Oil Cooler ducting

Hi,

I've been following the cooling mods / glass work with great interest. It has got me thinking in various areas and I would like to hear some ideas from AJ / Bob A etc.

We have a standard cooler mounted behind #4 clyn and a AL hard top upper plenum and an area I've been thinking about is the oil cooler exit. Other local builders are finding that they need a way of varying the amount of oil cooling summer / winter.

Oil cooler rectangular area is about 3 1/8" x 5 1/2" = ~17 sq".

So questions / ideas:

• Is there a benefit of ducting the out air towards the cowl exit - SCAT tube?
• Should the air exiting the cooler be 'speeded up' - ie. smaller exit duct - any suggested ratios? (~5.5" diameter exit is 'equal')
• Does a 90* mini-duct pointing down give any benefits?

I know I should wait until I'm flying, but I'm in a fibreglass mode at the moment and just 'thinking'

Thanks,

Carl

Winter and Oil Cooler

Just a noteworthy observation:

I have the SJ plenum and installed the standard Van's oil cooler behind #4 as per plans except lower to clear the cowl and top of plenum. It worked very well in summer. But as late fall lowered the OAT, I was running too cold. I safety wired a piece of aluminum to the aft side and that worked, but not so great. I was still not getting temps to 180 anymore. More like 160.

Yesterday was a very rare day in Michigan. We had 60+ degrees OAT at 3500'. On the way home from an expensive lunch (3.50/gallon, not the food) I used 75% at 4500'. Well, my GRT EIS did its job. The oil temp went over 220 deg. I had to slow down.

Moral of the story - if you live in a highly changeable climate, allow for inflight adjustment of any baffles that affect oil cooling!

The oil cooler issue is one that I will be paying close attention to.

I am thinking of remotely installing the oil cooler low on the firewall near the low pressre exit (ramp area) and using a kit like this one from Van:



I don't like Vans kit because ot blasts right down the cener of the cooler. If I don't find one with a wider mouth, I will make my own from fiberglass.

Carl, I think there may be some benefit of exiting the scat tube where we have mentioned. I suspect that ram pressure combined with the venturi effect will aid in flow. I could be all wet, but it makes me feel all warm and fuzzy just thinking about it!

I am also thinking of installing the oil cooler shutter to help in engine warm ups on cold days. I won't do this until I confirm sufficient cooling on hot ones though!



CJ

zkvii said:

Hi,

I've been following the cooling mods / glass work with great interest. It has got me thinking in various areas and I would like to hear some ideas from AJ / Bob A etc.

We have a standard cooler mounted behind #4 clyn and a AL hard top upper plenum and an area I've been thinking about is the oil cooler exit. Other local builders are finding that they need a way of varying the amount of oil cooling summer / winter.

Oil cooler rectangular area is about 3 1/8" x 5 1/2" = ~17 sq".

So questions / ideas:

• Is there a benefit of ducting the out air towards the cowl exit - SCAT tube?
• Should the air exiting the cooler be 'speeded up' - ie. smaller exit duct - any suggested ratios? (~5.5" diameter exit is 'equal')
• Does a 90* mini-duct pointing down give any benefits?

I know I should wait until I'm flying, but I'm in a fibreglass mode at the moment and just 'thinking'

Thanks,

Carl

Click to expand...

You mean something like this?








More info at the bottom of the page at...


http://www.lazy8.net/fwf2.html


I wish I could say I gained 5 kts or something but I didn't, at least as far as I can tell. My oil temps range from 175 to 180 dF summer and winter, but they did before I added the outlet steering, so maybe all I did was add some weight and a couple of $$.

Have fun!!

But John, does it make you feel all warm and fuzzy or what!?!

CJ

Attached is an oil cooler plenum that I made out of fg. It is fed from above the #4 thru a 3" SCAT tube which has since been upgraded to a 4". The plenum lay up was made on the cooler using floral foam for the funnel shape--the fit is tight (I covered the cooler in plastic wrap). My oil temps run 178-188 currently in S. Texas. I mounted to the firewall because many of my friends who have theirs mounted to the #4 baffle have had baffle cracking problems--this way eliminates most vibration. The down side is that you do need an efficient plenum system to get good cooling.

I intend to post a little report on the fine tuning of this when I have some time.

Cheers,

db

[/URL][/IMG]

Now THAT is exactly what I was talking about!

I like it!

CJ

Oil Cooler Outlet

zkvii said:

Hi,

I've been following the cooling mods / glass work with great interest. It has got me thinking in various areas and I would like to hear some ideas from AJ / Bob A etc.

We have a standard cooler mounted behind #4 clyn and a AL hard top upper plenum and an area I've been thinking about is the oil cooler exit. Other local builders are finding that they need a way of varying the amount of oil cooling summer / winter.

