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Adding aftermarket EFI?


Capt Vince Pierleoni

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When I rebuilt my engine last fall I also looked into changing to injection. Since you have a chevy engine it would be a little simpler and cheaper than my ford engine. You use a regular chevy throttle body injector and a chevy control module. You might have to drill and tap ports for the other sensors or buy exhaust manifolds designed for a TBI system. I found kits at affordable-fuel-injection.com. They offer complete kits or just wiring harnesses. The sensors are standard automotive type it seems although some are quite expensive.

I don't use my boat enough to justify the cost of conversion vs the fuel savings so I'll stick with a carb for now. I would be interested in the results of a conversion however. I had posted a inquiry last fall on this but didn't get any replies.

High Bidder

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Dear Vince P.,

Switching to EFI has some expensive equipment involved. The ONLY gains you will achieve is better starting! No increase in power or better fuel consumption. The engine mfg's have had to switch to EFI in order to meet EPA smog requirements. Practically every 8.1 big block I have seen has the injection taken off within 12 months due to the cost of replacing injector parts! Lots of these units around (8.1 Mercruiser) If I stumble across any Vortec 5.7 unit take offs, I will give you a jingle. You must have a laptop with the EFI units in order to properly diagnose and set fuel parameters. Mercruiser will not sell anyone the program unless you are a MERCRUISER BONA_FIDE DEALER. The sensors and small parts are GOLD plated! That means you have to have a Mercruiser dealer hook up his diagonostics!!$$$$$ I was going to do it in 1998 when I still had connections at GM Powertrain. About 3500 then, I opted for a new carburetor with a custom Edelbrock Intake manifold. Numerous engine power tests have been conducted on all types of engines.....CARBS still are used! They even have intakes for the new GEN III small block chevy for carbs!

In 1998 I could have bought complete EFI marine 5.7 SBC Vortecs for $8,200 at the end of the model year. Almost did it until I checked out the calibration/Computer cost! I still don't believe its worth the expense in my humble opinion!

Jet Boat Bill...Webster, NY (from Sanibel Island...temp is 78 F!!!!)

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As Bill said there is really nothing to gain in my experience except added grief, down time and expense especially when time is money. A properly tuned carbureted engine will troll and preform just as well if not better than the injected version with the ability to readily and economically repair a problem if it arises.

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Wow, I'm impressed with the knowledge on this subject. Maybe I'm getting exaggerated info about the EFI's. I was told by several owners that they felt increased performance and economy was achieved when they went to them. These were the same concerns I had when I chose the carb motors. They start beautiful with the Holleys they came with. Hank, do you think going with the Edelbrock carbs would improve performance or economy? I have heard good things about these as well. Thanks for the responses guys.

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hate too be the odd ball here but efi motor's burn cleaner make more power and use less fuel and always have a perfect tune where carbs do not, may take a few years too see the cost off set but over all a good up grade from carbs , I would like too add a carb running at XX temp tuned perfectly could match an efi set up @ W.O.T but as soon as temps changes so dose ur air to fuel ratio and ppm's! where the EFI will will not go lean or rich! basicly when is cold out ur carb motor runs lean and will run alittle warmer and when is hot out your engine will run rich or fat using more fuel than needed! with efi this is not a factor alway running perfect air to fuel ratio resulting in a better over all running motor !

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Rochester Quadrajet and Edelbrock go hand in hand. Same basic carburetor that has been standard oem on small and big block GM engines for many years. (including marine applications) As far as improving over all performance and economy I truthfully can’t answer that one for ya. Although I will say for overall day in and out use and trolling I would personally take a Quadrajet/Edelbrock over a Holley.

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Dear Motoman,

Yes!!!, EFI with an ECM (Electronic Control Module) does everything you say but with a very high end maint. cost to the long term owner. Rebuilding carbs or purchasing outrite has distinct price points considerably below an EFI fuel pump! Other problems with the ability of an ECM to withstand low voltage situations(common in BOAT Operation) or static charge build up in storm conditions can really wreck havoc with boat operation/control! I see enough electronic problems with the current marine electronic ignition systems to tax any good mechanic's patience. I love the new electronics age, but why complicate the fuel delivery system! EFI has been forced upon us by the EPA in order to meet smog/emissions requirements. The final cost of EFI/ECM is born by the owner/operator. ..........I believe its the right approach for cars with their constant RPM/load changes, but the constant RPM and heavy load conditions in boat operation do not demand complicated fuel management systems.

