IO-540 Rust

[210TC]

The barrier is the plating. Nickel and silicone, which I am sure you have more knowledge about than I.

Here is some good stuff on valve train
http://egaa.home.mindspring.com/engine3.htm

[Green Hornet]

David,
The article brings up many questions:
1. When was it wriiten?
2. It is insinuated that Lycoming disagrees with the conclusions?

"1. Because of its design, the parallel valve cylinder is unable to transfer sufficient exhaust valve and guide heat to the atmosphere, despite normal cylinder head temperature, in some operating conditions. 2. Because of their design, the Lycoming mushroom style hydraulic lifters provide only a minuscule flow of oil to the rocker boxes of the cylinders. Significantly increasing this oil flow creates the second heat transfer path mentioned above. Our data shows that the addition of this path is successful in providing augmented exhaust valve and guide cooling that extends the longevity of those components which receive it."

3. Has their been any effort by Lycoming to improve on the design?
4. Does the same the same design effects all size engines?

"What you need to remember is simply that we have found an inverse correlation between oil flow to the rocker boxes and valve and guide distress. Valve/guide distress in turn places huge loads on the lobes of the camshaft during the valve opening sequence and we believe this is most likely the cause of Lycoming's camshaft problems, which also have never been formally solved. You also need to know that even if you do everything involving engine operation and maintenance perfectly, you may still encounter upper end problems if the mission of your aircraft involves extended flights with cruise power and cruise mixture set, regardless of CHT levels . This is the fault of the design, not of the pilot or of the mechanic who maintains the aircraft. In short, if you have this problem, there is nothing you can now do to prevent its continuation other than to fly at greatly reduced power levels and/or enriched mixture settings."
5. The Firewall Forward STC (holes) offsets this issue?

I know lots of questions but that is the learning method that works for me

[210TC]

Yes, sure does bring up allot of questions. The author is very knowledgeable without a doubt.
I just think the more info we read and ask question about, the more powerful we become.
This tells me it is much more important to pull the valve covers on the odd cylinders? And of course, watch the exhaust temp more closely on odd cyl's for an indication of sticking (temp will drop).
I will run my engine's as I have always.

[210TC]

After reading this http://egaa.home.mindspring.com/new.htm
I will adjust oil pressure to the upper limits.
I wonder if this causes any oil foaming problem's? I know a loss in HP will take place.

[a64pilot]

Too much oil will cause foaming from the oil being beaten by the crankshaft, pressure increase within realistic limits should not cause foaming. Pump up the pressure too much and it could cause oil starvation as your pumping oil into the engine top end faster than it can drain back. I don't think turning up the oil pressure to run continously at the top of the green will do that though.
There are other considerations. For example the vernatherm's cracking pressure to bypass the oil cooler is 60 to 90 PSI. Do the new engines run a different vernatherm? Turn up your oil pressure too much, and your oil temp could go up with it. How about your oil filter adapter gasket? Will it take the increased pressure? Oil cooler? Prop? etc?
Lycoming makes an adjustable oil pressure relief valve. I would use it instead of shimming the standard one. Before I changed oil pressure, I would temporarily install a known accurate gauge, don't go by the old factory one.
Use of a lower viscosity oil (semi-synthetic multi viscosity for example) will increase flow far more than turning up pressure with a straight 50W will, (standard day of course).
There will be a HP loss and or an increase in fuel flow, but it should be so small that I don't think it would be measurable. I don't think it's a consideration.
But, if it's been running for years and years with no problems, why mess with it?

[a64pilot]

I believe the FWF STC addresses wear of the cam and lifter, not anything else.
I believe Lycoming's new roller cam is the best answer for that problem. An opinion of course. Time will tell.

[210TC]

I'm looking into the foaming. I was more interested in the spraying of the oil under 115psi, not the movement of engine parts. I think they only conduct this test on hydraulic oils. I will know soon.

More info on WATER http://newsgroups.derkeiler.com/Archive ... 00719.html

[a64pilot]

I want to think the top of the green is 90 PSI, at least for an IO-540W1A5D anyway, but I'm in Rabat Morocco now so I can't look .
There were several things wrong with that article. For example the presumption that they pulled the oil pressure off of the front of the engine because the pressure was lowest there. There are alternate explanations, for example that would be the place to pull oil pressure from if you were trying to show a drop in pressure from a partially blocked cooler or oil filter for example. I can't imagine that if it made the engine last longer that Lycoming wouldn't either issue a SB directing you to turn the pressure up or push the airplane manufacturers to certify a higher oil pressure if required.
If your trying to increase flow the way to do that is by lower viscosity or looser clearences, not higher pressure.
Don't go to automotive oils though, they are NOT formulated to deal with lead anymore.
I wouldn't change the operating parameter of my engine based on an internet article, but's that my opinion.