[email protected] (Dave Williams)
gnttype  11 Feb 1996
- -> motor back together, I'm just going to rehone the cylinders, put in
  -> fresh rings and fresh bearings, new cam and lifters, and get the
  -> heads done.  No need to bore anything.
- There's some interesting information in the backs of the TRW, Hastings, and 
  Speed-Pro ring catalogs.  All three recommend that, if the walls aren't 
  scored and the ring gaps are okay, that you do *not* hone or use new rings.  
  I used to automatically hone and rering when I could, but now I don't feel 
  nearly so bad about a few I just basically cleaned up and put back together. 
- For another chuckle point, some people, books, and articles go on at length 
  about how awful it is to spiral rings on and off pistons, how you should 
  always use an expander tool, etc.  I just bought a set of high-zoot Speed-
  Pro .060 moly rings for a stroker motor, and the instructions show you how 
  to install them by spiraling them on... 

[email protected] (Dave Williams)
Ford  22 Jun 1998
- -> the cylinder wall by about 50%. One way of doing this is to use a
  -> laser to create pits surrounded by hardened areas on the wall
  -> surface. Subsequent final honing grinds off any protruding peaks on
  -> the surface but leaves the pits. Both the pits and the slightly
- Mazda has been doing something roughly similar for years on their Wankel 
  engines.  Or were; I don't think they make a Wankel any more, now that the 
  RX7 is dead. 
- Back in WWII, plain old cast-iron cylinders, normally quite effective, 
  proved to be unsuitable for 5" bore military aviation engines. Entire 
  cylinders were forged from chrome moly steel, heat treated, ground to size 
  inside, chrome plated, etched, and polished.  Those engines had to last a 
  thousand hours at full power to get their type rating.  That'd be the 
  equivalent of going to a big oval track like Indy or Talladega and keeping 
  the hammer down for 30,000 miles. Unfortunately piston rings and valve seals 
  weren't up to modern standards; oil consumption was rated in gallons per 
  flight. 

email  20 Nov 1998
>-> cylinder walls to allow rapid ring sealing. These hones look like
>-> bottle brushes with a little dingleberry marble of carbide at the end
>-> of each bristle.
>
> Yep.  A few years ago those were the hot setup.  Nowadays the ring
>manufacturers want a smoother finish than the Brush Research hones
>provide.  I have some of their technical papers and like the idea, but
>they haven't come out with hones in finer grits yet.  Modern rings want
>something close to a mirror finish.  When boring oversize, I usually
>step down 150-220-280-400-600.  Next time I have some spare bucks I'm
>going to pick up one of the plateau hone sets.  They have silicon
>carbide bristles instead of stones, but they fit regular stone holders.
>I have one of the larger brush type units, but it gives something like a
>220 finish; I do much better than that with conventional stones, so I
>use the fancy expensive brush hone for cleaning out rusty cores.  
>
>
>-> The article quoted some shop that builds WWII aircraft engines for
>-> racing, and it said that without this honing, motors took 20 to 30
>-> hours to 'dry up' (not burn oil, I guess), whereas with the honing it
>-> takes 30 to 60 minutes.
>
> There's a major difference in cylinder walls there.  Most WWII aircraft
>engines used cylinders that were forged from chrome moly steel, heat
>treated, internally ground, and chrome plated inside.  Cylinder wear was
>a major issue, as they has to pass type testing at 1000 hours at maximum
>power output.  Most car engines probably couldn't pass that... anyway,
>oil consumption was not an issue.  Some of those things used many
>gallons of oil *per flight*.  See if the library can get a copy of
>Graham White's "Allied Aircraft Engines of WWII" for you through ILL; in
>many ways, even the ever-so-highly-PR'd Formula 1 stuff is still behind
>1945 aircraft fangleage.  
>
>
>-> What do you think?
>
> Engine building is like programming; there's no One True Way.  I like
>to keep an eye out on what other people are doing; sometimes I think
>they're on to something and I'll emulate, sometimes I think my way is
>better.