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tx_jayhawk

Well Known Member
As the OAT has climbed up to 95 deg and above, I am now getting oil temps higher than I am comfortable with. I find myself very closely watching temperatures throughout the flight. I've read all the threads and theories, but it seems there are several ways to address it. My configuration is RV-7A, 0-360, James cowl and plenum, and standard firewall-mounted stewart warner oil cooler fed by 3" SCAT. I am not interested in re-jetting my carb (seems like a bad solution).

Options I am considering are as follows:
1) Go to 4" SCAT from back of baffles to oil cooler. I worry that this will rob excessive air from the #4 cylinder, and possibly raise that CHT temp. It will also require some customer fiberglass transition pieces, and it may be tough to fit the 4" SCAT witht the current routing.
2) Go to the bigger stewart warner oil cooler. I probably have room to mount this on the firewall if needed.
3) Keep with the existing 3" SCAT and make cutom fiberglass transition pieces on the inlet and outlet of the cooler to smooth the airflow. The current Van's firewall mount bracket does not really provide for a smooth airflow transition.
4) Install louvers on the bottom of the cowl (both sides next to the tunnel).
5) Other?

I know there are a number of threads on this, but I would appreciate any feedback from others with a similar configuration that might have specifically performed some of the above changes.

Thanks,
Scott
7A
 
What oil temps are you seeing? Oil temps in an air cooled engine are going to be higher this time of year. The lubrication engineers I have talked to (Shell & Phillips) don't even get nervous with temps under 250f.

Have you considered modifying your flying habits in warm weather? Throttle back a tad, fly at higher altitudes for cooler air, step climbing, etc?

How many hours on the engine? Is it broke in yet?

Just trying to help.
 
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From the experience of folk downunder, with RV7's etc, the standard cooler will never be big enough in warmer climates.

Fit a bigger cooler and a sliding gate to restrict airflow in winter.

Its not unusual......simple as that.

We did the same on our -10.
 
Two things that helped get my oil temps down:
  1. Smooth fiberglass oil cooler inlet transition duct to replace Van's "top hat".
  2. Stewart-Warner oil cooler.
I put off the $$$ oil cooler for a long time, but finally bit the bullet and bought it. It got me the final 8-10 degrees F. I still watch the temps on a climb in hot weather when heavy. I think the cowl exit area of the A's contributes to the problem. I've tried to figure out a way to smooth the firewall corner at the exit, but can't figure a way to fit it. It's a jumbled mess. Louvers helped my CHTs, but not the oil temps.

Good luck.
 
RV6A, 0360, standard cooler mounted behind the #4 cylinder on the baffle. I even have the Van's slider plate installed. No problems at all, and we have daytime temps in the 90's as well as above 100 sometimes. A friend with his 9A and 0320 runs the same as mine. Another friend with a 6A and rebuilt 0360 does have temp problems.

L.Adamson --- RV6A
 
tx_jayhawk said:
standard firewall-mounted stewart warner oil cooler fed by 3" SCAT.
Click to expand...

By "standard" SW oil cooler, I presume you mean the SW8406R? (6 plates)

In my opinion and experience, a 6 or 7 row oil cooler just simply cannot dissipate enough heat generated by a lot of 360 engines in warmer climates.
There are a few builders out there who have had success with using the smaller coolers on a 360, but I believe they are in the minority.

An RV-7 builder at my field who recently completed his plane (low compression IO-360), had the SW8406R and as soon as the OAT hit the mid 90's and higher, his oil temps started rising too much at higher power settings and in climbs. His cooler was baffle-mounted and he just swapped it out for the Aero Classic 10-row cooler (which fit... barely) and now he can fly in 100 degree OAT at full power and in climbs without oil temp problems. The problem was solved with the bigger cooler.

On the RV-8 in my avatar (ECI Titan high compression IO-360), we originally started out with the stock Vans-supplied 7-row NDM cooler, which was totally overwhelmed. We now have the 9-plate SW10599R cooler --- very expensive, ~ $650.

The Aero Classic 10-row coolers are about $263 and do a fine job of cooling a 360 engine. They also have a 9-row cooler for a couple dollars less in case you're worried about the tight fit of a 10-row next to the engine mount tubes in an RV-7.

