REFLECTOR: Cylinder repair followup

[John Dibble]

I'm going to replace my oil pressure sensor to see if it is giving the
right reading.  It's a VDO sensor (RMI monitor).  Anyone know the exact
model and where to get it?

John

Al Gietzen wrote:

> John;
>
> For the same ‘average’ temperature of the oil cooler; the lower
> temperature drop across the cooler is increasing the outlet temp;
> but reducing the inlet temp. Of course to really know what’s going on
> we need more data than just one temperature.
>
> Perhaps a key point based on what we think we know, is that the
> ‘average’ oil temp seen by the engine is lower – maybe very little,
> but lower.  That; combined with higher flow, I would surmise, could
> only be a good thing for the engine.  Higher flow will reduce the
> average bearing surface temp by moving more oil through, which is a
> key factor.
>
> Don’t get too focused on the temp that you are measuring at one
> particular point in the system. In the extreme you could reduce the
> flow until the engine was being damaged, and your measured cooler
> outlet temp could be comfortably away from the red-line temperature.
> One view of what you are seeing is that it suggests looking at ways to
> increase air flow to the cooler, or consider a larger cooler.
>
> I don’t know what the criteria or margins are built into the
> ‘red-line’ temperature.  It’s a function of the oil you are using.  If
> it is a good synthetic, you could bump the limit up a few degrees if
> it makes you more comfortable (but I would never actually suggest you
> do that).
>
> Al
>
> -----Original Message-----
> From: reflector-bounces at tvbf.org
> [mailto:reflector-bounces at tvbf.org] On Behalf Of John Dibble
> Sent: Monday, June 29, 2009 9:25 AM
> To: Velocity Aircraft Owners and Builders list
> Subject: Re: REFLECTOR: Cylinder repair followup
>
> Al, that makes perfect sense and I have been thinking that all along.
> Basically, the hotter the oil leaving the cooler, the more heat is
> being removed.  In that sense, hotter is better.  But the fact remains
> that with an OAT of 86 F, the oil leaving the cooler was 107 C, right
> near red line and the oil entering the cooler must have been hotter.
> I recall flying 2 years ago with a similar OAT and seeing an oil temp
> around 95 C.   I think what is happening is that I am now removing
> more heat via the oil cooler, heat which otherwise would be removed
> via the engine cooling air.  For sure, if the oil flow is reduced, the
> temp will be lower.  I'm just struggling to decide which senario is
> best for engine operation.  Seems like lower temp is better.
>
> John
>
> Al Gietzen wrote:
>
>> The increased flow will reduce the delta T, the change across the
>> cooler (and correspondingly in/out of the engine).  Depending on
>> other factors, for the same air flow, the amount of heat removal
>> would be about the same or a higher, so the average oil temp would
>> be a bit lower.  However; with the heat removal air flow limited the
>> measured oil temp out of the cooler could be a bit higher; while the
>> temp in (out of the engine) would be lower.  Make sense?
>>
>> Al
>>
>>
>>
>>
>>
>>
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