Oil Cooling Modifications

Oil Cooling Modifications

Tim Olson

Added 3/15/2011

For 695 hours I’ve had just the standard Van’s cowl, with the exception of louvres I added about a year ago, and the standard Van’s oil cooler…in my case, one made by Aero-Classic, whereas some kits are sold with the Niagara brand oil cooler.  My temps have been reasonable.  If you look at past write-ups, you’ll see that diligent work on the cowling seal gave me better CHT’s, and my oil temps were generally pretty good too.  When I’ve had oil temps get hotter, it’s been from doing things like extended slow flight, like the approach to OSH during the show, especially when loaded near gross weight.  With the family on trips, we’re often traveling near gross weight, too, so sometimes in hotter regions, I’ve seen oil temps climb during climbout, or when operating ROP especially, in warm weather.  In cruise, my oil temps were almost always 185-187F, and the engine regulated itself pretty well.  In the winter, or even on some higher altitude LOP cruise trips, I would get oil temps below 180F, which is too low.  And when loaded heavy in climb, I’d set my yellow alarm for 200F, and my red at 216F or so.  On the worst of days, for long climbs to 10,000’+, I could have oil temps even hit in the 220’s…in the worst cases.  Usually it stayed under 220F.  On my last long trip, up the California coast, I was a bit disturbed when at 1200′ msl, I’d cruise up the coast (yes, it was hot out), and my oil temps went to 204 or 205 just from cruising up the coast at near gross wt.  This kind of bugged me.
I know what you’re thinking….205 is a fine temp, and you’re right.  Keep it below 215 or 220F and you’re probably fine.  But, it was enough to get me thinking.  I’d already tried the oil cooler box splitter, and I knew I had my cowl buttoned up nicely.  My CHT’s have been fantastic for me for a long time…it was just the oil temp that gets warm.  Maybe at certain AOA’s, I lose some of the cooling efficiency after adding the cowl louvres…I don’t know.

Beyond that, I also fly in the Wisconsin winters, and up here it can easily be 10F or 20F on a nice flying day, and as soon as you climb, you may be well sub zero F.  In these temps, on my old plane, I used to intall a plate in front of the cooler that restricted the air to the size of a quarter.  On the RV-10, I had no way to do that.  Also, I was not going to install any sort of restrictor unless I could open/close it in flight, AND until I had excess cooling to work with, in case I had any restriction by adding a slotted or butterfly type valve.  With that in mind, I let things sit…probably for too long, while I pondered what to do.

Rumor had it from other RV-10 buyers, that there was a cooler made by Airflow Systems that was suppsed to be more efficient.  It’s the 2006X cooler, available at Aviation Tech Products and other places….only for experimentals.  I called Alex at RVtraining.com and decided to see if he really thought the cooler he sells was better.  He says it does cool more…and without a direct quote, I think he said 7-10 degrees cooler…or was it 7-15?.  Anyway, I decided to bite the bullet and I ordered the new cooler from him.

At the same time, I knew that if I installed a higher efficiency cooler, I’d have even WORSE problems this winter in Wisconsin, so I ordered the RV-10 4″ oil cooler butterfly control valve from Nonstopaviation.com.  I had recently spoke with Scott, who had bought but not installed the valve, and he tipped me over the edge on it.  So now I had the control method, and the added cooling (purportedly).





Above are the photos taken straight from nonstopaviation.com on their valve installation, and of the valve itself.  The valve is pretty simple, but well thought out and put together.  The ONLY concern I have is that in every case, the more complex you make something, the more likely it is that you can have problems.  Adding a control valve of ANY sort can mean you could have the valve stick closed or something, causing an emergency.  So, as with anything you install, do a good job, tighten everything well, and understand it fully…verify that you have minimized the chances of problems.As you can see from the above pics, they mounted theirs on the back of the engine baffling.  In my case, the 4″ SCAT tube bumped into the engine mount too badly when I tried the valve there.  Besides that, I didn’t need one more cable strung out from my firewall.  So, I mounted mine to the oil cooler box itself.  Either way works fine, so I went with the cleanest installation.  It also prevents added weight from hanging on the baffle flange…and I’ve heard from at least one person who’s flange had broke before (unrelated to this valve).  I prosealed the halves of mine so that a weld break wouldn’t break the whole thing. At any rate, you can see that the valve is pretty simple.  You do have to think through the opening and closing of the valve in relation to how the cable approaches the valve.  That took some head scratching to find a good route for the control cable.
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Here are my oil cooler pictures.  I’ll have to say, at first when I unboxed the Airflow 2006X cooler, and put it side by side, I was pretty ticked off.  The 2 coolers are VERY identical in most every way.  The machining looks like the parts were made on the same machine….down to almost every detail.  In fact, on the bottom of the cooler is stamped what looks like 2-letter initials of people, and even some of the 2 letter combos were the same between the 2 coolers. I was convinced that in reality, there would be no difference…and that I had wasted over $400.  I emailed the Matronics List to make sure there was at least ONE person other than me who had SWITCHED coolers….not had originally started with a 2006X, but who had flown with the others, and switched to it, who had actually seen a temperature drop.  Sure enough, there were a couple people who had, so I decided ot install the fittings and install the cooler.  If you look really carefully, the only differences I can see between them are:1) the Aero-Classic is either gold cad plated or anodized in some way to look gold
2) the Airflow 2006X has maybe 10 or so more “VVVVVVV” shaped pleats per row…they’re narrower V’s.

