Carbs vs FI... Pros/cons
11-28-2013, 01:41 AM
#11
Charter Member # 55
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I've had both Carbs and EFI. Both have their plus's and minus's.
I've had carb engines flood the fuel bowls when lauching the bow high and pulling back on the sticks.
I've had some minor vapor lock issues with my MPI's in exteme hot humid weather.
I thought most of the marine EFI set ups used fixed curves for fuel mapping and do not self adjust because of the lack of O2 sensors????
I've had carb engines flood the fuel bowls when lauching the bow high and pulling back on the sticks.
I've had some minor vapor lock issues with my MPI's in exteme hot humid weather.
i run carbs on my 8.3L whipplecharged engines,but i am thinking about going to efi.a good efi system compensates for humidity,altitude&temp.there is a reason all newer cars and almost all newer boats have efi.as far as power,i dont see any measureable difference from one to the other.imo,the determining factor in choosing is price.
11-28-2013, 09:37 AM
#12
I had one engine builder tell me that one of the main reasons for the marine industry switching to FI was due to emission standards, along the same lines that catalytic converters added to new marine engines.... Other than that he claims carb better than FI since maint and repairs easier....
11-28-2013, 09:37 AM
#13
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I think its really a tough comparison to say which is ''better". Theres a lot of different EFI systems, and different carbs.
Hands down carbs are much cheaper. Carbs today are much better than they were 15,20, 30 years ago. Once you figure them out, tuning them is easy. And you can install 02 sensors, which really helps for an efficient tune. Years ago, all we could monitor was spark plugs. Today, with 02 sensors, you can fine tune your engines from idle, to wot. You can eliminate that "pig rich cruise", or "lean wot meltdown" etc. Basically you can fix holes in the fuel curve easier. Fuel system is pretty basic, a mechanical pump and a decent size fuel line is usually all that's needed.
EFI, has some great systems out there. A port injection will deliver outstanding fuel distribution, much cleaner idle, etc. Throttle body injection is nice, but if I were to make the jump to efi, I'd really like to go with port injection.
I think its more of a personal preference, and budget oriented, on which system is best. Both can work really well. Generally speaking, there isn't much "power" to be gained one way or the other. The one thing I have always loved about carbs, is generally, parts are super cheap, and can be fixed at the dock with a quick trip to autozone should you have a gasket leak, power valve blow, or needle seat mess up. With EFI, you might be down until parts get shipped to you should something fail.
Hands down carbs are much cheaper. Carbs today are much better than they were 15,20, 30 years ago. Once you figure them out, tuning them is easy. And you can install 02 sensors, which really helps for an efficient tune. Years ago, all we could monitor was spark plugs. Today, with 02 sensors, you can fine tune your engines from idle, to wot. You can eliminate that "pig rich cruise", or "lean wot meltdown" etc. Basically you can fix holes in the fuel curve easier. Fuel system is pretty basic, a mechanical pump and a decent size fuel line is usually all that's needed.
EFI, has some great systems out there. A port injection will deliver outstanding fuel distribution, much cleaner idle, etc. Throttle body injection is nice, but if I were to make the jump to efi, I'd really like to go with port injection.
I think its more of a personal preference, and budget oriented, on which system is best. Both can work really well. Generally speaking, there isn't much "power" to be gained one way or the other. The one thing I have always loved about carbs, is generally, parts are super cheap, and can be fixed at the dock with a quick trip to autozone should you have a gasket leak, power valve blow, or needle seat mess up. With EFI, you might be down until parts get shipped to you should something fail.
11-28-2013, 10:17 AM
#14
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If question is carbs vs a total ecu system there is no question. With a good ecu like merc 1075 there is no comparison. No way you can make the consistent hp with the longevity with just carbs. Good computers will take so much info a maximize power through all rpm. Some computers can read each cylinder and sense detonation, and it will pull timing out of each individual cylinder. It reads so much info its crazy. But I do agree that carbs up to 1000 hp are a great way to go, you are not stuck with all the tune up guys, plus there are so many sensors on a ecu motor to go bad it can make you nuts.
11-28-2013, 10:17 AM
#15
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Really is a toss up, but if your filters clog up with an efi system and your pressure drops it could equal meltdown. A lot harder in my opinion to melt a carb'd motor once its dialed in. As stated earlier both have there pro's and con's. I for one and am not 100% locked on either.
