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LQ9/LQ4

Discussion in 'General Discussion' started by mobileaudio25, Jan 11, 2018 at 10:50 PM.

  1. mobileaudio25

    mobileaudio25 Master Mechanic

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    Im going forced induction so I’m looking at the LQ4/LQ9 iron blocks. I plan on having the machine work done and dropping all new internals into the engine. I know the LQ9 has better pistons and rods, my question is since I’m going to beef everything up would I be better off looking for an LQ4 since they are normally cheaper? I’ve also read 2005+ is best if possible? I just want to make sure that other than rods/pistons the motor are identical, because if not I’ll pay more for an LQ9.

    I also am going to run a 4L80e did they ever come behind the LQ4s or only some of the LQ9’s? I’m assuming I’m going to have to reflash the computer no matter what.
     
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  2. Qdub24

    Qdub24 Royal Smart Person

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    The LQ4 is the better option for forced induction, lower compression ratio.
     
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  3. Turbolq4

    Turbolq4 Apprentice

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    The same years will have the same rods. Only real difference is pistons which changes the compression ratio. I agree with Qdub. The LQ4 is a better starting point for boosted applications but if you're going to really throw the boost to it then it needs forged pistons and rods anyway.
     
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  4. CaliWagon83

    CaliWagon83 Master Mechanic
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    LQ4 is also a lot more common and a lot cheaper than the LQ9.
     
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  5. vandall

    vandall Not-quite-so-new-guy

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  6. 87National

    87National Greasemonkey

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    How much power are you looking to make? Some folks are making 800 - 1000 whp on a stock gen 4 bottom end. Reliability may be an issue at that level.......but if your goal is closer to 5-600 whp.... I would get a good, low mile, stock 04-06 motor, re-gap the rings....and save the money you would have otherwise spent at the machine shop, on rods/pistols, etc.
     
  7. Turbolq4

    Turbolq4 Apprentice

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    $8300+ for one if those. Could build an angry machine for that kind of scratch. Didnt see what kind of warranty it has but I'm guessing it's nothing if you actually boost it.
     
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  8. 81cutlass

    81cutlass G-Body Guru

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    lq9 is higher compression but harder to find, only came in escalades, H2's, denali's.
    lq4 came in box vans, railroad service trucks, you name it. Came in long crank iron headed versions also.

    lq9 all have gen 4 rods which are ~850hp safe
    lq4 can have gen 3 which are ~650hp safe, or the gen4 if its 03/04ish or up.

    Both can handle 1000hp stock but it depends on how bad you want to drive over your rods at 130mph. If you aren't going to have a 10.0 cage and run a 275 MT ET Pro all the time a gen 3 is fine totally stock. The chance of hooking a 850hp stock bottom lq9 and blowing the rods out the side and not already dumping 10G of chassis work in to handle it is low. By the time the car can handle 850hp your going to have enough money in tripple 450 fuel pumps, cage, bump boxes, boost controllers, and other stuff that you will have put rods and pistons in long ago.

    Buy a 03 2500 work truck lq4 and 80e, pull drivetrain out, drop it in G body. Savannah van works too.

    Most lq9's had an AWD 60e. 80e really didnt come come in until 2500's and vans and the lq4 was what you got there. Im sure GM bolted 2wd lq9 to 4l80e but its going to be like finding hens teeth.

    Buy engine, swap cam and valve springs, and call it fine. Bonus is if you get a 150k mile one the rings are pre gapped for boost :) Basically the rods fail well before the rod bolts do, cranks don't flex until 1300hp+, and putting head studs doesnt do much because the decks flex due to thickness or they push water due to agressive timing and bend rods long before the heads lift due to poor clamp load.
     
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  9. motorheadmike

    motorheadmike Royal Smart Person

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    But, but, but... everyone wants 1000hp.

    I agree, find a nice stock Gen IV engine and tweak it. There is no good reason to incur the expense of a fresh build - unless you hate your money.
     
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  10. mobileaudio25

    mobileaudio25 Master Mechanic

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    I like the idea of that. Could save a thousand or so. I guess I could always rebuild the motor down the road when I want more out of my build. I’m looking to make 500 to the wheels. I have a built 8.5 in and anything more and I’ll need a 9” I think.
     
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