Possible to replace a 4.5 with a 4.9?

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Cadillac Allante Forum Discussion, Possible to replace a 4.5 with a 4.9? in Past Cadillac Vehicle Discussion; I'm kicking around the idea if replacing a 4.5 liter Allante engine with a 4.9. I think they are very ...
  1. #1
    Greg81 is offline Cadillac Owners Member
    Automobile(s): Cadillac
    Join Date
    Jan 2008

    Possible to replace a 4.5 with a 4.9?

    I'm kicking around the idea if replacing a 4.5 liter Allante engine with a 4.9. I think they are very similar except for displacement. If anyone call tell me, off the top of their head, what problems would be encountered with such a swap I would appreciate it.

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  3. #2
    MoistCabbage's Avatar
    MoistCabbage is online now Cadillac Owners 10000+ Posts
    Automobile(s): 2001 Seville STS, 1990 Seville (RIP), 1972 Sedan Deville
    Join Date
    Sep 2010
    East Boston MA.
    Anything is possible, but there would be some modifications required.

    The 4.5 in the Allante is not the standard 4.5, it's a high output version, with 200 HP, and 270 FT-LBS of torque. Same HP as the 4.9, and only 5 less FT-LBS. If you're looking for a performance upgrade, you might want to consider selling, and buying a '93 with a Northstar.

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