11-28-2013, 11:49 AM
#16
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Properly setup EFI engines should always out perform carbs in the long run, especially when talking about blowers motors. With carbs your pumping liquid thru a compressor designed to move air. Sequential port injection is way more efficient here.
As Mild Thunder touched on the biggest carb risks above, I had this same conversation with a friend some years ago while driving home with his two 1300hp Cobra engines that were properly dyno tuned, twin dominators on top PSI's. Once installed in the boat, those fresh engines only made it 10 minutes before melting the heads down. Seems they didn't like being starved for fuel when he forgot to switch on the electric boost pumps. I wasn't around to see it happen, but heard the result was a violent 120mph spin out when that first one seized up..
Had those been EFI with O2 and knock sensors, she would have automatically pulled timing if the ECU detected it going lean and detonation started. As someone else listed above, the popular open loop EFI setup from Merc used for years isn't the best option out there today. With the new wide band O2 sensors and closed loop setups, there is no reason modern EFI shouldn't out perform carbs at any HP level. It's just finding an engine builder who understands EFI tuning, and that's not always easy to do when your talking marine engines.
As Mild Thunder touched on the biggest carb risks above, I had this same conversation with a friend some years ago while driving home with his two 1300hp Cobra engines that were properly dyno tuned, twin dominators on top PSI's. Once installed in the boat, those fresh engines only made it 10 minutes before melting the heads down. Seems they didn't like being starved for fuel when he forgot to switch on the electric boost pumps. I wasn't around to see it happen, but heard the result was a violent 120mph spin out when that first one seized up..
Had those been EFI with O2 and knock sensors, she would have automatically pulled timing if the ECU detected it going lean and detonation started. As someone else listed above, the popular open loop EFI setup from Merc used for years isn't the best option out there today. With the new wide band O2 sensors and closed loop setups, there is no reason modern EFI shouldn't out perform carbs at any HP level. It's just finding an engine builder who understands EFI tuning, and that's not always easy to do when your talking marine engines.
11-28-2013, 12:26 PM
#17
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I've had both Carbs and EFI. Both have their plus's and minus's.
I've had carb engines flood the fuel bowls when lauching the bow high and pulling back on the sticks.
I've had some minor vapor lock issues with my MPI's in exteme hot humid weather.
I thought most of the marine EFI set ups used fixed curves for fuel mapping and do not self adjust because of the lack of O2 sensors????
I've had carb engines flood the fuel bowls when lauching the bow high and pulling back on the sticks.
I've had some minor vapor lock issues with my MPI's in exteme hot humid weather.
I thought most of the marine EFI set ups used fixed curves for fuel mapping and do not self adjust because of the lack of O2 sensors????
Last edited by mike tkach; 11-28-2013 at 12:43 PM.
11-28-2013, 12:33 PM
#18
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Properly setup EFI engines should always out perform carbs in the long run, especially when talking about blowers motors. With carbs your pumping liquid thru a compressor designed to move air. Sequential port injection is way more efficient here.
As Mild Thunder touched on the biggest carb risks above, I had this same conversation with a friend some years ago while driving home with his two 1300hp Cobra engines that were properly dyno tuned, twin dominators on top PSI's. Once installed in the boat, those fresh engines only made it 10 minutes before melting the heads down. Seems they didn't like being starved for fuel when he forgot to switch on the electric boost pumps. I wasn't around to see it happen, but heard the result was a violent 120mph spin out when that first one seized up..
Had those been EFI with O2 and knock sensors, she would have automatically pulled timing if the ECU detected it going lean and detonation started. As someone else listed above, the popular open loop EFI setup from Merc used for years isn't the best option out there today. With the new wide band O2 sensors and closed loop setups, there is no reason modern EFI shouldn't out perform carbs at any HP level. It's just finding an engine builder who understands EFI tuning, and that's not always easy to do when your talking marine engines.
As Mild Thunder touched on the biggest carb risks above, I had this same conversation with a friend some years ago while driving home with his two 1300hp Cobra engines that were properly dyno tuned, twin dominators on top PSI's. Once installed in the boat, those fresh engines only made it 10 minutes before melting the heads down. Seems they didn't like being starved for fuel when he forgot to switch on the electric boost pumps. I wasn't around to see it happen, but heard the result was a violent 120mph spin out when that first one seized up..
Had those been EFI with O2 and knock sensors, she would have automatically pulled timing if the ECU detected it going lean and detonation started. As someone else listed above, the popular open loop EFI setup from Merc used for years isn't the best option out there today. With the new wide band O2 sensors and closed loop setups, there is no reason modern EFI shouldn't out perform carbs at any HP level. It's just finding an engine builder who understands EFI tuning, and that's not always easy to do when your talking marine engines.