I was convinced that the added V’s couldn’t possibly make a big difference, and that if anything, they’d restrict the airflow more.  But, I pushed ahead and installed the cooler.  I did take the time to fix an old “bad”.  When installing the original cooler, I used the supplied aluminum blue fittings.  As it turns out, you don’t want aluminum.  Not only are they less durable, but aluminum into aluminum galls a bit.  So, I switched my fittings to steel with the new cooler.  It’s not a big deal, but steel is really the better way to go.

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From the above pics, you can see the Airflow systems cooler installed. I took it for a test flight to leak-test the fittings before I installed the valve.  I flew last Friday for an hour, and I was able to get 185-187F out of the original Aero-Classics oil cooler.  The weather that day was high 20’s-low 30’s F.  That would be perfect for me, if it stayed there year round.After installing just the 2006x cooler, today’s flight,  I flew only maybe .4 or so hours.  It was maybe 20F out, but maybe a little less.  I flew until I hit 174 or 175F and it didn’t climb very fast in temp at all. I got the feeling that the 2006X cooler did indeed cool a little more than the other, but the day was colder too, so it was hard to tell.

I was becoming a bit happier with my expenditure of greenbacks.

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So then the next step was to install the nonstopaviation.com cooler butterfly valve.  This took some thinking.  As I mentioned above, I installed it on the cooler box.  I’m sorry that I didn’t take any preliminary pictures where you can see the valve, but the above center picture has the valve installed. It raised the attach level for the 4″ SCAT tube about 2-3″ or so…but otherwise didn’t have any real effect on the hose routing.  I installed it so the control lever faced the center of the plane, and the push-pull cable came in from above.  That orientation allowed the valve to open and close well.  I then used some existing holes with bolts and screws in them to route the cable across the firewall above the other lines as you can see.  The -3 size clamps are perfect…I only had 2 of them, so I used some -2’s in some places which seem to work OK.  I can easily replace them another day after I order -3’s if I want.  The cable goes through the firewall, and then up next to my throttle quadrant.  As you can see in the photo below, I now have 2 black knobs.  The LEFT one is my Alternate Air for the filtered air box.  That’s a “pull it once” knob, because you have to land and un-cowl to re-set the valve.  So I labeled my new Oil cooler control knob “Pull to Heat Oil” so I wouldn’t get confused.  Other than that, there’s no other cockpit related change.
After doing the installation, I went for a quick flight of only .3 or .4 hours.  I kept the valve closed until the oil temp hit 190F after takeoff.  Then I set the valve wide open and it went down under 180F for a bit, and then climbed back up to 183F or so after a couple minutes.  The weather outside was a little warmer today…ground temps were in the 30’s….and I believe slightly warmer than Friday.  This gave me the idea that the new cooler was maybe 7-8 degrees F more effective…but the temps climbing back to 183F or so made me unsure.  It could be as little as 4 degrees.Now, none of this is scientific, but, it does appear that even with just looking at this tiny snapshot in time that isn’t very well compared, that the 2006X cooler does drop the temps a little….maybe at least 4 degrees, but just guessing by the way it reacted to going full open, it could be more towards 7 or even 8 degrees F lower.  I don’t know that I’ll believe it’ll do 15F lower, but something in the neighborhood of 5-10F is probably likely.

Now, again, this is only a very very small snapshot in time.  I’ll have to play with it on some longer flights, especially when I get on vacation in a couple weeks where it’s warmer (coming up shortly!!), and see how the temps look now.  At present though, I’m thinking that Nonstopaviation.com valve is probably a pretty nice thing to have for us cold-weather fliers (or for LOP flying at higher altitudes on cold days) to keep the oil temp in the good range, and that the 2006X cooler is probably worth the added $$$ if you drop the Van’s standard cooler from the parts list and order that one instead.  If you always fly in warm weather, you may not want the valve, but, you may still find your temps don’t get up high enough to hit that 180-185 degree minimum to burn off moisture…especially if you have good oil cooling….so it’s something to look at.

Now for a quick un-paid-for plug.  Although you can get the cooler from other places, if you’re going to get one, try emailing Alex at rvtraining.com. I’ve found him to a good source for a couple of things, and he is a good guy for Transition training too.  If I were starting from scratch, I’d buy that cooler from the get go.  My other cooler did work ok for me, and many other folks, but if there is something better, then I guess that’s the way to go.

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