Converting to MPI

[indy245]

Anyone hear about converting a carburated mercruiser 5.0L to MPI ?

 

[Bondo]

Re: Converting to MPI

It'll only cost a Couple of Grand,...........<br /><br />Very Doable though........

 

[garycinn]

Re: Converting to MPI

Here's an option:<br /><br /> http://www.affordable-fuel-injection.com/marine-fuel-injection-systems.htm

 

[rbezdon]

Re: Converting to MPI

gary, that link looks like a "TBI" type system, not MPI. Not nearly the HP gain but more affordable I think.

 

[AdamB]

Re: Converting to MPI

Actually, I just purchased a MPI system from Affordable fuel injections. It is a MPI in that it has 1 fuel injector/ cylinder. It does have a TBI type throttle body, but no injectors, just 670 cfm throttle body.

 

[Boomyal]

Re: Converting to MPI

Originally posted by AdamB:<br /> Actually, I just purchased a MPI system from Affordable fuel injections. It is a MPI in that it has 1 fuel injector/ cylinder. It does have a TBI type throttle body, but no injectors, just 670 cfm throttle body.

Adam, MPI is Multi Port Injection. One injector per cylinder and most often the injectors are sequentially and variably fired, by the ECU, right behind the intake valve just as it begins to open. I believe Holley makes a non sequential MPI system.<br /><br />TBI uses a single or double injector that continually and varialbly injects into a plenum, thru the throttle body, just like a carburetor. Each intake valve then injests it's fuel mixture, thru manifold runners, that had been injected previously. TBI, in fact, is no more than a computer controlled carburetor.

 

[Dunaruna]

Re: Converting to MPI

Originally posted by Boomyal:<br />

TBI, in fact, is no more than a computer controlled carburetor.

Eggzachary.

 

[rbezdon]

Re: Converting to MPI

Thanks Boom, I thought they would get the idea when I pointed out the system was TBI and not MPI. I like the analagy of the computerized carb. Thay is exactly it. Not real performance gain from TBI, just gets rid of the pain in the a$$ stuf from the carb like floats, needle valves, other stuff and most of all ckokes. Makes starting easier too. But again, little to no HP gain. That comes from the Multi port injection directly to each cylinder. That takes more timing info, usually different heads and a whole raft of other stuff. Seems to me to be a rough retrofit job unless you swap the whole engine and get one with the crank timing info and all the other stuff needed. This would be very expensive I would guess.

 

[bluewater19]

Re: Converting to MPI

Vatter,<br /> check out the duel fuel rails on the pics.<br />They are using the throttle body only from TBI to meter the air. You would not be able to see the butterflies if this were TBI because the injectors would be sitting right on top of them.

 

[rbezdon]

Re: Converting to MPI

Blue water, I checked out the detail link on the first page. It appears they have placed injectors at each cylinder in the intake at each cylinder. They are claiming most of the efficience of multiport injerction using this method. I saw the throttle body injection notes and didnt read further. I also see the ECM is $500 on top of the basic system and you still have to have the fuel delivery system. Too rich for my blood.

 

[AdamB]

Re: Converting to MPI

My MPI system was complete (and I know the difference between MPI, TPI, TBI etc), new distrubutor with cap and rotor, waterproof GM ECM from corvette, Holley intake MPI manifold, Holley throttle body, wiring harness, MAP sensor, check engine light, fuel pump, etc, etc. The real beauty of this system is that it is using a GM ECM, not a aftermarket Holley. Oh, and my stock flame arrester will fit on top of the throttle body. <br /><br />I was originally going to attempt to put a TPI unit from a mid 80's corvette into my boat, but the TPI unit with the air cleaner on front would have been a pain to put marine thermostat housing etc on.<br /><br />I currently have the Thunderbolt IV ignition with Rochester 4-barrel carb set up. I am sure I will see improvement over the old system, and if anybody wants to upgrade to electronic ignition, mine will be complete, from carb to distributor to intake manifold etc. to Thunderbolt IV module.

