EFI to carb conversion?

[frdvschvy]

I have heard several others mention that ditching the fuel injection on a 7.4 LX MPI, and switching to a carb setup makes a nice difference in the HP department. Anybody have any experience to bring to the table on this issue? I am assuming there is more to it than just bolting on the new intake w/ carb. What all would be involved in this project? Worth the trouble?
Thanks in advance for all the advice.

[Hustler]

I dont think I would go from EFI to carb maybe the other way around. I think there is probably better tuning available via the computer for the EFI stuff

[Beer-30]

Never go backwards.

[frdvschvy]

Any idea what kind of power this iduction system could support? Is this motor just a wast of my time and money to begin with?

[Beer-30]

Any idea what kind of power this iduction system could support? Is this motor just a wast of my time and money to begin with?
It can be made to support whatever you need. You can change injectors, have it extrude-honed (opened up) put on a larger TB, and revamp the ECM.

[Squirtin Thunder]

Any idea what kind of power this iduction system could support? Is this motor just a wast of my time and money to begin with?
In my eyes yes it is but if you would just go with the Big Bad Ford you would be so much more happy, and be able to look at yourself in the mirror in the morning. Dare to be different !!!

[atomickitn]

i do this mod all the time if you need proof ask phatt daddy how he likes hi new set up, and how much more useable power and tunability he has now , i will gladly asist you in any thing you need help on . pm me for more details :rollside:

[atomickitn]

It can be made to support whatever you need. You can change injectors, have it extrude-honed (opened up) put on a larger TB, and revamp the ECM.
for the money you would spend on thease mods you can gain 20/40% more power going to a carb set up .................... fact is , and been proven on many dynos that carbs make more hp.... hands down :)

[djunkie]

for the money you would spend on thease mods you can gain 20/40% more power going to a carb set up .................... fact is , and been proven on many dynos that carbs make more hp.... hands down :)
liar liar pumpkin eater!!!! :D :D :D

[Froggystyle]

While you are at it, switch from e-mail to fax. Much larger use of paper. ;)
Never go back. The worst EFI is miles better than the best carb, period. More power, better economy and far better driveability.
Now, a poorly set up EFI is just as bad as a poorly set up carb.
Set it up right, and stay in the same century... trust me.

[Beer-30]

I guess that's why GT builds all of his motors with carbs?..........Oh wait, all of his motors are EFI. Oh, but Merc Racing still has carbs. Oh wait, all are EFI also.
The ZO6 7.0L makes all of it's 505HP with a carb. Ooops, it's EFI, too!

[atomickitn]

the reason that they have made the switch is for several reasons , emissions , and user friendly ie the consumer. no adjustments to make. prety simple .. :rollside:

[atomickitn]

I guess that's why GT builds all of his motors with carbs?..........Oh wait, all of his motors are EFI. Oh, but Merc Racing still has carbs. Oh wait, all are EFI also.
The ZO6 7.0L makes all of it's 505HP with a carb. Ooops, it's EFI, too!
yes gt still builds moter with the carb set up , it's just that people are asking for injection because others have said that one is better than the other .... i think that it is preference...... everybody has there own opinion :rollside:

[Froggystyle]

the reason that they have made the switch is for several reasons , emissions , and user friendly ie the consumer. no adjustments to make. prety simple .. :rollside:
Not even kind of. But thanks for playing. ;) This is what a lot of people that don't tune EFI say.
They are more difficult to set up properly because unlike a carb which does most of the work for you during running condition (metering, delivery etc...) the computer has to be told (programmed) exactly what to do at every RPM/temp/O2/knock/MAP setting on the map. Once dialed though, the integration of sensors, rev limiters, pressure settings and consequently power settings, injector dwell and cycle time etc... makes the EFI not only WAY better at making power but significantly better at being reliable.
The EFI is the reason we call 425HP motors "stock" these days. It isn't the cams or heads that have gotten way better, it is our ability to maximize performance by more correct metering in far closer to real time increments.

[atomickitn]

[QUOTE=Froggystyle]Not even kind of. But thanks for playing. ;)
ok soooo what do i win? ha ha ha ha ... as you can tell im sort of old school and i like carbs, just my preference.... if something goes wrong out on the water .. i can fuss with it and get back to the ramp... if the comp goes haywire your done!...... just my 02 :rollside:

[bigkatboat]

Please PM me if you have used Merc. EFI systems for sale CASH! I'm just learning about these things, and I think they are great. Big and small block, I like them all.

