Nigel Graham wrote:
> H Richard
>> Oil thermostat - 251 grams !
> Yep....I'm holding my hands up. Thats much lighter than
> I expected.
>
>> ......"This is gonna run and run and run :-)"
> No, I think we're about there now. In your original
> posting of the 23rd, you were so unhappy that you were
> contenplating taking your oil thermostat off and I
> agreed with you.
>
> ........My oil did not warm up quicker. ...... .....My
> feeling is that the waxstat in the thermostat is
> opening too early ...... I am contemplating ripping the
> whole thing off ...........
>
> and now you are arguing robustly in its defence. By a
> process of cunning reverse psychology, I have persuaded
> you to keep it.
>
> Nigel ;-)
I don't do psychology - just practical :-) And hating to
be beaten, liking to know what is ACTUALLY happening.
The original intention in fitting the thermostat was
primarily to keep the oil temp up in the cruise (keeping
the oil out of the cooler) and as a secondary effect I
could uncover the oil cooler (1/2 covered up) which would
allow better cooling in the summer. I needed the oil temp
up in the winter to keep the water temp up so that the
carb heaters would work properly !
I flew it again today. It was only 4 degrees when I took
off ! On a hard climb to 2495 feet (LTMA at 2500) the oil
went up to 80 and didn't go above (although this wasn't a
really long enough test). I went to Stapleford for lunch
thinking that it would only have a short time to cool so
the oil would start hotter, but got lumbered with filling
in on Air-Ground for an hour so the oil HAD cooled).
In the cruise the oil temp went down to 60.
I have the coolers in the standard position now with no
baffling at all.
So I have come to the conclusion that in the cruise (25.5
MAP 4600 rpm) the engine just doesn't produce much heat -
not enough to keep the oil at 80. A little baffling on the
water radiator might generate more heat in that which
would then cross to the oil. More experiments to come.
Perhaps a half blocking of the air intake that feeds the
cylinder cooling shroud.
And what was different this time compared with last time
when the oil went to 95 in the climb ? The widening out of
the ports to 10 mm (in particular the one that goes to the
oil pump) meant that in the fully extended position the
waxstat wasn't blocking off the by-pass completely. So
that means that as the oil would MUCH prefer to bypass the
cooler rather than go through it, the oil wasn't getting
much (any ?) cooling and so the temp went up. So for today
I had modified the thermostat to give an extra 1.3 mm
movement, and although I didn't give it a conclusive test,
I think the thermostat is opening and achieving at least
the secondary effect.
This is all done of course in 4 degree weather and that is
not representative of the likely operating conditions in
the spring summer and fall (I mean autumn !)
So anyone who is contemplating putting on this thermostat
should chat with me first about how and where to widen out
the ports, before getting their drill out ! Just drilling
out all the ports to 10mm will mean that the thermostat
will always bypass the cooler - which would not be a good
thing !
Maybe the oil tank needs a nice woolly jacket (fireproof
of course) to retain the heat !
--
Richard
Richard F.W. Holder 01279 842804 (POTS)
Bell House, Bell Lane, 01279 842804 (fax)
Widford, Ware, Herts, 07860 367423 (mobile)
SG12 8SH email : richard.holder@avnet.co.uk
Europa Classic Tri-gear : G-OWWW, High Cross
PA-28-181 : Piper Archer : G-JANA, EGSG (Stapleford)
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