Oil cooler rectangular area is about 3 1/8" x 5 1/2" = ~17 sq".

So questions / ideas:

• Is there a benefit of ducting the out air towards the cowl exit - SCAT tube?
• Should the air exiting the cooler be 'speeded up' - ie. smaller exit duct - any suggested ratios? (~5.5" diameter exit is 'equal')
• Does a 90* mini-duct pointing down give any benefits?

I know I should wait until I'm flying, but I'm in a fibreglass mode at the moment and just 'thinking'

Thanks,

Carl

Click to expand...

Click to expand...

Hi Carl, I don't have any great answers but I'll try to help. For one the oil cooler placement on my -6 that you saw in the pictures works very good and I have no cooling problems, but the exit air is in a poor area after I made my lower glass baffle. My exit air on the cooler has to flow around the back of the firewall and eventually find a path or means to somehow get out the cowl and it's poor right now. I have plans to reposition the oil cooler with a glass duct exit to direct it out of the cowl separate of the cowl outlet. I like what John Huft did on his RV-8 by directing the oil cooler exit out down towards the cowl outlet. I think anything you can do to get the air out the cowl the smoothest way is best and not let the air get all turbulent. But none of us or I should say me, don't have miniture cameras inside the cowl to test tuft work to see where the air is really going and what is happening inside. I agree with everyone else that the oil cooler should have some means of a way to control oil temp from inside the cockpit via a door, slider, or something. I live in an area where it can be 30F in the winter to 105F in the summer. I have noticed that most RVs oil coolers are to small to begin with for summer use. I'm not sure what size or Brand of oil cooler you have or what HP of engine. There are around 20+ RVs in my area and nearly all of them have had oil temp problems from the get go. 90% of them have had to replace the oil cooler and get bigger ones. Just something to think about if you plan on doing a lot of glass work on an oil cooler duct or making the installation look nice. As far as exit area size, I don't know. I think a person would need to put the oil cooler on a flow bench and make different shaped or sized outlets and play around with that area. Good luck and I hope some others might post some more ideas on here because I'm kinda curious about the questions that you ask.

Wow - mind reading - what a Nuisance.....

Hi,

Well John is very good at reading minds - or (more likely) I've previously seen his website and I was just (sub-conciously) describing his solution!

Questions / reference: We are ~180hp (TMX-IOF) and the 'cheapy' VANs cooler. We get from -5C to 35C (~20 - 95F) OAT ground temps here.
My expectation is to replace with a SW if I have any cooling problems.

I can feel the bug for cooling drag / performance tunning begining to bite - and I don't even having a flying aircraft yet!

Thanks for all the input - sounds like it might be interesting option - the worst case will be remove it...

Carl

3" scat is marginal

Search the archives for one of the following "oil cooler" or "diffuser". Here is one:

http://www.vansairforce.com/community/showthread.php?t=2629&highlight=diffuser

Vans oil cooler kit is a terriable design. The 3" SCAT is too small (7 sq-in). May be good enough for a O320, but not enough for the 180HP and up or hot climates. As you point out the cooler is 17 sq-in (actually it's less than 17 sq-in with solid fin/tube area removed but you're on track). Its not area but its CFM or volumn airflow for a given pressure. 3" SCAT will not feed the typical SW 8406R or 10599.

SCAT is NOT a great surface for flow, so keep the SCAT to MIN LENGTH or use smooth wall ducting (couple of ways to do that). The easy way is to keep the duct to min length.

The diffusers shown above are 1000 times better than Vans sheet metal box.

If you look at the engineering data for a Stewart Warner/South Wind you will see 3.5"-4" dia area is needed to get the volumn of air for max efficiency at the pressure head we operate. 3" dia will work but you are not getting full performance out of the cooler. If you have a 150-160 HP engine and live in a mild climates, it might be fine?

The "other brand" coolers are not as efficient. The "you get what you pay" for really applies here with oil coolers.

Mounting a BIG cooler on the back our your baffle is brutal on the cooler and baffling. Really consider moving the cooler just off the baffle, supporting it off of something solid (engine mount). You don't have to mount it on the fire wall necessarily. Using a flex couple/duct connection between baffle and cooler will avoid cracks of the baffle and cooler.

Van's is using 4" ducting on the RV-10 kit which is good, so even Van's saw the light.

Here's another data point: I have a "stock" FW fwd: O-360-A1A, carb, mags, stock Van's oil cooler located per plans behind #4. My experience was pretty much the same as "hevansrv7a", above - running too cool most of the time. I fabricated a couple of rails on the back of the oil cooler so I could slide in plates of different lengths to cut down on the air flow through the cooler. Worked OK, but kind of a PIA because it required removing the top cowl to adjust. So I bought and installed the Van's adjustable shutter (picture on "Captain John", above). Clever and nicely made gadget. Works pretty well so far. It's been closed all the way much of the time since I installed it (it don't get too warm, too often, where I live), but oil temps have been up to at least 175 even at OAT of 15-20. I suppose it's possible there won't be enough cooling air flow at higher OAT's as the shutter covers roughly half of the inlet area when it's open all the way. Cooling has been plenty sufficient up to 80-ish and I didnt' have it open all the way. It certainly is nice to be able to dial in whatever temp you want from inside the cockpit.

