carguy516

Might look at an 01 with 79k tomorrow but the seller said it's bored over .025 with the ap2 trans. Is that a good thing/bad thing. Does that mean the motor was blown and rebuilt? Is there anything wrong with buying it?

Miasma

It means they bored out the engine's cylinders which essentially means blown then rebuilt. Maybe they did a good job, maybe they didn't. I would personally steer clear unless you REALLY trust them and whoever did the work.

s2000Junky

Yep. This boring over is common when rebuilding an engine, because the the cylinders either got scored or ovalized, and without over boring to the next size up, the piston and rings would otherwise never seat properly. .025 is just taking the minimum amount of material out of the bores to accomplish a new proper bore.

carguy516

Thanks for the advice, ill pass on that car.

jetrep

More specifically, it means the diameter of the bore was increased by .025" Larger pistons are then installed. This is not a large enough increase to be considered a performance improvement...this minor increase is typically done to clean up a damaged bore

ron1999

for whomever knows that -
as the F20/F22 cylinder bores are carbon-aluminum hybrids,
does over-boring them leaves enough material to keep the structural rigidity of the original sleeve?

rpg51

In general over bore is something that you do when an engine has been damaged somehow - usually just old age, maybe somethings else - such that oil is coming past the pistons into the cylinders. Often it is scoring on the cylinder walls just from age - but there can be other causes. The fix is to re-bore the cylinder walls to a slightly larger diameter and install oversize pistons and new rings all designed to match the new bore size. It is done in different ways on different engines. But it is a good solid fix and will return the engine to like new performance so long as it is done correctly. Sometimes if you have the engine apart for another reason you might do this on a high mileage engine even if the existing cylinder walls and rings are ok just to extend the life of the engine when you put it back together. So unless there is some other explanation for the over bore I would want to know what happened to this engine and why it was re-bored. Also, I would have assume that this engine rebuild will impact the fair market value when compared to a similar car without an engine rebuild and you have to keep that in mind when pricing the car.

rpg51

There should be manufacturers specs on this. Anyone know?

hecash

I'm assuming that the block was "honed" and not bored to the 0.25mm oversize. Honda offers both the proper hone for this process and OEM pistons and rings in the 0.25mm oversize as replacements for the original production line components. If a Honda hone was used by a reputable machine shop, the pistons/rings are Honda OEM replacements and the bearings were properly sized (quite likely), then I would not have any issue with such a block.