Last edited by mike tkach; 11-28-2013 at 01:49 PM.
11-28-2013, 12:34 PM
#19
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Properly setup EFI engines should always out perform carbs in the long run, especially when talking about blowers motors. With carbs your pumping liquid thru a compressor designed to move air. Sequential port injection is way more efficient here.
As Mild Thunder touched on the biggest carb risks above, I had this same conversation with a friend some years ago while driving home with his two 1300hp Cobra engines that were properly dyno tuned, twin dominators on top PSI's. Once installed in the boat, those fresh engines only made it 10 minutes before melting the heads down. Seems they didn't like being starved for fuel when he forgot to switch on the electric boost pumps. I wasn't around to see it happen, but heard the result was a violent 120mph spin out when that first one seized up..
Had those been EFI with O2 and knock sensors, she would have automatically pulled timing if the ECU detected it going lean and detonation started. As someone else listed above, the popular open loop EFI setup from Merc used for years isn't the best option out there today. With the new wide band O2 sensors and closed loop setups, there is no reason modern EFI shouldn't out perform carbs at any HP level. It's just finding an engine builder who understands EFI tuning, and that's not always easy to do when your talking marine engines.
As Mild Thunder touched on the biggest carb risks above, I had this same conversation with a friend some years ago while driving home with his two 1300hp Cobra engines that were properly dyno tuned, twin dominators on top PSI's. Once installed in the boat, those fresh engines only made it 10 minutes before melting the heads down. Seems they didn't like being starved for fuel when he forgot to switch on the electric boost pumps. I wasn't around to see it happen, but heard the result was a violent 120mph spin out when that first one seized up..
Had those been EFI with O2 and knock sensors, she would have automatically pulled timing if the ECU detected it going lean and detonation started. As someone else listed above, the popular open loop EFI setup from Merc used for years isn't the best option out there today. With the new wide band O2 sensors and closed loop setups, there is no reason modern EFI shouldn't out perform carbs at any HP level. It's just finding an engine builder who understands EFI tuning, and that's not always easy to do when your talking marine engines.
11-28-2013, 12:35 PM
#20
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iTrader: (3)
Properly setup EFI engines should always out perform carbs in the long run, especially when talking about blowers motors. With carbs your pumping liquid thru a compressor designed to move air. Sequential port injection is way more efficient here.
As Mild Thunder touched on the biggest carb risks above, I had this same conversation with a friend some years ago while driving home with his two 1300hp Cobra engines that were properly dyno tuned, twin dominators on top PSI's. Once installed in the boat, those fresh engines only made it 10 minutes before melting the heads down. Seems they didn't like being starved for fuel when he forgot to switch on the electric boost pumps. I wasn't around to see it happen, but heard the result was a violent 120mph spin out when that first one seized up..
.
As Mild Thunder touched on the biggest carb risks above, I had this same conversation with a friend some years ago while driving home with his two 1300hp Cobra engines that were properly dyno tuned, twin dominators on top PSI's. Once installed in the boat, those fresh engines only made it 10 minutes before melting the heads down. Seems they didn't like being starved for fuel when he forgot to switch on the electric boost pumps. I wasn't around to see it happen, but heard the result was a violent 120mph spin out when that first one seized up..
.
As far as the carb'd psi blown deal melting down, well sure, starve it for fuel and its over in seconds. A simple set of fuel psi gauges, or low fuel psi switch with a warning light would probably saved those engines. . Fuel system issues in any engine will lead to melting parts. But, like you said, not all EFI systems are created equal. Something more modern, with 02's, knock sensors, etc, will be much better than some of the primitive injection systems, like merc offered not long ago. To take full advantage of the benefits, you really need to build in the safety factors into the system.
I really like EFI, but it has to be the right setup. Just because its ''electronically controlled" doesn't mean anything to me. A late 80's GM TBI injection is "electronically controlled'', but it still sucked. It really offered nothing over its carb'd predecessor other than you can start the engine without pumping the accelerator.
I have friends who aren't very engine knowledgeable in general, that are boat shopping. They have the impression that, as long as its ''EFI", its reliable, safe, and will offer trouble free boating. And if its carb'ed, its gonna be unfriendly around the docks, require constant tuning, and use more fuel. that just always isn't the case.
