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IO360 High Oil Temps

M

mattsmith

Well Known Member
I am having a problem with my oil temps. The baffles are tight and I don't think I am loosing cooling air thru them ( CHT seem to confirm) but my oil temps are still at 195 degree F on a 53 degree F day, here are the numbers.

IO 360 A1A (angle valve)with 51 HRS since major
Philips xc oil
23" at 2400 RPM
10.5 GPH
CHT 350 (hottest)
EGT 1350 (hottest)
OAT 53 degree F
oil temp 195 degree F

The oil cooler is mounted on the #4 baffle and is a Aero Classics #8001689 from Pacific Oil Coolers. I have the oil cooler standing off the baffle with a 1" spacer to allow the whole oil cooler area air flow and have made a air dam that wont allow the air to go over the top of the # 4 cylinder fins and pre-heat than into the oil cooler. My last try at lowering the temps was to seal the inlet ramps on the upper cowl which made no change to any of the temps.
I know 195 is within spec but when I talk to other pilots that have flown that day with similar set ups they say they are struggling to see 180, I live in Reno and am afraid this summer I will be seeing higher than I want oil temps

Anyone have any ideas as to what the problem could be?
 
Forgot to mention when I get back to the hanger and de-cowl the oil cooler is to hot to leave my hand on so I don't think it is plugged, it is also has 51 Hrs. since new.
 
Temps

Are the other planes Angle or Parallel valve ? 195 on an angle valve sounds in line .
 
mattsmith said:
I am having a problem with my oil temps. The baffles are tight and I don't think I am loosing cooling air thru them ( CHT seem to confirm) but my oil temps are still at 195 degree F on a 53 degree F day, here are the numbers.

IO 360 A1A (angle valve)with 51 HRS since major
Philips xc oil
23" at 2400 RPM
10.5 GPH
CHT 350 (hottest)
EGT 1350 (hottest)
OAT 53 degree F
oil temp 195 degree F

The oil cooler is mounted on the #4 baffle and is a Aero Classics #8001689 from Pacific Oil Coolers. I have the oil cooler standing off the baffle with a 1" spacer to allow the whole oil cooler area air flow and have made a air dam that wont allow the air to go over the top of the # 4 cylinder fins and pre-heat than into the oil cooler. My last try at lowering the temps was to seal the inlet ramps on the upper cowl which made no change to any of the temps.
I know 195 is within spec but when I talk to other pilots that have flown that day with similar set ups they say they are struggling to see 180, I live in Reno and am afraid this summer I will be seeing higher than I want oil temps

Anyone have any ideas as to what the problem could be?
Click to expand...


I'm not sure I would agree that your CHT's confirm your baffles are tight. I have an angle valve on my RV-8 and almost never see 350 on CHT. I performed several sea level to 17500 climbs at Vy or slower on my way to Sun 'n Fun and never crested 335. In high power cruise I seldom get over 300. Mine is under a very tight plenum though. I would take a close look at your baffle sealing all the way around. That means between the cylinders, the rear baffle to cylinder pieces....basically every bit of air entering the front should have to exit past a fin. Also look closely at how your rubber fits to the top cowl. I'm no expert in that as I went with a plenum but its another area for cooling air leaks.
 
Bill, what oil temps do you see in cruse, what is the OAT, what cooler do you have? I will drag some of the builders from the airport around to double check my baffles.
 
Bill, what oil temps do you see in cruse, what is the OAT, what cooler do you have? I will drag some of the builders from the airport around to double check my baffles.
 
mattsmith said:
Bill, what oil temps do you see in cruse, what is the OAT, what cooler do you have? I will drag some of the builders from the airport around to double check my baffles.
Click to expand...

