Today's Message Index:
----------------------
1. 02:51 AM - In Flight CHT's (Richard Ranger)
2. 03:49 AM - Re: In-flight CHTs (bkspero)
3. 05:10 AM - Re: In-flight CHTs (Bvnj)
4. 08:33 AM - Re: In Flight CHT's (Linn Walters)
5. 10:18 AM - Re: In Flight CHT's (BILL9725@AOL.COM)
Message 1
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Gary, you have raised some very interesting issues on your flight to SLC, and I
hope it stimulates good discussion.
Firstly, your hotted up engine does not sound as though it is yet run-in. The CHT's
you observed are very high and consistent with a new powerplant. From my
own experience, it took 30 hours at 75 percent power and very high (and expensive)
fuel flows for the CHT's to settle below 400 F in cruise and for oil consumption
to fall. They are now consistently between 360 and 390 at 65 percent power,
with oil consumption minimal.
At standard atmosphere 75 pc power can only be achieved with wide open throttle
(WOT) at 8,000 ft and less if the temp is higher; so that is probably the maximum
altitude to bed in the engine. At 12,500 ft and WOT max power is only 63
percent, which is a power setting that should never damage an engine according
to Lycoming, but is below 'running in power' settings.
That you can achieve such high CHT's at 12,500 ft is concerning, given the limited
power at that altitude, and their variability without changing mixture or
throttle setting is strange. Timing issues or preignition need to be excluded.
You are correct in saying that engines without 4 cyl monitoring may be running
temperatures way out 'normal', yet they seem to run OK. Are we being over careful?
Richard Ranger
AA5b
Sent from my iPad
Message 2
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| Subject: | Re: In-flight CHTs |
Hi Gary. Give Clytie my best regards.
Try downloading and plotting the data. Sometimes I can see things in a broad overview
that aren't apparent otherwise. I find that the free plotting features
of the Savvy Analysis website are the easiest way to look at engine analyzer data.
Barry Speronello
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=447143#447143
Message 3
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| Subject: | Re: In-flight CHTs |
Hi Gary,
I think this engine is not fully broken in yet. The temps should stabilize once
it is fully broken in. My temps also were all over the place until after 50 hours
or so.
Boris
>>>>>>>>
> Last Sunday my wife, Clytie, and I flew N626FT back to Auburn from Salt Lake
City.
> It has a fairly new engine; less than 20 hours on it. The engine is a tricked
> out engine from LyCon. It also has a Power Flow Exhaust System.
>
> Getting to SLC was at full throttle and richened to keep the CHTs under 430 on
> an EDM 800. We got terrible gas mileage.
>
> Coming back, we went up to 12,500 feet (set the heading and altitude with an
S-Tec
> 30) and I played with the mixture, throttle, and carb heat settings to see
> what I could get. The interesting observation was that I could quite easily
> get the engine to run smooth lean-of-peak. The odd thing was, at full throttle,
> it wouldnt stay there. I can only think it had something to do with local temps
> and pressures.
>
> What I observed was: #1 & #2 were always the coldest (by about 10 to 20 degrees)
> and I never thought much of them. Between #3 & #4, #3 was the first to go lean
> of peak and was very predictable. #4, however, would go lean, run smooth for
> a while, then it would richen enough to raise the CHTs. I left the setting
> alone and just observed the outcome. The CHT would go from 405 to 415 and back
> (plus or minus 10 degrees). Then, occasionally, keep getting hot to 450 and
> then go lean again and the temp would go down; one time to as low as 397.
>
> If I leaned slightly more to keep #4 cooler, it would run OK for a while, go
lean
> enough to run rough for a while. I tried carb heat to see if it had any effect.
> Minimal effect at best.
>
> Then I tried pulling the power back to 50% (well, between 50% and 55%) and various
> lean settings. The lean-of-peak setting was a lot more sensitive. I aimed
> for a maximum CHT of 415. As before, the engine would run great for a while
> and then the CHTs would move up or down for no apparent reason; i.e., no RPM
> change, no throttle, mixture, altitude or speed change.
>
> In all of this experimentation, only one time did the settings produce CHTs &
EGTs
> (by-the-way, EGTs were in the 1500 range at max lean) that were steady for
> over 15 minutes. Reproducing the setting was fruitless.
>
> Only one time did the #4 CHT go above 450. This was during a full power lean-of-peak
> setting. Gradually pulling the power back (no change in mixture setting)
> stopped the increase at 465 and all cylinders began getting cooler. When #4
> got to 400, I went back to full power and the CHT went back up to 455 and then
> back down to 430. Very weird.
>
> When I think of all the cross country flights (or local flights) without an engine
> analyzer, I wonder how many times the engine was really running over maximum
> temps.
