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  1. #1
    Join Date
    Aug 2019

    1970 GTO LS Turbo

    Hello everyone, my name is Josh and I have a 1970 GTO to rebuild. It is complete but rough. I have torn it down to body, frame and powertrain left. It is a rust bucket. Bought another clean 70 GTO body out of Reno. After spending weeks, slowly realizing rebuilding a Pontiac motor by anyone good will cost a small fortune. I decided to go LS. I am shooting for a $15k budget. I am going to Turbocharge the LQ4 block out of a2005 H2. Its a 6.0L iron block, aluminum head truck motor. I am either going to fully build the motor or leave it stock. Shooting for 500-600 whp. 4l80E trans. Stock rearendwth 3.23s. Will post picks soon.

    stock rebuilt 4L80E or stage2-3 but cost is a factor
    summit pro LS pistons and rods stock length and bore because boost and thin walls after boring- .005 over max, -12cc dish pistons stock rod length, summit rings
    18x8 front wheels, 18x10 rear, 245/40r18 front tire, 275/40r18 rear tire
    .550 int/.550 exh cam from jegs
    Cam Motion full valve train kit, seals, retainers, dual springs, timing kit, pushrods, etc. or just PAC 1218 springs and stock hardware, with upgraded trunnion kit
    stock crank, micropolished
    LS6 intake
    80mm truck TB
    stand alone wiring harness stripped (by me)
    80 lb/hr siemens injectors Ev6
    flat truck 6.0 flexplate, with spacer/adapter and bolts
    corvette 58 psi fuel regulator
    450 lph pump with manifold and fittings
    EFI tank notched
    holley 302-2 oil pan with gaskets and pickup
    melling water pump
    LS9 head gaskets- on 4.00-4.005 bore block
    summit control arms fr/rr, springs, shocks,
    s475 turbo
    precision turbo 46mm wastegate and 50mm bov
    arp head studs
    summit stock oil pump
    speedmaster fuel rails
    summit intercooler
    160 deg thermostat
    summit sway bars and spindles stock height
    CPP or Right Stuff big brake kit
    HP Tuner Pro
    and probably some things i forgot

    Thanks. -JB

  2. #2
    Join Date
    Aug 2019
    I came back to post pics and it I harder than I expected. I guess I am unsure of how to do this haha. I will get pics up though. Any help is appreciated. Thanks- JB

  3. #3
    Join Date
    Oct 2004
    Its a pretty good start.

    A stock 4l80e rebuild with dual feed and recalibration will take you pretty far. Dont forget the converter$$$.

    I dont think the vette fuel regulator will work. You need boost referenced.

  4. #4
    Join Date
    Oct 2004
    Country Flag: United States
    Unless the LQ4 needs a rebuild (and usually they don't), I'd recommend leave it alone. Even on high mileage examples, they show very little bore wear. For the intake, use a Dorman LS2 and a truck 88mm throttle body.

    On the wheels, if you're running 245s, you'd be better off with 18x9s. Measure, but with the right offset, you may even be able to fit 255s on the front.
    Red Forman: "The Mustang's front end is problematic; get yourself a Firebird."

  5. #5
    Join Date
    Aug 2019
    Hey guys, thanks for the info. Keep the suggestions coming. The only thing I have bought so far is the LQ4 and a LS6 intake. Bought the LS6 because of the flow numbers were best for a stock intake other than the tbss intake but it was ugly and I would have had to change some stuff and more moolah!
    The LS6 bolts up, uses my existing tb with 3 bolts and after searching for dbw tb's I realized the cost to power increase was negligible, since I am going boosted anyway. Might port match the intake and tb though, who knows. The 4L80E in stock form is pretty stout from all accounts but they are costly for a
    beefy built stage 2-4. Think the stocker rebuilt with maybe a little something extra. Any thoughts? Converter I am thinking Circle D or Jakes. For fuel regulator, I chose the corvette because its a filter and pushes exactly 58psi to the rails. You think I should add an Aeromotive reg up front and somehow
    tie in a boost solenoid to give the computer fuel reference? Or what did you imply? Finally, the wheels I haven't bought yet, butI am finding it hard to find wheels I like that aren't $2000 a set so I was sticking with American Racing VN510's 18x8, 18x10 because they are cheap, look good, and that's what size they come in. Still may change my mind if I can find some with a 18x8.5 or 18x9. I have read 18x9 up front is doable on my car but difficult and has to be perfect to fit well and not rub. Thanks again. Can anyone recommend a trans shop for the 80e?

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