Feedback needed on Porting & Polishing

I've been asked to do an article on Porting & Polishing for The Aviation
Consumer as it pertains to certified engines. Would like some user
feedback, good or bad.

If you have a certified aircraft and had your cylinders Ported and Polished:

- Why did you do it?
- How much did it cost (per cylinder)?
- Did the shop flow match or use a flow bench? ("Don't know" is okay
answer.)
- Did the shop do a fancy valve grind as part of the package?
- If you flew the engine before the change, and if that's all that
changed (i.e. no higher compression pistons) can you tell any
difference in performance? Any WOW! factor?
- How did climb, top speed, cruise speed and fuel burn change?
- Any problems related to P&P? (any cylinder cracking in the head?)
- If the shop worked the valves, did you have any problems with
valves before and are you having any problems now?
- What kind of paperwork, if any, discusses the modification to the
cylinders?
- Was it worth it? Would you do it again?

I would appreciate your input. Please respond to

mppalmer at a o l . c o m

Thanks,

Mike Palmer

Light Plane Maintnance had an article on porting and polishing in the May
issue, and it was written by Mike Palmer.
If you are Mike Palmer, why are you asking again and why don't you use
you're own email address?





"JohnSmith" wrote in message
news:SQ3he.10087$D91.6833@fed1read01...
I've been asked to do an article on Porting & Polishing for The Aviation
Consumer as it pertains to certified engines. Would like some user
feedback, good or bad.

If you have a certified aircraft and had your cylinders Ported and
Polished:

- Why did you do it?
- How much did it cost (per cylinder)?
- Did the shop flow match or use a flow bench? ("Don't know" is okay
answer.)
- Did the shop do a fancy valve grind as part of the package?
- If you flew the engine before the change, and if that's all that
changed (i.e. no higher compression pistons) can you tell any
difference in performance? Any WOW! factor?
- How did climb, top speed, cruise speed and fuel burn change?
- Any problems related to P&P? (any cylinder cracking in the head?)
- If the shop worked the valves, did you have any problems with
valves before and are you having any problems now?
- What kind of paperwork, if any, discusses the modification to the
cylinders?
- Was it worth it? Would you do it again?

I would appreciate your input. Please respond to

mppalmer at a o l . c o m

Thanks,

Mike Palmer

Light Plane Maintnance had an article on porting and polishing in the May
issue, and it was written by Mike Palmer.
If you are Mike Palmer, why are you asking again

I was asked to rewrite the story from a user's perspective. The article
I wrote in LPM was from a mechanical perspective. I didn't supply any
user feedback in the LPM article. I'm asking for it now.

and why don't you use you're own email address?

Because I don't wish to get spammed by the spambots that troll the
newsgroups.

You can email me at the mppalmer at a o l . c o m address (without the
spaces) if you have input for the article.

Thank you,

Mike Palmer

Well, I'll give a data point of one.
Back in 1985 or so, I had a IO-320 that dyno'd at 181hp. During that
era, TCM cylinders could vary 8-9 per cent. Lycoming cylindersw could vary
up to 17%. An acceptable matching would have all within less than 2%.

I haven't seen it first hand but I been told by reputable sources that the
latest generation of PMA investment cast cylinders are within 2%. And that
generally these will show on dyno's, 3-5 % higher HP figures on the
average.

regards,
Kent


"MikePalmer" wrote in message
news:y4hhe.10190$D91.1571@fed1read01...
Light Plane Maintnance had an article on porting and polishing in the
May
issue, and it was written by Mike Palmer.
If you are Mike Palmer, why are you asking again

I was asked to rewrite the story from a user's perspective. The article
I wrote in LPM was from a mechanical perspective. I didn't supply any
user feedback in the LPM article. I'm asking for it now.

and why don't you use you're own email address?

Because I don't wish to get spammed by the spambots that troll the
newsgroups.

You can email me at the mppalmer at a o l . c o m address (without the
spaces) if you have input for the article.

Thank you,

Mike Palmer

The one owner I know had his Lycoming 0-360 ported and polished when it
was rebuilt and it was a disappointment. If anything the engine
performed worse after the rebuild. I know it is a data point of 1 and
might be due to other factors, but that is what he experienced. My take
is Lycoming ports and polishes pretty good. It might be possible to
improve it, but I've never seen the evidence. It's a pretty inexpensive
procedure to change it as they port and polish anyway, and if there
were a better way to get more flow, Lycoming would do it. Porting is a
bit of a black art, sometimes it works and sometimes it doesn't, air
flow being the random thing it is. Lot of people try, it is fun to look
at those compound curves and nice polished surfaces and think you might
be able to improve it or enhance it. I certainly wouldn't pay any more
for a custom port job, and I'm not sure there are any STC's for it
anyway, which supposedly you would need as it is a change in the engine
configuration.

He stated he would not do it again.

Sorry I can't be more hopeful.