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Firewall Mounted Oil Cooler

TCONROY

TCONROY

Well Known Member
I've read in several threads about baffle cracks over time with the stock oil cooler mounted behind the left-aft cylinder (#3?) per plans. I keep seeing recommendations for mounting on the firewall but can't seem to find many examples. Van's sells an accessory called "EA 3" OIL COOLER DUCT" that is meant for mounting the oil cooler to the firewall. Does anyone have pictures of their firewall mounted oil cooler using this accessory kit?
 
I am in the same boat as you. I searched and asked for comments and nearly all recommended engine mounted cooler as better for cooling and no difference in overall cooling drag. I have a few examples of firewall, but just a few.

The firewall kit from Vans has poor airflow and may not cool as well. The inlet just dumps into a box and has no aero transition.

My plan was to lean the cooler back as much as possible w/o hitting the engine mount and then beef up the attachments. Beef up how? No plan at this time, so if others chime in it will be helpful for us both. I am coming up on baffles soon I hope.
Here are a few picts I found:
oilcooler001hv5et9.jpg

oilcooler3raes5.jpg

oilcoolermount1uw8.jpg

Good luck!
 
My setup

Hi

Here's my RV-7 setup. I'm using the standard vans cooler on a superior IO-360.
Works fine, but I do live in the UK so temps are not often above 25 degrees C.
For the winter I have a butterfly valve so I can shut-off the airflow and get the oil temp up to 180F
Putting the cooler on an angle allowed me to keep the prop cable in its normal position.

Peter

2hdy5us.jpg
 
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Go 4"

Hi Trevor,

I had mine firewall mounted and used 3" ducting. It was inadequate. Remounted to the baffle.

On my new one, I'm going to go to the RV10 mount and 4" tubing. Got to have cooling in the tough AZ heat.
 
TCONROY said:
I've read in several threads about baffle cracks over time with the stock oil cooler mounted behind the left-aft cylinder (#3?) per plans. I keep seeing recommendations for mounting on the firewall but can't seem to find many examples. Van's sells an accessory called "EA 3" OIL COOLER DUCT" that is meant for mounting the oil cooler to the firewall. Does anyone have pictures of their firewall mounted oil cooler using this accessory kit?
Click to expand...
Just put an extra piece of angle on that back corner and mount the cooler on the baffle. I haven't seen any reports of baffle cracking for those who have done this pretty routing addition to the stock plans. Another option is to use a cross brace between the back baffle and the #3 cylinder since the back left baffle corner moves with #3. Unless I thought cooling would be better on the firewall, I'd much prefer it out of the way on the baffle where it doesn't get in the way of accessing the rear side of the engine. Hope this helps.
 
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Thank you for all the comments and pictures! I've been looking at various single-engine aircraft in our hangar and see the oil coolers are mounted on the baffling on the rear of the engine. I've noticed that area pretty heavily reinforced on Cessna 172's and 182's so it sounds like Van's had the right idea but maybe just didn't reinforce enough. I would like to build per plans so I think we will mount in the stock location but just beef up the mounting brackets to prevent cracks.
 
Trev,
I put the cooler on thw FW with the Vans kit. Works great. I also installed the air door to block it off when needed. I highly prefer this over the baffle mounted version. No cracks... Ever...
 
Firewall Oil Cooler and performance...

I mounted the oil cooler on the firewall after repeated cracking in the baffling - very similar to the pictures shown earlier. Also, I'm using a custom plenum arrangement with Van's baffle kit for the sides, back, and bottom baffles.

As an interesting aside, I was tinkering with increasing oil temperature by changing the size of the duct (using a butterfly valve) and I noticed that I was able to gain airspeed (tested at 1000 ft intervals from 3000 to 8000 ft, same day, pressure & temp). I expected to achieve better cooling (lower CHTs) and warmer oil temps but the A/S increase was a pleasant surprise.

My next tweak is to build a better air box for the oil cooler (a SW 8406R) and provide an exit path for the oil cooler air -- instead of dumping into the low pressure side of the cowling... who knows :)
 
bjdecker said:
As an interesting aside, I was tinkering with increasing oil temperature by changing the size of the duct (using a butterfly valve) and I noticed that I was able to gain airspeed (tested at 1000 ft intervals from 3000 to 8000 ft, same day, pressure & temp). I expected to achieve better cooling (lower CHTs) and warmer oil temps but the A/S increase was a pleasant surprise.
Click to expand...

No surprise. Mass x velocity loss = drag, and you reduced mass. Increase exit velocity and you'll get even more. Go for it!
 
More Firewall Oil Cooler Mounting Questions

I've been formulating ideas for a firewall oil cooler mount on an 8 and like Bill's approach.

Bill - were you able to come up with a way to reinforce the mount shown in the photos? I see you're using aluminum brackets on the firewall....perhaps an aluminium doubler and additional brackets on the interior side of the firewall?

Also, did you fabricate or purchase the white transition piece between the scat hose and the cooler? It looks perfest for the application.

