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-   -   Remote Oil Cooler Ideas (https://vansairforce.net/community/showthread.php?t=146953)

MarkW 02-23-2017 06:43 AM

Andy,
I have been through the oil cooler remote mounting issues.
I started with the Van's firewall kit that has a very poor 3" SCAT connection to the cooler. Temps were a little high so I made a FG transition. Things improved. My RV-9 engine mound required I mount the SCAT inlet on the back of the baffle very low behind cyl. #4. I added some DanH impregnated cloth on the fins to help keep the cooler air going that way rather than passing through the cyl. fins first. Little help. Now after 350 hours I have higher temps again so I am back to looking for a better solution. I am forming a new inlet that is larger and higher on the baffle but reduces to a 3" and points the right direction to go through the motor mount. 3"x5" to 3" Mine is on the firewall and I have no exit duct. A large exit duct could be a good idea if the duct is large and opens in an area with low pressure. If pointing toward the cowl exit it may even scavenge some air to help. I don't have the room to add the exit duct without moving the cooler and starting from scratch. I have a IO-320 with good cyl. head cooling and I believe the 7 row is large enough for the engine.

BillL 02-23-2017 10:48 AM

Quote:

Originally Posted by crabandy (Post 1152308)
I have an RV7 with a parallel valve O-360 and the stock Niagara 7 row cooler on the baffle behind #4. Currently my oil temps are decent 180-190 in cooler weather and 215 max on hot climb-out in the summer.

I'm thinking of remote mounting my cooler on the engine mount tubes on the left side, I didn't plan for this and my firewall is probably out due to other items already mounted.
-I'm thinking I should make more of a structural bracket that clamps to the engine mount with adell clamps to hold the oil cooler so the body of the cooler doesn't have any bending forces on it.

Searching the archives it seems like most people use a 3 inch hole and scat tubing for the smaller 7 row coolers and 4 inch for the larger coolers from the baffling. There needs to be a nice smooth transition from the scat tube to the cooler face.
-I'm thinking I could make my own inlet from the baffling in just about any shape (more options on where to pull the air from) as long as the opening has a bell-mouth directing the air in and then a nicely shaped duct to the cooler face? -I'm guessing I should also be shooting for about 7 inches of area, the same as a 3 inch circle?

I would also like to make an exit duct directing the air from the cooler to the cowling exit.
-Am I shooting for about 7 degrees of divergence on the exit duct?
-How large should the exit be?

Bell mouth - (1" radius) inlet - good
7 in^2 in throat - good
Then - 7 deg divergent to the face of the cooler from the baffle - Actually, I might keep the same flow area down to discharge near the exit if possible.
I talked to Dave about this and he did the above. Then, with a rigid diffuser from baffle to the cooler he just picked a point and cut it and added a neoprene boot with a small clearance between the two pieces for float to the engine. Then the exit duct can be rigid and very close to the cowl.

Andy, did you wrap your barrels and heads? That might balance the cooling between the oil and head/barrels if both are within expectations.

Some of Daves' changes are aided greatly by his additional speed and pressure available. Also, the head find density of the angle valve vs our parallel fin spacing.

crabandy 02-23-2017 07:14 PM

Thanks for everyone's replies.

BillL, I did wrap the barrels and heads when I put the new cylinders on my engine. I've since removed all of the wraps except cylinder #4, I plan on removing the wrap on #4 soon. I anticipate I'll see a 20*F CHT reduction as I did when I removed the wraps on the first 3 cylinders but I wanted more flight time to be sure.
I've since added the same Ultra Black infused 8.9 oz cloth to the lower baffling that wraps around the other three cylinders with no noticeable increase in CHT's. Not sure why or how being stuck on the baffle cools better than being stuck on the cylinder cooling fins.
I'm thinking there is quite a difference between the cooling fins of the Parallel valve and angle valve heads that the wraps interact with.

airguy 03-13-2017 07:54 AM

I completed my conversion from 3" SCAT on the remote oil cooler to the 4" yesterday, and test flew it. I did some hard climbs and got it all hot and bothered, previously this would result in 220-225 oil temps with current ambient air temps, but I was unable to get it higher than 208 this time. Normal cruise power settings gives me 185-195, right where it should be with the vernatherm working.

I'm calling this one resolved.


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