REFLECTOR: Oil Type

[Tom]

Tom,

Your experience fighting the oil temp probably was interesting, though one statement stood out that was particularly so; "The Lycoming gurus say that the engine wasn't set up to pump oil through 30 feet of rigid line.".

I don't know that that is a provocative statement, but it's certainly intriguing.  For instance, if the oil pump on an IO-540 is expected to put out 70 psig, the pump does not know whether there is 2' or 30' of oil line down stream of pump, or whether it is flex or rigid tubing.

If the oil is cold and viscous, some, or most of the oil may by-pass initially until it is warmed up, but that is more an issue with the pressure relief system.  The long tube run may cause by-passing for a longer period of time before warm up than a shorter run, but that is simply a few minutes at start up.  During normal operations, the pressure drop through 30' of rigid tubing is negligible, so it's difficult to see the effect.  

That being said, I don't know the gpm of the oil pump, but with 3/4" tubing, the flow rate would have to be pretty high before onset of turbulent flow in the tubing would result in rapidly increasing pressure drop.

Did the Lycosaurous gurus offer a technical explanation for their statement?  Then again, maybe I'm looking at this wrong.




Chuck, what you say makes sense to me. I waited for the main guru at Lycoming booth at Sun-N-Fun 2 years back to ask his help on 
chronically hot oil temps. That was his response, no I didn't press him for a technical explanation sorry..Tom
Someone at Oshkosh could probably get one from them.