REFLECTOR: Franklin Oil temp and flow data

[John Dibble]

Recently my oil temp has been creeping downward.  With an OAT of 60 F, 
it's running 50 C.  I let it warm to 40 C before takeoff.  Sometimes it 
goes back down to near the OAT right after takeoff and then slowly 
inrcreases after a few minutes.  My oil temp is measured at the cooler 
outlet. Suspecting that the bypass spring I made had gotten weaker, I 
checked it.  It seemed slightly weaker.  I replaced it with a stronger 
one that I calculate will give 35 psi.  As I expected, the oil temp 
increased by 10 C, indicating that more oil is going to the cooler.   
What surprised me is that my oil pressure decreased by 10 psig (from 70 
to 60).  Part of that must be due to the warmer oil temp, but 10 psig 
seems like a lot.  Before I discovered that an oil pressure spring (80 
psig) was installed in the bypass spot, my oil pressure was running 
50-55 psig with oil temp at 70 C.  FWIW

John

On 11/15/2013 12:07 PM, Brian Michalk wrote:
> Yeah, I've been thinking about that too.  The relief valve wouldn't 
> cause any additional pressure drop.
>
> For an experiment, I would like to put in a dummy blank filter in 
> place of my current filter.  I suppose I could rearrange some hoses.  
> Removing the filter would take one variable out of the equation to see 
> if the same symptoms happen again.
>
> On 11/15/2013 12:01 PM, John Tvedte wrote:
>>
>> Brain,l
>>
>> I am not understanding why you would be concerned about a filter that 
>> has a relief valve.  That relief valve works on the pressure 
>> difference across the filter media. Primarily for cold starts, but 
>> effective also for the unthinkable clogged filter media.  The oil 
>> filter assembly won't block the flow of oil.   An oil filter bypass 
>> operates at a reasonably low pressure difference of a few psi -- and 
>> so it would not 'rob' the circuit pressures of any more than those 
>> few psi.
>>
>> John
>>
>> *From:*reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] 
>> *On Behalf Of *Brian Michalk
>> *Sent:* Thursday, November 14, 2013 8:28 PM
>> *To:* Velocity Aircraft Owners and Builders list
>> *Subject:* Re: REFLECTOR: Franklin Oil temp and flow data
>>
>> On the data I sent out, right after engine start, the engine surged 
>> to 1500RPM.  The oil pressure coming out of the engine was 117PSI, 
>> the oil pressure returning to the engine was 98PSI.  It wasn't that 
>> cold.  70F.
>>
>> I am measuring the galley pressure where PZL says to measure it, 
>> which is off the port on the bypass plate.  I measure the pump 
>> pressure right at the oil cooler, which is after about three feet of 
>> -10 stainless braided hose.
>>
>> I am logging 46 unique channels on the airplane.  I am logging more 
>> parameters than that, but don't count them, like I count fuel counts 
>> and fuel flow as one unique signal.
>>
>> The more I think about this, the more I am suspecting the oil 
>> filter.  I am using the K&N HP-3002, and in looking back at my 
>> manual, I had selected the HP-2002. They are both 550PSI burst 
>> pressure, but the 3002 has a PSI relief valve, bypass valve and 
>> anti-drain back valve. The 2002 has none of those.  I probably picked 
>> up the 3002 because they didn't have any 2002's on the shelf.
>>
>> On 11/14/2013 06:54 PM, John Dibble wrote:
>>
>>     On 11/14/2013 1:29 PM, Laurence Coen wrote:
>>
>>         Brian,
>>
>>         There are two valves in the "bypass plate" and they perform
>>         independent functions.  The pressure regulator valve sets the
>>         oil pump pressure at 80PSI.  That is the maximum pressure
>>         that can exists anywhere in the system and is also the
>>         maximum pressure that the oil cooler can see.
>>
>>     Well, with the 80 psig spring in the cooler bypass location, at
>>     start up on  cold days I would see 99 psig at the cooler outlet
>>     (99 is the max reading for my RMI monitor, so it could have been
>>     higher).  Seems like the pressure going to the cooler would have
>>     been higher yet.
>>
>>     John
>>
>>
>>       Please note that this has nothing to do with the external loop
>>     bypass valve.  Your data would indicate that your statement that
>>     no oil flowed for nine minutes is incorrect.  I don't how you are
>>     measuring oil flow or where but the fact that there is a
>>     differential pressure at the output of the oil cooler and the
>>     galley is only possible if there is flow through the cooler.  In
>>     a hydrostatic system (no flow) where two points are connected the
>>     pressure will be the same. Your graph shows a differential
>>     pressure at opposite ends of a tube connecting the oil cooler and
>>     the oil galley.  This indicates oil flow through the cooler from
>>     start up to shut down.
>>
>>     Functionally, the Franklin set up works the same as the pressure
>>     regulator/"Vernatherm" in a Lycoming.  In a Lycoming, when the
>>     oil is cold, The Vernatherm opens a bypass on the oil cooler
>>     loop.  When the oil gets hot the Vernatherm closes the bypass
>>     forcing the oil to flow through the oil cooler.  On the Franklin
>>     the fact that cold oil is thick when cold causes a large drop in
>>     pressure through the external loop. This in turn opens the bypass
>>     just like the Vernatherm on the Lycoming.  When the oil is hot,
>>     the pressure drop in the external loop decreases allowing the
>>     bypass to close, just like the Vernatherm did in the Lycoming. 
>>     In both cases the pressure regulator simply sets the output
>>     pressure of the oil pump.
>>
>>
>>
>>



---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.tvbf.org/mailman/private/reflector/attachments/20140301/e7921da5/attachment.html>