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From: Lehanover@aol.com
Message-ID: <d9.1bd50d94.2ef186d2@aol.com>
Date: Wed, 15 Dec 2004 07:23:46 EST
Subject: Re: [FlyRotary] Oil Cooling/Pumping
To: flyrotary@lancaironline.net
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In a message dated 12/15/2004 12:45:40 AM Central Standard Time, 
jewen@comporium.net writes:

<< With all the problems encountered with leaking oil coolers, I was wondering
 if the following has any merit.
 
 Instead of using the engine driven oil pump to circulate oil through the
 cooler, why not install a secondary cooling loop. A seconary oil pick up
 would be connected to an auxilary oil pump which would circulate the oil
 through the cooler and return to the sump.  The secondary loop could be run
 with a lower pressure and larger hoses to maintain an adequate flow rate,
 putting less internal force on the oil cooler.  The normal engine
 connections for the oil cooler would be directly connected to each other to
 maintain oil flow in the engine.
 
 One downside might be the couple of extra pounds for the aux oil pump, but
 that sounds like a small price to pay.  I appreciate anyone thoughts or
 comments.
 
 Joe (Still waiting for an engine mount.)
 
  >>

Oil coolers operate for the life of the vehicles in millions of applications 
around the world. Aircraft installations require very carefull planning to 
avoid failure induced by vibration. The cooler with oil is heavy and must be soft 
mounted and protected against striking or rubbing any fixed item as the 
cooler responds to various harmonics. The hoses connecting the cooler must be light 
weight, and flexible, and the must not be clamped down tight close to the 
cooler. Everything forward of the firewall moves around. It shakes (low 
frequency) and vibrates (high frequency).

If you soft mount the cooler (good) but tie the hoses to a close by item that 
moves around, the cooler will fail. A nice 90 degree turn in a soft flexible 
hose leaving the cooler is a good start to a long life. Even a soft hose 
becomes very stiff when pressurized to 85 PSI. A hose that is stiff with no 
pressure in it becomes an iron bar when pressurized to 85 PSI. 

The mounting tabs are for connecting the cooler to a rubber..........you fill 
in the blank. But only rubber. A (soft) standoff, A section of radiator hose, 
whatever, but not metal anything. Or, the tab and or, a piece of the cooler 
will break off.


I have an electric oil pump on my race car that circulates trans oil through 
a cooler. Works great. The trans used to get so hot that the rear seal would 
loose it's press fit and fall out. No more. So it does work. A bit heavy, maybe 
3 pounds, but it does work, and really hot oil dosn't bother it. Speedway 
engineering has them.
The idea of cooling the oil outside of the pressurised oil system has 
possibilities.

I would like to see a study of how much oil passes through the oil pressure 
relief valve once cruise RPM is reached. The oil is just dumped back into the 
pan and adds to oil foaming, which is a bad idea. Why not route that expended 
oil through a cooler and then back into the pan? No additional pump required. I 
think Peterson has external adjustable oil pressure relief valves, to the 
hook up would not be difficult.


Lynn E. Hanover