Author Topic: Temps for the O-320 160hp  (Read 39238 times)

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Offline allen

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Temps for the O-320 160hp
« on: September 09, 2007, 09:40:29 PM »
Iím a new owner and have a few questions about the proper care and feeding of an O-320. I have CHTís for all four hamsters and two EGTís. The exhaust system is 2-into-1 so I have one EGT for each side. The pervious owner also mounted a temperature probe to monitor the carburetor temp.

I have a few questions for you vets out there. What is a good cruise RPM and what temps are you seeing? What temperature spread are you seeing between each of the cylinders? What temperature are you seeing for long climbs and dissents? What power settings are you using to descend in order to avoid shock cooling?  

The book says not to go above 425 degrees. My A&P says that anything above 325 is cause for alarm and I'm seeing my number three in the 350 range in cruise at 2500rpm. Number 4 reads right about 300 or so. One and two are both high 200's. Left side EGT runs 1090 and the right side runs about 1300.

After looking at Bill James and his set up I am inclined to build a similar set up.

The plane is a dream to fly! Landing this thing takes some getting use to.

Allen
N701DS
Allen
Long-Ez N701DS
1998 O-320 160HP
http://www.freewebs.com/wonderingwingnut

Offline rglos

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Temps for the O-320 160hp
« Reply #1 on: September 10, 2007, 01:08:31 PM »
I see you have the P-51 style scoop. Where are your probes? on the top plugs, bottom plugs or bayonets on the bottom.

There have been many discussions on this.I searched all the forums and the consensus is that on updraft cooling the sensors should be on the top  and on down draft cooling, on the bottom. If you have the thermistors on the top and are running the temps that you are, then you have no problems

The "Lycoming" hand book I have on the O 235 and O 290 lists the Cylinder max temps at 500 degrees F and Oil temps at 245 degrees F.

I'm breaking in a completely overhauled engine and still running the break in oil but I too would like to research better cooling. The baffles shown in one of the Cp newsletters did nothing for me. To be fair, I should wait untill the engine has some more hours on it before going further.

I ran the old engine with no CHT probes for 20 years. I was nearing 2000 hours when I had it overhauled so I can't say it was due to any worn out jugs but without the probes  I can't say that this was OK to do either.
Long EZ, 0-235L2C, 1986

Offline allen

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Temps for the O-320 160hp
« Reply #2 on: September 10, 2007, 01:20:08 PM »
Thanks for the reply. I have also dug through the threads. I have also been on the Lycombing website searching for hard numbers. So far I have not had great luck, but I will keep looking. I am going to order one of the operators handbooks from them this week as well. It's just good to have on hand.

Allen
Allen
Long-Ez N701DS
1998 O-320 160HP
http://www.freewebs.com/wonderingwingnut

Offline Drew

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Temps for the O-320 160hp
« Reply #3 on: September 10, 2007, 11:34:27 PM »
The Longez owners manual has most of the numbers that you need.  The lycoming manual is ok---but will more or less tell you what numbers to not exceed----and I would say don't get close to them.

Take a look at some of the engine monitor sites.  They give some pretty good advice on using their monitor---and what temps you should be running.  And of course they will give you the disclaimer on checking the manufacturer's manual.

The Sacramento Sky Ranch book (if I remember the name) is a weath of engine information.

There is also a series of books---one of them called Firewall Forward---that are very good.  There are several more books in the series---once you find Firewall Forward, you will find the rest.  All those books---very very good.

All the lycoming engines run more or less the same.

Takeoff: full power with a carb to get the extra cooling from the extra fuel dump.  Use about 120 mph for your climb to cool off the motor.  Don't let it exceed 400.  Throttle back and level off in the climb if you have too.  The engine will quickly "recover," then power back up and resume the climb.  Can you get over 400---yes---book says you can go to 435 (memory) continuous---but don't recommend.

Cruise:350 for an EZ is pretty good.  I am up around 470 (both Long and Cozy) with no ill effects.  Don't exceed 75% power if aggressively leaning.  The power charts in the manual are not suitable for the cockpit.  You can make your own cheat sheet based on them----but they are difficult to interpret.  There is an RV guy on the web (might be rocketboy--but can't remember) who has a spreadsheet for a lycoming that calculates all the values.  I use his spreadsheet, (you can change the HP if he has a different size motor), to calculate my cheatsheet that I carry in the cockpit.  You will need a MP gauge to do this however.  You don't need mp in a 172 because it is fixed pitch---and the test pilots already took mp out of the equation.  Your HP for your prop can only be determined from MP, rpm, OAT, and altitude.  Most likely if you are in the 2400 to 2500 regime below 8000 ft, you are probably ok no matter what fixed prop you have----unless you have something real crazy.  Above 8000ft (std day), your engine can't develop 75% anymore---so you could go full throttle.  I normally don't---I usually just max it out at 2700 rpm.

