Fraunhofer Institute for Machine Tools and Forming Technology Honing

[Superfuelgero]

Was looking over this
New engine-making tool should result in more fuel-efficient cars

And was wondering what the difference would be between torque plate honing while the block was heated to operating temp (hot hone). I imagine this method, while more expensive would be better for tool life.

Also if this method could be used for file fitting piston rings to tighter tolerances (plus a margin for elevated temps).

[smokey442]

Assemble block and head with gasket and fasteners that you intend to use. leave out crank, rods and pistons. Circulate 200 deg. water through the coolant cavity. Hone from the bottom with stones designed for a blind hole. If you use Total Seal gapless rings you will achieve 100% cylinder sealing all the time. Pull an 8" depression in the cranckcase for even more gain.

[gone-ot]

Someone needs to invent "self-gapping" rings, ie: steel rings having a bimetallic "plug" across the location where the two ends of the ring "meet"...such that "normal" operating friction temperature expands the bimetallic plug just enough to expand the ring into optimum cylinder wall contact.

And, a similar approach could be applied to re-adjust--ie: "contract"--piston ring contact 'away' from the cylinder when the temperature is TOO high.

[Superfuelgero]

Interesting method for honing without a torque plate, kind of old school. I would worry about ridges though.

How would you pull vacuum under this situation though? I'm used to using vacuum to check post machining, but not during. If you have any links please post, because the only reference I can find is LS engine related.

With gapless, do you think erring towards 12ra or lower is possible?

[smokey442]

The final finish is dependent on the ring material you intend to use. Example chrome needs a more aggressive finish vs moly faced or filled. I use Sunnen equipment. Old #s were an300 for chrome, an500 for moly. Use engine vacume to pull a depression.

[Cobb]

Ive always wondered how they machine the crotch rocket sport bikes that have oval shape cylinders.

All we had was a torque plate for boring. Our main concern was magnafluxing stuff to look for cracks.