EFI vs MPI

[96blackhawk502]

What exactly is the difference? which is better? Im assuming since my 96 Blackhawk is an EFI that EFI is better? not sure though.

Kevin

[Ranman]

EFI is Electronic Fuel Injection. MPI is Multiport Fuel Injection. To me EFI is a more Generic term and could reference a tuned multiport setup down to a throttle body setup. MPI to me is a bit more specific in that it denotes a tuned runner setup with injectors for each cylinder. This is generally preferred over a throttle body setup that uses typically one or two big injectors that spray at or near the throttle body. I'm not sure exactly how this relates exactly to the MerCruiser motore. Maybe someone else can clarify???

[Tidbart]

Kevin,
I just bought a series of videos off Ebay by Merc. 5 service videos about their EFI fuel injection. If I get some time, I will look at them and see what kind of info is on them. If you are intersted in seeing them, I am sure we can work something out. If I remember they were produced around 96, 97.

Bob

[Ranman]

Bob, My 18 is a 97 and it is equipped with the 350 MAG MPI. This engine looks like a mini 454 or 502 MPI. The ones with the big "bent" intake plenum and the rectangular flame arrestor on the side. I think my engine was only made in 96 and 97. If you have any info on this engine, PLEASE contact me. Thanks. Randy

[Tidbart]

Randy,
I have the same engine in my '96 18. If you are interested in the seeing the videos, I will try to view them this weekend. I also have the Merc Manuals on them. IF I can answer a specific question for you, just email me if you want.

I'd be glad to research anything for you.

Bob :D

[FJB20]

Retro-fit ---- If One Wanted to Go from Carburator to MPI __ Cost Would be a Big Factor
Any Idea on Price Since Most Opinions Say --
-- Go to the MPI ---

[Ranman]

I would love to have that info on file. Is any of it copyable? I'd pay a few bucks for the trouble to copy and send if it can easily be done.

Are you going to the Owners Rally in Sarasota? I'll be there then. Maybe I could leaf through some of the stuff there. Let me know. Thanks

Is your 96 18 as strong a runner as mine? My 97 motor seems to outrun even the new MAG 350's, just wondering if yours is the same way.

Randy

[Ranman]

BTW, Ted (HP500) also had a 96 or 97 18 Classic. I bought a prop from him and he sent me a video on the 96 or 97 18 Classic. It's like a test report you'd see on Powerboat TV or something. I could copy it (although it would be a copy of a copy) if you're interested.

[Tidbart]

Randy,
I'll bring whatever I have to Sarasota. Will be there Friday eve.

My boat has been running strong. Been playing with props lately because I think it should be running a little faster than it has. No doubt about it, it's good engine. One of the only down sides to this one is you need a merc handheld computer/analyzer to tell you anything about how exactly it is running. There are several sensors on board that can cause some headaches. Even some good mechanics have a hard time analyzing ignition problems with the analyzer.

The Merc Service Manual, great for repair, can't beat them. The engine manuals are a two book set, the Bravo book is a single. They add up to about 3-4"s of reading. Not really worth copying. They are worth buying. A small repair shop owner in NH ordered them for me and gave them to me at cost.

All 3 books go for about $70 list. Worthwhile investment. I have the part numbers if you need them, and if you have a bravo. The Alpha book, obviously, is different.

Like I said, I'll bring them with me. We can have drink at Cheetah's and look at all the great diagrams in them. :D :D :D :D

Bob

[DonCig]

Randy and Bob, did you guys ever find out if there were any differences between the first Merc. 350 MAG Mpi engines versus the later years of production. I am making the assumption that the engine was released in late 1996-1997, and that the later models started in 1998. I called Mercruiser in OK and received absolutely no information from them.

Thanks,

Don

[Barry Phillips]

EFI is a generic term for fuel injection, MPI is Multi Port Injection which uses a fuel rail on either side of the intake manifold to form a continuous fuel delivery loop at a continues fuel pressure. The fuel is then squirted into the cylinders determined by the firing order and the computer. Throttle Body injection works like an electronic carburetor and injects it's fuel into the center of the manifold, the fuel than travels through the intake runners and into the cylinders. MPI is much more efficient and ironically simple in function.

SO-SLO