Oil Cooler - Again (Just comments)

[N520TX]

This is an issue that's been on my mind to do something about for a while but was just too set in the "not broke, don't fix it" mentality.

As anyone who went to LOE knows, central Texas has been hot lately - that's nothing new, it's always hot here in summer. Well, during the flight there and back; while at 9,500 and 10,500 respectively; my oil temps were running about 210ish give or take with a fuel flow around 10-11 gph. I could lean it some more, but then the oil temps obviously go up. It always runs like that in the summer here and I just didn't give it a second thought.

That all changed yesterday. My neighbor here flew out to Midland in his 50 yr old Bonanza V35 with its 6 cyl Contintental bangin away. When he returned, we talked about the flight where he relayed to me the fact that he was burning about 10gph - for a 6 cyl ! Well ... that doesn't sit well with me. My O-360 4-cyl fuel burn was greater than the larger engine.

Of course the reason is due to running rich - due to the high oil temps. My baffling and seals are in great shape (I think) - so I need to find the other reasons for it. I recalled a thread by DC on his web site a while ago about swapping out for a new cooler. After digging a bit on rvproject, and on this site, I found all the details - and sure enough, I'm running a cheap Positech ($165) oil cooler. I admit it, I chose that cooler based on PRICE alone. I mean the SW is $450 .. is it really THAT much better at 3 times the price ??

Based on all the evidence I've read, I've come to the conclusion that the answer is YES. Not sure why it took this long to tackle, but the straw that broke the back was obvious. So far, I have 300 hrs (+-) on my RV, and figuring an average fuel burn overage of 1.5 gph, that is an extra $450ish of gas burned that I didn't need to. That alone pays for the better cooler. The order for the SW-8406R is going to go out today.

Just thought I'd relay a story - perhaps someone might find it usefull.

[Kahuna]

Originally Posted by N520TX

That all changed yesterday. My neighbor here flew out to Midland in his 50 yr old Bonanza V35 with its 6 cyl Contintental bangin away. When he returned, we talked about the flight where he relayed to me the fact that he was burning about 10gph - for a 6 cyl ! Well ... that doesn't sit well with me. My O-360 4-cyl fuel burn was greater than the larger engine.

He could have been at 6gph. Has as much to do with the black and blue knob as the red one.

[gmcjetpilot]

Originally Posted by N520TX

I admit it, I chose that cooler based on PRICE alone. I mean the SW is $450 .. is it really THAT much better at 3 times the price ?? I've come to the conclusion that the answer is YES. The order for the SW-8406R is going to go out today.

You get what you pay for. The cooler is one of the MOST important accessories for the engine. The alternative engine guys brag about how better water or liquid cooling is. Well Lycomings are liquid cooled, OIL. The more efficient and higher capacity the oil-cooler, the lower the temps at the valves. The valves (especially the exhaust valve) are oil cooled (and fuel another liquid). If course air over the heads is important. What you read at your Oil-T gauge is about 20-25 degrees (F) lower than what the TEMP is at the valves, so 210F is really 235F! You start to break down oil like crazy at those temps.

A Porsche, air-cooled 6 cyl +300HP Horz opposed engine, are air & OIL cooled and have +16 qts of oil & two large oil coolers. The BMW "boxer" air-cooled twin motorcycles are air and OIL cooled; BMW says so right in their technical specs. The Police version of the BMW motorcycle has a much larger cooler for slow driving.

DON'T GO CHEAP ON THE COOLER, BUY THE SW.
DON'T USE VANS REMOTE COOLER KIT; 3" SCAT IS TOO SMALL & PLENUM POORLY DESIGNED FOR ALL BUT 320's IN MILD CLIMATES. IT CAN'T FLOW ENOUGH AIR TO FEED THE SW COOLER.

