Today's Message Index:
----------------------
1. 06:49 AM - Re: EA-81 cooling (Larry McFarland)
2. 07:56 AM - Re: EA-81 cooling (cgalley)
3. 09:32 AM - Re: EA-81 cooling (Larry McFarland)
4. 05:11 PM - CHT readings revisited (Larry McFarland)
Message 1
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| Subject: | Re: EA-81 cooling |
--> Stratus-List message posted by: "Larry McFarland" <larrymc@qconline.com>
Subject: Re: Stratus-List: EA-81 cooling
> --> Stratus-List message posted by: "gary" <FlyinK@Efortress.com>
>
> did you calibrate the coolant temp sensor? dip in boiling water while
> hooked up as-is. plug hole with 1/8" NPT. single or two wire sensor?
> right after thermo?
>
> what's your oil temp? without good airflow thru the cowling, the muffler
> puts a lot of heat in the cowling. i saw similar temps for a few of my
many
> configs, either got good water and high oil or good oil and high water.
> stock zac stratus cowling with bottom open?
>
> gary
>
Gary,
You're right, I have to do a boiling water test on both CHT and
coolant sensors. EIS Grand Rapids Technologies said there's potential for
as much
as 10-degrees of error. The water sensor has a gage wire and a ground wire.
Water and oil temps have never been out of range, water at 188, oil at 190,
EGTs were very high,
but are 1360 now. The CHT went to 247, which is too high, even at 3800-rpm.
These temps were
obtained after changing out the main jets from 170 to 180. Standard is 162.
I did the test with a 12"
radiator puller fan, thinking I'd clamp temps there, but the water temps
never had an effect
on cylinder head temps. Plugs 1 & 2 were white-tan, 3 & 4 were brown-tan
after shutting down
abruptly at 3800. That puzzles me because before they were all rather
tan-brown.
You're right, my cowling opening around the muffler is not more than
1/2" in front of the muffler, so air has to go over the muffler, down and
out. I intend to open it
up a couple of inches in front of the muffler.
Right now I'm mostly concerned about the nearly 60 degree difference between
CHT and water temps.
Thanks,
Larry
Message 2
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| Subject: | Re: EA-81 cooling |
--> Stratus-List message posted by: "cgalley" <cgalley@qcbc.org>
Larry,
If you are using a spark plug ring, they are always higher than a well type
CHT probe even on an aircooled engine. I am not an expert but I would
expect that difference. You are measuring the spark plug shell temp and not
the coolant.
Cy
----- Original Message -----
From: "Larry McFarland" <larrymc@qconline.com>
Subject: Re: Stratus-List: EA-81 cooling
> --> Stratus-List message posted by: "Larry McFarland"
<larrymc@qconline.com>
>
>
> Subject: Re: Stratus-List: EA-81 cooling
>
>
> > --> Stratus-List message posted by: "gary" <FlyinK@Efortress.com>
> >
> > did you calibrate the coolant temp sensor? dip in boiling water while
> > hooked up as-is. plug hole with 1/8" NPT. single or two wire sensor?
> > right after thermo?
> >
> > what's your oil temp? without good airflow thru the cowling, the
muffler
> > puts a lot of heat in the cowling. i saw similar temps for a few of my
> many
> > configs, either got good water and high oil or good oil and high water.
> > stock zac stratus cowling with bottom open?
> >
> > gary
> >
>
> Gary,
> You're right, I have to do a boiling water test on both CHT and
> coolant sensors. EIS Grand Rapids Technologies said there's potential for
> as much
> as 10-degrees of error. The water sensor has a gage wire and a ground
wire.
>
> Water and oil temps have never been out of range, water at 188, oil at
190,
> EGTs were very high,
> but are 1360 now. The CHT went to 247, which is too high, even at
3800-rpm.
> These temps were
> obtained after changing out the main jets from 170 to 180. Standard is
162.
> I did the test with a 12"
> radiator puller fan, thinking I'd clamp temps there, but the water temps
> never had an effect
> on cylinder head temps. Plugs 1 & 2 were white-tan, 3 & 4 were brown-tan
> after shutting down
> abruptly at 3800. That puzzles me because before they were all rather
> tan-brown.
>
> You're right, my cowling opening around the muffler is not more than
> 1/2" in front of the muffler, so air has to go over the muffler, down and
> out. I intend to open it
> up a couple of inches in front of the muffler.
>
> Right now I'm mostly concerned about the nearly 60 degree difference
between
> CHT and water temps.
>
> Thanks,
> Larry
>
>
Message 3
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| Subject: | Re: EA-81 cooling |
--> Stratus-List message posted by: "Larry McFarland" <larrymc@qconline.com>
Subject: Re: Stratus-List: EA-81 cooling
> --> Stratus-List message posted by: "cgalley" <cgalley@qcbc.org>
>
> Larry,
> If you are using a spark plug ring, they are always higher than a well
type
> CHT probe even on an aircooled engine. I am not an expert but I would
> expect that difference. You are measuring the spark plug shell temp and
not
> the coolant.
> Cy
Excellent point Cy,
There's a coolant sensor 4' downstream of the engine, but I should know what
CHTs should
be reading either from a rear block sensor or the spark plug thermocouple.
I've got to hook up
the block sensor from Stratus or place the spark plug ring under a bolt and
washer on
the block to check out the difference. It would seem the Stratus sensor
would be a better
determinate for the "230-degree CHT".
Anybody have an idea of how much that difference is?
Larry
Message 4
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| Subject: | CHT readings revisited |
--> Stratus-List message posted by: "Larry McFarland" <larrymc@qconline.com>
Hi guys,
There wasn't anything ambiguous with the guidance provided by Stratus, but
somewhere in the process of finding correct temps, things got lost while selecting
CHT sensors. The ones that come with
the Stratus VDO gage weren't used because I'd purchased an EIS system and made
the assumtion that CHT was much the same
for any Subaru.
Today was 80+ degrees and the engine had been re-jetted from 170 to 180 to lower
CHT. The engine didn't run smooth as before and soon cyliinder head temps were
247 with a 230 limit flashing from the EIS system.
This seemed serious enough, but one of my emails from Cy suggested that spark plug
thermocouples would read hotter than either the bolt-thermocouple or the Stratus
sensor, but after a few phone calls, no-one else seemed to know how much,
so at the hangar, I moved the oil-sensor wire to the Stratus-provided block-sensor
and did a run-up.
Mother nature spoke as soon as I was able to read the numbers. The block sensor
CHT per Stratus began cooler than the spark plug CHT by 27-degrees, (143 versus
170). Differences increased as rpm was raised in 500-rpm increments. At 3500-rpm,
the block sensor read 185-degrees while the spark plug thermocouple read
250, a 65-degree difference.
The main jets were re-jetted to 170s to smooth out the running and now I'm much
relieved.
Well, that's it, so when selecting these things, consider the detail and perhaps
you'd not stub your toe like I did.
Larry McFarland 601HDS (Now I can go back to flying!)
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