Lots of questions, LS1 swap.

Discussion in 'High Tech Retrofits' started by OldSchoolFormula, Feb 10, 2006.

  1. OldSchoolFormula

    OldSchoolFormula Veteran Member

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    May 26, 2004
    Livermore
    I have a complete A4 2001 Trans Am I just picked up. I'm thinking of the beauties of the LSX design now and all the advantages. For what I do with my car, there is not a single disadvantage to the LS1. I drive my car hard, and it'd be nice not to have to worry about it stalling under hard braking or off throttle cornering. Shaving a few hundred pounds off the car can only be a great thing performance wise, and the damn bottom ends are nearly bulletproof. It would be nice for it to warm up faster. The mileage is nice. I use the car as a D/D. Retrofit cost is high though. I'd like to change that.

    Anyway, being I have the entire car, what would I need to save/reuse to get this thing installed and running in my '73 as cheaply as possible? I figure the entire car is in my garage runnign right now, everything I really need is there besides things needed to make the darn thing fit. Looking for functional right now, not pretty.

    I'm also thinking about keeping my BTO 2004R instead of the 4L60, just because its already built to Stage 3 specs. Assuming I do keep the 4L60E, Besides VATS(they have that VATS thing on ebay), and the rear 02's(sim's?) what specifically will need to be changed regarding the harness and the PCM? What might it be looking for that I could swap over?

    I'm also kind of tossing around the idea of using the 01's gauge cluster, being it will receive the correct signals as is, and it looks kind of cool.

    Heres a question... since my '73 steering column is very basic, no tilt, no dummer on the stalk, no wiiper delay, no cruise, etc, and if I can find a '81 T/A with those options... could I take the steering column, and then use the new column to be able to use the cruise control switch? Thats a mod I'd LOVE to have on an older car. Has anyone else set up a cruise control using the LS1 stuff? If so, how?

    And further more,whats involved with modifying the harness? I found all the pin-outs over on LS1Tech, do I simply remove whatever wires I don't need? Ideally I'd REALLY like to do this, to get it in and running, as quickly and as cheaply as possible. I can tidy it up later. If it simply means pulling the wires, or even just leaving them disconnected and bundled up, I'll do it. Theres not a lot emissions wise on the LS1, and most of it looks like it will swap to the '73 fairly easy, with the exception of the evap system and the rest of the gas tank. Still not sure how I'm going to do that, Any ideas? I looked closer at the two tanks last night and that LS1 tank is tall, I don't think the fuel pump/sending unit it even going to be possible to make it work in the '73, and the only way to get the LS1 fuel tank into the '73 would be to cut the trunk out. I don't really wnat to do that, even though I cant remember the last time I even opened the trunk.
    The other option is to keep my existing tank and put on an external fuel pump (Walbro 255?)Now, how would I do the return? I notice theres a "T" fitting under the 01, is that how the 01 regulates it's fuel return? If possible I'd like to keep that. The idea is to buy as little new parts as possible.

    Thanks guys.
     
  2. MikeM79

    MikeM79 Moderator Lifetime Gold Member

    7,022
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    Mar 5, 1999
    East Quogue, NY
    There are lots of ways to handle the fuel.

    Here is what I did:

    - stock 71 gas tank
    - 3gen Camaro sending unit...drops right in.
    - internal Walbro 255lph pump
    - I fabbed a slosh tray...not really needed if you keep fuel level high enough
    - rubber fuel injection hose to C5 Corvette fuel filter / pressure regulator combo unit mounted on rear frame rail
    - return from C5 filter back to 3gen sending unit
    - -6AN single line to fuel rail with a pressure gauge spliced in to verify 58 psi

    You can sell the stock 4gen fuel tank setup to recoupe some of the expense.

    I would not play around with trying to get the stock 4gen fuel tank to work. Others have done it...but hacking up the trunk floor is not worth it to me.

    Also, double check the VATS thing. It has been a while, so my recollection may not be that sharp, but........... I think the VATS defeat thingie you are talking about only works on systems earlier than yours. In your case I believe you need to use LS1 edit to get rid of it.....again...double check me. I sent my computer and harness out for re-working. It was expensive, but worth it to me....plug and play after that.
     
  3. BC's71'

    BC's71' Veteran Member

    1,125
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    May 16, 2000
    North Chicago Suburbs
    I'm with ya all the way until the tray part.
    Any specifics on how you fabbed the tray, and more importantly, how you got it inside the tank? Did this involve cutting open the tank and welding in the tray and then repairing the tank????

    I'm trying to find a cost effective way to drop in my 3rd gen sender and keep fuel slosh to a minimum. Seems easy enough to keep minimum half tank of fuel in there at all times, but I know that can be a pain in the arse after awhile or on any road trips.
    Any advice? :shy:
     
  4. OldSchoolFormula

    OldSchoolFormula Veteran Member

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    May 26, 2004
    Livermore
    Does the 3rd gen sending unit use the standard 0-90 ohm resistance as the 2nd gen does, or does it use the 4th gen resistance? Is the travel the same (does the gauge read correctly?)
     
  5. MikeM79

    MikeM79 Moderator Lifetime Gold Member

    7,022
    0
    Mar 5, 1999
    East Quogue, NY
    By the time you get done modifying the 3gen fuel unit you will have hacked off the fuel level sending part of it. I ended up installing an aftermarket fuel level sender elsewhere on the top of the tank.

    http://www.nastyz28.com/MikeM79Stuff/Stuff/3Genfueltank.jpg

    http://www.nastyz28.com/MikeM79Stuff/Stuff/3Genfuelsender.jpg

    I used a section of 3 inch exhaust pipe then welded that to a tray that I fabbed from sheet metal. I wish I had a pic...but I don't. The whole thing ends up "L" shaped and will drop into the tank if you have measured carefully enough. Lots of trial and error fitting to get it "just so".
     
  6. OldSchoolFormula

    OldSchoolFormula Veteran Member

    110
    0
    May 26, 2004
    Livermore
    Hmmm, so it might actually be easier to just sump the stock tank, use an external pump, and use the stock 2nd gen sending unit and run the return to the stock 2nd gen lines. But then, the noise. :confused:
     
  7. schitzo

    schitzo Veteran Member

    1,300
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    Feb 12, 2005
    Minneapolis MN
  8. BonzoHansen

    BonzoHansen Administrator Lifetime Gold Member

    That looks really nice & clean. Do you plan on any kind of access panel from the trunk floor? Just curious.
     
  9. 1978LT

    1978LT Veteran Member

    16,280
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    Feb 24, 2002
    Poquoson, VA USA
    Just a side note, since you are using an auto I'd spring for up to a 3800 stall, but no more....or it will screw with the electronics ;)
     
  10. schitzo

    schitzo Veteran Member

    1,300
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    Feb 12, 2005
    Minneapolis MN
    thought about it...but I would rather drop the tank than cut the car
     

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