Van's Air Force
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IO360 High Oil Temps
- Thread starter mattsmith
- Start date
Exit is the throttle. Added inlet area would add pressure, but it's easily offset by shrinking exit area, which limits mass and increases velocity, a cooling drag reduction.
FasGlas
Well Known Member
One thing to add to this hot oil discussion is, the oil coming out of the cooler is mixed with the very hot oil being pumped back to the filter adaptor, where most engine have the temp probe. I have three sensors that monitor temps at: The mixed oil (on the filter adaptor), in the sump at the screen just as the oil goes up the to the pump and on the output of the oil cooler (SW10599). On a warm SoCal day I'll show about 203F at the adaptor, 230F at the sump and 165F at the cooler output. This shows that the cooler is removing 65F from the sump oil, but when mixed at the adaptor the temp gains 40F for the 203F most monitors indicate. Adding additional oil coolers would lower the cooler output temp but the results may not be as drastic is you might expect. Less volume of oil would flow through the cooler(s) (path of more resistance) then flowing from the pump into the engine (least resistance). This is why adding a few more rows on a cooler shows little to no difference in cooling. The temp differential verses flow paths is not a big help. And, as mentioned earlier in this thread, the second cooler in series is less efficient then the first cooler. With all the said maybe the best approach is to get the right sized cooler and make sure it's flowing the required air efficiently. Obviously the hotter your flying area the more cooling you need.
Fasglas,
Thanks for posting that data. It makes me very curious to learn more about just what is going on with my oil temperatures before putting a second, or possibly a different oil cooler in my plane.
Since I have eliminated the vernatherm and installed the Lycoming "oil plunger assy", according to the schematic that Dan sent, it does not appear that I have higher temp oil from the sump mixing with the cooler oil from the cooler, unless of course the oil pressure should overcome the spring tension of the plunger which I understand would be 100 PSI or so. Can anyone verify?
Writing that statement has me wondering if the increased pressure drop of my Meggit 8432R could still be causing the mixing you refer to.
I am curious what led you to measure your oil temperature in three locations as you have done. Were you experiencing oil temp problems. If so did you make some changes to resolve the problems.
Thanks again for posting your data.
Randall
Thanks for posting that data. It makes me very curious to learn more about just what is going on with my oil temperatures before putting a second, or possibly a different oil cooler in my plane.
Since I have eliminated the vernatherm and installed the Lycoming "oil plunger assy", according to the schematic that Dan sent, it does not appear that I have higher temp oil from the sump mixing with the cooler oil from the cooler, unless of course the oil pressure should overcome the spring tension of the plunger which I understand would be 100 PSI or so. Can anyone verify?
Writing that statement has me wondering if the increased pressure drop of my Meggit 8432R could still be causing the mixing you refer to.
I am curious what led you to measure your oil temperature in three locations as you have done. Were you experiencing oil temp problems. If so did you make some changes to resolve the problems.
Thanks again for posting your data.
Randall
That's a fascinating set of measurements. I'm serious. Which oil filter adapter do you have?
Here's an AC adapter:
FasGlas
Well Known Member
I'm using a Lycoming filter adaptor with a Lycoming Vernatherm, like most everyone uses. I didn't set out to monitor all these oil temp points but since I have an MGL iEFIS setup I can install many extra sensors and write gauges for them. So I figured I'd monitor temps that some pilots are curious about. I'm my case I made and installed temp probes at: Oil sump, oil cooled out, cowl behind the baffles, left and right Pmags. Using LM35x temp sensors and my MGL RDACs it's a simple installation. As it turned out I was able to see the cooled oil mix back with the sump oil at the adaptor probe point. Just a bit more information to ponder. And before anyone asks, I recently sent in my cooler and Vernatherm to Pacific for overhaul and test. One other test I haven't gotten to yet is connecting my manometer to the in and out of the oil cooler to see the pressure differential. More information I probably don't need. 
Ok, so that's the AC-style adapter pictured above, right?
Your numbers say the vernatherm arrangement isn't doing as we've been taught...but I think I can see how it might happen. Let me get an adapter in hand...
Sorry Randy, missed your question. You're correct...the plunger should fully block the center hole in the adapter pad, the direct route from the pump.
Oil Coolers
Tremendous amount of info most of which over my head. So, after all, my question is with the angled valve 200hp IO-360 A1B6 engine with p-mags, RV-8, standard Van's cowl, Texas home, which is the recommended oil cooler and mounting location? Have been investigating the SW 8432R and the 200006A.
Tremendous amount of info most of which over my head. So, after all, my question is with the angled valve 200hp IO-360 A1B6 engine with p-mags, RV-8, standard Van's cowl, Texas home, which is the recommended oil cooler and mounting location? Have been investigating the SW 8432R and the 200006A.
Angle valve motor, w/squirters, typical lower CHT and higher oil temp as compared to an parallel valve. SW/Meggitt 10610, 10611, or equivalent if you want to stay under 200 in all but radical circumstances. If you find higher temps acceptable, go with something smaller.
I don't care for the 8432, but that's just me:
http://www.vansairforce.com/community/showpost.php?p=1056255&postcount=26
Yeah, but mine is kinda specialized to match a particular optimized cowl setup.
Assuming a stock Vans cowl, go with the basics...a bellmouthed entry off the rear plenum wall, 4" SCEET tube minimum, diffused entry to the cooler (no abrupt expansion from tube area to face area).
There are two reasons to duct the oil cooler exit. One is to accelerate the flow with a converging duct, trading pressure for velocity. This doesn't apply to your application unless you manage to build a duct of the correct shape, and direct the exit rearward. As a practical matter, it easier to simply dump the cooler outflow into the lower cowl volume, and then worry about creating a high velocity exit for the entire cooling flow. Both are beyond the basics.
The other reason is to place the end of the exit duct in a region of pressure less than the lower cowl pressure, thus increasing pressure delta across the cooler, thus increasing flow through the cooler without increasing flow through the cylinder baffles. Given a standard cowl, that means the end of the oil cooler duct would need to be outside the lower cowl.