Hi Matt,

My oil cooler is the Stewart Warner (now Meggitt Troy) 8432r. It's mounted flat against the #4 baffle. Going through some recent data from a Florida trip, at 75 degrees OAT, my oil temp hovers around 172 running 26 squared (I was in a hurry). In the winter I put one of Vans shutters in front of it to keep temps up. It runs a few degrees cooler at higher altitude and lower OAT but 170 is a pretty average oil temp for my setup without the shutter. Hope that helps in some way.
 
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mattsmith said:
I will drag some of the builders from the airport around to double check my baffles.
Click to expand...

You don't need friends, you just need a dark hangar and a concentrated beam flashlight.
Look for any place that light leaks between baffles and the engine, that there is not cooling fins. Including the inter cyl baffles that are at the bottom between the cyl.
Then look for evidence of baffle seal rub everywhere on the top cowl.
 
Timing?

So - 51 hrs since major. Is this engine new to your RV? What kind of ignition system does it have. I believe the A models have cooling jets, and advanced timing will cause more heat rejection to pistons and thus to the oil.
 
Bill I have E-mags on the A curve. Timing is per manufacture.

what are others seeing for temps wit OAT or around 55 F
 
mattsmith said:
Bill I have E-mags on the A curve. Timing is per manufacture.

what are others seeing for temps wit OAT or around 55 F
Click to expand...

OAT at 55F, that's 55F at my altitude I see 195F, at 75+ I see 197 to 202 in cruse. I have never been over 225F on very hot long climbs. I dont think you have a problem. I'm running IO-360-A1A, it has oil nozzles that spray oil on the bottom of the pistons, takes heat out of the cylinders and puts it into the oil.
 
55 degrees OAT, my oil temps are 178. and the CHT's are 334-324 range. My ignition is dual Lightspeed but the numbers did not change much when i switched from Mags. I can see your results while cruising hard and low but not at 6k plus in altitude.
This is running LOP at 8.5 GPH. Have you looked at your numbers while running lean?
 
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mattsmith said:
Forgot to mention when I get back to the hanger and de-cowl the oil cooler is to hot to leave my hand on so I don't think it is plugged, it is also has 51 Hrs. since new.
Click to expand...

Does oil enter the cooler at the top or bottom?

To guarantee that the entire volume of the cooler is full of oil (and transferring heat), oil needs to enter at the bottom.
 
Tad I have never ran LOP, would that lower my oil temps that much?

Kyle I have a 2 pass oil cooler so both the connections are on the bottom.
 
Matt you will be amazed. Climb to 7.5k all in and prop to 2450, pull the mix till she is rough then nudge it back till it runs smoothly. Report back your results.
Best
 
mattsmith said:
Tad I have never ran LOP, would that lower my oil temps that much?

Kyle I have a 2 pass oil cooler so both the connections are on the bottom.
Click to expand...

Is it possible to get an air pocket in the cooler in that configuration? Would having both the in and the out on the top be preferable so you're guaranteed the cooler is full of oil and transferring as much heat as possible?
 
Kyle Boatright said:
Is it possible to get an air pocket in the cooler in that configuration? Would having both the in and the out on the top be preferable so you're guaranteed the cooler is full of oil and transferring as much heat as possible?
Click to expand...

IIRC, engine oil flow is around 7 gallons per minute. The pressure drop across a 2-pass cooler is quite high (SW8432R is 15 psi @ 50 lbs per minute)...meaning oil velocity in the cooler passages is high. I doubt it can trap air. Anyone seen evidence to the contrary?

BTW, while thinking about that 15 psi drop, consider the vernatherm. It must extend to close the bypass opening and force all the oil flow through the cooler. If it doesn't fully close, some oil bypasses the cooler.

The pressure drop across the identical form factor single pass cooler (SW10599R) is only 3.5 psi at 50 lbs per minute.
 
DanH said:
Anyone seen evidence to the contrary?
Click to expand...

I can't say for sure one way or the other, but years ago I ran across a particular Piper model (don't remember which one) that used a special made stand pipe in the oil cooler to make sure it had to fill fully before oil began flowing out. I don't remember specifics, but I guess it required a specific orientation of the cooler that had the hose ports on the top.