I've come to the conclusion that on a Lyc 360 engine, that 9 or 10 rows of oil cooler is the minimum acceptable size if you expect to fly in warm/hot climates.
 
Thanks fl-mike. How much reduction did you get from smoothing the transition (I have the top hat)?

I don't think my temps are totally unreasonable given the OAT (up to 222 before I start enriching or backing off), but I want to get them lower for the piece of mind if nothing else.
 
Interesting thread...

I recently flew from FL to MT and back, at altitudes ranging from sea level to 11,500', and ground temps from 65? to 104?.

My OT reached as high as 230? for a time, but was normally between 175? and 200?.

What is considered a normal range for an RV-4 with an O-360 and FP prop?

Thanks,
 
Options I am considering are as follows:
1) Go to 4" SCAT from back of baffles to oil cooler. I worry that this will rob excessive air from the #4 cylinder, and possibly raise that CHT temp. It will also require some customer fiberglass transition pieces, and it may be tough to fit the 4" SCAT witht the current routing.

Closing the 4" scat air supply to the remote SW cooler causes #4 CHT to go down 8F. At least thats what happened this morning with OAT at 82.
 
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ccsmith51 said:
I recently flew from FL to MT and back, at altitudes ranging from sea level to 11,500', and ground temps from 65? to 104?.

My OT reached as high as 230? for a time, but was normally between 175? and 200?.

What is considered a normal range for an RV-4 with an O-360 and FP prop?

Thanks,
Click to expand...

Lycoming says continous operation in the 165F to 220F is acceptable -

http://www.lycoming.textron.com/support/tips-advice/key-reprints/pdfs/Key Operations.pdf

Redline is usually 245F, so you are only slightly over some times...
 
I also had high (230 in climb was my step climb cue) oil temps on an IO-360 injected, 9:1 piston, electronic ignition engine. After many failed attempts I bit the bullet and retrofitted an SW 10599r oil cooler to the same spot on the rear baffle. It required enlarging the hole for the cooling air. Problem is now completely solved even on hot days doing slow flight for a half hour at a time.

And if anyone asks why I would do slow flight for a half hour, it's the nude sun bathing colonies that my flight instructor always was trying to get me to see "if you just fly slow enough"!:D

Jeremy Constant
 
Naca Scoop

tx_jayhawk said:
As the OAT has climbed up to 95 deg and above, I am now getting oil temps higher than I am comfortable with. I find myself very closely watching temperatures throughout the flight. I've read all the threads and theories, but it seems there are several ways to address it. My configuration is RV-7A, 0-360, James cowl and plenum, and standard firewall-mounted stewart warner oil cooler fed by 3" SCAT. I am not interested in re-jetting my carb (seems like a bad solution).

Options I am considering are as follows:
1) Go to 4" SCAT from back of baffles to oil cooler. I worry that this will rob excessive air from the #4 cylinder, and possibly raise that CHT temp. It will also require some customer fiberglass transition pieces, and it may be tough to fit the 4" SCAT witht the current routing.
2) Go to the bigger stewart warner oil cooler. I probably have room to mount this on the firewall if needed.
3) Keep with the existing 3" SCAT and make cutom fiberglass transition pieces on the inlet and outlet of the cooler to smooth the airflow. The current Van's firewall mount bracket does not really provide for a smooth airflow transition.
4) Install louvers on the bottom of the cowl (both sides next to the tunnel).
5) Other?

I know there are a number of threads on this, but I would appreciate any feedback from others with a similar configuration that might have specifically performed some of the above changes.

Thanks,
Scott
7A
Click to expand...

Have you consider installing a Naca Scoop on the left side of the lower cowling ? and not use air from the plenum to cool your oil cooler
 
Conifer said:
Have you consider installing a Naca Scoop on the left side of the lower cowling ? and not use air from the plenum to cool your oil cooler
Click to expand...

I believe the pressure in the lower engine compartment is such that air will flow out a NACA scoop, not in, unless the flow is completely contained in a duct to and from the cooler.
 
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