.060 on iron block LQ4/9?
My old GEN Is i used to build would go .080 but they had some meat in the blocks cylinder area.
I would go smaller if you have the choice, or have any future plans for the block, after 0.060" most people junk blocks for street applications.
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Can you share the sonic test results? I only went .005 over on my 400,000 mile block for future overbores and you could still see the cross hatch in the cylinders. The block cleaned up perfectly @ .005 over
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The rings may be lower tension than the SBC, but you're giving that too much credit. Most of it has to go to the PFI. Look how the TBI engines tripled the bore life with no change of iron or rings. Then TPI, then the LTx, then the Vortec, then the LSx. Ever more precise fuel control, ever less bore wear.
Excess fuel washes the oil off the cylinder walls, and that's when wear happens.
The LQ has plenty of iron for a 4.080" bore at the stock 345 HP level. The more HP you want, the less the overbore should be.




