High Oil Temps----Problem Solved

[airguy]

Phase I is going good so far - just not enough time to fly, I've only got 17 hours on it so far. I did a fair bit of "cleanup" on the fiberglass of the inlets, and ended up hacking on my lower cowl exit to open it up 1" forward of the firewall. Now my temps in cruise are very nice indeed, I've lost a couple knots of top end speed from the additional drag, and I'm still seeing high temps on climb unless I run just slobbering rich.

My left side (#2 and #4) run warmer than the right, due to the oil cooler air spilling off that side and the fact that my left side air inlet is not aligned correctly between the plenum and cowl opening, with the result that the neoprene connector between them is wrinkled and buckled slightly, producing some drag there and cutting down on the inlet flow on that side. I'll have to cut that left plenum inlet and reglass it slightly lower and slightly inboard to solve that problem, and I think I'm going to install the Anti-Splat Aero electric cowl flap to enable me to dump large volumes of air out of the lower cowl for climb, and add back about half of the exit area I cut off the lower cowl exit previously to see if I can get those couple knots of top-end speed back without raising the cruise temps. That's going to be a bit of a balancing act, but the nice part is that it's just fiberglass - you can hack it off and redo it any time you want.

Believe it or not, I may end up with a 13-row oil cooler on this airplane. I'm having no real problems keeping the CHT's in check, but with the piston squirters on this engine I'm just dumping huge amounts of heat into the oil at full power. I just changed from mineral oil for break-in to Phillips XC standard 20-50, I'll fly for a bit with that and see if it affects anything before jumping off the bridge on the oil cooler.

[PilotjohnS]

Piston squirters... What a great idea. Seems like you are now like porsche. Air and oil cooled

[airguy]

Originally Posted by PilotjohnS

Piston squirters... What a great idea. Seems like you are now like porsche. Air and oil cooled

It wasn't intentional, I wouldn't have done it by choice. I bought a used engine from a Reno race-engine builder and he had installed them, I didn't realize they were in place until it was flying.

[TX7A]

Greg
I have an O-360 ECi with squirters. Last summer when I flew my plane for the first time I was getting high oil & CHT temps as well. Oil cooler was a Stewart Warner 8406R, firewall mounted with a 4" duct. Also had a very nicely formed fiberglass plenum on the cooler. I did all the things to help mitigate the problem: baffle seal leaks, air dam trimming, etc. The next thing I did was install the Antisplat cowl flap on left side (just under where the oil cooler is mounted). CHTs came down some but didn't help the oil temps much. So, I bit the bullet & got a 10611R cooler from Pacific. It's an Aero Classic which is now made by Pacific Coolers...or a sister company maybe. It had the same bolt pattern & same length as the 8406R; just more (11) rows. I did have to fabricate a new fiberglass plenum for the 4" duct.
Since the install, rarely do I see oil temps over 200*. Back in September when it was still pretty warm here in Abilene, I had a 96* OAT day and never saw oil temps past 193*.
I still have hotter #1 & #2 CHTs, but I still need to do some more air dam trimming.

[DanH]

Originally Posted by airguy

My left side (#2 and #4) run warmer than the right, due to the oil cooler air spilling off that side..

Probably not. One of my cooling experiments was to take oil cooler air from the rear baffle wall behind #4, and in a different iteration, ducting it from just inside the cowl inlet...i.e. no air "stolen" near #4. CHT did not change.

...and the fact that my left side air inlet is not aligned correctly between the plenum and cowl opening, with the result that the neoprene connector between them is wrinkled and buckled slightly, producing some drag there and cutting down on the inlet flow on that side.

More likely. Perhaps not drag in the usual sense, but pressure loss. Velocity wasted in flow separation and turbulence does not result in plenum pressure rise. Pressure moves air through the fins.

Originally Posted by TX7A

...I bit the bullet & got a 10611R cooler from Pacific... Since the install, rarely do I see oil temps over 200*. Back in September when it was still pretty warm here in Abilene, I had a 96* OAT day and never saw oil temps past 193*.

Same here with the 390. The small coolers seem to be fine with squirters if the owner is happy with 200F+ on a regular basis, but nothing but a large cooler will bring happiness if you want temps under 200F in the hot parts of the world.

[airguy]

Originally Posted by DanH

Same here with the 390. The small coolers seem to be fine with squirters if the owner is happy with 200F+ on a regular basis, but nothing but a large cooler will bring happiness if you want temps under 200F in the hot parts of the world.

I can hold 200-205 oil temp now at 60%-65% cruise, I was hoping for 190-195. I can still get it up to 230 pretty quick on a Vy climb at full power though, that's what has my attention right now.

[Neal@F14]

My buddy's RV-8 with ECI Titan IO-360 that has piston squirters sure has nice CHTs (typically 350-365 even in TX summer heat) but we ended up installing an expensive SW oil cooler to get the oil temps under control. We had a 13 row cooler on it for a short while but that one worked a little too good and mounted on the rear cyl 4 baffle, it rubbed the engine mount and the fiberglass cowl too. A 13 row cooler firewall mounted with an adjustable butterfly valve to vary the airflow into the cooler would've worked fantastic but we didn't have the room, or willpower to do that, so it got the SW10599 on the baffle instead.

[PG13]

It seems like every time there is a photo shared on this website, its gone. I?m looking for the before and after trimming pics of the cowl for cooling. Image Shack doesn?t have them. Why do pics not work very well for very long on VansAF? And.. does anyone have any pics with a successful trimming for high cht? Thx
cl65@sbcglobal.net if you do.

[Bruce]

Tony,
Another thread is going right now with pics.

Boomer

[Bruce]

Tony

It?s OP-58 thread that is up now.