I have now been playing with LOP (I am fuel injected).  Works great---fly a little slower----but really sip the gas (3ish gph less---and cyl head temps way down also).
Drew Swenson
Cozy N171ML

Offline GlennBob

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CHT's
« Reply #4 on: September 11, 2007, 01:05:09 AM »
Drew,

Good memory ! !

Direct from the 0-235 and  0-290 series manual, pp 3-5:  " For continuous operation cylinder head temperatures should be maintained below 435 degrees F. (224 C). "

I tried to scan the page but the E.Z. site said it was too big.

Glennbob
N600EZ  O-320-E2A,  Hertzler prop, Trio AP, Narco HSI, Custom headers, Oil heat.

Offline allen

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Temps for the O-320 160hp
« Reply #5 on: September 11, 2007, 12:05:16 PM »
Last set of numbers I got. How do they look to you guys? From what I'm finding on line it looks well within limits that Drew mentions. The probes are bayonet type and located under the motor. This is also a P-51 style intake.

_________________________________________________________
Oat: 95F, density alt:1500 feet, solo at 30gallons of fuel, 25 miles trip

Taxi:

Cht1:280, cht2:284, cht3:299, cht4:287, egt1:998, egt3:1015 airbrake was down

Climb at 100 kts to 1200 feet:

Cht1:339, cht2:311, cht3:371, cht4:325, egt1:1090, egt3:1312

Cruise at 2300 rpm:

Cht1:315, cht2:299, cht3:345, cht4:313, egt1:1120, egt3:1265 , oil press:80, oil temp:160

________________________________________________________


The LOP idea is new to me. I do not have a MP readout. I have read up a bit on LOP but I still do not get how exactly to do it. More reading to be done in that area.
Allen
Long-Ez N701DS
1998 O-320 160HP
http://www.freewebs.com/wonderingwingnut

Offline Bill James

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Temps for the O-320 160hp
« Reply #6 on: September 11, 2007, 05:34:29 PM »
Allen-
A couple of thoughts on changing cooling-
-Your cylinder numbers sound pretty good. I flew mine 400 hours over three years before going to downdraft plenums. It was productive time learning the plane and engine, and getting out among the other eze drivers.
-My cooling target was to be able to fly wide open at sea level on a 100 degree day. While it is very gratifying to have accomplished that fairly challenging goal, for most of us a better target is just good numbers for normal climb and cruise, which it sounds like you already have.
-A parallel target was to play with augmented cooling draw through the cylinders, and of course oil cooling, all good now. Its fun when someone stops by and suggests this or that and I pull an ugly inlet or ramp or tunnel out of the box and say "Like this?" My curosity is pretty well satisfied there, and now some components are being tweaked and minimalized or removed.
All this has been done after having flown the plane all over the place for several years, which I hope you have a chance to do. Maybe along the way you will luck into a back seat ride in an operationally well balanced plane where you can observe someone good up front working their cruise climb magic on the way to altitude. Good flying-
Bill James, Fort Worth VariEze N95BJ
Downdraft Plenums, QuickCowls
There was supposed to be anhedral?
ATP, Society of Flight Test Engineers

Offline Drew

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Temps for the O-320 160hp
« Reply #7 on: September 11, 2007, 11:13:05 PM »
Keep the probes on the bayonettes.  Get up to 8500 ft and 2700 rpm (or as high of rpm that you can get without exceeding).  You can probably go to 2900 rpm (2700 rpm more geared to swinging an aluminum prop)---but why put up with the noise and additional fuel flow?  Then lean out the engine.  Leaning techniques sort of vary and depends on how balanced your cylinders are.  If you lean to peak and then add until you are 100 degrees rich, you should be ok.  If you monitor all four pipes (which you are not) then you can tighten up the 100 deg part.