Based on this I have always assumed (assumed they must know something I don't) it was possible.
 
Normal

mattsmith said:
I am having a problem with my oil temps. The baffles are tight and I don't think I am loosing cooling air thru them ( CHT seem to confirm) but my oil temps are still at 195 degree F on a 53 degree F day, here are the numbers.

IO 360 A1A (angle valve)with 51 HRS since major
Philips xc oil
23" at 2400 RPM
10.5 GPH
CHT 350 (hottest)
EGT 1350 (hottest)
OAT 53 degree F


oil temp 195 degree F

The oil cooler is mounted on the #4 baffle and is a Aero Classics #8001689 from Pacific Oil Coolers. I have the oil cooler standing off the baffle with a 1" spacer to allow the whole oil cooler area air flow and have made a air dam that wont allow the air to go over the top of the # 4 cylinder fins and pre-heat than into the oil cooler. My last try at lowering the temps was to seal the inlet ramps on the upper cowl which made no change to any of the temps.
I know 195 is within spec but when I talk to other pilots that have flown that day with similar set ups they say they are struggling to see 180, I live in Reno and am afraid this summer I will be seeing higher than I want oil temps

Anyone have any ideas as to what the problem could be?
Click to expand...

I don't see anything a miss for an angle valve engine in your numbers. Angle valve engines have oil jets that shoot oil into the backside of the pistons pulling out additional heat from the extra 20 horsepower. My oil temps climb into the 200's during high power climbs, and settle down to the low 190's for cruise. 350F CHT's with a fuel mixture that would lead to a 1350F EGT would be about right. 380F is a good target for your CHT's Cylinders are bored tighter at the top of piston travel, and larger at the bottom. When they heat up to operating temperature everything straitens out. A 180 F oil temp is ok, but would be as cool as you would want to continuously operate at. Expect cruise oil temps in the 190's.
 
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There is quite a difference in heat generated in the angle valve vrs parallel engines.

The last time I flew with OAT in the 70's and oil cooler 100% blocked from winter ops, oil temp topped out at 190.

Not as much HP and not as much heat for sure. This with the Barrett Superior IO360 180HP engine and standard cooler at #4 baffle. I am making an adjustable exit so as to be able to control oil temp during summer months, it runs too cool.

I agree, the numbers Mattsmith posted are not that unusual for that engine.
 
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rvbuilder2002 said:
I can't say for sure one way or the other, but years ago I ran across a particular Piper model (don't remember which one) that used a special made stand pipe in the oil cooler to make sure it had to fill fully before oil began flowing out. I don't remember specifics, but I guess it required a specific orientation of the cooler that had the hose ports on the top.

Based on this I have always assumed (assumed they must know something I don't) it was possible.
Click to expand...

I hear you brother. I've read something similar (a certified model trapping air), but can't recall details. I did in fact install my cooler (currently a 10611R) with fittings up) so it could not trap air, and only later realized that with the fittings pointed up, the trade was that it held some quantify of dirty oil at changes. Next time, fittings top and bottom....more education and recreation.

BTW, here's the trap/no trap argument. A two-pass cooler with fittings on the bottom has to pass all its flow through the end cap. It would drop roughly 7 psi in the first pass, so oil would be jetting into that space...high flow, high velocity, and even if it did trap a little air up there in the cap, it's not a finned section of the cooler; lack of heat transfer from the cap shouldn't make much difference.



A single pass cooler mounted upside down moves oil across multiple passages, with less restriction at each cross passage. I can see where it might trap some air in an upper passage or two, and that would reduce cooling, as those are finned passages.



Theory. True, false...darned if I know. Anyone have plexiglass oil cooler handy?
 
