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Remote Oil Cooler Ideas

C

crabandy

Well Known Member
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?
 
If you are going to remote mount it with SCAT tubing, you'll definitely want the 4" tubing. I ran 3" for mine (IO360, firewall mounted cooler) and it's barely adequate during winter and completely inadequate for summertime temps. I'll be changing mine very shortly to 4" to move more air.
 
Have you reviewed the Lycoming Operator's Manual?

Your temperatures seem right in line with what they should be. It is normal for your oil temperatures to rise during climb and 215*F is well below the maximum.

You want to be careful you don't get the oil so cool that any moisture in it won't boil off. Remember, the oil temperature probe is a good distance from the oil sump, which is often above 212*F. (That tidbit came from a Lycoming tech some years ago.)

Average
Ambient Air.............Desired......................Maximum

Above 80*F..........180*F (82*C)..............245*F (118*C)
Above 60*F..........180*F (82*C)..............245*F (118*C)
30* to 90*F..........180*F (82*C)..............245*F (118*C)
0 to 70*F.............170*F (77*C)..............245*F (118*C)
Below 10*F..........160*F (71*C)...............245*F (118*C)

* - Engine oil temperatures should not be below 140*F (60*C) during continuous operation.
 
Gary, Thanks for the link.

Airguy, I believe the IO-360's needed the extra cooling capacity the 4 inch provided. I have a carbuerated parallel valve engine.

Bill, I realize my temps are in line with recommendations but this same cooler used to keep my oil temp at 178 after level off. New cylinders-plenum etc lowered CHT's but raised oil temp. I also would like to get the air pointed in the right direction as it leaves the cooler. My lofty goal would be similar to Dave's setup:
http://vansairforce.com/Community/showthread.php?t=139328&page=10
 
crabandy said:
...

Bill, I realize my temps are in line with recommendations but this same cooler used to keep my oil temp at 178 after level off. New cylinders-plenum etc lowered CHT's but raised oil temp. I also would like to get the air pointed in the right direction as it leaves the cooler. My lofty goal would be similar to Dave's setup:
http://vansairforce.com/Community/showthread.php?t=139328&page=10
Click to expand...
Got it!

Why don't you first try making a fiberglass hood that goes on the back of the existing oil cooler and transitions to a 4" scat tube that you can direct to the exit?

This is something we made for a friend's -7A and it dropped his oil temps almost too much. It would be easy to make another shroud to direct the exit air out the hole.

Oil%20Cooler.jpg
 
N941WR said:
Got it!

Why don't you first try making a fiberglass hood that goes on the back of the existing oil cooler and transitions to a 4" scat tube that you can direct to the exit?

This is something we made for a friend's -7A and it dropped his oil temps almost too much. It would be easy to make another shroud to direct the exit air out the hole.

Oil%20Cooler.jpg
Click to expand...

Making a duct for the rear of my existing setup would be pretty easy....but I really think some of the inefficiency in the stock setup is part of the oil cooler is blocked by the cylinder head. I'll have to look at this closer.

For your Friend's 7A what was the previous setup, as in same oil cooler just moved from the rear of the baffle to the firewall with a shroud and what size hole/scat tube? I/O or O and parallel or angle valve engine?

Thanks!
 
crabandy said:
Making a duct for the rear of my existing setup would be pretty easy....but I really think some of the inefficiency in the stock setup is part of the oil cooler is blocked by the cylinder head. I'll have to look at this closer.
Click to expand...
I understand but was wondering how much performance improvement it would give, if any. Then changing it to the setup you are envisioning, if it would gain anything over that.

crabandy said:
For your Friend's 7A what was the previous setup, as in same oil cooler just moved from the rear of the baffle to the firewall with a shroud and what size hole/scat tube? I/O or O and parallel or angle valve engine?

Thanks!
Click to expand...
He started with this Van's firewall mounted oil cooler kit.

The problem was that it used a 3" hose and the opening was right on the oil cooler. By changing it to the 4" hose with the transition piece we made, it allowed the entire cooler to cool the oil. Had we mad a transition piece for the 3" hose, he probably would have been fine because he ended up over cooling his oil with that setup, even on the hottest Carolina summer day.
 
FYI- a 3" hose placed directly on the oil cooler only gives you 7" of cooling area but a 4" hose placed directly on the cool gives you 12.5" of cooling area.

By creating that fiberglass transition piece, you allow all the air coming from the back of cylinder #4 for pass through the oil cooler, not just 12.5" of cooling area.

Creating a transition from the 3" hole to the oil cooler will allow the air to slow down and as I said above, would probably prove more than adequate. More so, if you make a transition from the backside to the exit to help draw the air out.
 
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.
 
crabandy said:
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?
Click to expand...
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.
 
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.
 
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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