ok, so a couple of weeks ago I was looking around online and found a add on system that allows for o2's to be added to the existing mercruiser efi setup. Therefore making it go closed loop. I went looking for it today and cannot find anything on it. Can anyone tell me who makes this and what is the website? Thanks
EFI add on system for closed loop?
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DaveH
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closed loop implies a feedback circuit to the ECU to allow the engine to make changes to the fueling based on what the 02's read.
I may be mistaken, but the merc/ MEFI ecu's used in marine applications dont have this ability. maybe some of the newer stuff does, i dont know.
maybe this "system" you are refereing to does this another way (reducing fuel pressure) to try and manipulate the fuel strategy.
keep in mind, depending on how much reversion you have in your exhaust, WBo2 is not the "end all be all" measuremetn many think it to be. other factors come into play. what is your reason for wanting to do something like this? Its no secret merc runs there stuff on the rich side. you may see some minor fuel economy benfit to making changes, but it wont be huge.
I may be mistaken, but the merc/ MEFI ecu's used in marine applications dont have this ability. maybe some of the newer stuff does, i dont know.
maybe this "system" you are refereing to does this another way (reducing fuel pressure) to try and manipulate the fuel strategy.
keep in mind, depending on how much reversion you have in your exhaust, WBo2 is not the "end all be all" measuremetn many think it to be. other factors come into play. what is your reason for wanting to do something like this? Its no secret merc runs there stuff on the rich side. you may see some minor fuel economy benfit to making changes, but it wont be huge.
rivermobster
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STV_Keith is the man on those. I helped him with the beta testing a few years back.
It's a piggyback control unit made by Dynajet. I think this is the link: http://www.dynojetcmd.com/cmd_marine.aspx
It's a piggyback control unit made by Dynajet. I think this is the link: http://www.dynojetcmd.com/cmd_marine.aspx
As mentioned, DynoJet system. STV-Keith is the resident associated with this system. Effectively elongates or shortens the injector pulse signal intercepted coming from the ECM to achieve a targeted AFR. Wideband O2 a must, and very useful. This is a gross simplification of the process but should give you the idea.
rivermobster
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Maybe. Your engine builder should help you with those decisions.
Go with whatever he says. [emoji106]
Here's my take. First, regarding the injectors find out what size injector you have. From there you can calculate how much HP that injector will support typically based on an 80% duty cycle and about 42 psi rail pressure. There are various calculators out there for doing this. RC Injection in Torrance is but one (I'm not affiliated). If you have enough injector to carry the stroker hp then you would be fine but my guess is you would want to go with a bigger injector and allow for some head room.
Second, the CMD system won't adjust timing, IAC count and the numerous other ECM facets that may need to be adjusted. So in short you'd want to play with the ECM .bin file. Where the CMD system comes in handy is automatically targeting desired AFRs for the various operating regimes.
Short summary:
Get bigger injectors, get tune, tune fuel tables manually with wide band O2
OR
Get bigger injectors, get tune and use the CMD system to target AFRs automatically.
Lastly, I would build your motor and get it all back together with an installed wide band O2. Start and run it on the STOCK tune and injectors to get a baseline. This would also be a good time to set base timing. The motor should run and idle adequately doing so. I DO NOT recommend calling that good and hitting the water. This merely gets a baseline to see where you are at. Then you can swap injectors if required and start the tuning process in earnest.
I wish you the best.
Nice information, thank you. In the end, is it more cost effective and beneficial to go with another injection system for the sake of having a self learning set up, like a atomic MSD, holley or edelbrock? I'm not necessarily looking for the cheapest way out, but the easiest and most effective way to get the best horsepower and fuel efficiency.
mobboss
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If your having an engine built by someone then that should be set up by them. You getting in there and trying to FIX it or change the setup could be very bad for the engine and your pocket book! If what you are trying to do is have some say and get your hands dirty, talk to the engine builder and ask if you can help.
That's a tough call. Depends on who's getting their hands dirty. As noted by others don't counter the work of the builder.....
I've heard good things about the Holley Marine EFI system. Super easy, lots of parameters, self learning etc. It's going to cost $2-3k as a guess.
On the other hand you have a robust system in place that can and will work, but at the expense of playing with the tune. That was the route I chose but I enjoy it and have had great success doing so.
If you want to keep your hands clean so to speak the Holley Marine EFI might suit you best.
If you want to immerse yourself into EFI tuning keep your current MEFI-X and go from there.
Don't sweat the fuel efficiency aspect.
Have fun and best of luck.
I am a master mechanic by trade, the only thing i wont be doing to the engine is the machine work to the block and assembly on the short block. I will be installing the top end, and whatever injection system I decide to go with. As for tuning, I have no problem sending out the mercruiser ecu for reprogram with new engine specs and running the cmd system with it. I would like to have it dynoed and dialed in. If its gunna cost more than buying a self learning injection system over having my ecm reprogrammed and running a cmd, then I would think the the self learning system would be the way to go. Im looking in the range of 600 hp, is the mercruiser setup efficient enough after reprogram? I don't know, I'm not familiar with it.
