6.0L bottom end and machining
6.0L bottom end and machining What are yalls opinions on rebuilding lq4 bottom ends? What mileage is good enough to not touch? What mileage would you re-ring? Would you put all new bearings in? New rod and main bolts and resize rods and main caps? Motor would be n/a no more than 550hp
If you want an engine to last, mileage in an of itself is no basis to judge the condition of an engine on. unless you've owned the motor it's entire life, there's no way of knowing how it was driven or maintained.
Case in point - I bought a motor with 38k miles on it thinking I'd simply be able to drop it in and turn the key. I didn't want any surprises, so I checked it out anyway. Turned out that rod, main, and cam bearings were all shot. Piston to bore clearances were excessive, and the crank had a casting defect on one of the main journals.
If I wanted a reliable 550 hp motor, I'd be taking everything apart to take measurements to see what I could re-use and what I could not. Re-ringing would depend on the condition of the cylinder bores - if there's no huge amount of o-o-R or thrust side taper then I'd probably do a clean up hone to knock of the glaze and throw new rings on to help my compression. New bearings are a no brainer given that they are relatively inexpensive to replace. At 550 hp, ARP hardware on all the critical components I'd say is a good idea. Rod bolts are good insurance - though I opted to put that associated machining cost towards aftermarket forged rods instead. I also installed main studs but ended up not needing a line hone. You'll need to check yours to be sure though.
Just my 0.02.
Case in point - I bought a motor with 38k miles on it thinking I'd simply be able to drop it in and turn the key. I didn't want any surprises, so I checked it out anyway. Turned out that rod, main, and cam bearings were all shot. Piston to bore clearances were excessive, and the crank had a casting defect on one of the main journals.
If I wanted a reliable 550 hp motor, I'd be taking everything apart to take measurements to see what I could re-use and what I could not. Re-ringing would depend on the condition of the cylinder bores - if there's no huge amount of o-o-R or thrust side taper then I'd probably do a clean up hone to knock of the glaze and throw new rings on to help my compression. New bearings are a no brainer given that they are relatively inexpensive to replace. At 550 hp, ARP hardware on all the critical components I'd say is a good idea. Rod bolts are good insurance - though I opted to put that associated machining cost towards aftermarket forged rods instead. I also installed main studs but ended up not needing a line hone. You'll need to check yours to be sure though.
Just my 0.02.
I bought and LQ9 from LKQ Corp salvage yard with what they claimed to be 55k miles. I have been street driving and drag racing it for 2 years. It runs strong, does not smoke and burns not a drop of oil.
When I bought it, I merely installed a cam, ported heads, painted it and put it in the car. You can see the drag strip times in my signature.
When I bought it, I merely installed a cam, ported heads, painted it and put it in the car. You can see the drag strip times in my signature.
TECH Fanatic
Joined: Jul 2011
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It is a case by case basis. Like others have said I have worked on 150k mile engines that were maintained and treated well that ran like clocks but I have also seen 50k mile engines that were completely clapped out. Depends on how the engine was treated and maintained.
If you do rebuild, make sure your machinist is familiar with the LS family.
I had to take my pistons/rods back because 1-3-5-7 were pressed on incorrectly.
Gen III rods all face the same direction, make note of it with plenty of pictures during dissasembly.
I had to take my pistons/rods back because 1-3-5-7 were pressed on incorrectly.
Gen III rods all face the same direction, make note of it with plenty of pictures during dissasembly.