Lean of peak will only work if you are fuel injected---carb engines don't really like it on the "other side" due to the vastly different conditions between the cylinders.  Even if you are fuel injected, it may not like it "over there" unless the fuel flow between the cylinders is balanced real well (all cylinders peaking on EGT at the same time---or near the same time).

Your temps are good---but I think you may be down on the power---that's why I say get to 8500 (<75% even at full throttle) and get up to 2700 rpm).  BTW, it is nice and cool up there too---and the engine will thank you for it.  At those conditions, I would like to see the oil temp a little higher---about 180.

One thing you can do for your winter project is to verify that all of your probes are accurate----and even check your rpm with one of those optical tachs (see if you can borrow one).
Drew Swenson
Cozy N171ML

Offline GlennBob

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Tach check
« Reply #8 on: September 12, 2007, 12:24:08 AM »
Drew and gang,

Here's a FREE way to check your tach and I know it works cause I've done it.  

Must be done at night.  Taxi near a ramp light or hangar light that is flourescent.  I'm not sure if the high press sodium work or not, but with our elect service at 60 cycles, the prop will shadow and " stand still " at any rpm that is a multiple of 60.  So . . .1200 rpm,  1800 rpm, 2400 rpm you will see the prop " stopped ".  It's a cool way for free to check your tach and it works ! !

Glennbob
N600EZ  O-320-E2A,  Hertzler prop, Trio AP, Narco HSI, Custom headers, Oil heat.

Offline rglos

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Temps for the O-320 160hp
« Reply #9 on: September 12, 2007, 11:10:44 AM »
While you may be comfortable with the readiings on the bottoms of the cylinders, I found a post indicated that there was as much as a 90 to 100
degree difference between the tops and the bottoms.

I copied it for discussion.


"Well, yesterday I did two things:

1) I installed an aluminum, air deflector in the ram-air box forward of the
filter leaving sufficient space between the filter and the deflector to allow
air to pressurize all faces of the filter more equally.
2) I moved the sparkplug probe from the upper sparkplug of the #2 cylinder to
the lower sparkplug of the #4 cylinder so I could directly measure the delta T
top to bottom.

Today, I flew to measure the effects.
Here are the happy camper results:

1) Upper probe temperatures dropped by 20 to 30 degrees F.
2) Engine performance improved noticeably
3) There was no switching of relative temperatures between #3 and #4 with a
change in throttle position.
4) The delta T measurements showed that the upper TC was indicating - gasp!!-
90 to 100 degrees hotter than the lower TC. Yes, the TCs are calibrated.

I am NOT going to take the easy CHT cooling solution of switching all my probes
to the lower cylinders. Besides, if I did that, my cylinders would probably be
running TOO COLD ;-). I will stick with my current and known arrangement with
the probes on the upper sparkplugs.

The saga continues. That's why the plane is called EXPERIMENTAL."

Marc Borom
LEZ N966EZ
Ryan Field (KRYN)

That being said, on climb out your #3 cylinder temperature on the top could be as high as 475 degrees.

Rick
Long EZ, 0-235L2C, 1986

Offline allen

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Temps for the O-320 160hp
« Reply #10 on: September 12, 2007, 12:15:05 PM »
Well I cannot say that that article gave me any warm and fuzzy feelings :?

There is one aspect to this that has not been addressed fully I feel. The TC relies on heat conduction passing through the various metals of the spark plug and motor into the TC. The TC is also somewhat exposed to the outside environment based on the sheer nature of how it is applied. The bayonet type probes are taking reading from within the cylinder itself. Correct me if I am wrong here, but I am under the impression that the bayonet type probes are more accurate regardless of their location since they are gathering temperatures inside the motor right from the source. Granted the probe wire will be influenced by the outside air, but I doubt that it would be 100 degrees worth of variation.

It would be interesting to see the numbers for a motor with bayonets on the bottom and TCís on the top. I would postulate that they would not be that different on an up-draft style Long-Ez. However, I have never been accused of being terribly bright.

Thoughts?
Allen
Long-Ez N701DS
1998 O-320 160HP
http://www.freewebs.com/wonderingwingnut

Offline rglos

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Temps for the O-320 160hp
« Reply #11 on: September 12, 2007, 02:07:11 PM »
Very good questions Allen. I hope someone address this. My engine does not have bayonet access on the top so I have no choice.

One thought: If the bayonets are on the inside closer to the heat source the spark plug type should theoritically be cooler. (because they are closer to the cooling source) That is if they are mounted on the bottom side as well.