The resistance of air flow (inside the cooler passages) to the delta-P is lower than the oil. Small passages mean that a bubble counter to flow would be pushed with the flow. I can not see where a bubble would last very long in the cooler, unless it was very cold outside, no shutters, and the oil/air area was extremely sub cooled resulting in very high viscosity that could not be cleared by hot oil. One can calculate the rise velocity of an air bubble.

On the upward flow configuration, it seems that the HX performance with hotter oil being first cooled by the hotter air off the head (applies to baffle mounted only) would result in an overall better Delta-T and performance factor. i.e. greater heat rejected.

edit: One additional condition - as the vernatherm (VT) opens slowly, and before the air is cleared, it could be possible to have an oil temperature spike (peak is more a appropriate description) as the cooling rate was low, and the bubble clearance time allowed the sump temperature to rise rapidly before the bubble was cleared. Thus the VT would finally fully open and when cleared, would slowly close

Just theory, not based on data.
 
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Temp

I also have had a hard time cooling angle valve started with standard Vans on back of #4 real high temps over 200.Then remote mount with twice the cooler a 14 row still high temps over 200 down low and climbing could get down to 195 in cruise above 5000 I have SJ cowling started looking at exit which is quite small made a 3/4 lip 16" long bolted to exit and temp went down 15 degrees and speed 10 mph.So I think I will have to install some type of cowl flaps as I get it back to flying soon.
Bob
 
Danny King said:
A 180 F oil temp is ok, but would be as cool as you would want to continuously operate at. Expect cruise oil temps in the 190's.
Click to expand...

Absolutely agree that the angle valve motors with piston oil jets tend to run higher oil temp and lower CHT. However, I must respectfully disagree with the numbers presented.

I'm running an IO390, a big bore version of the Danny's IO360. The Lycoming operator's manual is clear; "For maximum engine life, desired oil temperature is 180F (82.22C)".

The maximum is of course 235F, and no, I don't think 190 cruise, or excursions to 210 during a hard climb is going to damage anything....but it's not desirable.

Personal opinion; oil cooler size selection is mostly based on what we've seen others do in the past, and acceptable oil temperatures are what our hive mind has gotten used to while flying old GA installations with miserable baffles.

Always check the instrumentation. Not being the brightest of bulbs, a few years of flying passed before I noted that my oil temp indication is 7~8 degF too high. Just flip on the EFIS power in the hangar a few mornings and compare oil, EGT, and CHT at ambient.
 
OIL temps

Make sure your oil temp probe (and Vernatherm) are mounted in the adapter not on the engine. Most of what you are trying to fix are CHT problems not oil temp (I know I did the same thing). Took me a year to find this solution. Good Luck.
 
6 Gun said:
I also have had a hard time cooling angle valve started with standard Vans on back of #4 real high temps over 200.Then remote mount with twice the cooler a 14 row still high temps over 200 down low and climbing could get down to 195 in cruise above 5000 I have SJ cowling started looking at exit which is quite small made a 3/4 lip 16" long bolted to exit and temp went down 15 degrees and speed 10 mph.So I think I will have to install some type of cowl flaps as I get it back to flying soon.
Bob
Click to expand...

IO360? Do you have to IO or O cowl? The IO has less exit area. What size is your cooler supply hose? Square or rounded entrance from baffle wall? (if square it is a 20% loss of flow).

Pictures?
 
cowling

The cowling is IO which has smaller opening my cylinders ran way cool from 270 to 315 the highest I saw .Oil cooler mounted on fire wall with two 3" scat to cooler 1 from each side .Down low when outside temp above 85 I need more exit air from cowling it cooled OK above 5k and it has less cooling drag with smaller opening . I think ideal setup is large cowl flaps down low and being able to close up after reaching cruising .Its been said after 50 hrs the pistons get dirty with carbon and it runs a little cooler.I like SJ cowling for the extra speed I was running 216 mph at 25-25 not bad.
Bob
 
So if my numbers are in line with an io 360 when the outside temp is 55, what can I expect when it is 100 degrees?
 
mattsmith said:
So if my numbers are in line with an io 360 when the outside temp is 55, what can I expect when it is 100 degrees?
Click to expand...