[Tom Brown]

the reason that they have made the switch is for several reasons , emissions , and user friendly ie the consumer. no adjustments to make. prety simple .. :rollside:
User friendly to the consumer? Are you kidding me? Setting up a fuel curve on an EFI setup is a huge pain in the ass. It's easy on a carb because you don't have the same amount of control to detail the cuve exactly the way you want it.
I love EFI but setting up a fuel curve isn't for the novice like a carb is.
Oh... by the way... my advice is to stay EFI. Make sure you get a money back gaurantee with any claims of 20~40% power gain with a simple induction change. If that were the case, we should all sue Mercury for massive incompetence. It's best to file those claims in the same bin with the 200 mpg carburetor.

[Tom Brown]

... makes the EFI not only WAY better at making power ...
If the carb is jetted properly and the EFI system is set up properly, top end power will be identical. A well tuned EFI will pull better through the entire RPM range, though.

[ECeptor]

Anyone denying the role EPA emission laws have had in driving the development of EFI needs to check their history books a little closer.
Is a cost-no-object carb setup better than a cost-no-object EFI? I wouldn't think so. But if we are talkin' bang for the buck it makes for an interesting conversation for those who choose to look at facts and not generalities.
It all depends on what you have to start with (current setup + budget) and what your goals are (hp, rpm, bsfc, emissions, etc.) as to which of the two is the best solution for a given individual.

[Beer-30]

[QUOTE=Froggystyle]Not even kind of. But thanks for playing. ;)
ok soooo what do i win? ha ha ha ha ... as you can tell im sort of old school and i like carbs, just my preference.... if something goes wrong out on the water .. i can fuss with it and get back to the ramp... if the comp goes haywire your done!...... just my 02 :rollside:
And you're right. It's preference. But, to say a carb is superior to an EFI setup is just not correct. Facts are facts. There are NO vehicles being produced right now that are carbed. Sure, emissions are a factor, but it's more of a bonus. No more pumping throttles. No more stuck chokes. Sure, if the ECM doesn't have a limp home mode, like 95% do, you are on a tow rope. But no fuel going in is better than a stuck float that bends a rod / collapses a piston.
If you like carbs, run em. I just don't agree with telling someone to pull of an already fully functional EFI setup to go back to old school. That's all I mean.

[MACHINEHEAD]

You guys get off track so easy! It wont make any difference what you put on it with the ultra small LX cam. The injection is already more than enough.Cam then carb.

[Beer-30]

You guys get off track so easy! It wont make any difference what you put on it with the ultra small LX cam. The injection is already more than enough.Cam then carb.
Well, yes and no. He wanted more HP. Ok, on that note, he can do headwork, a cam change, and ECM programming to get another 80-100 HP. He has cast pistons, so he wouldn't want to start pushing the envelope past that.
He had been told to dump the EFI and a carb would give more HP. A very good explaination of how a carb and intake swap would probably give the same HP is along the right track.
A cam change would make more HP with EITHER setup - of course, then limited by what the heads will breathe.
The bottom line is, he can make around the same HP with a carb or the stock EFI. If he reverts back to a carb he is losing resale, driveability, lack of maintenance, easy cold starts, easy hot starts, efficiency, and adding gas fumes to a currenly fume-less engine bay. It just doesn't make sense at all.

[frdvschvy]

I am liking what I am seeing here. I like the idea of being able to do a cam swap, head work, and ECM reprogram. With the MAG style induction that the LX motor has it should support the power I will need. I don't have plans to push this motor past about 420 HP.
Anybody here have any knowledge of a cam and head combo that will work well on this motor? Also, any recomendations for who to go to on the ECM re-program? Maybe a builder that can take care of all three in the socal area?

[Froggystyle]

I am liking what I am seeing here. I like the idea of being able to do a cam swap, head work, and ECM reprogram. With the MAG style induction that the LX motor has it should support the power I will need. I don't have plans to push this motor past about 420 HP.
Anybody here have any knowledge of a cam and head combo that will work well on this motor? Also, any recomendations for who to go to on the ECM re-program? Maybe a builder that can take care of all three in the socal area?
There are many builders that can locally. I would hang out here a little while and find some good referrals for shops people have used successfully. I know that Arizona Speed and Marine has a pretty good rep for doing this.
What you really want is a shop that has a favorite cam and package. That way you can use their "stock" map and be really close to the mark for optimization. Doing all of the work yourself will be time consuming and expensive to say the least.
Good luck!