Jet Boat Bill........from Sanibel Temperature 73F.

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Hey Vince,

I am probably just adding fuel to this potential fire .

I choose 5.7 EFI over others. I had two 5.0 carburated that needed to be replaced or rebuilt.

I gained 90 horsepower per side by going up an engine size and to EFI

I troll at .7 to .9 gallons per hour that is much better than my old 5.0 carburated that were 1989s. I also went down two inches in prop size.

One of the reasons I chose this engine was my 2002 truck that had a 5.7 EFI. I put 150,000 mile's on it and did nothing to the engine, with that kind of performance I can't complain. I have 50,00 miles on the current truck and haven't done anything to it.

I'm old school an would have to admit that either it runs or it doesn't, and I couldn't

fix it if I had too. That's why I have two engines!!

In talking with Tom Burke he has 8.1 and no problems and that boat flies for a 38.

IMHO EFI is the wave of the future. How many new cars are with out it? Dave

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yep 5.7 vortec fuel injected would be the cats ass , carbs are a thing of the past and the EPA did'nt make anyone put it on anything they wanted the air cleaned up witch was done with carbs and efi. EFI was invented too be better than a carb and less maint. not more . i have a carb on my boat and it works as it should but id be fooling my self if i thought it could produce as well as efi. EFI on a motor will make the engine last longer also, No more piston wash on start ups. go for it Capt.vince

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I would ask Jim at the Boat Doctors Vince. If he doesn't service EFI motors.....there is your answer. If you would have to haul it out and wait for it to be fixed......how much money would you loose from lost clients? Carbs are easy to fix when they go bad. Ask any marine mechanic what type of engine they would like to work on......what is the cheapest to fix....I think you know the answer already.

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All good points and good info! If I were you leave a good thing alone and as long as it aint broke dont fix it!!!!!!!!!!!!!!! Aftermarket can be difficult to assemble and not always worth the savings over oem so if you do go efi I would suggest going with a Mercruiser system. The cost of the systems would take years to recoop in fuel savings and the chance for failure is still there and harder to diagnose! Just my opinion and I am a Mercruiser tech with 18 years expierence and well versed when it comes to efi!

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Wow, last season we rebuilt 14 carbs (approx. $300.00 ea.) and only used our diagnostic computer 10 times ($100.00 charge) and we can usually guess IAC valve (idle air control) or knock sensor (water in fuel) by the way they describe it on the phone. Many of my 5.7, 6.2 and 8.1 MPI customers carry a spair IAC valve in their boat ($80.00) and can change it in less than 5 min..

Fuel injection has a set idle and we can't adjust it with the computer and the factory will not give us downloads only factory reps can change mapping (had it done on one motor, 2005 8.1 volvo). My fishermen do like the carbs because they can drop the idle 100 less than an efi. (be carefull of transmission chatter)

I would not recommend switching the components from carb to efi; too costly. Going forward I would recommend motors with efi, they do run smooth day in and day out. The new electronic shift units have an electronic troll mode at the helm to fine tune slow speeds with a push button. It blows cable shift away.

New EPA law: January 1, 2010, all boat motors in US must have fuel injection & catalytic converters. Builders made a deal that they can use non-cat on the remaining 4.3's and 8.1's till they are gone (sometime in the 2010 year). These motors are $3,000.00 to $3,800.00 more, we get our first next week.

Tim Habecker

Krenzer Marine, Inc.

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New EPA law: January 1, 2010, all boat motors in US must have fuel injection & catalytic converters. Builders made a deal that they can use non-cat on the remaining 4.3's and 8.1's till they are gone (sometime in the 2010 year). These motors are $3,000.00 to $3,800.00 more, we get our first next week.

Tim Habecker

Krenzer Marine, Inc.

Tim,

That only applied to new boats correct? Older boats will be grandfathered I hope? I'd hate to think that if I ever had to repower my Thompson (which you guys sold originally by the way :) ) that I'd be forced into those expensive upgrades on a 25 + year old boat.

Tim

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