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1. 05:58 AM - Re: CHT readings revisited (gary)
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| Subject: | Re: CHT readings revisited |
--> Stratus-List message posted by: "gary" <FlyinK@Efortress.com>
Larry,
Good that you figured it out and you're moving again. I was going to ask
if it was the stock Stratus sensor and placement, didn't sound right. I had
a hand-written note in my manual that said I had a 300 deg sender and 250
deg guage or whatever, and that the temp would read about 20 deg off. I
figured that was unacceptable and went out and bought a new matching set of
VDO sender/guage. Didn't want to guess what temps were when testing a new
system. Those are the best cooling problems though, the instrumentation
ones. Easy to fix and good to know it's not (and wasn't) running hot.
Fly safe!
Gary
----- Original Message -----
From: "Larry McFarland" <larrymc@qconline.com>
Subject: Stratus-List: 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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