[frdvschvy]

Thanks. It would really like to go with a package that is tried and true. I would be nice to duplicate a "package" that someone else has already used and tested successfully. If anyonee has any success stories with combos for this motor please feel free to chime in.

[uvindex]

easy cold starts, easy hot startsThese are huge EFI advantages to me. When I'm drifting toward a hazard I want my boat to start RIGHT NOW. If I'm drifting and some yahoo is coming at me and I want to move, I want my boat to start RIGHT NOW. :)

[Never Too Old]

Glad to see this subject come up.
How many people have lost time on the water due to EFI problems?
All those circuit boards, sensors, etc...on the water....seems like potential for problems.
I know that alot of the early EFI diesels had ,many problems.
Anybody here have EFI problems?
Thanks

[SummitKarl]

Not even kind of. But thanks for playing. ;) This is what a lot of people that don't tune EFI say.
They are more difficult to set up properly because unlike a carb which does most of the work for you during running condition (metering, delivery etc...) the computer has to be told (programmed) exactly what to do at every RPM/temp/O2/knock/MAP setting on the map. Once dialed though, the integration of sensors, rev limiters, pressure settings and consequently power settings, injector dwell and cycle time etc... makes the EFI not only WAY better at making power but significantly better at being reliable.
The EFI is the reason we call 425HP motors "stock" these days. It isn't the cams or heads that have gotten way better, it is our ability to maximize performance by more correct metering in far closer to real time increments.
Bla,bla,bla, wait till you have to clean those injectors, or the o2 sensor takes a dump in the middle of the lake, or some drop of water finds your computer (and don't tell me how great you are at sealing the computer, or that you use some awesome O2 sensor Wes.)
Try programing a Merc575.....oh wait you can't........they lock the computer.
any day, anytime, anywhere A carb(s) will smoke EFI PERIOD!!!!!!!!!!!!!!!
you want reliability in a boat........try a Edelbrock carb and a set of points.

[Beer-30]

Thanks. It would really like to go with a package that is tried and true. I would be nice to duplicate a "package" that someone else has already used and tested successfully. If anyonee has any success stories with combos for this motor please feel free to chime in.
Yeah, ASM has all you would need. I recently toured their facility. There were several very nice boats there getting upgrades. Top notch company. I saw at least two 500HP EFIs just sitting around that had come out of boats. There were at least two HP EFI setups (blue intakes) laying around. Headers all over the place. They just play around all day with this stuff. There is a guy there, Ben Benevides that is an avid tuner. He could answer any questions you have. He is the email link on their website. If you email them, it goes to him.
http://www.azspeed.com/mapepa.html

[Tom Brown]

I thought all modern EFI systems had a limp-home mode in which they would run heavily rich if the O2 sensor goes sour?
I prefer a system that runs right after being stored for the winter. Having to rebuild carbs every spring isn't my idea of a good time.

[Tom Brown]

... you want reliability in a boat........try a Edelbrock carb and a set of points.
I had one of those back when they were branded Carter. It worked great and never failed. Back then, it seemed like the best carb of the day.
Of course, I spent quite a bit of time tinkering with the metering rods to adjust for temperature, elevation, etc. Something you don't have to do with EFI.

[Beer-30]

I thought all modern EFI systems had a limp-home mode in which they would run heavily rich if the O2 sensor goes sour?
I prefer a system that runs right after being stored for the winter. Having to rebuild carbs every spring isn't my idea of a good time.
O2 sensors are not standard on boats. Only the real bitchen setups have them. I am sure we will see more of them in the future.

