Front Mounted Oil Cooler Sizing

[CKearns]

I am building a Javron cub with an O-360. I am planning on mounting the oil cooler below the starter similar to some of the factory set ups and was wondering how many rows do I need to provide adequate cooling? I am not using a front mounted alternator so I have space to mount it and am thinking of either a 3" flange to bring a scat tube to the cooler shroud or have the cooler sit flush with the nosebowl. I know some folks mount the cooler behind #4 cylinder on the baffle or on the firewall with a scat tube from the baffle, but I am in Texas and do want to pull any air off of the baffle other than cylinder cooling since as we still see #3 and #4 getting hot in the climb here (except for February and March when it gets down in the 70's :lol. If anyone has any pics of this set up I would appreciate it.

Thoughts?

Thanks
Charlie

 

[stewartb]

If you can fit a 9 row? It’ll cool better than 7 rows. If that’s not enough? You can go to a dual pass 9 row. I’m tempted to try one on my plane that has dual 9 row coolers.

https://www.aircraftspruce.com/catalog/pnpages/08-00810.php

 

[Oliver]

What nosebowl do you intend to use on your project?

 

[CKearns]

Fiberglass nose bowl provided by Javron

 

[Oliver]

The only downside that I can see with front mounted oil cooler is the potential to pressurize, to some extent, the lower cowl. Solution for this is a well fitted cowl opening to prevent ram air air from entering around, instead of thru the cooler.
A fiberglass nosebowl lends itself well to this.
im running a hopped up o320 in southern cal. I’ve never seen oil temps over 200 with a 7 row. CHT’ rarely exceed 400°
on a hot day climb out, hot day 95° level cruise 370° #4.
I think as much focus should be directed to engine cooling as oil cooling because they go hand in hand.
I am not a fan of rear mounted coolers - robbing air from cylinders, cluttering up firewall, and a lot more complicated to fab. others May disagree.
I’m not familiar with javron nose bowl but assuming it’s similar to a standard cub bowl, here’s some photos of fitting a carbon concepts bowl to a front mounted cooler.

first step is to properly fit the nosebowl to the cowl, remove it and mount cooler then determine size and location of cutout
on the bowl.
then glass up a rounded lip on the cutout allowing enough room for engine movement.
i use kydex for a form when glassing. PK screws to keep it in place for your first layup on the back.
releases easily from resin.
use rubber “P” molding to seal around the cooler when you’re done.

 

[CKearns]

Thanks that is exactly what I’m looking for. Do you have any pics of how you mounted the cooler to the engine?

 

[stewartb]

To the engine? The cooler should be mounted to the nose bowl. Duct the air so it doesn’t affect the bottom cowl pressure.

I saw a member’s nose bowl in progress a couple of days ago. He’s mounting a 13-row cooler behind the engine and feeding it through a scoop under the nose bowl so it doesn’t take air from the top. I’m looking forward to seeing how that turns out.

My nose bowl has two oil coolers. Nephew’s got the newest Mackey airplane I’ve seen and it has one cooler offset to the left side. Lots of ways to set the cooler(s) up.

 

[Oliver]

I’m not sure that the amount of air that flows thru the fins of a cooler is significant enough to justify the hassle of dealing with a cowl mounted and ducted cooler.
stewart, where are you ducting it to?

here’s shots of mounted cooler:
certified, original cub mounts. field approval composite bowl.
btw, in 5 years I’ve split the bowl once, not worth two going with 2 piece
nosebowl.

 

[stewartb]

Mike built some outflow collectors with butterfly valves. They have short scats to outlets in the bottom cowl. I need to make a new hose and feed both coolers from the bottom. I’m curious how much that’ll affect temps.

 

[CKearns]

I am going to fabricate mounts similar to the factory one above and keep it tied to the engine. I would like to keep the weight of the nosebowl down as well as easier to remove without disconnecting lines. I am leaning towards a 3" flange in the nosebowl with scat tube going to a shroud on the cooler itself. Thanks everyone for the info and pics. I will let you know if this is a succces or start over!!!!!

 

[hunt/trapak88]

Did you end up mounting a 9 row up front? I’ll be using a 10 and wanting to keep it up front if it won’t interfere with alternator. Thanks

 

[acroeric]

I'm at this same point in my build and will likely do something creative with a 10 or 11 row cooler mounted to my nosebowl. I've asked many people that have experience with the experimental Cub's and the rear mount oil cooler seems hit or miss at best. It also impacts CHT's from what I am hearing.

I have not heard of an aircraft having high oil temps with the cooler up front. I'm running the Monkworks generator off the vac pad for charging so I have a little extra space up front for the oil cooler/ ducting.

In addition, I have modified my rear baffles to give space for airflow behind #3 and #4 and hope some creative aero work will result in good oil temps as well.

Appreciate any pics of progress for ideas. If anyone has a Javron or other experimental Cub that runs sub 400 CHT and sub 200 oil temp please chime in.

 

[stewartb]

In. Oil temps in the 190s, CHTs in the 350-ish range. I’m betting when I change my oil line in-out arrangement this winter my oil temps will drop.

You parallel valve guys need to worry more about CHT than oil temp unless you have high compression. Then you need to worry about both.

 

[acroeric]

Yes, I am running a parallel valve O-360 (stock engine). I really want to get by with a single oil cooler. I guess the end all goal is to be able to fly at high DA without having to worry too much. Sorry to hijack the OP's thread!!

 

[CKearns]

I have not mounted the cooler yet but still intend on doing so. Like I mentioned I am using a Monxworks rear mounted generator so no clearance issues.

 

[hunt/trapak88]

Which brand 11 row will you be using?

