Another boring question :)

[BigBadLou]

For the mechanics out here:
An automotive block can be bored out a little and pistons installed with new rings to accommodate the increase in cylinder bore.
An aeromotive block has limited thickness of the cylinder walls so I wonder whether any boring at all is allowed and how much.
As an example, for this mental exercise, let's look at a typical Cessna IO-360.
And if this is done to an engine, is that pretty much what they call "top overhaul"? (I realize that might include additional work, such as valve and seat lapping etc)

Just curious about this process with air-cooled blocks.
My apologies if this has already been posted, I searched this forum for a similar topic and did not find one.

 

[Unit74]

I'd like to know if doing this would result in an appreciable increase in HP as well. And if legal!

 

[tyndall]

Cylinders can typically be bored .010 and .020. Not done too often. Usually it is a problem with the valves or head cracking that puts a cylinder out of service. Boring out is mainly for corrosion or scoring. No real increase in HP.

A top overhaul is usually new or overhauled cylinders. Overhauled can be anything from a cheap cleanup to new valves, guides and seats.

 

[coloradobluesky]

There is no water jacket on the "boxer" style aircraft engines so you don't have an "engine block". What they bore out is the cylinders, which attach to the "case" (the case most closely analagous to an engine block). Case is two piece and bolts together
https://www.google.com/search?q=dra...=g0GAV6iNIMv8jwOfsK6oCQ#imgrc=Pz-U_FhCAznxuM:

 

[Skip Miller]

...and Cessna doesn't make engines. Lycoming and Continental do. I bet you know this! -Skip

 

[BigBadLou]

LOL I wrote "Cessna IO-360"?? I don't recall. Somebody must have modified my post. We have gremlins on this board!
Really, Friday afternoon post, my brain was already up in the air. LOL

Got it, boring cylinders only for corrosion or scoring, i.e. to improve compression I assume.
Thank you for the answers.

I better re-read my next Friday post.

 

[jaybee]

Technically, for discussion's sake, if you overbore your engine it will increase the compression. Not by an appreciable amount but it does.