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1. 04:33 AM - Re: Stratus first run-ups (gary)
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| Subject: | Re: Stratus first run-ups |
--> Stratus-List message posted by: "gary" <FlyinK@Efortress.com>
Larry,
You should be able to feel the hoses and know when the thermo opens. The
heater hose will get hot as the engine warms up but the main radiator hose
(after the thermo) stays cool. When that hose gets hot then you know the
thermo just opened so the water temp is around 190 (I forgot exactly what is
is 185, 190 or 195?).
The oil temp will definitely lag way behind the water and CHT for the first
5 minutes or so anyway. It takes a while to start coming up.
Like Dick said, don't apply full power until temps are warm so that the
aluminum heads and block expand. The manual says 120 oil temp minimun and
180 CHT minimum.
As far as what temps lead after it's warmed up, I think it depends on your
cooling system. I've been messing around a lot (I've got over 6 major
reconfigurations just in the last week with a runup or test flight for each)
and it really varies.
On my bad oil days, when the radiator is properly ducted but not enough
airflow over the oil pan and muffler, the water comes up to 185 - 190 and
stays there whether I'm at idle or WOT. The oil keeps creeping up and will
go to redline if I let it (260) but I usually shutdown by 250 or so since
it's obvious that version isn't going to work. The CHT is funny because it
goes up well past the water unlike many people said. It's "supposed" to
track water temp and you would think so, but it ends up somewhere between
water and oil temp.
On one of my last attempts to get better airflow for oil, the oil took a
long time to come up and the water beat it to redline ( I have it set to 230
vs 240 in the manual) and the CHT was higher than both getting to 250. That
was my ZAC copy where I cut out the whole lower cowl around the muffler and
back, and let the airflow right thru. It worked for oil but with a small
lip around the rad instead of a nice duct, the water came up too high.
I was going to try a 3-way vertically spilt duct next so left and right go
to rad and center goes by pan/muffler but I think I am giving up on all
these "attempts" and will reweld the exhaust to get it out of the cowling,
away from the oil pan, and not in front of the radiator anymore. I already
split it horizontally so half was for rad and half for oil pan and muffler
but couldn't get enough airflow for oil. I found that a heat shield dropped
oil temps around 5 degrees. I feel like I'm wasting my time trying to get
it to work with the stock (ZAC style) exhaust when I know if I had to
redesign it from scratch I'd move the exhaust.
ooops, I've gotten off track here so don't get me started on engine
temperatures again ;<}
Keep cool,
Gary
----- Original Message -----
From: "Larry McFarland" <larrymc@qconline.com>
Subject: Stratus-List: Stratus first run-ups
> --> Stratus-List message posted by: "Larry McFarland"
<larrymc@qconline.com>
>
> Hi Guys,
> These second runups are after RAM redid the heads.
> The engine sounds a little deeper than before, but runs
> real smooth without prop but I was reluctant to let it go
> more than 10 minutes and not over 2000 rpm
> because I'm trying not to exceed temperature limits.
> The hoses feel there's water pressure, but I was never certain
> that the thermostat had opened or not. Temps got to 955 on EGT,
> and 155 cylinder head temps before I shut it down.
> Oil pressure was 66 psi............
> The question is, what of these things reach recommended limits first?
> Does the thermostat open enough to balance cylinder head temps in time
> or is there enough coolant bypass flow to keep things in check at higher
> temps?
> Does anyone have a sequence with regard to first runups
> or is it just watching oil temps and CHTs? I'd like to hear some of your
> experiences at this critical time if you can recall. As you know, there's
> little said in the Stratus user's manual about this time.
>
> Getting very close to transporting it to the airport.
>
> Larry McFarland 601HDS
>
>
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