 

[acroeric]

Had a really good conversation with Pacific (Wayne) today about oil cooler options. He really took his time to explain things. It seems one thing we can do right off the bat to increase oil cooling capacity is to go with a slightly more expensive bar and plate type cooler. Wayne sent spec sheets on several that chart heat rejection data. If you compare the HR numbers of the bar and plate type with the cheaper drawn cup type, you will see that there is a sizable difference in HR for a given size cooler. So sizable that an 8 row Bar and plate Aero Classics HE series has more cooling capacity than a 10 row drawn cup type.

If I can fit a 10 row (P/N 8001646) Aero Classics HE series in the nosebowl I will but if not, I believe the 8 row (P/N 8001599) is good enough if mounted up front.

 

[KootenayKub]

I just came across your thread. How did your oil cooler mods go? I need to do something about mine and am looking for any suggestions - from anyone. I currently have a rear baffle mounted 13 row Niagara cooler (I used to have a 9 row, but oil temps were too high; now they're almost too low) but that setup is robbing air that could be cooling cylinders, especially #4. I'm struggling to cool the engine during climb out. I'm running an IO375 on an SQ2.

 

[CKearns]

Sorry for the delayed post, yes I am using a 9 roe cooler. Still working on the mount.

 

[skywagon8a]

(I used to have a 9 row, but oil temps were too high; now they're almost too low) but that setup is robbing air that could be cooling cylinders, especially #4. I'm struggling to cool the engine during climb out. I'm running an IO375 on an SQ2.

Do you have a baffle behind #4 separating the air going over the cylinder from the air going into the cooler? Without a baffle directing cool air into #4, the air will take the path of least resistance through the oil cooler.

 

[Steve Pierce]

Do you have a baffle behind #4 separating the air going over the cylinder from the air going into the cooler? Without a baffle directing cool air into #4, the air will take the path of least resistance through the oil cooler.

View attachment 67703 View attachment 67704 View attachment 67705 View attachment 67706

Did you have any data before the baffle on the back of #4 or did you do that from the start?

 

[skywagon8a]

I did it from the start. The idea was/is that the incoming air could be warmed by passing over the top of the cylinders (particularly #4) prior to entering the oil cooler. This way with the #4 baffle extending up into and facing the airflow a certain amount of cool air would be directed down and through the cylinder fins while the unaffected cool air in the top of the air mass being forced down through the oil cooler. Tilting the top of the cooler back lowered the upper air pressure restriction enabling a more even airflow through the cooler. At least that was my thinking and it seems to have been correct. Oil temps have never exceeded 190F. The only after the initial installation mod done was to add a small baffle in front of #1 to raise the CHT.

This has been cut down to about half the height shown in the picture. The CHTs now have a maximum difference of about 15 degrees with the high well below 400.

 

[CKearns]

Does anyone recognize this oil cooler setup? I am looking for a part number? It is larger than the factory Piper cooler.

Thanks

 

[hotrod180]

Wow, that looks like a very nicely made & sturdy oil cooler bracket!
I can't tell from the pic, is the cooler supported on the RH side also?

 

[KootenayKub]

Do you have a baffle behind #4 separating the air going over the cylinder from the air going into the cooler? Without a baffle directing cool air into #4, the air will take the path of least resistance through the oil cooler.

View attachment 67703 View attachment 67704 View attachment 67705 View attachment 67706

No I don't have an 'intermediate' baffle, but that seems like a really smart idea. I'm not sure I have room to tilt back the 13 row oil cooler like you did (yours looks like a 9 row). I'm running an IO 375, and high CHT's during climb out (I need to go from 3000' to 10,000' on most flights) are my primary concern. I had a 9 row cooler in the back and my oil temps were too high, now I have a 13 row and temps are likely too low. My current thinking is that if I go back to a 9 row cooler, and front mount it with dedicated intake and ducted to bottom of cowling, I can then prioritize ram air for cooling cylinders. Alternatively, I'm considering a NACA duct on my top cowl dedicated to the oil cooler, rear mounted (but that seems like a lot of complexity and faffing about). Anyone else out there running a 375 and needing to climb out a lot?

 

[skywagon8a]

No I don't have an 'intermediate' baffle, but that seems like a really smart idea. I'm not sure I have room to tilt back the 13 row oil cooler like you did (yours looks like a 9 row). I'm running an IO 375, and high CHT's during climb out (I need to go from 3000' to 10,000' on most flights) are my primary concern. I had a 9 row cooler in the back and my oil temps were too high, now I have a 13 row and temps are likely too low. My current thinking is that if I go back to a 9 row cooler, and front mount it with dedicated intake and ducted to bottom of cowling, I can then prioritize ram air for cooling cylinders. Alternatively, I'm considering a NACA duct on my top cowl dedicated to the oil cooler, rear mounted (but that seems like a lot of complexity and faffing about). Anyone else out there running a 375 and needing to climb out a lot?

Try one thing at a time or you won't know what did what.
Make a baffle to go tight behind and extend above #4 with the top bent forward similar to mine. Try a simple test piece which can easily be removed if it doesn't help. This would be the easiest for starters rather than moving the oil cooler.

Tape over a couple of rows on the oil cooler to raise the temp.

 

[KootenayKub]

Try one thing at a time or you won't know what did what.
Make a baffle to go tight behind and extend above #4 with the top bent forward similar to mine. Try a simple test piece which can easily be removed if it doesn't help. This would be the easiest for starters rather than moving the oil cooler.

Tape over a couple of rows on the oil cooler to raise the temp.

Sage advice. I'll try a simple test piece first like you suggested. I've been experimenting with tape over portions of the oil cooler - still need to experiment some more. thanks.