Lastly, was wondering if anyone ever uses a dedicated NACA duct mounted to either the side or bottom of the lower cowel to feed air directly into the cooler (see link below for example). It would seem much more efficent from a heat transfer perspective to use outside air rather than air that's been warmed by passing it over the hot cylinder heads. Since the air mass flows over the oil cooler in either case, seems like the drag losses would be comparable. I'm using a Superior IO 400 and planning on the 8432R cooler (or clone) to be sure I have plenty of cooling capacity.



http://www.vividracing.com/catalog/...t=89965&ph=1&gclid=CIzZz-Sms7wCFQIOOgod5xQAqg
 
Chris Engler said:
Lastly, was wondering if anyone ever uses a dedicated NACA duct mounted to either the side or bottom of the lower cowl to feed air directly into the cooler (see link below for example). It would seem much more efficent from a heat transfer perspective to use outside air rather than air that's been warmed by passing it over the hot cylinder heads. Since the air mass flows over the oil cooler in either case, seems like the drag losses would be comparable. I'm using a Superior IO 400 and planning on the 8432R cooler (or clone) to be sure I have plenty of cooling capacity.
Click to expand...

I've made a few measurements in recent years. IIRC, temperature rise between OAT and oil cooler face averaged around 16 degrees F.

I suspect an 8432 will be marginal for an IO400, unless you figure a routine 200F and often higher is perfectly acceptable. I'm not sayin' it isn't...except for mine.

Flying this now (fully ducted 10611) with a 390 and a variable cowl exit. It's fed from the cowl intakes, but Alan Judy's direct-from-the-outside is probably better.

x1wtb8.jpg
 
Air Temp Delta

Dan

Have you ever measured the air temp after the oil cooler compared to the air temp in front of the cooler? Just curious if you or anybody else has data, with an oil temp of 185 or 190 Deg F. Am contemplating additional cabin heat.
Thanks in advance.
 
F1R said:
Dan, Have you ever measured the air temp after the oil cooler compared to the air temp in front of the cooler? Just curious if you or anybody else has data, with an oil temp of 185 or 190 Deg F. Am contemplating additional cabin heat. Thanks in advance.
Click to expand...

Sorry, don't recall ever doing that pair.
 
I suggest you search "baffle crack" and see what comes up.

My solution was to simply nest a big piece of AA in the corner of the #4 baffle. 200 hours and no cracks. The original baffles cracked at less than 100 hours.

This mod is simple and easy to do but probably the biggest advantage is it doesn't clutter up an already cluttered engine compartment.

Here is a picture of my bracket:

2012-01-27_21-53-53_700.jpg


PS. That is an O-360.
 
I mounted Vans EA OIL COOLER 2006A with a VA-186 mount on the left side of my RV-8 firewall with a 4" scat off cyl 3 baffle. Put a 4" damper on top of the mount. The left side of the firewall was to congested with throttle, gov, mix cables, fuel etc. Cooler size may be overkill but I thought to much is better than to little - damper can always allow me to cut back on the cooling.

Still debating about changing the 4" scat to 3.5" as it is a little tight going thru the engine mount.

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FW Mount

Just as a data point:

The first pic in post #3 is my airplane before it was flying---note the clecos still in the firewall flange. After flying the plane (originally based in very warm S. Texas) I made a number of modifications to the oil cooler inlet system. First I reworked the fg diffuser and inlet to accept 4" sceet tubing. I found the 3" inadequate for my IO360 oil cooling. Additionally, I extended the pickup and diffuser fg tubing to minimize the use of sceet (fg is smoother inside) and I slightly changed the angles on the tubing to provide more of a straight shot through the sceet from the pick up point to the diffuser. Since I have a James plenum and the original installation instructions called for positioning the plenum low on the engine, much of the original pick up point was behind the #4 cylinder. I formed a tapered "extended top" onto my plenum top and raised the pick up point up relative to the cylinder to allow more of the cooler air streaming high in the plenum to flow into the pick up point. I also formed a fg outlet to get the exit point low in the cowl closer to the lowest pressures. I don't have a pic handy but if anyone is interested I will try to get one.

Cheers,

db
 
I will follow Dave with another data point.

RV-9 with IO-320 firewall mounted stock oil cooler. Installed using the kit from Van's.
xkt17s.jpg


This setup has a poor transition connection to the cooler. I had higher than desired oil temps. Partially because of break-in and also higher CHT due to advanced timing.
I molded a better scat tubing transition to the cooler out of fiberglass (sorry no picture) and saw an improved temperature. I have also fixed my advanced timing and finished break-in. My Oil temps now run about 200 on a 80 degree day at low altitude cruise.
I will continue to work on this. Next problem is where I connected the scat tubing to my baffle. On the TW planes the motor mount has the gear leg towers in the way. I connected the scat tube very low to the cylinder and I am picking up CHT heat.
Difficult to see in the picture but it is very low.
2ljnm9l.jpg

I do have a butterfly damper mounted at the baffle.
Before summer I will mold a transition from the baffle down through the mount to get the take-off higher on the baffle.
I think the firewall mounted cooler is a good option.
 
Oops on post 20

Firewall mounted cooler is on the right side of the firewall (like the picture), not left side as indicated the write up.
 
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