LT1 engine upgrades

Discussion in 'High Performance Modifications' started by Dad's 73 camaro, Oct 31, 2017.

  1. Dad's 73 camaro

    Dad's 73 camaro Member

    May 9, 2011
    port saint lucie, fl
    Upgrading my stock steel head LT1 after a few years of restoring the car. Using MSD distributor, LT4 Hot Cam, aluminum heads with 2.02, 1.06 valves and 1.6 rockers. Also using a 58mm throttle body and modified intake. Not sure if I want to use 30lb injectors. Any advise is welcome.
  2. hoppin5478

    hoppin5478 Veteran Member Lifetime Gold Member

    Jul 20, 2015
    Tucson, AZ
    It really depends on what your trying to accomplish, HP goal, budget, etc. I'm assuming this is a mid 90's Caprice/Impala LT1 with Iron heads. The Iron heads actually slightly outflow the aluminum Camaro/Vette version but the aluminum heads also have there advantages, weight, heat transfer etc. Both sets of heads flow well in stock form. What type of controller are you running, a stock computer that your getting a custom tune on or an aftermarket set up that you can tune yourself? The tune is extremely important to maximize what you have. I'm running a Megasquirt 3, LS1 style coil near plug and twin turbo's, stock intake and bottom end. I have the aluminum heads with a mild port job and 60lb injectors but we set up my fuel system to be able to handle just north of 600hp on 20psi of boost with water injection. You can go as mild or wild as your budget and expertise will allow but I strongly suggest deciding what you want to use it for and your HP goal and build it accordingly.
    Turbo70Camaro likes this.
  3. 1980RS

    1980RS Veteran Member

    Jun 17, 2006
    The LT4 hot cam is a great street strip cam pulls to 6500 with ease, it's easy on the valve train too. Mine was in a carb engine but in FI LT1 it's dynamite. Get your stock intake ported when you change the cam, worth the money.
  4. Lowend

    Lowend Administrator. .a car, a man, a maraca. Staff Member Lifetime Gold Member

    Mar 25, 1999
    San Jose, CA, USA
    there are some pretty simple equations to figure out injector size. Here's a calculator
    You actually want the smallest injectors you can get away with. Smaller Injectors = smaller droplets = better atomization. However for a variety of reasons you don't want fuel injectors working at over 90% of their duty cycle.
    A stock LT1 runs at 41-47 PSI fuel pressure, so using a 41 PSI baseline (always use the lowest number for safety), with 425 HP at the crank (about where you are), and 90% duty cycle, you need 30 lbs injectors.

    If you think someday you might go with a supercharger or something, go bigger. Otherwise 30lbs should be fine
  5. Ihada70Z28B4

    Ihada70Z28B4 Veteran Member

    Oct 4, 2002
    I'm running the same engine configuration but with the GM Lt1 carb intake with the 600hp Fitech. You can go with a bigger injector if you have the PCM programmed for them no problem. I had 65lb inj on my Buick GN and the 3.8 liter ran smooth as glass. Get enough injector to accommodate future upgrades.
  6. hoppin5478

    hoppin5478 Veteran Member Lifetime Gold Member

    Jul 20, 2015
    Tucson, AZ
    I agree, I would build the fuel system to handle any future modifications that you plan on as long as your running a programmable ecu of some type and can compensate for it. One of the main concerns with an injector that is too big is that you can have poor idle quality due to not being able to get the pulse widths small enough that its not flowing to much fuel at idle. My LT1 idles smooth as glass as well on the 60lbs with a stock cam and all the othe mods.

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