should i change over to fuel injection?

[nola mike]

Scott Danforth and achris and others are always going back and forth on this...I remember a contentious pissing match thread a few years back that I don't believe was ever resolved (I think involving QBhoy as well?). I would LOVE to see a comparison of fuel efficiency, power, etc, on the carb v. FI variants of the same engine on the same hull. I don't know that I've seen it...
I think the argument that for the carb'd marine engine that I've heard is that the main benefits of the FI in fuel efficiency is at fluctuating throttle, differing loads which isn't as much of an issue for the marine engines as auto?

 

[Scott06]

I think Chris more or less provides this but anecdotally as he had a 4.3 carb and 4.3 mpi in the same hull, although I assume one was non Vortec

 

[Scott Danforth]

I think Chris more or less provides this but anecdotally as he had a 4.3 carb and 4.3 mpi in the same hull, although I assume one was non Vortec

however Achris has mentioned a 25% increase in fuel economy. i tend to find that a bit optimistically high. it may give a bit if economy at one or two points on the prop curve, however nothing more than 3-5% unless there was something wrong on the carb (and Chris mentions that as well). BSFC for the internal combustion engines doesnt change much unless you start to change engine architecture a bit.

my experience in one of my hot-rod builds with the same exact motor/trans/tires/body/weight/fuel, going from carb to MPI, I dropped 15 peek HP (because I had to change the cam for more signal for the EFI per the tuner) and my fuel economy remained the same. 32mpg on the highway at 65mph and about 2 gallons every 1/4 mile run. it did clean up my AFR in the 2000-2500 RPM range, thus preventing loading up after pro-longed low-speed driving......Then I lost an injector and ran lean on one cylinder for a bit too long....that is another story

 

[netting one]

So i went out over the weekend and the water temp was 50 degres and moved around about 6 times, one of the guys on the boat says man i thought your boat would hit the second you hit the key! Sort of erked me a bit! I was really paying attention to how it started and im going say it needs fuel. What i was thinking is maybe taking some quick start and give it a spray before starting one time? If it kicks quick then i would know. Is there a good after market kit for the MPI? thanks again

 

[Bondo]

I was really paying attention to how it started and im going say it needs fuel. What i was thinking is maybe taking some quick start and give it a spray before starting one time? If it kicks quick then i would know.

Ayuh,..... So crack the throttle,.....

Quick-start is ether, which hammers the rings to bits,.....

 

[alldodge]

My MPI (older VST version, and now cool fuel) when cold, would crank for a couple seconds before it fires up. Once warm, it fires within one revolution or less, must cases less.

When the motor is cold I like the idea of cranking a couple to get oil moving

 

[Scott Danforth]

My MPI (older VST version, and now cool fuel) when cold, would crank for a couple seconds before it fires up. Once warm, it fires within one revolution or less, must cases less.

When the motor is cold I like the idea of cranking a couple to get oil moving

I ran my fuel pump and ignition on the 468 thru an oil pressure switch to make sure that I have oil pressure prior to the motor starting. mainly because the motor would start at just a tick over one revolution when the second or third cylinder fired.

 

[nola mike]

Curious on why anyone cares whether it starts in 1 second or 3? Long as it starts...

 

[thumpar]

I think you are obsessing with fuel injection. If you want it that bad sell the boat and buy one with it. That is the cheapest and easiest way to get it. If it was me I would just spend the money on tune up and fuel.

 

[aerobat]

i agree there is no sense to convert to fuel injection on an existing engine .

that said lets be fair : when it comes to turn key starting cold , warm or hot , idle stabilisation and stall prevention during docking , plug fouling and fuel economy especially at trolling speeds in different temperatures or altitudes - a MPI will outperform any carb every day all day long .