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Thread: Boost and pump gas

  1. #1
    1968Droptop
    Opinions please. Currently running 9:1, 521c.u., B/T al heads, 57 lower and 62 upper which equals 5lbs. of boost. Thinking about trying an upper 60 tooth, which by the on-line charts equals about 7lbs of boost. Will it live on 92 pump ??? BTW, currently removing .5* per pound of boost with my map sensor, total set at 30*. Suggestions ? Thanks.

  2. #2
    don johnson
    Depends on a few variables.... Is the engine intercooled? How cool does the engine run? Is the air/ fuel at safe levels?
    With 9.1 comp should run fine on pump gas up to 8 maybe 9 lbs of boost with an intercooler, aluminum heads, air/fuel at safe level and low water temps. Also should safely run up to 32 degrees of timing.

  3. #3
    1968Droptop
    Depends on a few variables.... Is the engine intercooled? How cool does the engine run? Is the air/ fuel at safe levels?
    With 9.1 comp should run fine on pump gas up to 8 maybe 9 lbs of boost with an intercooler, aluminum heads, air/fuel at safe level and low water temps. Also should safely run up to 32 degrees of timing.
    At this time it is not intercooled. That's one of my plans over the winter. Jetting is good, as my plugs are blackish on the outside, but meduim brown on the electrode insulator. I've been told 9, maybe 10 with i/c, but can it live at 7 w/o an i/c ? Thanks for the reply.

  4. #4

  5. #5
    ULTRA26 # 1
    Don't think I would turn it the boost any higher until you can cool the
    charge, at least on pump gas. Of course this depends on how you run the motor. If you run at WOT for any length of time, 5 pounds non intercooled, at 9:1, is on the edge. IMO

  6. #6
    born2burn
    Im running 10 #'s on straight 92 intercooled. 43 top and a 54 bottom.

  7. #7
    KNOT-RIGHT
    I am running 11lbs intercooled Aluminum Dart big chiefs
    80 bottom pulley 46 top pulley 40% over
    93 pump gas 32 locked timming.
    8.5 static.
    I would be cautious with out intercooling.
    the above post with the plug reading will go a long way.

  8. #8
    MKEELINE
    Opinions please. Currently running 9:1, 521c.u., B/T al heads, 57 lower and 62 upper which equals 5lbs. of boost. Thinking about trying an upper 60 tooth, which by the on-line charts equals about 7lbs of boost. Will it live on 92 pump ??? BTW, currently removing .5* per pound of boost with my map sensor, total set at 30*. Suggestions ? Thanks.
    Take a look at Torco Accelerator racing fuel concentrate. If your running pump gas and you want to bump-the octane up this does it. It's not octane boost, it's concentrated racing fuel. The chart on the back of the can shows 1 32 oz can mixed with 10 gallons of 93 octane fuel will give you 103 octane. I think those are the numbers(my memory sucks)but don't hold me to those exact numbers.
    Check it out at www.torco.com

  9. #9
    1968Droptop
    Thanks for all of your opinions. Too many are saying 5 is about it, so 5 I will stay at (for now). I hope to be upping the ante over the winter though. How much power will an extra 3-4 lbs. of boost add ? Thanks agin for your opinions.

  10. #10
    DMOORE
    Well, that 3-4 extra pounds of boost could add up to 150HP (or more) with and intercooler. Like others have said, an intercooler is the only way to go on a blower motor for a boat. It's damn near free horsepower if you will.
    Darrell.

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