Carbs vs FI... Pros/cons
11-28-2013, 12:38 PM
#21
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Take cost out the equation and the choice becomes clear. EFI wins everytime the only reason for carbs is cost plain and simple.(or rules if you are racing in class, but again thats to control cost) New EFI systems, like Holley, Fast ect. are not hard to use, they just cost more.
11-28-2013, 12:57 PM
#22
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Take cost out the equation and the choice becomes clear. EFI wins everytime the only reason for carbs is cost plain and simple.(or rules if you are racing in class, but again thats to control cost) New EFI systems, like Holley, Fast ect. are not hard to use, they just cost more.
I the reasons carbs have been used so much is cost based, simplicity, and generally they just work. If price wasn't a concern, without a doubt I'd have injection. But, I'm on a budget, want to go fast, can't afford blowers AND efi. Like the old saying, "INJECTION IS NICE BUT I'D RATHER BE BLOWN".
If you can have both its a win!
11-28-2013, 01:20 PM
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One nice thing about EFI though, it can be a big help for some of the guys running radical cams, combined with 18'' six blade props. A lot of times in order to get a carb'd setup not to fall on its face when shifted with big props, you really need to give them a lot of fuel and air. Which then becomes a problem of a fast neutral idle speed, or a rolling idle(surging), in order for them not to stall. Some builders have fought this problem, by adding shift solenoids, so that the throttle lever will be bumped up when put into gear. This eliminates that 1200RPM Nuetral, 700 in gear scenario when setup right. With EFI, the controller can take care of that.
11-28-2013, 03:27 PM
#25
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My experience with those older TBI style setups, Holley or FASS, you could give it to me and I'd probably still trade for a good carb...
However one can easily hit the local bone yard and scavenge everything ya need to convert any marine engine to modern EFI for a little bit of nothing. With all the aftermarket ECM tuning options available today, I'd opt to build my own setups. Browse one of the LS forums and you'll find everything ya wanted to know about swaps. Big cams, blowers, turbos, all purr like a kitten when topped with modern fuel injection..
However one can easily hit the local bone yard and scavenge everything ya need to convert any marine engine to modern EFI for a little bit of nothing. With all the aftermarket ECM tuning options available today, I'd opt to build my own setups. Browse one of the LS forums and you'll find everything ya wanted to know about swaps. Big cams, blowers, turbos, all purr like a kitten when topped with modern fuel injection..
11-28-2013, 03:54 PM
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yep and what makes me laugh is the person that has no phuckin idea on how all this stuff works try's to drive through it instead of parking it and blames their phuck up on the guy that worked on his $hit last..
11-28-2013, 04:00 PM
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As far as the carbs pumping liquid through the blower, I cant say I agree that, that ''hurts'' efficiency. The fuel has been known to help cool the air charge, and reduce internal heat inside the compressor, at least on a roots blower. This is one of the reasons Roger at C&S carbs, will put his carbs up against any port injected blow through setup, HP wise. Especially with the ''aerosol design". Not to say the carb is better, because I would much rather have EFI on a blow thru setup. Even on a roots blower, Id love EFI, but its honestly not in my budget to put together the proper system, that in my opinion, will be worth the added expense to convert.
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.
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.
11-28-2013, 05:20 PM
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I have had two stage v racing carbs built by Dean Nickerson . You would swear my engines were fuel injected by the way they fire and run . Never a problem in rough water and both engines run very crisp . I run Marvel Mystery Oil through the carb at the end of the season and let it on the engine . I never drain it as I have seen too many problems caused by dried out shrunken gaskets and ruined accelerator pumps . Dean is pretty close to you , give him a call .
11-28-2013, 07:33 PM
#29
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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, 07:36 PM
#30
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Take cost out the equation and the choice becomes clear. EFI wins everytime the only reason for carbs is cost plain and simple.(or rules if you are racing in class, but again thats to control cost) New EFI systems, like Holley, Fast ect. are not hard to use, they just cost more.
on max effort blower engines i think, that is where efi shines... rm
