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Temps

 
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JOHNTMEY(at)aol.com
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PostPosted: Sat Feb 18, 2006 6:52 pm    Post subject: Temps Reply with quote
Mine only has 15 hours and I'm watching analyzer like a hawk:

Quote:
From last ride: Recorded at 3500', about 65F OAT, 20"/2400 rpm, 185 mph IAS

EGT CHT
1 1365 343
2 1396 389
3 1372 380
4 1385 380
5 1367 387
6 1396 403

So, CHT for number 1 is notably cool... number 6 is the hottest.

J Meyers N5800

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nico(at)cybersuperstore.c
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PostPosted: Sat Feb 18, 2006 7:43 pm    Post subject: Temps Reply with quote
Isn't this standard for the cylinders closest to the initial airflow to run
the coldest? The same thing happens in water-cooled engines where the #1
cylinder closest to the radiator would run considerably cooler than the last
cylinder and would, as a result of that, show more wear at the end of the
engine's life.

I made some calculations on your temps as follows. Col A is the variation in
temp with the previous cylinder, while col B is the variation with cyl. #1.
Your readings show an overall cylinder head temperature spread across the
engine of 57 deg.

EGT A B CHT A B
1 1365 343
2 1396 +31 +31 389 +46 +46
3 1372 -24 +7 380 -9 +37
4 1385 +13 +20 380 0 +37
5 1367 -18 +22 387 +7 +44
6 1396 +29 +31 403 +13 +57

If EGT was a problem there would have been a (near) consistent variation in
CHT linked to EGT but check cyl #3 : the EGT is only 7 deg hotter, while the
CHT is 37 deg hotter. It could point to a cooling problem. Perhaps a baffle
is not installed properly or it is missing? Why #2, which shares the front
row with #1, runs so much hotter than its sibling, could be an injector
tuning problem because the CHT is higher consistent with the EGT. They
should both be cooler than the rest, unless there are other factors
influencing the cooling.

Very interesting! Just some observations - I am sure the gurus would be able
to give a clearer picture on what this story tells. Smile

Nico
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fairlea(at)amtelecom.net
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PostPosted: Sun Feb 19, 2006 5:29 am    Post subject: Temps Reply with quote
The comparison of EGT values between cylinders is of little practical value.
Check this website http://www.gami.com/frames.htm for a very in depth
explanation. The short story is that you are only interested in the exact
temperature of a particular cylinder's EGT at the moment it reaches peak and
the fuel flow at that time. Ideally all cylinders should reach peak EGT at
the same fuel flow. The minor differences between EGT probe temperatures has
more to do with probe location in the exhaust system than it does engine
performance.
Cylinder #2 often runs hotter than one due to the fact that the
cylinder fins on these cylinders are not symmetrical on each side. The
front of number 2 does not have as many fins, as the front of number 1.
This is also why 5 will run hotter than 6. This is the reason that taking
air from the number six cylinder for the oil cooler is generally a better
location than behind number five.
I have been flying my rockets, using the gami philosophy, for eight
years. It will change the way you operate your engine and increase your
range and engine life. There are some very good articles on AVweb as well
regarding these techniques.
During this thread there was also a mention of leaning on final to
reduce engine popping. This will work but it might get you in trouble if
you have to do a quick go around. A rapid application of throttle may cause
the engine to cough, or quit, due to lack of fuel or be at such a lean
setting that it could cause engine damage in a full power situation. Yes I
am aware that we are supposed to push all levers forward for a go around but
it is better to already have the prop and mixture controls in the go around
position should the need arise. Engine popping on final can be greatly
reduced with a slower more gradual reduction of power in the circuit and on
final.

Tom Martin

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JOHNTMEY(at)aol.com
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PostPosted: Sun Feb 19, 2006 1:47 pm    Post subject: Temps Reply with quote
Great thread (engine temps) !

A bit disconcerting though...
other than #1 running cool,I didn't know I had a problem. I'm still
thinking that nursing the baffles to warm #1 CHT up is OK.... then let this puppy
run for a few hundred hours.

do not archive John M N 5800

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mytyweav(at)earthlink.net
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PostPosted: Sun Feb 19, 2006 9:14 pm    Post subject: Temps Reply with quote
Thanks Tom.... Aren't you still mounting the oil cooler at an angle behind Number 5?
Weav

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