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350 TPI vs. 454 TBI / h.p/$$

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Yuba K5, Aug 12, 2002.

  1. Yuba K5

    Yuba K5 Registered Member

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    i have a 90 k5, it has an efi 350.i am planning an engine swap this spring. options i am considering are either having my 350 block rebuilt, and swaping the intake to a tpi.i have called around and its gonna cost about $1000 for the computer,intake,wiring,harness,all that good stuff.Or for $2500 i could get a low milage 454 tbi from the same place with everything i need for it.which would be an easier swap?what are the differces in horse power,and torque. which would you rather have in your truck? any advice apreciated.
     
  2. ftn96

    ftn96 1/2 ton status

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    With the 350 being bone stock other than the TPI vs. a stock 454 TBI.....I'd pick the 454 anyday. /forums/images/icons/wink.gif/forums/images/icons/grin.gif
     
  3. 88Jimmy

    88Jimmy 1/2 ton status

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    I would pick the BB 454 but I'm having trouble feeding my 350 LOL
     
  4. Thunder

    Thunder 3/4 ton status

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    If you are after power and torque. I think you should go with the 454.
    2500 for a good running 454 including everything seems like a good deal. The TBI in the 454 is just about the same as the one in the 350 and is a pretty easy swap. The only diference between the wireing is the IAC (idle air controll) valve on the 454 throttle body has a diferent plug than the one on the 350. Other than that your 350 TBI wireing harness is exactly the same as the 454TBI so you can use the one already in your K5
    You can get an adapter plug for the IAC from these guys:(link)turbocity.com.
    Call them or Email them they can set you up with any other TBI performance mods you might need.
    The only thing else you will need is to pull the prom chip out of your computer and replace it with the one from the 454 computer. Or if you want you can just swap the ECMs(computer). Other than the prom chip they are both pretty much the same.
    If you have a 700r4 trans the 454 may push it to its limits. But if you keep the motor mostly stock and the tranny is in good condition it should hold up ok. If your 700 is high milage you may need to get it rebuilt and beefed up to handle the power the 454 puts out.

    There are a few guys here running 350s with TPI and they really like it.
    If you decide to rebuild your 350 I highly recomend you get Vortec heads if you go with TPI. They really add quite a bit of power and will make the swap a lot easier. The TPI will take a bit more modifing/wireing to get to work. But from everything I have heard it is worth it. If you decide to go with the TPI. I'm sure you can find someone here on these boards that can help you with questions you have.
    The TPI engines make a good ammount power/torque and will get better gas milage than a 454.
     
  5. pauly383

    pauly383 Daddy383 Staff Member Moderator

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    with the right gearing in axles and transfer case you could run
    any motor and have performance. i prefer smallblock motors because i am comfortable building them and its all i've had. the big block is great for torque and power but it will weigh a bit more and you need to change a few things ( better cooling system come to mind ) . you could get your 350 made to have decent torque, horsepower and economy. your trans would last longer too.
     
  6. Bubba Ray Boudreaux

    Bubba Ray Boudreaux 1 ton status

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    What about smog? /forums/images/icons/grin.gif
     
  7. Yuba K5

    Yuba K5 Registered Member

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    smog aint much of a problem up here in marysville. anything can pass it might just cost you a bit more.but i talked to a smog ref. and he said as long as the motor was available in the same year rig or newer,and all the smog equipment that came with it is on. it can pass smog but you will have to have a ref. look at it and sign it off
     
  8. BLUESMAN

    BLUESMAN 1/2 ton status

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    Are you going to upgrade your tranny?What trans do you have?Remember that 454 will produce alot more torque than a 350.....hence parts breakage.Hope you have an SM465 trans and then all is good.Mike
     
  9. Bubba Ray Boudreaux

    Bubba Ray Boudreaux 1 ton status

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    </font><blockquote><font class="small">In reply to:</font><hr />
    but i talked to a smog ref. and he said as long as the motor was available in the same year rig or newer

    [/ QUOTE ]
    454 wasn't offered in our generation of K5's was it?
     
  10. BLUESMAN

    BLUESMAN 1/2 ton status

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    I don't think the 454 was evered offered in the K/5 series.
     
  11. dremu

    dremu Officious Thread Derailer Premium Member

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    Big blocks were only ever sold in 3/4 ton and bigger trucks (in the 73-91 model years), and since Blazers were only ever 1/2 ton, yup, they didna come with the 4-feety-4.

    Nevertheless, *some* Chevy trucks came with them, therefore a Blazer with one is just another Chevy truck with one. You're still gonna hafta do a referee station every time, so I wouldn't touch it, but then I hate the freeeekin ARB bastards and the smog shops that have such a great racket going screwing people.

    Guess what Aaron is doing with his new Blazer this week? (Actually had a good experience at the DMV ... amazing ...)

    -- A
     
  12. fr8train

    fr8train 1/2 ton status

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    I think you should PM BlazzinOR. 406TPI sounds good to me. I dont know many inspectors that can visually tell a 350 from a 406. You would get the best of both worlds this way.
     
  13. Yuba K5

    Yuba K5 Registered Member

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    when i originaly talked to the smog ref i was asking about the tpi. he said if everthing was changed over correctly that it wouldnt be a problem passing smog. he didnt say that it would have to go back to the smog ref every two years. he only said it would have to pass as if it were a camaro. i have seen a 76 ford f 100 with a 460 that had a smog sticker saying the engine had been changed to a 460 from a 351m. im not sure of the details but i am wondering, how can this be done legally?
     
  14. Jeremy

    Jeremy Registered Member

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    Does anyone know the exact weights of a 350, 400, and 454. I was under the impression that a 350 and 400 weight almost the same. And how much mores does a 454 weight than the small blocks?
     
  15. Bubba Ray Boudreaux

    Bubba Ray Boudreaux 1 ton status

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    Here's what I've been told about this swap. If the 454 came from a truck that wasn't "heavy duty emissions" labeled, then it can be used. But most trucks that came with 454s are HD emissions and the non-HD engines are rare. This is only what I've been told so I'm not going to guarantee it. Other than finding a smog guy that will "set you up", registering your truck in one of the few counties in the state that don't require smog tests, or in another state *cough* Nevada outside Reno and Vegas, don't know anyother advice to give you. But if you find a totally legitimate way of doing it, let me know, I want a big block.
     

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