'94 Firebird LT1 into '78 Camaro project back on

Discussion in 'High Tech Retrofits' started by sbca96, Jun 21, 2010.

  1. sbca96

    sbca96 Veteran Member

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    So decided to get serious about fixing the "temporary" exhaust so that I can put
    down some REAL numbers to what an LT1 can do. The reducer has to go. I took
    some measurements and was surprised to find the y-pipe on the Magnaflow CAT
    back is just 2-1/4 inch!

    [​IMG]

    I thought they would have at least gone 2-1/2. So it isnt JUST the reducer that
    needs to go, but the front of the Magnaflow needs to get cut off as well. I have
    roughly 6 inches of 2-1/4 single exhaust.

    [​IMG]

    This is outside diameter, so its actually less with wall thickness, from Y pipe back:

    Tube before CAT : 3 inch
    CAT : 3-1/4
    Adapter/reducer : 3-1/4 to 2-1/4
    Forward tube of Magnaflow CAT back : 2-1/4
    Y-junction splits to two 2-1/2 tubes to twin mufflers.

    I was looking at the Flowmaster ball flange kit in 3 inch to 3 inch.

    [​IMG]

    I can have an exhaust shop cut the Magnaflow y-pipe at the Y so the 3 inch
    tube can be oval-ed to meet up without restriction.

    Tom
     
  2. sbca96

    sbca96 Veteran Member

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    Anyone ever use the Summit Racing ball flange? They claim it is better then the
    2 or 3 bolt system and they offer a 304 SST version for 30 dollars ...

    [​IMG]

    They have two 3 inch options, 3 inch internal and 3 inch external. I am temped
    to get the 3 inch internal, since my CAT measures 3-1/4 on the outside.

    Tom
     
  3. sbca96

    sbca96 Veteran Member

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    So .. I'm guessing no one has used either of the above?

    Tom
     
  4. formula73

    formula73 New Member

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    This is a fantastic thread. I just signed up to the forum as I am now the owner (again) of a 78 Firebird Esprit with a factory sbc 350 and was considering the change to LT1 and this is an invaluable resource! I especially love the radiator 'lean' and top cover. While I'm in VA and don't require any kind of emissions inspection, it will still have to pass a visual (which, for 78, means it has to look like it has a cat or 2 if I go duals), so a whole lot of your work applies to me, as well.

    Being VA, it's also hotter than hell in the summertime. Did you ever consider keeping the A/C or reinstalling it?

    Sorry, I see the info is in here, though the Bowers link isn't working. Anyway, awesome thread!
     
    Last edited: Jan 11, 2015
  5. perfectroller89

    perfectroller89 Member

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    You can use the bracket from a lt1 vetted if u want a.c. in these cars
     
  6. sbca96

    sbca96 Veteran Member

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    Thank you for the positive input, its nice to see there are some still seeing the
    potential of the LT1. The high flow CATs really do not rob much HP I think it is
    around 3-4 tops less each if you run two. EFI cars tend to smell a bit ripe w/o
    a CAT, my old 1993 Camaro Z28 LT1 in a drivethru was awful idling. I googled
    the relocation bracket and found the link (not sure if its changed) :

    http://www.bowersrodshop.com/lt1-ac-relocation-kit/#!/LT1-Kits/c/335901/

    1978 Firebird is the Bandit years, I actually always liked the '70s Firebirds over
    the Camaros, first 70s F-body I liked as a kid was Ponch's on CHiPs.

    [​IMG]

    Remember how he got it?

    [​IMG]

    This is true ... but good luck finding that bracket! They were sold out of GM as
    soon as the LT1 gained popularity as a swap engine YEARS ago.

    Tom
     
    Last edited: Jan 18, 2015
  7. perfectroller89

    perfectroller89 Member

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    I cannot remember who made them but there used to be s polished bracket u could buy that was similar to the vettebracket
     
  8. perfectroller89

    perfectroller89 Member

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  9. formula73

    formula73 New Member

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    Fantastic. Thanks, guys. Now, I just need a couple grand for a 94-97 donor.

    What years are preferred and why? I know 93 is all weird because of my brother's Z28 and I don't feel like messing with it.

    I notice a lot of people seem to go for 94. Why is that?
     
  10. perfectroller89

    perfectroller89 Member

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    Alot of 94s . But id recommend 95 96 97 preferably 96 97 my reason for that is the optispark changed in some 95s and in 94 on the ro admasters the early optispark sucked in water causing it to fail the new one is vent though the vacuum and give a much longer life . I speak from experience I owned the same motor he installed 94 trans am formula lt1 I went throw 6 optisparks in 2 years until I finally installed a msd one although the vacuum on the msd wasn't as sturdy as the 95-98 optisparks it did provide thw venting that the 94 need so much.

    If u do decide to go 94 u can change out some things to take the newer Prospero but its much cheaper to run msd or get the newer style opti
     

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