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    Mechanical Fuel Injection VS. Electronic Fuel Injection ( EFI ) for Street & Race Usage

    Issues and possible solutions to running mechanical fuel injection on the street – VS EFI ( Electronic Fuel Injection )

    Cold starts – need to prime 2 or 3 times (minor annoyance) (Actually cool at cruise nights)  I make a small electric primer pump with one way check valve. See Primer kit sold on web site .
    Hot starts – not all cylinders fire at first (minor annoyance)
    Use fuel shutoff to prevent vapor lock or peculation of gas.  
    Use above mentioned primer pump to fill lines/nozzles .
    Surging and bucking at cruise
    All mechanical injections will surge and buck slightly under no load while cruising at 2000-2500 RPM. This condition clears up under power. Tolerable for Weekend Warrior type vehicles- This is the main reason that the manufacturers say they are not street able.    
    Fluctuating idle –  
    Need two return springs on manifold, one on each side. Butterflies need to be set with instructions from Alkydigger web site under technical tips.
    Idles is not adjusted with butterflies, it is set with the barrel valve.
    Heat soak – (major aggravation)- When the water temp goes above 200, car is almost un-drivable – vapor lock symptoms, fuel starvation, refuses to start.
    If fuel pump is cam driven and you want to run gas you will need to use at least a 3” or 4” extension to get the pump away from engine heat.
    We recommend a belt driven pump drive to help keep pump cooler, since gas boils at about 200 degrees. E-85 performs better and runs cooler. If you can get E-85 , it provides 105 octane and a much cleaner burn. We have to re jet the manifold to accommodate E-85 since it burns more fuel than gas, and does not have the same chemical properties.
    Run thicker radiator for more cooling and/or electric fan .
    If Fuel cell is located in the trunk, the outlet must face backward.
    Under hood or bumper mounted tanks are the best, but not always  necessary.
    Use a surge tank under the hood  and  pump from the main tank to fill the surge tank – The mechanical pump will then draw fuel from the surge tank and return it to the surge tank, resulting in  your ability to carry much more fuel in the main tank but still feed the fuel injection from the front-  We will have a nice surge tank available after March 1, 2014 , that will accommodate this problem.

    Pros and cons of electronic fuel injection system :
    Pros – A Hilborn EFI System from Alkydigger will  solve all above problems. ( Look at EFI Blown and un blown system on our site )
    Cons – Expense- $5500- to $7500 –   vs  $2000 to $3000  for full mechanical system
     EFI ‘s are Not allowed in some nostalgia racing organizations