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Thread: CARBS vs EFI

  1. #1

    CARBS vs EFI

    Took this from a website while trying to sort out my winter build.. I did a search here and got too many useless results so hopefull this will help people that may have this question.. Pros chime in with any info you can add to this!!

    Carburetors or EFI?
    Discussion has been circulating at that local hang-out between car enthusiasts over what type of fuel delivery is better. I am here to offer my opinion along with facts. I will admit that I am a little bias toward EFI, but will offer my 2.5 years of training and 5 years of experience concerning this matter.
    Carburetors have been around for over a century. This is a device that, simply put, delivers the amount of fuel an engine needs in relation to the amount of air that is pushed through it by atmospheric pressure. Carburetors work on a pressure-drop principle in which I will not go into great detail other than when tuned properly for atmospheric and weather conditions, carburetors work very well.
    There are many types of Electronic Fuel Injection on the market today. I will touch base on 3 major types known as: Throttle Body Injection, Port Fuel Injection, and Direct Fuel Injection. All of these systems are controlled by very similar computer systems and related sensors.
    Throttle Body Injection is the most simple type of EFI and the closest to carburetion in operation. Fuel is injected above the throttle blades by one or more fuel injector nozzles. Both fuel and air are carried throughout the entire intake tract.
    Port Fuel Injection is the most widely utilized form of injection today. Fuel is injected at each intake port, usually at the cylinder head and intake manifold. Only air travels through the intake tract until it reaches the point in which fuel is injected. This method allows a wide variety of intake system designs to be explored and utilized depending on application, thus making super- and turbo-charging extremely feasible.
    Direct Fuel Injection is a new technology. This system utilizes injectors similar to diesel engines in which fuel is injected directly into the cylinder. Obviously cost is high due the custom cylinder head configuration and high-temp injector required. Not much is known about this system relating to performance usage be the foundation has been laid for previously untold amounts of attainable power potential.
    CARBS vs. EFI
    The real question: Which is better? Well, this depends on a lot of factors. For one, what do you do with, and how do you drive your car? Obviously, if you race a vehicle professionally in which rules are involved that restrict the type of fuel delivery that can be used, you have little choice.
    The age old question has always been disputed: Which makes more power? Well, this too is a good question. Carb enthusiasts argue that carbs make more power over port injection because the fuel helps "cool" the intake manifold. If this were true, what about Throttle Body Injection? I have seen little evidence to prove that carbs out-perform port efi on identical engines and vice-versa in controlled conditions.
    Again, your choice depends on what you plan to do with your vehicle. In my opinion, carbs work great in ideal weather conditions and areas of the country which see little climate changes. Unfortunately, there are rarely 'ideal' conditions present. This leaves you to change jets and tune your carburetor to the changing weather conditions as the day goes on. On the other hand, EFI systems automatically compensate for changing conditions.
    What about cost?Well, here again, it depends on what you want to do with your vehicle. If you don't mind drivability problems when the engine is cold or the humidity is high then carbs are for you. Simply put, no carburetor can do what a feedback efi system can do compared by cost. I have never seen a carb that you didn't have to tune to offset changing conditions. These changes require carb disassembly in most cases. EFI can compensate for most any change in weather conditions. Those that cannot be automatically compensated for by the ECM can be easily reprogrammed by PC or Laptop computer in just minutes without getting your hands dirty.
    But carbs only cost $200 compared to $1000 for EFI system and programming hardware/software. Where are the savings?Well, $200 is just the initial cost of the average carb, new. Later, jet kits, gaskets, various diaphrams, and springs are required to maintain and tune carbs. Most efi systems have a highway mode operation in which fuel can be saved during periods of cruising that don't effect any other driving period. Personally, I have experienced a 4+mpg gain in fuel mileage utilizing such "built-in" features of GM EFI systems. Cost savings are self-explanitory, not to mention the time you save by simply sitting at a computer to tune your car instead of disassembling a carb.
    What kind of features does EFI offer over carbs? Well, simply put: a carburetor just sits there. A typical GM EFI computer system can be programmed in the following areas:
    Fuel Delivery based on MAP(Manifold Pressure), TP (Throttle Position), RPM, ECT (coolant temp)
    Spark Advance based on MAP, TP, RPM, ECT
    TCC Lockup characteristics based on TP, VSS(Vehicle Speed)
    Highway Mode Air/Fuel Ratio based on MAP, TP, VSS, Time
    Open Loop A/F Ratio and Power Enrichment Changes
    Closed Loop parameters
    Manifold Air Temp influence on timing and A/F ratio
    Idle Speed based on ECT
    Transmission Shift firmness and Shift Points (electronic automatics)
    Cooling Fan(s) Operation besed on ECT, VSS
    Trouble Code Parameters
    and Much, Much More....
    The Facts:
    Carbs EFI
    Winter Drivability: PoorExcellent

    Summer Drivebility: Excellent Excellent

    Skill Level Required: AverageAdvanced

    Initial Cost: $200+$1000 (typical)

    Long-term cost: HighManageable

    Performance: Good Better

    Turbo-compatible: PoorExcellent

    Supercharger-compatible: DependsExcellent

    N2O-compatible: Good Good

    Emissions Friendly: PoorExcellent

    "Wow" Factor: FairExcellent

    Reliability: GoodExcellent

    Fuel Distribution: FairExcellent(Port and Direct)

    Intake Configurations: LimitedUnlimited (Port and Direct)
    Pros: 6 12
    Cons: 8 2

  2. #2
    Here is my take! if you can find a motor that has EFI great! but you won't be swapping one on to a carbed motor very easily if at all! and the Mechanical fuel injection aftermarket stuff is rare and time consuming

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