[Beer-30]

Bla,bla,bla, wait till you have to clean those injectors, or the o2 sensor takes a dump in the middle of the lake, or some drop of water finds your computer (and don't tell me how great you are at sealing the computer, or that you use some awesome O2 sensor Wes.)
Try programing a Merc575.....oh wait you can't........they lock the computer.
any day, anytime, anywhere A carb(s) will smoke EFI PERIOD!!!!!!!!!!!!!!!
you want reliability in a boat........try a Edelbrock carb and a set of points.
Why would you need to program a 575?
Points? what are those? Oh yeah, I think my lawn mower still has points.
Open up a Chevy High Performance, Hot Rod, or Truckin' magazine and you will be hard pressed to find a centerfold in there with a carb on it. Carbs are only for the people that can't afford EFI. And that's fine. Just don't knock a superior product just because you don't understand it. Everyone had their preference.
You're 100% right, though. Carbs smoke compared to EFI; I seem to recall it is black smoke?

[Froggystyle]

Bla,bla,bla, wait till you have to clean those injectors, or the o2 sensor takes a dump in the middle of the lake, or some drop of water finds your computer (and don't tell me how great you are at sealing the computer, or that you use some awesome O2 sensor Wes.)
Try programing a Merc575.....oh wait you can't........they lock the computer.
any day, anytime, anywhere A carb(s) will smoke EFI PERIOD!!!!!!!!!!!!!!!
you want reliability in a boat........try a Edelbrock carb and a set of points.
You are right. If I lose a computer, I may get stranded.
The rest of the time, we will be getting better mileage, power, performance, reliability and driveability.
I am fine with that tradeoff.
But on that note, what kind of ignition would you use on a carbed motor?
MSD? I have seen no single part of a boat that goes out more regularly than an MSD box. Including the marine version. I have personally lost two of them.
The only thing that is in the running for things that have gone bad on boats of mine is stuck fuel bowls and clogged needle and seat valves. No filter seems to stop it. And if you get some water in the fuel, have fun diagnosing that problem come spring.
HEI? What if the controller goes bad? What if water gets in your distributor cap?
Points? I don't even need to make fun of this... it makes fun of itself.
What if, what if, what if...
Fact is, you are just as likely to have one thing go bad as the next in a marine application. Starter, fuel pump, injectors, computer, etc... All of it can be day ending. I have been stopped by everything from drain plugs to sucked valves. You don't plan around the potential though, you plan around the benefit.
Carbs are no more reliable than anything else. Clogs, floats, mechanical linkage, needle and seat valves, jets and leaks all put them on the trailer badly. Some so badly you can kill a motor from a lean condition at high throttle.
EFI has far more benefits than drawbacks, and is clearly the way of the future. Embrace it now, before you look bad. ;)

[Beer-30]

Nice.

[MACHINEHEAD]

Start "right now" how hard could a 420 hp motor start, even a neglected one. If it dont start, park it. Carbs suck because people dont understand them, you would think so after all this time, but they just dont. EFI comes out of the box with less problems and no external adjustability. That gets the tweekers in trouble. So there is no need to understand EFI! Just wash your hands of it and pay the pros to re-cal your majic box, now the motor runs better and you look like you know what your doing.
Milage- no Stock merc about 12-12.3:1 a/f ratio aftermarket leans them to about 12.8=more power
Power-no
Drivability-all in the tuning
Reliability-tune
Performance-draw (under 700 hp)
Mallory Marine mag pick and coil only Most reliable Ive tested so far
Rebuild a carb every spring, come on! :boxed:

[MACHINEHEAD]

Oh yea, how many chicks look at your motors and think to themselves, nice, goodlooking, and he has that sweet lookin efi system. Most are just shity looking.

[sanger rat]

Here is a great do it yourself EFI. Cheap too. http://www.diyautotune.com/catalog/megasquirt-complete-c-25.html

[atomickitn]

And you're right. It's preference. But, to say a carb is superior to an EFI setup is just not correct. Facts are facts. There are NO vehicles being produced right now that are carbed. Sure, emissions are a factor, but it's more of a bonus. No more pumping throttles. No more stuck chokes. Sure, if the ECM doesn't have a limp home mode, like 95% do, you are on a tow rope. But no fuel going in is better than a stuck float that bends a rod / collapses a piston.
If you like carbs, run em. I just don't agree with telling someone to pull of an already fully functional EFI setup to go back to old school. That's all I mean.
first of all i never told anybody they should ditch there current setup , he ask if anyone had any info on if this could be done and what there input was, i have personaly done this convert several times with great success and the clients have been real happy , and ther boats continue to run harder than they have ever run before........ again it is a preference, and a dollar for dollar thing..