AdamMRTwo

So I just tore down my recently rebuilt turbo GSR motor after cracking sleeve 1 on the track. Motor was put together by me with some very experienced help. Proper tourqe was applied to both rods and mains, as well as having block checked for for any out of round mains by machine shop. Bearing clearances on mains were on looser end of spec, on 1,2,4, and 5, and a bit tighter on 3.

New Manley alas rods, LS crank, all std size ACL mains and rods. About 200 miles of run time on them.

All were within Honda spec. I don't remember exact numbers and I know that isn't ideal (lost my paper w numbers written down) but I'm seeing some of what I consider peculiar wear on the main bearings and am curious on any opinions.
The wear seems really inconsistent and sporadic. These are pics of the tops of the mains.

I have heard 2 different theory's now about possible issues, one being a Line Bore issue, the other being a main bolt lack of tourqe issue. So I'm looking for anyone with experience to tell me their opinions. Do these show an obvious issue or does it look fine? Thanks





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motoxxxman

1 2 and 5 look like a line bore issue. 3 looks normal. 4 looks like someone took a scotchbrite pad to it.

what's with all the scratches? some of em look pretty nasty, especially the wear on 4.

also, I'd need to see the other halves of each to properly give an opinion on the wear. the lower halves are the ones that see the highest load anyway. the top halves really just help hold the crank in place, no real load on them besides inertia

to give you an idea on uppers vs lowers, I rebuild mine fairly often, and I usually replace the lowers 1 to 3 times before ever touching the uppers. some builders will ask why. I answer with; because I can, and it's cheaper.

LightningTeg

Just curious why do you feel the need to rebuild often?

motoxxxman

I rev higher than I should with a terrible rod/stroke ratio and heavy pistons, my engine series is known for minor oiling issues in rod 3 that noone has ever been able to officially determine the cause of, and I still use oil squirters in the rods which sometimes flakes the bearing coating off around the hole in the bearing shell which then sometimes scores the rest of the bearing as it works its way out.
and, because I can
And because I race autocross, which sloshes the oil up away from the sump more than you might imagine during some manuevers that even overfilling doesn't always prevent.
I also do a LOT of testing of all sorts of engine related parts, and lots of dyno sessions often including fairly aggressive tuning, and occasionally surpassing the limit of pump gas purely to find the true limit of each setup. All of which at times will fatigue or collapse upper rod bearings and lower main bearings. even with a det can, minor det and pre-ignition is very difficult to hear in my motor, which is why my next project is a custom head chamber design with heavily modified quench areas to replicate B-series vtec heads, for a better burn and anti-det characteristics, and with hopes of a side effect being more audible det and pre-ignition

AdamMRTwo

So here are the lowers 1-5. Scratches are from engine builder checking clearances multiple times with dial bore gauge. I'm curious your reasoning behind believing it's a line bore issue? Just trying to fully understand what makes you believe that for my own knowledge lol



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motoxxxman

yeah that looks like align bore. or possibly the mains not being torqued in proper sequence or to proper spec.

reason I say align bore is because the wear is quite uneven. some have more wear on the top half, some have more wear on the bottom half, some have near zero wear, some have wear on both upper and lower. and the wear on a few of them is tapered across the width of the bearing shell.
seems the bores might be slightly out of round, slightly out of taper, and slightly misaligned.

or you have a bent crank, which could also cause all the above