baffle mounted oil cooler

painless · #1 02-17-2005, 02:01 PM

Hi group:

I am in the process of mounting my oilcooler on the rear baffle. To those that have mounted theirs here, what size did you make the opening in the rear baffle? In the drawing from van's depicting the oil cooler installation (I'm at work so I don't have the number available) it shows the opening the full size of the cooler. But the drawing in the baffle instructions shows to cut the opening at the bottom to conform to the shape of the cooling fins on #4 cylinder.

Thanks in advance folks.

Regards,

robertahegy · #2 02-17-2005, 07:56 PM

I made the opening the same size as the cooler. Works great in the summer and for winter I cover the backside of the cooler completely. I have an 0-360.

painless · #3 02-17-2005, 08:50 PM

Thanks Roberta. What do you use to cover the cooler in the winter?

Regards,

redbeardmark · #4 02-17-2005, 08:52 PM

Quote:

Originally Posted by robertahegy

I made the opening the same size as the cooler. Works great in the summer and for winter I cover the backside of the cooler completely. I have an 0-360.

I did/do the same, but cover about 75% of cooler outlet in winter and also cover part of cowl inlet(for CHT purposes). Also using O-360. Good results.
Mark Andrews N598X

robertahegy · #5 02-18-2005, 03:51 PM

I used a piece of 0.040 AL sheet fastened to the backside of the cooler. I slotted two of the mounting holes to slide it under two bolts and added one bolt where there was on open hole.

Hey, Mark. How are you covering your inlets?

My CHT is running about 300 deg F. on a 20 deg F day. Oil is about 175 with the backside of the cooler covered up. It will warm up to 180 on the ground after a flight.

redbeardmark · #6 02-18-2005, 05:38 PM

Quote:

Originally Posted by robertahegy

I used a piece of 0.040 AL sheet fastened to the backside of the cooler. I slotted two of the mounting holes to slide it under two bolts and added one bolt where there was on open hole.

Hey, Mark. How are you covering your inlets?

My CHT is running about 300 deg F. on a 20 deg F day. Oil is about 175 with the backside of the cooler covered up. It will warm up to 180 on the ground after a flight.

Roberta,
I'm a little embarassed to say this, but I use duct tape to cover the inboard 1/3 of each inlet. However, when the hangar warms up, I plan to make some fiberglass "straps" that will attach with screws/nutplates. Easy to install for winter operation, easy to remove when headed south or during summer, lightweight and easy to store onboard. Also will make two different sizes of "straps": one set for really cold northern flying(covering 1/3 of inlets), one set for cooler spring flying(covering maybe 20% of inlets).

With the cowl inlets partially covered, less air gets through so you might need to cut down the oil cooler cover. Mine covers about 3/4 of the oil cooler outlet. Went flying today with OAT around +12 to +16F, cylinder head temps were 310-350F, oil temp was a little cool at 160-165F.

Previous flight last week with OAT around +25F gave CHT at 350-375F and oil temp at 175-180F. And, funny enough, about the same CHT and oil temps when the OAT is +45F.

As a side bar, my lycoming manual lists desired oil temp of 160F when OAT is below 10F, 170F when OAT is 0F to 70F, 180F when OAT is 30F to 90F.

I'll post photos when the "straps" are done.
Mark Andrews N598X

robertahegy · #7 02-18-2005, 06:00 PM

Thanks, Mark.

N808VR · #8 02-22-2005, 11:16 AM

I also mounted the cooler on the baffle; however, I used a couple of U-shaped channels that were riveted to the baffle. This allowed the inlet face of the cooler to be offset from the rear cylinder by about an inch to an inch and a half. This not only allowed the hole in the baffle to match the size of the cooler with unrestricted air flow, but it allowed for easier removal of the oil cooler. The bolts holding the cooler on pass throught the brackets on the cooler and the nuts and washers are in between the two flanges on the U-shaped channel. Another benefit of this set up is it provides for additional structural support on the baffle with the weight of the oil cooler filled with oil.

Dan Frank
RV-8 N808VR

redbeardmark · #9 02-22-2005, 12:19 PM

Here's an update to the data previously posted regarding oil temps:

I flew on Saturday when the OAT at 4,000' was +6F. CHT spread was 295-345F. The CHT spread is less on warmer days. Oil temp never got above 146F(Lyc manual says avoid continuous operation below 140F). It would appear that covering 3/4 of the oil cooler outlet isn't enough for those single-digit days.
Mark Andrews N598X