MPI or Carburator Performance? Water Crossover or not? Mystery will finally be solved

[pierpressure]

Several post about carburetor vs fuel injection, performance and efficiency, definitely some advocate for MPI and other love Carburetors.. and the undecided ones.. I think I will have the answer (at least I will have it soon)

Here we go! I'm schedule to do a general maintenance and clean up on my bilge compartment, painting, engine maintenance, etc etc. so I decided to do a little experiment (I applied for government funding under green initiative but got denied..lol)

What I have?
I have a pair of 2002 6.2L MX MPI engines with 2010 Bravo III outdrives, on a 2002 Sea Ray Amberjack, Signature 4x4 propellers 22p, my performance it's about 1 mile per gallon (real life) but definitely not accurate since I made those calculations on fuel consumption but I don't have a real way to measure it since I have 555 ECM's (pre-smartcraft computer)

What I want to accomplish?
1.-Take readings of fuel consumption and performance on the boat with both OEM engines. (GPH, RPM's, SPEED, ETC) will install a pair of Garmin GFS10 Fuel Sensors before the project starts.
2.-Both engines are running fairly good, compression it's fine, so I will take the Port engine and modify it, the second engine will stay the same (OEM specs)
3.-Take reading again after modification and compare the performance of both engines (also compare numbers on the boat performance overall)

What modifications? (port engine)
.-We will remove MPI system and computer and replace it with Carburetor system (new)This includes Intake Manifold, fuel pump, lines.
.-Mercruiser raw water pump will be eliminated and replaced with a crankshaft mounted one (-1 pulley, easier to replace)
.-Hydraulic pump will be removed since it's not doing anything in this engine(port side), it's just sitting there connected to nothing (-1 pulley, less weight)
.-Raw water circulation pump... Gone!! will replace it with a crossover. (-1 pulley, less weight)
.-and maybe, we will replace the exhaust manifolds to stainless steel ones.
.-No modification on the engine itself (internal parts)

What I hear so far?
.-Q=why you want to use an Old technology when MPI it's more modern?
A= not accurate, carburetors technology have evolved as well, I'm not installing a 1979 carburetor
.-Q=Water crossovers are evil and will not let your engine warm up equally and fuel consumption will be terrible, why?
A= Have friends running crossovers for years and not mechanical problems reported( I mean 10+ years), less moving parts, less maintenance. terrible fuel consumption? let's find out. (also, boat it's in South Florida, water don't get too cold around here)
.-Q=You will loose the benefit of having the computer giving you the warnings, alarms and shutting your engine down if somethings it's wrong like the iac valve and many others.
A.- Exactly!!! we will install as many alarms as needed, visual and sound, also, fuel pump will have a automatic shut down if oil pressure isn't there. don't want a computer deciding how my day will end. If I'm in an emergency situation and I need to burned my engine to the ground to move out of the way.. I want to decide that myself.. not a computer.
.-Q=Why?
A=Why not? also, once the project it's done I can literally have all the parts I need to fix this boat anywhere, specially while in the Bahamas. (no computer involved)


So, if you have any suggestions or questions let me know. Project should be done before December (hopefully) and will be updating as frequently as possible. :smt024

 

[blaster]

Re: MPI or Carburator Performance? Water Crossover or not? Mystery will finally be so

You seem to have a lot of time on your hands. Post lots of pictures.

 

[pierpressure]

Re: MPI or Carburator Performance? Water Crossover or not? Mystery will finally be so

I have to take both engines out anyway, I need to paint the bilge plus a bunch of other small things. Lots of pictures for sure.

 

[dpmulvey]

Re: MPI or Carburator Performance? Water Crossover or not? Mystery will finally be so

I'm subscribing to this one.

If one considers both engines, post surgery, as "new", we could garner the most important data necessary. TOTAL COST OF OWNERSHIP!

Just curious..... How are you going to ensure the MPI engine is at an "as new" condition as well? Injector service? Electronic check ( if such a thing exists)? Etc.....

To a number cruncher like me, this is damn near better 'n sex. Did I say that? Crap!

 

[pierpressure]

Re: MPI or Carburator Performance? Water Crossover or not? Mystery will finally be so

None of the engines are new, both have about the same hours, injectors are working perfectly in both engines as per ECM readings. Now, the important part will be to compare current performance to the performance after the surgery. It's true that I have to consider than the carburetor it's new and the MPI system it's being in service for a long time but has no injectors codes or problems reported, so being an MPI system the performance numbers should be pretty consistent regardless of age.

in fact I'm not sure if an MPI system will loose performance over time.. good question.

 

[Creekwood]

Re: MPI or Carburator Performance? Water Crossover or not? Mystery will finally be so

None of the engines are new, both have about the same hours, injectors are working perfectly in both engines as per ECM readings. Now, the important part will be to compare current performance to the performance after the surgery. It's true that I have to consider than the carburetor it's new and the MPI system it's being in service for a long time but has no injectors codes or problems reported, so being an MPI system the performance numbers should be pretty consistent regardless of age.

in fact I'm not sure if an MPI system will loose performance over time.. good question.

If you replace the raw water pumps with one and a cross-over, you have effectively turned your boat into a single engine vessel as far as getting home one one engine if you have a problem. You might want to rethink that mod.