Not sure it is possible to extrapolate - if the 190 is being managed by the vernatherm, then you only have partial flow. If 190F was with known full oil flow, then the oil-ambient delta would apply. If -If it did then, 235F, but testing is needed.
 
BillL said:
Not sure it is possible to extrapolate - if the 190 is being managed by the vernatherm, then you only have partial flow. If 190F was with known full oil flow, then the oil-ambient delta would apply. If -If it did then, 235F, but testing is needed.
Click to expand...

As Bill said you need to test it, I have flown mine around in 100F for about 40 minuets and it stabilized at about 207F, I normally climb out of those temps though. As I said before I don't think you have a problem at least not tell you test it in warmer weather and see what it does. As bill stated could be the case and I believe is the case with mine, the vernatherm is holding the 190s and allowing more flow as it gets hotter giving me very stable oil temps over a wide range of ambient temps, that is what it's supposed to do.
 
195 is okay, maybe a little low

I disagree with Lycoming, you want to oil to be hotter so all the water boils out of your oil.

I base this on knowing someone who has a fleet of about 20 planes that fly all the time.

Many problems went away when they starting blocking the oil coolers to get oil temps over 200.


Hans
 
It depends on where the oil temp is measured. I think the oil temp sender for most or all Lycomings is downstream of the oil cooler, so that is the coolest temperature the oil sees. From there on it gets hotter as it makes its way through the engine into the sump, which is probably the hottest point in the system. A temp reading below the boiling point of water at the oil cooler outlet does not mean the oil does not get hotter than the boiling point of water.

Also, the oil does not have to boil the moisture out. The hotter the oil the more the moisture will be driven out. I would expect the moisture will go out the crankcase breather. I can't think of any other place it could go. If the coolest oil temperature is after the oil cooler and before the oil goes through the engine, then the hottest place is probably the oil in the sump.

Last point, the boiling point of water goes down as pressure goes down so as we climb the oil does not have to get to 212 F to boil.

I think regular operation of the engine at flight temperatures is more important than being above some temperature unless the temperature is really cold. I think 185, 190, 200 is all good.
 
So after flying a little this summer I am happy to report, straight and level in cruise I see 193 oil temps. This is well within Lycoming numbers, I do see higher temps climbing at more than 250fpm.

So the short answer to my original post, I was worried about a problem that did not exist.

Would like to get a little lower but think it would require Vernatherm.
 
New things.

It is always fun to explore new things. Just 2 cents here. A well adjusted vernatherm is always a good thing to have, just like your prop bolts I would check it now and then. And running in that 40* temp. band from 180-220 has worked well for many years on most of our little air cooled engines. If you want to race and run hi "B.M.E.P." all the time that is a costly zone to inter. For most of us ( get alt., pull the throttle back, and have fun while watching the temp. come down). Yours, R.E.A. III #80888
 
mattsmith said:
Bill I have E-mags on the A curve. Timing is per manufacture.

what are others seeing for temps wit OAT or around 55 F
Click to expand...

Check your PM's.

The IO-360-A1A should run at 20 degrees BTDC, not the 26 degrees the A curve gives you.

By lowering your timing to 20 degrees, your CHT's will come down, which may have a small impact on your oil temps but a big impact on lowering your CHT's.
 
nucleus said:
I disagree with Lycoming, you want to oil to be hotter so all the water boils out of your oil.

I base this on knowing someone who has a fleet of about 20 planes that fly all the time.

Many problems went away when they starting blocking the oil coolers to get oil temps over 200.


Hans
Click to expand...
In talking with a Lycoming engineer about this issue a few years back, he mentioned that the oil temp at the probe is significantly cooler than in the sump. Part of the reason is that the probe measures the temperature after it goes through the cooler. Thus, having 180 to 190*F oil temps means that the oil in the sump is hot enough to get rid of any moisture that may be present.