Question:

What "IS" proper oil temp?

Most people seem to like around 180 degrees. Is that right?

CJ

Heater?

Several of my friends use oil cooler exit air for cabin heat and claim that there is more heat than Van's exhaust muff and the threat of Co is gone.
Another friend has a Velocity with a 300 HP Lyc and the cooler mounted in the front of the airplane and uses it for cabin heat as well.

How many of you guys has experience with this type of heat?

BTW..180* -220* is fine, better than 160's because you need it hot enough for good lubrication and water evaporation.
Regards,

Oil Cooler for Cabin heat

pierre smith said:

Several of my friends use oil cooler exit air for cabin heat and claim that there is more heat than Van's exhaust muff and the threat of Co is gone.
Another friend has a Velocity with a 300 HP Lyc and the cooler mounted in the front of the airplane and uses it for cabin heat as well.

How many of you guys has experience with this type of heat?

Click to expand...

Pierre, you wouldn't happen to have any pictures would you of these installations and how they made the ducts and doors. I have a couple of friends in my area that were interested in doing the same thing with the oil cooler for cabin heat. Thanks AJ

Click to expand...

oil heater -> cabin heat

Something we were 'considering' but I was trying to work out if there were any health risks / problems. Reduction in CO risk seems like a +ve, pre-heating the air is a +ve. What am I missing on the -ve side?

Max cabin heat = lower cooling drag?

Carl

Here is my story

Captain_John said:

Question:

What "IS" proper oil temp? Most people seem to like around 180 degrees. Is that right? CJ

Click to expand...

green line, 165-210 F, the average is about 187 F. Keep in mind the oil is about 25 F hotter in the valve area. You want to oil to be at 212 F (aka, water boils at sea level) to burn mosture off. The min op (yellow) 160F, max 220 F, you are starting to cook (actual temp at valve 245 F), depending on the oil type and brand (additives). This can cause valve guide deposits and sticking valves.

Oil Cooler Shutter

I've had the Vans oil cool shutter installed for 11 months. Without the shutter I couldn't get the oil temp over 145 - 150 during cold winter days here in Michigan. With the shutter installed the temps are right up where they belong. Most of the winter the cooler is either shut or just slightly open. On a cross country flight last March the OAT varied from 10 F to 80 F from Michigan to Marathon FL. On the first stop I opened the shutter up slightly and 2/3 during the stop in GA. I've never had an issue with not enough cooling even on 95 F days.

I didn't want to mess up the panel with another cable so mine is installed along the rear baffle accessible through the oil door.




Gary N715AB

While my O-320 has never suffered from high oil temps, even on 100 degree F days, I have had to put a plate over the cooler to get the temps up on cool days. The Posi-tech cooler is mounted, pilot side, on the horizontal inlet ramp. So as to cover all eventualities, I have just made up an adjustable exit, fabricated out of alloy sheet and using a butterfly flap ( like a throttle plate) in the 3 inch exit, connected via a Bowden cable to the cabin. By rights, I should be able to get a slightly faster warm-up and keep the oil temp right on 180 F by adjusting the flap. I will test it in a day or two, and will post the results.

Martin in Oz

Oil Coolers

My 180hp standard RV-4 has an 8 row Niagara cooler mounted on the aft baffle (reinforced, but cracked, stop drilled, now OK). Standard cowl, no plenum. With a new engine, in Oz, my oil temps had trouble getting into the green. CHTs have also been good, around 150?C (302?F) at 75%. I fitted a blocking plate that covers 2/3 of the oil cooler outlet and temps now rarely get above 75-80?C (175?F) at 75% cruise. If doing hard acro it approaches 100?C (212?F). I have no ducting on the outlet. I expected oil temp/CHT problems before I flew but have had none, apart from not getting it hot enough initially.

The 8-row coolers are OK in my opinion, but I definitely think the supply of hot oil must go in at the top for maximum cooling effect, not at the bottom inlet/outlet where the cooler is shaded somewhat by the cylinder and baffle. I don't know if there is a standard plumbing method we all use or if some do it the other way about. Remote mounting of the oil cooler, while popular in many aircraft, has all the disadvantages mentioned earlier - weight, ducting (scat is terrible stuff, many engine installations remind me of the movie Brazil....?).

Sorry to boast (lucky me!), but just wanted to show that an 8 row can work.

VH-PIO 260hrs