Which Oil Cooler?

luv2flypilot · #1 10-16-2009, 03:01 PM

I have about 55 hours on my airplane now and still seem to get hotter oil temps than I prefer to see. I live in the East Bay Area, CA. and typically in the heat of summer we get 95-100 degree days. My oil temps are typically around 200 during normal cruise, but sometimes see up to 220 - 225 during hard climb take offs, high prop RPM, and when performing manuevers such as slow flight with higher loads on the engine.

My oil cooler is mounted behind cylinder #4 on the rear baffle, so I think the location is fine. I also feel my baffling is sealed up pretty good and getting good airflow.

I currently have the Van's $234 EA OIL COOLER II

http://www.vansaircraft.com/cgi-bin/...t=sw-oilcooler

and was thinking of replacing it with a Stewart Warner 8432R. I was hoping to get some feedback to see if the footprint was the same for an easy swap as well as would this be the best oil cooler for my application? Is there another oil cooler that may be even more effective than the 8432R and has about the same footprint, so that I can keep the same location? Van's website states that the oil cooler I have is a "Traditional Stewart Warner Style" but is the actual 8432R that much more effective? If I can get 10-15 degrees lower temps by replacing the oil cooler, I think I would be in the ballpark of where I would like to be.

Chino Tom · #2 10-16-2009, 04:22 PM

Do a search on this as there has been much discussion about this subject.
I would first check that your oil temp is accurate by boiling some water and
immersing the probe in it and checking the gage. Are you still using mineral
oil? Are you using multi grade oil? Switching to a single weight detergent oil
will many times lower oil temps. Not wanting to start a war here.... Do a search, but in any case try the inexpensive stuff first.

I use the same cooler you have mounted in the same spot will no issues. In fact my temps
are in the 170's most of the time. I only see 200 after quick turns in hot weather.

RV7Guy · #3 10-16-2009, 04:43 PM

Tom has some great points. I would look for the simple stuff first. I was able to lower the oil temp about 10 degrees by looking over the engine and baffling and sealing some areas I had missed. This is critical.

In Phoenix in the summer my oil will hit 210 but that is with 110 degrees OAT. Do the simple stuff first.

luv2flypilot · #4 10-16-2009, 04:55 PM

I switched from mineral oil to Phillips Aero SAE 20W-50 at 50 hours and was hoping to see lower temps, but really have not noticed much change. What type and weight oil would you recommended to try see if that helps before spending $600 on a different oil cooler?

I have looked over my engine and sealed up everything pretty well, so I am not sure there is much that I can do there to reduce temps much.

I also have dual LASAR ignition and have 9:1 compression. This may also contribute to my higher temps due to timming advance and higher engine compression?

Chino Tom · #5 10-16-2009, 05:07 PM

SoCal temps are pretty mild all year, so I use 50wt. AeroShell 100W.
I would check the the accuracy of the gage first, then try the single
weight oil. You may get a lot of different opinions on this.

luv2flypilot · #6 10-18-2009, 07:21 PM

Today I checked the oil temp reading with the outside air reading with my airplane in the hanger and sitting for the last 3 days without flying. The OAT read 72 F as well as the oil temp. With this comparison, I would think my oil temp gauge is pretty accurate. The question is, does it remain accurate at higher temps? Has anyone had any problems with the gauge reading higher than actual at high temps such as around 200 - 220 F, but accurate at lower temps? I guess I could try boiling water and checking the accuracy of the gauge, but based on this comparison I would think the gauge is pretty accurate. I am trying to get my oil temps down and trying to check all the simple and cheap stuff first before spending the money on a different oil cooler.

I flew for about 1.4 hours today with outside air temps at around 72 F. I did a climb at around 1000 fpm to 2,500 feet where I remained at cruise. I saw 205 F during climb and it settled down around 200 F during the rest of my cruise with my power settings around 23 squared and full rich mixture. When I tried increasing my RPM setting, the temps would start climbing 5-8 degrees. On downwind for landing, I pulled back on the power, and slowly added prop to full power and saw temps a little over 220 F before landing. I am wondering if there are some other mods that others have done such as possibly installing louvers in the bottom of the cowl or installing a scat tube to the oil cooler, that may help cool my oil temps before I spend the $600 an bite the bullet on a new oil cooler?

Bubblehead · #7 10-19-2009, 07:44 AM

If you'll do a search on 8432 or ""oil cooler" you will find at least 12 hours of reading on the subject. Here is one 10-page thread that has a lot of great information.

http://www.vansairforce.com/communit...ad.php?t=44225

I have 41 different subscriptions to threads on oil coolers, baffles, cooling etc. so I guarantee the information is there. You just need to do a little hunting.

The other way to find the info is to go to the "VAF Forums" then "RV Firewall Forward Section" then "Traditional Aircraft Engines" and page down through the threads. You should be able to find a lot of information that way.

Once you've boned up, come on back and ask some questions and I'm sure you'll get a better response.

hydroguy2 · #8 10-19-2009, 11:14 AM

getting ready to place my order soon. I'm leaning towards a Setrab -110 cooler for my IO-360.

Anyone got a compelling reason this won't work?

RV7Guy · #9 10-19-2009, 11:58 AM

Quote:

Originally Posted by hydroguy2

getting ready to place my order soon. I'm leaning towards a Setrab -110 cooler for my IO-360.

Anyone got a compelling reason this won't work?

Well, after pulling arrows out of my chest for being one of the "first" to try something, I'm firmly in the camp of using what others are using and has proven effective.

I have had great success with the Stewart Warner 8432R cooler. It has worked great in the AZ temps. No reason this wouldn't work great in Montana. I'd much rather have too much cooling than not enough. You can easily block the hole if necessary. I'm sure you plan to fly beyond Montana. Plan for the worst possible conditions.

I recently purchased another 8432R for my new project and IO 390.

Bubblehead · #10 10-19-2009, 12:50 PM

Quote:

Originally Posted by hydroguy2

getting ready to place my order soon. I'm leaning towards a Setrab -110 cooler for my IO-360.

Anyone got a compelling reason this won't work?

I've been working through the calculations on Setrab coolers with a tech guy from Setrab. Using the generally accepted heat rejection requirement from Lycoming for 180 hp you need to reject about 475 BTU/min for a 200 hp angle valve engine.

The 110 does not seem to have enough capacity to handle that. There is a posting in VAF that the 113 was tried and is often successful but at least once was unsuccessfull. I am considering the largest single pass Setrab that will fit on the baffle of my -8, the 119, which is 5.75" wide.

The problem we're having with the calculations is we don't have a lot of hard data. We have the Lycoming supplied number, and people on this forum have said that there generally is about a 6" H2O pressure drop across the baffles (and therefore across the cooler) and we want a return temperature of 190 or so. If you plug and chug with Stewart Warner performance curves it looks like there is not enough capacity.

Since we know SW coolers like the 8432 and 10599 work there must be some assumptions somewhere that are wrong. Heck, for a lot of people the 8406 works! I am working on instrumenting oil inlet and outlet temps on my oil cooler so I can get some real numbers. I'm also looking at instrumenting the baffles to get the pressure differential.

In summary, the 110 looks too small, the 113 might work, the 116 probably stands a better chance and the 119 should knock it dead. Since I live in Texas I'm going big, as well as improving the baffles, baffle seals etc.

I think a couple of the Rocket guys (Smokey?) have used Setrabs and I think Aden Rich mounted one but didn't end up using it. I hope they will chime in on model cooler, model engine and hp, and success or lack of it.

You might also search the forums for "Setrab." There have been a pretty good number of postings through the last couple of years.