my scan tool?

theres alot of variables in going from carb to fuel injection alone..but as far as being possible i believe it is...i have the knowledge to perform this task just not enough info on what the dos and donts and needs and dont needs are for the boat.....so if i forgot something other than o2 sensor and fuel issues let me know and what i need to do......thanx
the outdrive on my boat will hold the hp this motor is capable of

 

[HT32BSX115]

Re: vortech5.7? do`s,dont`s need`s and dont need`s

Howdy,


If I read you right.....you want to remove the marine 305 engine and replace it with a "off the shelf" automotive Vortech engine?

Aside from the fact that you'll need to replace the alternator, starter and EFI with USCG compliant marine units, replace the core plugs with brass, and replace the camshaft with a marine one, It should be "easy".

I think Holley has a Marine type EFI (throttle body) system. They're not cheap though.....

Of course after you replace the cam, you'd need to remap the EFI computer so that it has a different torque/HP range to match the marine cam and RPM range that the (Merc Alpha ? Cobra? Volvo Penta? Stringer? DANA?) drive you're using.....


You can forget about using O2 sensors in the exhaust. They won't survive long when they get a little water on them....


What you want to do has been done but it was not easy, and the hotly debated (USCG) legality is questionable.....

Your most bang for the buck will probably be just getting a good 350 long block and swapping your "stuff" from the 305 to it.

You'll spend minimum time getting back on the water.....



Good luck!


Rick

 

[erikgreen]

Re: vortech5.7? do`s,dont`s need`s and dont need`s

If you're replacing the whole block, I'd go with the vortec upgrade, you'll see an honest 300hp with a carb... which by the way is the limit of power a Mercruiser alpha series drive can really take, assuming you're using one of those.

Regardless, make sure you match the engine (specifically the flywheel, flywheel cover/mountings, and engine mounts) to whatever drive you're using.

Erik

 

[Aloysius]

Re: vortech5.7? do`s,dont`s need`s and dont need`s

You will not get max power with O2 sensor feedback..they're designed to run at the stoichiometrically correct mixture..14.7:1, which is not ideal for maximum power or full throttle performance. however, most engine management systems will override the O2 feedback at full throttle, and go excessively rich for engine safety.

I'd recommend old tech carb as mentioned above..tuneable, legal, and just as effective.

Remember, true vortec heads use a different intake manifold than non-vortec uses.