>
> Gary
>
>
>
>
>
>
>
>
>
Message 4
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| Subject: | Re: In Flight CHT's |
I'm no expert but have had good breakin results using WOT around 3000
AGL. I expect CHTs to be higher than normal and use mixture/throttle to
try and keep them below 450. The hottest may go above, but not for
long. Flights at least an hour at a time.
You have to remember that the numbers Lycoming uses are set for an
engine during certification, and by nature are conservative. I learned
a lot during an off-the-record discussion with a Lycoming engineer.
Early in the discussion his comment was 'you can't do that' but when
off-the-record he opened up.
Linn
On 9/17/2015 5:51 AM, Richard Ranger wrote:
>
> Gary, you have raised some very interesting issues on your flight to SLC, and
I hope it stimulates good discussion.
> Firstly, your hotted up engine does not sound as though it is yet run-in. The
CHT's you observed are very high and consistent with a new powerplant. From my
own experience, it took 30 hours at 75 percent power and very high (and expensive)
fuel flows for the CHT's to settle below 400 F in cruise and for oil consumption
to fall. They are now consistently between 360 and 390 at 65 percent
power, with oil consumption minimal.
> At standard atmosphere 75 pc power can only be achieved with wide open throttle
(WOT) at 8,000 ft and less if the temp is higher; so that is probably the maximum
altitude to bed in the engine. At 12,500 ft and WOT max power is only 63
percent, which is a power setting that should never damage an engine according
to Lycoming, but is below 'running in power' settings.
> That you can achieve such high CHT's at 12,500 ft is concerning, given the limited
power at that altitude, and their variability without changing mixture or
throttle setting is strange. Timing issues or preignition need to be excluded.
> You are correct in saying that engines without 4 cyl monitoring may be running
temperatures way out 'normal', yet they seem to run OK. Are we being over careful?
>
> Richard Ranger
> AA5b
>
> Sent from my iPad
>
>
> -----
> No virus found in this message.
> Checked by AVG - www.avg.com
>
>
Message 5
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| Subject: | Re: In Flight CHT's |
Hi Everyone
Have to add my two cents on this. I just came back from Carson City to
the Central Valley with my Tiger and while cruising at 12,500 with very
above normal outside temps, valley was over 100 that day, 12,500 was 17 C, and
thanks to Gary`s cowling, fine wire plugs and the Power flow was showing
max CHT`s at 406 for number 3 & 4 390 for 1 & 2, RPM 2675. Leaned to peak,
Electronic Tac and JPI.
Best news here is I still had over 1 Inch of throttle left and it would
red line over 2700 easily. So I can say temps can be controlled. Density
altitude was 15,000 so I know it is not the usual 360 but wanted to add
that you can control temps.
Thanks
Bill Stigle
In a message dated 9/17/2015 8:33:44 A.M. Pacific Daylight Time,
flying-nut@cfl.rr.com writes:
--> TeamGrumman-List message posted by: Linn Walters
<flying-nut@cfl.rr.com>
I'm no expert but have had good breakin results using WOT around 3000
AGL. I expect CHTs to be higher than normal and use mixture/throttle to
try and keep them below 450. The hottest may go above, but not for
long. Flights at least an hour at a time.
You have to remember that the numbers Lycoming uses are set for an
engine during certification, and by nature are conservative. I learned
a lot during an off-the-record discussion with a Lycoming engineer.
Early in the discussion his comment was 'you can't do that' but when
off-the-record he opened up.
Linn
On 9/17/2015 5:51 AM, Richard Ranger wrote:
> --> TeamGrumman-List message posted by: Richard Ranger
<richardranger@ozemail.com.au>
>
> Gary, you have raised some very interesting issues on your flight to
SLC, and I hope it stimulates good discussion.
> Firstly, your hotted up engine does not sound as though it is yet
run-in. The CHT's you observed are very high and consistent with a new
powerplant. From my own experience, it took 30 hours at 75 percent power and very
high (and expensive) fuel flows for the CHT's to settle below 400 F in cruise
and for oil consumption to fall. They are now consistently between 360 and
390 at 65 percent power, with oil consumption minimal.
> At standard atmosphere 75 pc power can only be achieved with wide open
throttle (WOT) at 8,000 ft and less if the temp is higher; so that is
probably the maximum altitude to bed in the engine. At 12,500 ft and WOT max
power is only 63 percent, which is a power setting that should never damage an
engine according to Lycoming, but is below 'running in power' settings.
> That you can achieve such high CHT's at 12,500 ft is concerning, given
the limited power at that altitude, and their variability without changing
mixture or throttle setting is strange. Timing issues or preignition need to
be excluded.
> You are correct in saying that engines without 4 cyl monitoring may be
running temperatures way out 'normal', yet they seem to run OK. Are we being
over careful?
>
> Richard Ranger
> AA5b
>
> Sent from my iPad
>
>
> -----
> No virus found in this message.
> Checked by AVG - www.avg.com
>
>
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