Also, Lycoming lists the max oil temp at 245*F. (And max CHT at 500*F, who knew and I'm not recommending you run your cylinders that hot.) If your engine has the piston squirters, you are trading cylinder temps for oil temps, and that isn't a bad thing.
 
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The idea that oil must reach 212F to evaporate water is one of the oldest old wives tales in motorsports. Evaporation is a function of vapor pressure. Water, which has a relatively high vapor pressure, evaporates at temperatures far below boiling point.

What we call "boiling" is merely a case of vapor pressure => local water pressure. Water at the bottom of a deep pool, for example, would not form bubbles until temperature rose well above 212F, while a shallow pot on a mountain top boils at less than 212F.

Trivia...when cruising at 10.5K, your cabin teapot would boil at 193F. I just threw that in there for the RV-10 guys who never get enough toys ;)

If your engine has the piston squirters, you are trading cylinder temps for oil temps, and that isn't a bad thing.
Click to expand...

Exactly true, but note it really is increased cylinder temperature, not increased cylinder head temperature...at least not directly. Heat transfer is from the piston crown to the rings and skirt, both in contact with the steel cylinder. The head is no doubt heated in turn through the screw joint overlap, but the piston rings are only in that area of the cylinder during the TDC part of the cycle. At BDC they're about 4" away. I suspect the primary purpose of piston squirters is improved piston strength due to lower temperature, but offhand I don't know the actual crown temperature reduction with squirters.
 
I run a temp sensor at two points. One in the normal oil cooler out, on the filter adaptor, and one near the bottom of the oil sump just as the oil moves up to the pump. The differential is typically 30 F average, give or take 5 F as the oil warms up or cools down.
 
FasGlas said:
I run a temp sensor at two points. One in the normal oil cooler out, on the filter adaptor, and one near the bottom of the oil sump just as the oil moves up to the pump. The differential is typically 30 F average, give or take 5 F as the oil warms up or cools down.
Click to expand...

That matches what the Lycoming engineer told me.
 
Oil Squirters effect on oil temperatures

http://www.yeeles.com/Reference/Hi-Temps.pdf

The link above is one I ran across as I researched what Lycoming had to say about high oil temperatures. In it they make it very clear that 180F to 220F is OK for continuous operation.

I am nearly complete in doing all I know that can be done regarding high oil temps on my IO-375, Low compression, dual Pmags, in RV7A. The last change I will make before adding a second oil cooler or some other big change will be to change to a stronger spring on my oil pressure regulator to get my oil pressure up to 80 PSI in cruise, per Aerosport recommendation. This may have some effect as the regulator bypasses some oil back into the engine rather than routing to the cooler if I understand correctly. Adjusting from 64 PSI to 70 PSI had no effect, now need stronger spring for more adjustment.

1. Guage is accurate from 100F through 200F
2. Measured pressure delta at cooler and reviewed results with Pacific Oil Coolers technician, verified that I am getting nearly all of the cooling ability I can get from my 8432R oil cooler. (10" WC differential at cooler)
3. Checked Vernatherm operation, OK. Then removed Vernatherm and installed Lycoming Oil Plunger Assembly, all oil goes to cooler all the time unless oil pressure exceeds 100 PSI.
4. Pulled 2 deg. then 4 deg off of the A curve on Pmags with flight tests after each adjustment. No change in oil temps.
5. Increased exit area slightly by cutting back lower cowl, I already have dual EZ Cool cowl flaps running with them open all the time.
6. Had Doug at Aerosport review the build log for my engine, he verified that it was built with oil squirters or nozzles.

The air sealing around the engine is tight and verified via pressure measurements.


