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Thread: Need block suggestions! Having issues

  1. #1
    Join Date
    Mar 2013
    Location
    Edmonton, AB, Canada
    Posts
    133

    Need block suggestions! Having issues

    Engine specs as of last build:
    -Thompson Motorsports 5.7l (Refurbished seasoned 5.3l)
    -72mm Magnum turbo
    -TU1 Custom Grind cam(spec speed.inc)
    -799 heads
    -GM MLS head gaskets
    -ARP head bolts
    -.660" Trick Flow dual valve springs
    -Titanium retainers & locks
    -7.400" Comp Cams Chromoly Push Rods
    -LS7 lifters
    -5.3l(LM7) rockers
    -Forged Probe Pistons 3.902" flat top
    -TMS Moly rings
    -4340 Forged scat I-beam connecting rod w/ ARP 8740 rod bolts
    -King racing bearings
    -Melling high pressure relief oil pump
    -TR6 spark plugs
    -"Muscle Car" oil pan
    -All other parts are stk 5.3l(LM7)

    So here's the story:

    Block #1: 5.3l out of a 120,000km 2001 Silverado
    Get on the dyno and after several weak pulls it starts venting bad. Pull the head Cylinder number 5 had a broken piston. After further inspection multiple pistons had cracks between the ring slots.

    Block #2:Thompson Motorsports 5.7l(bored from 5.3l) engine(The one described at the top of this post)
    Runs for about 15min while on the highway. I started accelerating going 130kmh with 5lb of boost. Engine locks up and wont turn over. Pull the block out- 3 cylinders cracked to the waterjacket, pistons are wedged in cylinder bore, and most of the rods are bent.(no damage on the gaskets or the head really, although the heads show signs of detonation.

    Block #3: Get warranty Thompson Motorsports 5.7l(bored from 5.3l) engine back
    Tried installing cam but it was very tight. Turns out the cam was bent from the last engine blowing up. Decide to get the whole thing gone through. Fix the cam, but the sonic test determines that the cylinder walls in some spots are .140". After doing some research a lot of people say it's ok for NA but not for boost(i plan on going up to 18lb).

    Additional info: Most parts have been reused several times now. I have used new head gaskets every time and got new head bolts as well.

    So: I have the first block still with some scoring in the cylinders and a freshly sandblasted lq4. What do you guys recommend I do? I am willing to buy a different block if need be, but if either of these could be used I would like to go that route.

    Any help would be greatly appreciated!

    I can post pictures if need be
    Last edited by shmiet; 05-12-2014 at 02:17 AM.
    Back Alley Motorsports 98 GMC
    -5.3l LM7 bored to 5.7l Thompson Motorsports -72mm T4 Magnum Turbo
    -TU1 Custom Grind cam(spec speed.inc) -799 heads
    -.660" Trick Flow dual valve springs -Forged Probe Pistons 3.902" flat top

  2. #2
    Join Date
    Dec 2008
    Location
    South Carolina
    Posts
    794
    what caused the first tms engine to lock up? im dealing with thompson right now and having some issues myslelf...
    2008 GMC Sierra SLE....370ci LY6 with some goodies SOLD
    1995 C2500- LS1 swap with a mp112
    build thread- http://www.ls1truck.com/forums/lsx-t...-ls1-swap.html

  3. #3
    Join Date
    Mar 2013
    Location
    Edmonton, AB, Canada
    Posts
    133
    What I am thinking is that the walls were too thin to begin with and with the light boost it split. They said they had no idea why it would break that bad but the only thing I can come up with is really thin walls. My engine builder wants me to go to a 4.8 just for the wall thickness to get a bulletproof setup. Ive already spent about $16000 on this project and I'm pretty sick of it. I am glad Thompson gave me a warrantied engine but when I sent it back they kept my head dowels($22 in Canada for 4) and they didnt clean out my oil pump or give me a new one. I pulled it apart myself to get the particulate out. Im really not too pleased

    And to top it off I'm stuck with a $3500 short block that I cant boost
    Last edited by shmiet; 05-12-2014 at 10:09 AM.
    Back Alley Motorsports 98 GMC
    -5.3l LM7 bored to 5.7l Thompson Motorsports -72mm T4 Magnum Turbo
    -TU1 Custom Grind cam(spec speed.inc) -799 heads
    -.660" Trick Flow dual valve springs -Forged Probe Pistons 3.902" flat top

