The International Cessna 170 Association

I just read a post at AVWEB by RAM engines

They show a cut away of cylinder loaded with rust.

I immediately wondered if they loaded their presentation with a dose of lamentation.

Which leads me to ask question on the forum.

What type alloy are pistons for Continental C 145 made?

Good luck in finding that out . That would be a state secret with continental .however I am watching with interest .

Curious, what would you do with that information if you had it?

Pretty sure it's a common aluminum alloy used by lots of engine mfr's.

Not bad question but I don't know, I've never needed to make one, when buying them was always an option. I did meet
A man that played a part in designing pistons for WW II planes, wish I had listened more intently at the time

The majority of piston engines use aluminum alloy heads threaded onto a steel barrel, which is nitrided or cyanide-ed on the inside. The c 145 fits this category.

According to Combustion Technologies high silicon 4032 is "common to most aircraft pistons - Lycoming and Pratt & Whitney". Here's an interesting article about the challenges of certifying a new piston. It mentions the involvement of Guido Perla who once had a link on our website to his "Bird of Prey" restoration. As the O-300/C-145 is 1940's technology I wouldn't be surprised if it used 2018 aluminum alloy like the W-670 did.

If i knew the alloy type I would then try to learn its coefficient of expansion.

The video by RAM seemed to imply that many owners were doing something wrong by taking aircraft out of hanger running 5-10 min and shutdown rehanger. I have never know anyone to do this.

Were they implying piston/cylinder clearance scuffing ?

http://www.engineeringtoolbox.com/linea ... -d_95.html

Google

https://www.quora.com/What-is-a-suitabl ... -IC-engine

Thank you D Wood for that response.That was very good as i have wondered what was made up in making a engine . I asked the Chief bottle washer at Superior once and he was very evasive and when pushed he explained it was a secret recipe of herbs and spices.

They were probably implying internal moisture issues due to not getting the engine (and oil) up to temperature.

flyingredyeti wrote:The majority of piston engines use aluminum alloy heads threaded onto a steel barrel, which is nitrided or cyanide-ed on the inside. The c 145 fits this category.

I'm pretty sure you misunderstood the question and are referring instead to cylinder construction. (Although some pistons have steel inserts to support ring-lands, none apply to our most common engine.)

gahorn wrote:

flyingredyeti wrote:The majority of piston engines use aluminum alloy heads threaded onto a steel barrel, which is nitrided or cyanide-ed on the inside. The c 145 fits this category.

I'm pretty sure you misunderstood the question and are referring instead to cylinder construction. (Although some pistons have steel inserts to support ring-lands, none apply to our most common engine.)

You are correct. I somehow overlooked the "piston" in the question, and was referring to cylinder construction. Sorry about the superfluous response.

Follow up to my senseless 2 cents: as I understand it, the issue RAM is referring to is the act (and I don't know who does this either), of running up the engine, for a very brief period only, for long bouts of hangar time. The problem there, as I understand it, is that the protective coating of oil in the cylinders is wiped away, and without running the engine long enough to fully circulate fresh, warm oil through the system, some internal surfaces, such as the barrels, are left bare of their protective coating. This leaves them unprotected from naturally occurring moisture in the engine (condensation), during extended sessions of inactivity.

On the other hand, I feel like I'm missing something here, as the engine run time suggested in the video seems quite long. Perhaps it's an interpretation of the minimum run time suggested by Lycoming, and perhaps Continental, per month.

The major problem I personally have with short run-times of engines which are actually in storage is.... the run time does not get the oil temp up high enough/long enough to drive water vapor out of the crankcase/oil and is a setup for corrosion of all surfaces. It's better to properly preserve and keep the engine preserved and dessicated/plugged.

I once observed an engine which had been so mistreated placed back into operation...(or at least the attempt was made)... and within a few minutes of running the engine coughed, and ran so rough it had to be shut-down. Stuck valve, bent pushrod, damaged piston-head.
The owner had religiously run it up for 10-15 minutes every month or so for 3 years thinking he was keeping it lubricated and excersized so that when the time came ...it could be put back into service. Nothing could have been worse, in my opinion.

I once owned a Baron with IO-470-L Contnentals which had been remanfr'd by LC Smith in the early '70s., run about 800 hrs, and then sat in Florida (New Smyrna Beach) OUTSIDE for seven years without starting or running. When I bought it, we changed the oil immediately, and flew it to Texas where another oil change was performed. They were oil-screen engines. (no filters) A month or so later I took it to a Beech service seminar where the TCM field rep. boroscoped them, showed me where the steel cylinders on one engine had rust above the ring-wear areas in the very top of the cyls and where the other engine had Channel-chrome cyls and did not show rust. At this point, they were 30-year old overhauls. His job was to sell engines and overhauls/remans from TCM. His advice? Keep running them.
I did...for 4 years, then sold the airplane in 1999 to someone who still has it and still running those same engines well past TBO. It doesn't fly much each year, but he believes me when I advised against short ground runs.
Bottom line: Either fly it or preserve it. No ground runs unless you want to add water to your oil.