I have gradually been relaxing my personal oil temp limit. I was taking corrective action at 200F. After much consulting with experts I have now experimented with allowing the temp to go to 220F, but find that even using that as a limit, I cannot run my engine at best power mixture for long periods or oil temps will climb right past the 220F mark. Experienced the above with OAT on the ground at about 80F, at 7,000' it was around 70F. If I pull mixture back to LOP, drop 10 knots off speed, the oil temp will gradually cool down to below 200F. I basically have to run my engine aggressively lean of peak to control temperatures. CHTs will hit 400F also, but lags behind oil temp so oil temp has been limiting factor. It helps some to make very shallow climbs, but getting altitude quickly to get into lower OATs also helps.

So that is my situation and here is my question:

How much increase in oil temperature do the squirters add?

Is there anyone with the same IO-375 engine with oil squirters that is not experiencing similar oil temp problems? I wold love an opportunity to discuss your set up.

Randall in Sedona
 
Randy said:
The last change I will make before adding a second oil cooler or some other big change will be to change to a stronger spring on my oil pressure regulator to get my oil pressure up to 80 PSI in cruise, per Aerosport recommendation. This may have some effect as the regulator bypasses some oil back into the engine rather than routing to the cooler if I understand correctly.
Click to expand...

The oil pressure relief valve is downstream of the cooler/filter/etc, and cannot bypass the cooler. See Fig1 in the linked document, or schematic below.



I am curious about the need for a stronger spring. What do you have in there now?




2. Measured pressure delta at cooler and reviewed results with Pacific Oil Coolers technician, verified that I am getting nearly all of the cooling ability I can get from my 8432R oil cooler. (10" WC differential at cooler)
Click to expand...

My compliments. May I ask at what true airspeed?.
 
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Dan,
The spring that I have is what came from Aerosport, I will learn the color when I pull it out to put in the new one. I believe Don at Aerosport said he was sending me a white spring. He wants me to have 80psi at 2400 RPMs and 180F oil temp.

I ran out of adjustment a little short of 70 psi. He said they set them up for 80 psi during run in but adding the governor and cooler etc changes the pressure.

I see the 10" pressure delta at the cooler in cruise of about 160 knots with my EZ cool cowl flaps open.

I just got back from another flight using 220F as my absolute redline. Staying way ROP I can climb out of the Phoenix valley into the cooler air up around 8,000' staying within the 220F limit. Adjusting to best power at 100F ROP will take oil temp right past that limit with CHT creeping up on 400F also. It is a good thing this engine runs well LOP. I can usually see 160 knots TAS @ 7.5 GPH. At best power it will get above 170 knots but I cannot run there very long without things getting too hot.

I am ready to have my old 6 row Positech cooler cleaned and install it with a 3" scat feed from the other side of the engine to see what happens. I hope it will give me enough extra oil cooling to help with CHTs also, since I have the nozzles...

Thanks for cluing me in on the oil schematic. Time for second cooler I think.

Is plumbing a second cooler in series the best method? I realize I already have 15 psi pressure drop from my 8432R, and this would add to that pressure drop. Some kind of parrellel plumbing might be possible but sounds more complicated.

Randall in Sedona
 
Okay, another data point for you with our RV-8 and angle valve engine. We used the Aero Classics HE Mod. # 10011599 as recommended by Pacific Oil Cooler for the angle valve. Expensive? Yes. First flight we were seeing oil temp peak at 203? and level off in the mid 190's. Today (photo below) I just reached 202? as I was leveling off at 7,500 in a WOT climb. A couple of minutes later it was around 185? and remained pretty close to that the entire flight.



Here's how we mounted it:





Note the brace across the top of the engine which is key for hardening the corner of the baffle and to avoid cracks.
 
One last thing to check

To Matt, the original poster, and any others interested,
My RV-8 with IO-360-A1A got similar numbers to Matt's. Not a real problem, but not as low as I might like.

I have the cooler mounted on a small plenum box on the firewall similar to an RV-10 installation, fed by 3.5" scat tube. It is the cooler that Van sells for the RV-10.