 

[newport dave]

Re: Converting to MPI

AdamB,<br />It would be great if you could post more info (and pics) from your project. I would be especially interested in how you will be tuning the system after installation.<br /><br />Dave

 

[Boomyal]

Re: Converting to MPI

Originally posted by newport dave:<br /> AdamB,<br />It would be great if you could post more info (and pics) from you project. I would be especially interested in how you will be tuning the system after installation.<br /><br />Dave

Especially using an automotive GM ECU. I thought those things would have been looking for input, even from your clock. Auto's have so many sensors that you would not use on a boat, I don't see how they would work. Maybe there is a chip that cancels out the need for input from some of the nonexistant sensors

 

[AdamB]

Re: Converting to MPI

Yes, the Corvette ECM was specifically programmed for my specific application, right down to the fact I run a 140 degree thermostat, and use premium fuel. <br /><br />It has a MAP sensor, and so runs off of engine vacuum to adjust the AFR's, it has the oxygen sensors etc programmed out. It does use coolant temp, intake air temp (IAT), throttle position sensor (TPS) etc. It has had the vehicle speed sensor (VSS) programmed out too. Nice thing about it is just turn the key and start, no matter how cold. It will automatically adjust the throttle plates just enough to run when cold, all controlled by the ECM. <br /><br />Wow, I should now be a rep for that company, but I'm not. I have been playing around with flashable ECMS in newer vettes for years, this system uses a chip that has to be replaced.<br /><br />If for some reason I find the system running too lean or rich, I just write the company and they send me a new chip with the tweaks included.

 

[AdamB]

Re: Converting to MPI

Oh, I forgot to mention, but for a couple hundered more, they'll change the chip to a flashable memory that you can change on your laptop.<br /><br />Since it is a boat, I doh't plan on continually changing things like on a car (headers, heads, intakes, gears, etc) so just opted for the cheaper version with the chip. I would recommened upgrading to the waterproof ECM though....<br /><br />I will hopefully get to start on this install next week, after my intake comes back from power coating. It is aluminum and I'm having it powder coated outside, and inside the coolant passage to resist salt water. The powercoat company said the powercoat will indefinitely withstand the salt water (that my boat will ocassionally see). I run fresh water 90% of time.<br /><br />I'm not trying to sell this system, but considering it comes with custom harness (with all unnesasary wires eliminated) and all others labelled, and everything you need (except linkage and fuel lines) it was a steal for the money I paid. I am most interested in the fact that the runners are raised and longer than on the stock intake, which should produce some more torque than the original. I'll let you guys know.

 

[AdamB]

Re: Converting to MPI

Hey, saw this old post of mine and wanted to say today I got boarded/ inspected by the USCG about 2.5 miles off of Atlantic City, NJ. Besides having expired flares and not having a NJ boat license?? (I'm from PA), I passed all federal requirements and got a slip of paper proving it. The USCG were just happy to see my life jackets, spark arrestor, and fire extinquisher and that fact that my blower worked seemed to make them happy as well. I don't think those young officers could tell the difference between a carb set up, and my MPFI set up. The saw the spark arrestor over the throttle body and stopped looking.

 

[bruceb58]

Re: Converting to MPI

And the reason you are teling us this is.....

 

[AdamB]

Re: Converting to MPI

People saying my MPFI kit wouldn't pass USCG inspection... thought that was obvious.

 

[bruceb58]

Re: Converting to MPI

Doesn't sound like they inspected your MPFI from your description.

I take it you didn't tell them what you had done?

 

[AdamB]

Re: Converting to MPI

well, I was chased down, (blue lights going and all), boarded by 2 USCG service men (who were actually very nice), while 4 others looked on from their vessel, and they asked if I had been boarded lately. I pointed to my 2005 Coast Guard safety inspection sticker. They boarded and proceeded to inspect my boat.

No, I did not tell them I had converted to MPFI, but they did ask questions about my motor like how much hp etc. I just told them the standard 260 hp. They checked the blower and spark arrestor and anchor and life jackets, etc. Like I said, it passed inspection. Good enough for me. Thank God they didn't set fire to my boat to see if it passed the USCG fire test .

Actually, because I was respectful and very cooperative, they were very decent to me. They did find some faults like my flares being expired, but I guess they were busy looking for terrorists to harass a hard working American like me LOL.

Actually, I had the oldest boat on the water and I'm sure they thought there would be lots of violations. But, I am very safety minded...