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Building Motor Should I Boring Anymore.


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Ok im kinda stuck. 3 years ago i lost #7 piston it cracked cause of a bad tune or so we thing. well i pulled the Stock LQ9 and i took it to my builder. at that point i was on a very tight budget. i told him to just put new set of stock pistons in it and refreshen everything else up. Well he went a head and bored the block .020 over and put it all back together. well after about 3k miles i bent a rod. So im to the point where im going with forged internals. but my stock LQ9 is already bored over .020 so is it worth it to bore it another .010 to get a 370. Or should i just have custom pistons made for a .020 bore. the cylinders look great cause it only had 3k miles on it. this is going to be boosted. heres a pic of the cylinders and all of them look this way.

IMG_3251.jpg

Edited by shawnss (see edit history)
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if you can clean it up @ 4.03 that will save you the most as off the shelf pistons are available and are cheaper than custom .

 

btw how did he use stock size pistons on a 4.02 bore?

Edited by 04CHASE (see edit history)
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if you can clean it up @ 4.03 that will save you the most as off the shelf pistons are available and are cheaper than custom .

 

btw how did he use stock size pistons on a 4.02 bore?

To tell you the truth I was wondering the same thing myself. That's what my builder told me. It was the first LS motor he has ever worked on. Funny thing is the first go around he ended up putting one 4.8 rod in it. Well I put the heads on and tried turning the motor over. Well that didn't work so well. The rod was way to long and was hitting the head. I ended up having the pull the motor back out of the truck. I lifted the heads off and found out that #7 rod was a 4.8 rod. What a bad mistake on his part. Needless to say ill never use him again. But I know the cylinder is bored .020 over. We measured it after the last tear down.

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I would certainly just go to a 4.030 bore just because now you also have to trust his machine work. I also agree with Chase, the bigger question is whether or not to just stroke it while you're there. It sounds like you will need to buy rods and pistons anyway which will just leave a crank keeping you from a much better 408. A 408 would be much stronger when not in boost and be considerably quicker in spooling the turbo.

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thats way to much . i woundt go past 4.060 on a 6.0 block for n/a and 4.040 boosted.

 

the 6.2 blocks can be taken that big not the 6.0s

 

Thanks Chase. I didn't know & wanted to... now I do. So putting a 4" stroke crank in a stock 4" bore 6.0 block will make it a 408?

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