So the final thing that made more difference than I would have thought was to seal the small leakage openings at the ends of each cooling fin on the cooler where it mounts up against the face of the baffle, or in my case against the cool air supply plenum. just a bead of orange RTV around the perimeter of the cooler. My oil temps dropped about 5-7F across the board. So, a long climb on a 95F day to 10K ft used to get to 220 F now gets to 214F. Cruise on hot day used to be 195 F, now about 185F.

I'm sure most people have done this seal, but it is an easy thing to overlook during the "final" mounting of the cooler.

In the picture on the previous post, you can see the seal bead on Pat Hatch's install.
 
Randy said:
Is plumbing a second cooler in series the best method?
Click to expand...

Theory says it would not be optimum, as the first cooler in the series would make the second less effective, heat transfer being based on deltaT.

That said, I have seen an RV8 with two coolers. IIRC, at least one of them was fed from an external NACA duct, a source of air not preheated in the upper plenum. That would push the second cooler's deltaT in your favor.

Personally I'd just install a single, much larger cooler, fed with a big duct.

No way I'd series an 8432. I think it has too much pressure drop already.
 
DanH said:
Theory says it would not be optimum, as the first cooler in the series would make the second less effective, heat transfer being based on deltaT.

That said, I have seen an RV8 with two coolers. IIRC, at least one of them was fed from an external NACA duct, a source of air not preheated in the upper plenum. That would push the second cooler's deltaT in your favor.

Personally I'd just install a single, much larger cooler, fed with a big duct.

No way I'd series an 8432. I think it has too much pressure drop already.
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I guess I need to ask the question why you would not put an 8432 in series. OK it has about 15 PSI pressure drop and I would be adding to that by 3 or 4 PSI, (I am not sure on this.) But what does that hurt? The vernatherm is not an issue since it is not in the system anymore.

Is there a danger here of pushing too much pressure at the oil coolers in order to get the prescribed 80 PSI back to the engine since the regulator is down stream of the coolers? I would hope another 3 or 4 PSI would not be enough to cause a problem.

Interesting that you mention an external duct. One of the reasons I am trying to chase this down is so I can get the plane painted and know that I am not going to be cutting into the cowl real soon afterward:) I have a neighbor with an RV7A and he solved his oil cooling issues with an external duct.

One item I have not measured is the temperature of the air getting to the cooler. Anybody got data on that?

Randall in Sedona
 
High Temps

Matt, I have an RV9A and recently changed out our prop to a whirlwind, that has much better performance, but with it came high oil temps along with CHT and EGT temps on climb out higher then I want to see them. After the usual checking into all the normal things that could help like sealing all the baffles ect. I came across AntiSplat Aero.. I called Al and talked to him about what my concerns were and he started telling me exactly what I was seeing as if he had been sitting in the plane with me. As it turns out he almost was as he has the same airplane RV9A and the same AeroSport Power engine in his. But I bought a couple of his Cowl Gate units from him, after doing some additional reading and research I installed them two weeks ago and on an 85 degree day I can climb out as step as I like, with none of the temps getting close to the yellow range, where before they would be pegged so its a fairly simple install and really did the job, i would recommend these to anyone having heating issues. But call Al and talk to him, you will be glad you did. Just google AntiSplat Aero or I think he advertises here as well and he is an RV builder flyer so he really knows his stuff works on these airplanes. good luck with it..
 
Randy said:
I have a neighbor with an RV7A and he solved his oil cooling issues with an external duct.

One item I have not measured is the temperature of the air getting to the cooler. Anybody got data on that?
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Measured at the inlet face of a ducted cooler, 16~17F higher than OAT. I installed insulated ducts on the underside of the plenum lid to bring air to the cooler without so much heating. It dropped oil temperatures. An external inlet would be better.

 
External oil cooler air = added mass airflow = reduced speed.

Dan you are full of surprises. I don't recall you sharing that one before.
 
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