REFLECTOR: Franklin Oil temp and flow data

[John Dibble]

On 11/10/2013 8:19 PM, Brian Michalk wrote:
>
>
> It was about 70F today, not that cold.  The oil flow is just very 
> strange.  It didn't start flowing until nine minutes into the flight, 
> and I don't think it's a sensor problem because the coolant temp 
> leveled off after it started flowing.  If this data is correct, I'm 
> not getting enough oil through my cooler.  The specs on the cooler are 
> for 7gpm, and I'm barely half there.  Yes, I'm having high oil temp 
> problems.

After my engine rebuild, my oil now takes 10 minutes to warm up.  It 
used to take 4-6 minutes.  The reason for so much time is because when 
the oil is cool, there is a high pressure drop across the filter/cooler 
and nearly all the oil bypasses until the oil in the sump, which warms 
faster, gets warm enough to reduce the pressure drop.  The reason mine 
took less time before is because the bypass spring was the wrong one.  
It was the same as the oil pressure regulating spring, which means there 
would be 80 psi across the filter/cooler, before it would bypass.  That 
means the pressure off the pump could get as high as 160 psig.  YIKES, 
but it ran without incident for 1100 hours.  I couldn't get one of the 
special bypass springs for the Franklin, so I made my own from a spring 
from the hardware store that I calculated would give 20 psi pressure.  
My oil runs 10 C cooler after the rebuild and I attribute most of that 
to new bearings.  New bearings have a smaller space between the bearing 
and crankshaft, so less oil passes through and therefore doesn't pick up 
as much heat.  That reduces the oil cooling requirement. Also, with more 
oil now bypassing the cooler, there is less oil to cool and that 
contributes to a lower oil temp (leaving the cooler) as well.  I should 
point out that I have a larger oil cooler than the standard.  My CHTs 
are 10 C lower as well and I attribute that to the lower oil temp.  My 
oil pressure runs 10 psig higher, also due to the lower oil temp.  One 
trick I use to warm the oil with less idling is to runs for 2 minutes, 
then shut down for 10-15 minutes.  When I start back up, the oil warms 
up in 2 minutes.  This way my CHTs are still low.

John
>
>
>
> _______________________________________________
> To change your email address, visit http://www.tvbf.org/mailman/listinfo/reflector
>
> Visit the gallery!  www.tvbf.org/gallery
> user:pw = tvbf:jamaicangoose
> Check new archives: www.tvbf.org/pipermail
> Check old archives: http://www.tvbf.org/archives/velocity/maillist.html

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.tvbf.org/mailman/private/reflector/attachments/20131111/d8464f82/attachment.html>