What would the temperature differential be between a Bayonet on the bottom and a spark plug type on the top?

I just finished reading the Schubert/Hertzler PP presentation on this subject and it has given me many things to try after the engine has broken in. I need a good baseline to work from.

In the meantime I'm just going to throttle back to keep the #4 jug below
425 degrees. Incidentally a friend in the Hounduras recently purchased his Long and is running nearly the same set up as you. (O-320, P 51 scoop) I think he is running nearly the same temperatures as you with probes on the bottom.

Contact him at saybeengineering@hughes.net
Long EZ, 0-235L2C, 1986

Offline Bill James

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Temps for the O-320 160hp
« Reply #12 on: September 12, 2007, 02:50:21 PM »
On sender location, over the years i ran washer senders on the tops and bottoms of cylinders at the same time. I also tried putting bayonet senders on the bottoms, which showed the same as the adjacent washer sender. The hotter sides indicated 'about' 60 degrees higher.
With dd cooling I run the senders on bottom for worst case readings. It is interesting to record the differing temps in climb versus cruise versus wide open on the deck.
After a while we can maybe detect which flight regime needs a little help and affect a benefit at that point without screwing up the other conditions too much.
I agree with Terry Schubert's Oshkosh cooling forum comment that different pilots get different performance and readings in the same airplane because of technique. Hopefully we all get better. At Jackpot i could outrun Beagle matched side by side but he always beat me because of his 20+ years of smarts. I'll get him next time.
Bill James, Fort Worth VariEze N95BJ
Downdraft Plenums, QuickCowls
There was supposed to be anhedral?
ATP, Society of Flight Test Engineers

Offline Drew

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Temps for the O-320 160hp
« Reply #13 on: September 12, 2007, 11:20:29 PM »
There is a discussion (I think the CPs) where someone had TCs on all spark plugs and the bayonettes with updraft cooling.  From there he made certain conclusions.

I have come to 2 separate conclusions:
1.  Running both of my engines (Long--downdraft; Cozy updraft----both with bayonettes) within the parameters that I listed in an above post---never was bad for me.  But to really know for sure----you have to start with a fresh engine and see how long you go until overhaul.---so maybe that one is not a really good conclusion
2.  I challange anybody that you really don't know what you have unless you are running downdraft cooling with TC in the bayonette boss.  The lycoming numbers are based on this.


There will be a delta temp from one side of the cylinder to the other---these machines are aircooled.  I would also assume (but don't know) that with engine sitting still on a test stand that the bottom of the cylinder would be hotter due to the proximity of the exhaust valve/port/pipe.
Drew Swenson
Cozy N171ML

Offline allen

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Temps for the O-320 160hp
« Reply #14 on: September 13, 2007, 01:22:37 PM »
Good points guys. Certainly food for thought.

   On my next flight Iíll head up to 8.5 and run at 2700rpm and see what those numbers look like. Honestly, I have not run engine at that high of an RPM in the past intentionally. While flying the FBO Cherokeeís with the O-320 I was cautioned to never run above 2500 rpm or it will harm the motor. My flight instructor would always walk it back to 2400rpm. I just got in the habit of running at 2400rpm I guess. Anyway, Iíll run it up and see the numbers.

   Frankly guys, I hate to admit it, but Iím scared that Iím going to ďhurtĒ the plane. Again it harkens back to my tin can days. Anything more than a couple Gís and I panic that the wings will rip off. After years of following these planes and reading about just how strong they are, I still worry a bit. I guess thatís where I get the fear about the causing harm to the motor by spinning it too tight. It is reassuring to hear from you guys that the temps are good. That was becoming a real fear for me.

   With regards to exhaust temps under the cowl I have a concern. The right side pipe has been wrapped in fiberglass to stop damage to the paint. The left one is still unwrapped and the paint shows signs of heat damage. I would like to wrap the left pipe to save the cowl. While at it, I would like to put in some felt style heat shielding that Berkut13 has on his website. This would theoretically solve two problems: it would save the paint and cowl from heat relate damage, and it would contain any heat radiating from the pipes into the compartment. Anyone out there doing this already?

   Thanks for the help everyone. Still leaning, and having a blast doing it! 8)
Allen
Long-Ez N701DS
1998 O-320 160HP
http://www.freewebs.com/wonderingwingnut