As for engine builders, I have a few in mind in my area that are very good, I have worked with them professionally for customers of mine. They are more into building and machining, not the efi side of things. So my dilemma being whether they know whats the right injection system or not. Thank you for all the replies.
As for engine builders, I have a few in mind in my area that are very good, I have worked with them professionally for customers of mine. They are more into building and machining, not the efi side of things. So my dilemma being whether they know whats the right injection system or not. Thank you for all the replies.
rivermobster
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I hate to say it this way, but in the end, you'll see what I'm talking about...
ANYONE can BUILD an engine. Anyone can torque bolts, assemble parts, adjust valves, and put gaskets in place that wont leak. It aint all that hard to do.
What IS hard to do is picking the right combination of pieces that will work well together. This is not something you can read in a book, or pick up on a forum. Cam/valve timing is Everything. So the most important piece is the cam. Compression ratios need to be determined, and set to work well with the cam. Piston dome shape needs to be considered. Valve size, rocker arm ratios. Intake and exh. manifold designs need to be considered. Is this going in a boat or a car? Different clearances will apply to each one. What idle speed is required? Will you retard or advance the cam? Where do you want the torque curve to be? There are a ton of things go consider when building an engine from scratch!!! Self tuning EFI is great, if you have the money to spend, but it wont compensate for bad decisions/combinations in the basic engine build. I just priced a system out for a customers car, that the base price for the system was 2800.00. By the time we got all the options he wanted, it came out to well over 7k. And that's with no labor, just the component prices!!! inglese.com holly and edelbrock are a little cheaper, but still a huge chunk of change.
You have the knowledge to build. Thats good. You have a good machinist picked out. Thats good. Do you know who is gonna dyno the engine? Yes? Then go have a nice long talk with him! What you need now is a reputable tuner to help you with these decisions. If he is worth his salt with a dyno, he will have some excellent recommendations for you on what components to pick.
We have people come in here quite often to use our dyno that built their engines themselves. And, more often than not, they don't run worth a shit, or don't put out nearly the numbers they expected it to, and end up walking away disappointed.
Don't take this the wrong way please! What I am trying to impress upon you is, the decisions your trying to make, are very important decisions. Have someone help you that does this every day for a living, and, that will be responsible for the end result. It's your money. Spend wisely. :thumbup::thumbup:
thank you for the input, in no way was I offended. The plan is too build a 496 stroker, with either scat or eagle set up. Run 18cc dome pistons and the edelbrock cnc 325 heads with 112cc chambers, port matched, keeping the compression around 10 to 10.5:1, all while keeping the power range from 1500 to 6000rpm. The main goal is to shed the weight, and gain as much of reliable power as possible. Rivermobster, Im out of Alta Loma area and I see you are in Glendora. What shop are you out of? I can stop by and talk sometime. This engine is for a 21' laveycraft xt ski. Thanks
The original premise of this thread revolved around wide-band integration into a MEFI ecm and not building and picking the right parts. That is a separate discussion. I am assuming that the engine build will be done appropriately. Having said that it is important to have prudent parts selection.
You don't want to send out the ECM for a tune. That will end up being a PITA. Best method is for builder to do it on the dyno and/or in the boat on the water for the fine tuning.
If you've tuned the motor you don't need the CMD system. The CMD system only deals with AFRs. If that was the only thing you had to tune then I'd likely go that route, but since there are other parameters that will need to be changed, like ignition timing, I'd simply tweak the ECM file.
The Mercruiser MEFI system will handle 600 hp. It is robust but to some not nearly as eloquent to tune as newer systems. It's not so much the ECM being able to handle the HP as it is the fuel system delivering that HP, i.e. injector size, fuel line size and fuel pump flow and rates.
It could potentially be a wash cost wise on whether you tune your existing MEFI ecm on a dyno and on the water (assuming you're paying someone to do it) or getting a new system such as the Holley Marine EFI system. In either case you'd likely need injectors.
Good luck.
You don't want to send out the ECM for a tune. That will end up being a PITA. Best method is for builder to do it on the dyno and/or in the boat on the water for the fine tuning.
If you've tuned the motor you don't need the CMD system. The CMD system only deals with AFRs. If that was the only thing you had to tune then I'd likely go that route, but since there are other parameters that will need to be changed, like ignition timing, I'd simply tweak the ECM file.
The Mercruiser MEFI system will handle 600 hp. It is robust but to some not nearly as eloquent to tune as newer systems. It's not so much the ECM being able to handle the HP as it is the fuel system delivering that HP, i.e. injector size, fuel line size and fuel pump flow and rates.
It could potentially be a wash cost wise on whether you tune your existing MEFI ecm on a dyno and on the water (assuming you're paying someone to do it) or getting a new system such as the Holley Marine EFI system. In either case you'd likely need injectors.
Good luck.
So after the build is all said and done, tweaking the ignition timing and fine tuning the ecm, installing bigger injectors etc., wouldn't the CMD come in handy if the boat was taken from lets say the river to then lake shasta, or if the boat was used in the winter to summer.
"If you've tuned the motor you don't need the CMD system. The CMD system only deals with AFRs. If that was the only thing you had to tune then I'd likely go that route, but since there are other parameters that will need to be changed, like ignition timing, I'd simply tweak the ECM file."
