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Thread: difference between lq4 and lq9

  1. #1
    Join Date
    Feb 2004
    Posts
    24
    is there any other differences besides higher compression pistons?
    1999 6.0, 2500. headers, True daul exhaust, K&N, 3:73's, locker, Nelson tune

  2. #2
    Join Date
    Apr 2003
    Posts
    1
    I've disassembled several LQ4's and they had powdered fracture rods just like the 5.3's. I tore down a LQ9 from a 2002 Escalade last week and it had a much different rod. Looked like a cast steel and had all flashing removed and it had been shot peened. It also had a full floating pin with a bushed pin end. It was also a fracture rod. This motor had never been into so it was the rods it left the factory with.

    The block and crank were the same as the LQ4's.

  3. #3
    Join Date
    Apr 2004
    Posts
    231
    according to my GM manuals the only internal defference I can see is compression ratio:

    LQ4 = 9.41:1

    LQ9 = 10.08:1
    2005 Chevrolet Silverado 2500HD ECSB 2WD
    365 CID motor built by "Rex", Magnuson TVS 2300,WCCH StageII LQ9 heads, EDC Cam, SW Headers, Magnaflow Exhaust, CPT 4L80E, PI 2800 TC, TRACK: Real Racing 16x12 wheels, M&H DOT Cheater Slicks, STREET: Intro Pentia 8 20x10 wheels, BFG KDW's
    2008 Nissan Frontier KC VQ40 V6 AUTO 2WD.....Daily Driver
    2002 Honda CBR954RR


  4. #4
    Join Date
    Nov 2003
    Posts
    30
    The heads on the LQ9 are 71cc, is that the same as on the LQ4?
    2003 Nelson Performance tuned SS: MagnaCharger Radix w/ 2.75 pulley,
    Yank Pro Truck 3000, Comp Cam 212/218 558/563 115,
    ASM headers, MagnaFlow dual in/out muffler, Flex-a-Lite fans,
    160 deg stat. And last but not least, JAG Performance built tranny.

  5. #5
    Join Date
    Apr 2004
    Posts
    231
    I can't say for sure, but the books show all measurements and tolerances to be the same. My best semi-educated guess is the difference is with the piston, not the head.
    2005 Chevrolet Silverado 2500HD ECSB 2WD
    365 CID motor built by "Rex", Magnuson TVS 2300,WCCH StageII LQ9 heads, EDC Cam, SW Headers, Magnaflow Exhaust, CPT 4L80E, PI 2800 TC, TRACK: Real Racing 16x12 wheels, M&H DOT Cheater Slicks, STREET: Intro Pentia 8 20x10 wheels, BFG KDW's
    2008 Nissan Frontier KC VQ40 V6 AUTO 2WD.....Daily Driver
    2002 Honda CBR954RR


  6. #6
    Join Date
    Nov 2003
    Posts
    30
    Yea, your right it is the pistons. The heads are identical. 317 casting right?

    We just had a guy on the SS forum blow a motor and was asking about pisons to lower his compression so he could run more boost.

    I am just going to go with a 76cc chamber on my heads to get the same thing.
    2003 Nelson Performance tuned SS: MagnaCharger Radix w/ 2.75 pulley,
    Yank Pro Truck 3000, Comp Cam 212/218 558/563 115,
    ASM headers, MagnaFlow dual in/out muffler, Flex-a-Lite fans,
    160 deg stat. And last but not least, JAG Performance built tranny.

  7. #7
    Join Date
    Dec 2003
    Posts
    246
    the lq9 heads flow better to
    old set up: 2002 chevy 5.3, procharger 12lbs boost, asm headers, ls1 edit, flames, 20inch budniks

    New Set up: 2004 chevy 5.3 ext cab, 12 inch twisted suspension lift, 36's, exhaust.
    future mods: 150-200 shot, ls1 edit, air intake, stall, 5.13 gears, 12s or bust

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