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question about 4 to 6 cylinder conversion

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  • question about 4 to 6 cylinder conversion

    I was wondering how easy it is to switch the fiero 4 cylinder engine to the 6 cylinder engine and what is involved. Also is it difficult to put power locks in a fiero without them because i don't want to have manual locks when i do a ferrari conversion. Thanks


  • #2
    Re: question about 4 to 6 cylinder conversion

    I have been just going all the same stuff for my car.  I bought a parts car to grab a few parts from and sell off all other parts to the Fiero pirannas in Calgary.  I saw that it had power mirrors and power locks and wanted the mirrors for sure but had not originally thought of the power locks.  The power mirrors are easy as they have a separate wiring harness that comes out very easily.  I found a set of instructions on one of the Fiero web sites.  Search Google for power mirrors Fiero and it comes right up.

    The same web site has power locks conversion as well.  I just fouind that one tonight and will be reading through it.  Sounds like the power locks are much more involved though as it looks like you need to replace the entire interior portion of the wiring harness.  I have not read through the whole thing yet but it doesn't look easy so far.  Taking the parts out of the door is easy but the rest of the wiring is still to be determined.  Do-able for sure if you still have a bare interior to make it easier to convert the wiring harness.  The one piece on the door that causes a bit of work is the door lock buttons.  They are plastic formed into the door handle panels so you need to carefully break the door handle panel away to get the buttons only.  You will then need to sort out how to mount them on to the Ferrari door panels or find other buttons and splice in the wiring.  If I do this, I think I will be replacing the buttons with another actuator.

    For the V6 engine, you also have some more to go through.  I sold the engine and wiring from my wiring harness and the Fiero guy that bought it has been back a few times for more parts.

    You will need the entire engine hrarness up to and including the ECU connections and ECU.  The through firewall pieces are the same shape so can be converted but do not try to take that joint apart, take the entire harness from the ECU back through the firewall and keep it attached to the engine harness.  I found that so much easier. 

    The harder part comes in when you want to hook the ECU up to the main wiring harness connectors.  These seem to be different from the 4 cyl to the 6 cyl. you will need the entire wiring harness again or splice the V6 wiring connectors for the V6 ECU into the 4 cyl wiring harness.

    Since you are looking to add power locks, it looks like you will want to replace the wiring harness anyway.

    More on the engine.

    Mounts are the same for 4 and 6 cyls. 
    Need the dog bone off the V6, as well as the engine shock that is near the front of the engine and on the firewall side of the engine.
    Air intake pieces are different
    Shielding around the engine, I think is the same.
    Exhaust y pipe down to the cat inlet.
    Air lines look the same around the engine compartment but I am not 100% sure.
    Get the V6 fuel pump as well as I think it has more pump to it.

    There really isn't more than that to convert your engine over from what I have seen so far.

    Door lock pdf instructions.

    Good luck
    308 Ferrari replica
    Prova Countach 5000S


    • #3
      Re: question about 4 to 6 cylinder conversion

      Don has some good suggestions. I converted my 4 into a V-6. Things that are different are:
      2) V-6 Computer
      3) V-6 Fuel pump
      4) 2 engine mounts (one in front of oil pan and the other for the transmission)
      5) Wiring from the computer to the V-6. (you can use the 4 cylinder but it is a pain to rewire)

      6) Shifter cables if going from a 5-speed to a 4-speed

      7) Cruise control module

      The 4 cylinder exhaust will work, just a little cutting and rewelding. The radiator of the 4 and the V-6 are the same (I have no problems with mine).

      If you go to Kick Hill's website he sells all the stuff needed.
      I hope this helps.


      • #4
        Re: question about 4 to 6 cylinder conversion

        Oh, last but not least. As for difficulty level. Doing the conversion took me 16 hours. So it is really not that hard. Once you start the project email me or look at my past post and get my number and call me I could walk you through to make it easier. Again I hope this helps.


        • #5
          Re: question about 4 to 6 cylinder conversion

          What they said for the stock 4 to 6cyl change or even 3.4. It's a different ballgame if you're talking about going to a 3400 or 3800, or something else.

          Bob custom '84 Fiero SE --->>> custom F408


          • #6
            Re: question about 4 to 6 cylinder conversion

            i want to go to the 3.4 change. And yes you all did help a lot. Don thanks for that complete explanation very helpfull, same to you pit bull. I thought that the 5 speed transmission would work for the 6 cylinder? What is the url for kick hill's website? So basicly for the engine swap need new ecu and wiring harness all the way back to the engine? simple if its anything like the last engine i did.


            • #7
              Re: question about 4 to 6 cylinder conversion

              Yea, the stupid bell housing on the transmission is bigger. Here is the site It is only $850.00 for everything you need. Oh plus shipping. The wiring on the inside of the Fiero's are all the same. Atleast Pontiac made something simple.


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