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garrys(at)tampabay.rr.com
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 Posted: Wed May 02, 2007 2:14 pm Post subject: CHT's and EGT's Spreads? |
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I just recently did my first flight in my RV-7A. All went very well and the
plane flew straight and true. As with all new builds, there are some
squawks I'm working through.........primarily related to the initial setup
of my Grand Rapids Horizon System EFIS.
The GRT requires me to input "ranges" (min, max) for virtually every engine
parameter known to man. My question to the group is what are typical ranges
for CHTs and EGTs? And more importantly, how much variation between
cylinders is acceptable, and how much deviation means I have a problem that
needs to be addressed. For example, if I have a 100 degree difference in
CHT from my coolest to my hottest cylinder, is that a problem?
My engine is an AeroSport (Lycomming clone) IO-360.
Thanks in advance,
Garry Stout
N498WT, Odessa Florida
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HCRV6(at)comcast.net
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| Posted: Wed May 02, 2007 10:05 pm Post subject: CHT's and EGT's Spreads? |
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With a new engine you might initially try 450 CHT's and 1450 for EGT's. Remember that 500 degrees is max allowable CHT and I don't recall the max allowable for EGT but I think it is 1500 degrees (I'm sure if that is incorrect someone on the list will provide the correct number). After the engine starts to loosen up with break in you can probably adjust those limits downward somewhat.
A 100 degree spread in CHT is more than you want but you will most likely be able to balance those temps with baffles plates in front of the front cylinders. Experiment with different sizes and shapes. Make certain that your baffles are well sealed so that all the cooling air is passing over the cylinder fins, not leaking around the sides or front of the engine.
BTW, congratulations on the first flight.
--
Harry Crosby
RV-6 N16CX, 339 hours
-------------- Original message ----------------------
From: "Garry" <garrys(at)tampabay.rr.com>
| Quote: |
I just recently did my first flight in my RV-7A. All went very well and the
plane flew straight and true. As with all new builds, there are some
squawks I'm working through.........primarily related to the initial setup
of my Grand Rapids Horizon System EFIS.
The GRT requires me to input "ranges" (min, max) for virtually every engine
parameter known to man. My question to the group is what are typical ranges
for CHTs and EGTs? And more importantly, how much variation between
cylinders is acceptable, and how much deviation means I have a problem that
needs to be addressed. For example, if I have a 100 degree difference in
CHT from my coolest to my hottest cylinder, is that a problem?
My engine is an AeroSport (Lycomming clone) IO-360.
Thanks in advance,
Garry Stout
N498WT, Odessa Florida
|
| | - The Matronics RV-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?RV-List |
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Doug Gray
Joined: 10 Jan 2006
Posts: 112
Location: Sydney, Australia
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| Posted: Thu May 03, 2007 1:11 pm Post subject: CHT's and EGT's Spreads? |
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I thinking about these very questions myself and went to the Skyranch
Eng Manual for some guidance.
To summarise for cruise:
Normal EGT range: 1200-1600 F no mention I have found for maximum
Oil Temp: 160-245 F with minimum continuous 165
CHT: minimum 150 F, normal 350-400 F (435 for turbocharged)
The Skyranch recommendation is to impose a secondary redline on CHTs of
400 F for normally aspirated engines, leaning should result in CHTs
below this.
The issue with uneven temperatures is possible uneven cooling of the
cylinders leading to cracking. The proposition is that large variations
between cylinders implies uneven airflow around the cylinders. The
recommendation is to balance the temps with baffling/deflectors.
This makes sense to me and it is the reason I am fitting individual
cylinder CHT monitoring.
Doug Gray
On Wed, 2007-05-02 at 18:12 -0400, Garry wrote:
| Quote: |
I just recently did my first flight in my RV-7A. All went very well and the
plane flew straight and true. As with all new builds, there are some
squawks I'm working through.........primarily related to the initial setup
of my Grand Rapids Horizon System EFIS.
The GRT requires me to input "ranges" (min, max) for virtually every engine
parameter known to man. My question to the group is what are typical ranges
for CHTs and EGTs? And more importantly, how much variation between
cylinders is acceptable, and how much deviation means I have a problem that
needs to be addressed. For example, if I have a 100 degree difference in
CHT from my coolest to my hottest cylinder, is that a problem?
My engine is an AeroSport (Lycomming clone) IO-360.
Thanks in advance,
Garry Stout
N498WT, Odessa Florida
|
| | - The Matronics RV-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?RV-List |
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