REFLECTOR: Franklin Oil temp and flow data

Fri Nov 15 12:07:19 CST 2013

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,
>
> 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.
>
>
>
>
>
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