  4. #4
    Join Date
    Dec 2008
    Location
    South Carolina
    Posts
    794
    yea that sucks. The 5.3 and 4.8 use the same block. The 3.902" is the pushing it on the 5.3 block imo. Iv always ran a 3.89" (factory ls1 bore size) bore when i punch out a 5.3 block and never had any problems
    2008 GMC Sierra SLE....370ci LY6 with some goodies SOLD
    1995 C2500- LS1 swap with a mp112
    build thread- http://www.ls1truck.com/forums/lsx-t...-ls1-swap.html

  5. #5
    Join Date
    Mar 2013
    Location
    Edmonton, AB, Canada
    Posts
    133
    Hmm, so do you think I should do the iron 6l or bore out my scored 5.3 to 3.89"?
    Back Alley Motorsports 98 GMC
    -5.3l LM7 bored to 5.7l Thompson Motorsports -72mm T4 Magnum Turbo
    -TU1 Custom Grind cam(spec speed.inc) -799 heads
    -.660" Trick Flow dual valve springs -Forged Probe Pistons 3.902" flat top

  6. #6
    Join Date
    Dec 2008
    Location
    South Carolina
    Posts
    794
    Do you already have an iron 6.0?
    2008 GMC Sierra SLE....370ci LY6 with some goodies SOLD
    1995 C2500- LS1 swap with a mp112
    build thread- http://www.ls1truck.com/forums/lsx-t...-ls1-swap.html

  7. #7
    Join Date
    Mar 2010
    Location
    Paris
    Posts
    305
    You probably could of built a 370 or 408 for what the iron 5.7 cost.
    Truck: 05 GMC CCSB SLT Z71,
    Go Faster: 5.3, 219/227 .607/.614 112, milled heads, eBay CAI, Circle D 2800, 3030 Built 60E, E-Fans, 3030 Tuned, LT's, Spintech Muffler, DuraGrip w/ 3.73's
    Look Better: 10K HID's lows & fogs, tinted Chevy tails

  8. #8
    Join Date
    Nov 2007
    Location
    Pittsburgh, PA
    Posts
    3,581
    Plenty of ppl made power with a iron57

    TMS may just not have their A game going on
    Also you get what you pay for..if a motor price is too good to be true it probably is

    I wouldn't run a TMS motor
    2002 Lightning - GT headed 5.5Litre w/ Twin 7665s
    2002 Silverado - 427Lsx w/ Twin gt4202s
    2010 Silverado crewcab Z71 - 5.3litre w/ procharger
    2000 Wrangler - 5.3litre with some stance
    2014 Xsport- 3.5 Eco boost
    412 Motorsports

    it ain't that I'm too big to listen to the rumors, It's just that I'm too damn big to pay attention to 'em..That's the difference

  9. #9
    Join Date
    Mar 2013
    Location
    Edmonton, AB, Canada
    Posts
    133
    Quote Originally Posted by chvy=power View Post
    Do you already have an iron 6.0?
    Ya I have it. Its been blasted so Ill do a slight bore and go from there. Neil @ Horsepower Solutions up here is telling me that its the way to go, considering he's got one of the fastest quarter mile LSX cars out there I'm gonna take his word for it haha.
    Back Alley Motorsports 98 GMC
    -5.3l LM7 bored to 5.7l Thompson Motorsports -72mm T4 Magnum Turbo
    -TU1 Custom Grind cam(spec speed.inc) -799 heads
    -.660" Trick Flow dual valve springs -Forged Probe Pistons 3.902" flat top

  10. #10
    Join Date
    Mar 2013
    Location
    Edmonton, AB, Canada
    Posts
    133
    Well its a little late not to run the motor haha. And as far as getting what I payed for goes, I've heard similar stories from guys who have bought LSX blocks and had similar problems within 10 min of running it.
    Back Alley Motorsports 98 GMC
    -5.3l LM7 bored to 5.7l Thompson Motorsports -72mm T4 Magnum Turbo
    -TU1 Custom Grind cam(spec speed.inc) -799 heads
    -.660" Trick Flow dual valve springs -Forged Probe Pistons 3.902" flat top

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