With elevation change and hot to cold weather and air density being different, wouldn't that effect AFR's on this system, therefore not running so great on the final tune? I'm asking because the boat will go from Shasta to Powell, to Havasu. I see that you have quite a bit of experience with the tuning, after reading some of your post.
Thank you, I appreciate the information.
"If you've tuned the motor you don't need the CMD system. The CMD system only deals with AFRs. If that was the only thing you had to tune then I'd likely go that route, but since there are other parameters that will need to be changed, like ignition timing, I'd simply tweak the ECM file."
With elevation change and hot to cold weather and air density being different, wouldn't that effect AFR's on this system, therefore not running so great on the final tune? I'm asking because the boat will go from Shasta to Powell, to Havasu. I see that you have quite a bit of experience with the tuning, after reading some of your post.
Thank you, I appreciate the information.
It would be handy, but it would not be necessary, that is assuming the ECM was properly and thoroughly tuned.
There are tables and adjustments in the MEFI file to account for elevation and temperature changes. The MAP sensor takes a snap shot of current atmospheric conditions at first key ON, then works off that baseline. In summary a properly tuned ECM would not need the CMD system.
Now let me be clear....I AM NOT bashing or trying to steer you away from using it (the CMD system). It offers a unique way to handle AFRs and perhaps at times a simpler way, but it is not necessarily required. Keep in mind you would really need to know what AFR you need to target to begin with. The dyno is the best spot to tune AFRs for peak torque and HP. At normal cruise and idle it isn't as critical as long as you aren't so lean it's detonating or so rich it's washing down the cylinders and wasting gas. Typically for naturally aspirated motors 12.8-13.2 works fairly well. No load idle you can lean it to 13.5-14.2 (that's what I do). As a side note, I believe you also need to add an additional MAP sensor for the CMD system to reference. Not a big deal, but simply a consideration.
Gauging from your feedback and questions I think perhaps the Holley marine EFI system might suit you. I enjoyed (and currently enjoy) messing with my MEFI setup and have had positive results. But I also realize that may not be everybody's cup of tea. Hopefully I didn't steer you in circles.
BajaMike
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I'm thinking a lot of time, money and frustration for very little reward!
STV_Keith
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This is true, assuming that the compensations for temp/elevation, etc are good and the air/fuel ratio stays optimum at all times. Otherwise, the closed loop system will have some advantages.
That's not correct. If the motor is staying aspirated, where the stock MAP sensor in the Mercury system has enough range to send valid MAP, the CMD will simply tap into this output. The only time you need to add a second MAP sensor is for forced induction applications where the stock MAP hits its upper limit and basically sees WOT all the time. You need a sensor that will see the boost areas and report those to the CMD system so that it can manage the fuel delivery in those areas.
rivermobster
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Thanks for the clarification regarding the second MAP sensor. I know we had spoken in the past about that but wasn't thinking about the boosted aspect.
530RL
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Wouldn't running a FAST system also be an option if you want mess around and learn?
I have no idea what I am doing but like to mess around with stuff and I find FAST easier than MEFI. More expensive but easier.
I have no idea what I am doing but like to mess around with stuff and I find FAST easier than MEFI. More expensive but easier.
DaveH
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some of the MEFI's will work with 2 and 3 bar map sensors. so no second one needed.
do yourself a favor and buy an engine managment system. the mefi is a PITA to modify with the available tuning software out there. i see these things all the time at my dyno. you will thank yourself in time (money) and agrevation trying to get it to work. it can be done, but a real engine management system is the only way to go.
ive got 4 Autronic SMC ECU's sitting here on the shelf I will off for a smoking deal. light years ahead of mefi or any piggy back.or a fast system for cheap too.
FrznJim
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Would you by chance have an extra cable for plugging the SMC into a laptop?
DaveH
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yes, but you can make one easily. the pinout is in the help menu of the SMC software. all you need is a 3.5 mini cable (ipod aux cable) and a DB9 connector. cut off one end of the plug and solder the three leads to the DB9....parts at radio shack.
USB adapters can be used, but HIGHLY recomend using an old laptop with db9 serial connection.
you can also cut off the 3 pin connector to the ECU and use whatever 3 wire plug you wish. weatherpak etc
racerden
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Pretty spot on Dave. All cars/trucks nowadays have a CL system, most utilize H02 sensors which get things cooking and enables A/F mixture tailoring pretty fast. Besides a few other players, another main ingredient is the MAF (mass airflow) sensor. This guy reports in to the ECU/ECM and translates air density and flow data in the form of voltage (usually a 5 volt reference) which is processed by the ECU. The O2's are the mixture tattletails which again are sending voltage readings back to the ECM. More volts, fat mixture less volts lean etc. The ECM has a 'delta' so-to-speak of what the ideal mixture(s) should be and in turn adjusts FI injector pulse widths to achieve this. The unfortunate thing about our boating/racing environment is the MAF; it takes a highly sophisticated set-up to make it applicable to the marine application environment because it usually involves sequential FI.
Whew!
DV
No thanks, my MEFI is working fine.