[JonJay]

I would guess that there are almost as many "cheap" oil coolers "over cooling" as "under cooling". Not sure of all of the factors associated with that, but I believe it has less to do with the oil cooler than with the plenum and who knows what. My "cheap" vans oil cooler is partially blocked off in the summer and still never gets above 185deg on a 95deg day. I am going to try Van's shutter for this winter. My cooler is mounted as high as will allow on the baffle, which I also believe is a significant factor. (IO-360 180HP, RV6, V-induction)
No doubt, from the many posts, the SW cooler cools better. That would be the opposite of what I need, so, my "cheapo" cooler is better for me.

One thing I did that may make a difference, isolate the cooler from the baffle. I used baffle seal material like a gasket. It may make a difference by allowing less heat transfer from the baffle to the cooler. Makes sense that heat from the cylinder head transmits into the baffle then into the oil cooler flanges heating the whole thing up. Given that cylinder heads are running at +- 300 deg., it kind of makes sense. Perhaps I need that heat and shoud remove the gasket and see if my oil temps warm up?

So, you might try this first. I am sure others would be interested in knowing if it helped.

[dan]

If your engine squirts oil on the piston skirts, definitely don't skimp on the oil cooler! In my book, that's the biggest factor.

That said, this talk about running rich to keep oil temps down...I don't subscribe to that theory. I'd rather run at PEAK EGT than 100F ROP if my engine is running hot (or obviously LOP if you *can* run LOP). I know some non-believers out there will think I'm nuts. Hey, it's your fuel, your engine.

And how high is too high? If your engine's oil runs at say 210F all day long but your CHTs are cool, what's wrong with that?

Would you rather dump your engine's heat into the oil which gets changed every ~50 hours, or would you rather your cylinders take the brunt of it?

Personally, I think a lot of the "you gotta keep your oil under 200F" stuff is overblown.

[doctornigel]

If you are running an IO engine with Gami injectors, you can run LOP just as cool as ROP. You sacrafice a few knots but save all that gas and you build up less stuff on the plugs and elsewhere. I just wouldn't do it above 75% power.

[dan]

Originally Posted by doctornigel

If you are running an IO engine with Gami injectors, you can run LOP just as cool as ROP.

Cooler. But you don't need expen$ive GAMIjectors to do it. Just balance what you've got. Call Airflow Performance to get you set up for waaaay le$$ than GAMI.

[JonJay]

Originally Posted by dan

If your engine squirts oil on the piston skirts, definitely don't skimp on the oil cooler! In my book, that's the biggest factor.

Never heard of Vans oil cooler failing have you? If it works, maybe too well, is that skimping? I am sure I would feel differently if I had high oil temps. I'll change it tomorrow if I hear that they air failing and causing loss of engine oil. To my knowledge, there are thousands of them out there working just fine. Correct me if I am wrong. I can take it.

[N737Z]

Hi gang from the hot PHX desert.

I lowered my oil temps by following Ken's suggestion of shimming out the oil cooler 1/4" off the back of the baffling. This gets the oil cooler out of the cylinder cooling air boundary layer which tends to add heat to the bottom part of the cooler thus raising oil temps. It sounded too simple, but Ken encouraged me to try this first. It lowered my temps about 20 degrees and put them right in the normal range. BTW I am using the Vans oil cooler on my ECi Titan IO 360 with good results in the Phoenix desert.

Don
RV 7
Stellar Airpark (P19)
Phoenix, AZ

[Bubblehead]

Here are two pictures of the oil cooler on my 180 hp IO-360 RV-8 built by someone else.

[IMG][/IMG]

[IMG][/IMG]

In 100 degree air I can crusie climb and oil temp gets up to 220 or so, and oil pressure drops to the low end of the green arc. It's manageable but I'd like to see a little lower temp so I could climb faster when I need to or just keep temps down for engine life.

Does anyone know the mfr of it? It looks like it's a nine row cooler. I did not get much documentation with the aircraft and most of it is stock Vans parts so perhaps this is the stock Vans IO-360 cooler.

I will try the suggestions in this thread about spacing the cooler back and adding some cowl seal as an insulator to see if temps come down a little.