Offshoreonly.com - Carbs vs FI... Pros/cons

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Quote:

Originally Posted by Young Performance (Post 4035448)

I don't agree. There is nothing about a carb that will cause it to make more power than an EFI engine. I see it as quite the opposite. I will get more aggressive with an EFI than I will with a carb engine. I have unlimited control over the timing, so, for example, I can put 38* in it at 3500 rpm and light load. As soon as you touch the throttle, down comes the timing. You can do that (to an extent) with a carb but it will take almost as much electronics as the EFI engine, and cost almost as much. I can run more timing across the board knowing that I have a very advanced knock protection system that has my back. In no way is it an absolute fail safe, but it does allow you to be more aggressive. If you are talking about a true sequential MPI, then you can dial in each cylinder for maximum performance and longevity.

As for tuning, you can spend a ton of time with some of the newer, fancier, sequential systems. But a basic setup that 98% of the boaters would use, takes no more time to dial in than a carb. It takes as long or longer to truly dial in a carbureted engine to make it the best it can be and offer drive-ability anywhere close to EFI.

If given the choice, I would choose EFI 100% of the time.
Eddie

Tried to view your website but the page is not available?

Thanks, I'll look into it.I really need to spend some time working on the website. I haven't had chance to update the website in quite some time. However, we have quite a few pics on our Facebook page.
Thanks,
Eddie

Quote:

Originally Posted by skaterdave (Post 4035563)

hi mike, hope you had a good thanksgiving..........

my point again, I've seen several people mostly w/carb motors mess with jetting or change out entire carb, normally for bigger and say they made more HP or gained speed. now if you can see a mph increase by all means continue on. but I've seen several people just chase their tails. as for efi, I don't run it so I cant say, but I have talked to people that send out ecu's to change parameters based off of similar engines then complain when their re-programmed ecu toasted a motor.

as for air flow sensors and meters, great I understand but how are you watching that at speed or under load ? are you running data loggers ? not seeing how that works if you plug motor in at the dock at idle ?

Engines will always change to some extent from dyno to boat. As far as I'm concerned, it is imperative to run the engine in the boat with Wideband O2's to be sure the tune is on. Every boat loads an engine differently. Most of the work is at idle, in and out of gear, and tip in (just when the throttle opens). There usually isn't much, if anything, to be done at WOT. I put my laptop either on the floor or on my lap. That's why it's called a laptop.....right? :) I always have someone with me to hold the widebands where I can see them while I'm driving.We run one Os sensor in each pipe, 2 sensors for a single, 4 for a twin, and so on. We always monitor each bank of the engine since there will be some discrepancies from bank to bank. Some are very close and others are not that close from bank to bank. It's really not that hard to watch the widebands while driving. I data log on the laptop so I can come back and look at it later.
Eddie

so for efi setup the headers in the boat have to have O-sensors in each pipe ?

I can see where the efi/laptop could be easier to setup once in the boat vs carb

Quote:

Originally Posted by skaterdave (Post 4035610)

so for efi setup the headers in the boat have to have O-sensors in each pipe ?

I can see where the efi/laptop could be easier to setup once in the boat vs carb

Each Collector.

To run in "Closed Loop" mode, the ECM needs to read A/F ratio of the exhaust to make slight changes on the fly. When tuning a setup that's Open Loop, ya still need those sensors to calibrate the fuel map tables. If you do all that tuning on a dyno and feel happy with it, then no sensors is required in the boat exhaust. But there is no good reason not to, unless you can't modify your pipes a bit to accommodate the sensors.

It's well worth the time and few extra $ to at least install an A/F ratio gauge on the dash, at bare minimum. When used by a modern EFI ECM, that O2 sensor might just save your engines one day. Computers can detect a lean condition and adjust for it, faster than any human. Guardian mode is the generic term for "fail safe" settings used by most EFI systems. In cars they call it limp mode, either way it's usually adjustable parameters to save a melt down. Merc's factory guardian settings tend to be a bit extreme on the SAFE side, from what I hear a real pain in the A$$ sometimes....

skaterdave,i had a great holiday,hope you did to.as far as o2 bungs in the pipes it is also used for tuning carbed engines,we read&write the numbers from idle to wot in 500 rpm incriments,then we make the necessary changes and check it again,you would be suprised to see how different they can be from the dyno room,a dyno gets it close but not exact.in the old days we read plugs,much more like a guessing game.i screwed a few up before i started useing the o2 gage to tune.also,most of the mercury marine efi systems have a pre programed map and dont use o2 sensors,but the newer stuff does incorperate o2 sensors and the better aftermarket units have o2 sensors and autocorrect the a/f ratio.guys like alex haxby and eddie young are master at mapping these aftermarket units as is dustin whipple.