REFLECTOR: Rear oil cooler

[Scott Derrick]

Andy,

I'll tell you how I plumbed my dual cooler installation for a TSIO520.  
I previously had an IO360 with one cooler in the nose, with a diverter 
flap in the cooling duct to direct air into the cabin for heating.  I 
thought the heater was marginal at best. It would put adequate heat into 
the pilots position if the temp was above about 20F.  The copilots 
position got cool to cold air because the 1.5 inch duct from the cooler 
duct to the other side of the fuselage up and over the nose gear leg 
would cool it off before it reached the cabin.  The back seat was just 
plain cold.  I'm talking winter flying up above 8500 ft in the west.  My 
only winter flying in a V near Florida was ferrying my V back to New 
Mexico in Feb.  I was on top at 12500 and froze my ass off.  Temps were 
0F to -10F.  miserable with the flu.  I had adequate cooling with the 
one cooler in the summer. Only time I would have to watch the temps were 
mid summer when we would stop for fuel and immediately take off from 
Vegas or some other hot place and need to climb with an engine that was 
already hot. I would sometimes have to cruise climb at 130-140 kias to 
keep the oil temp below 230(my personal red line).

So part of my new engine installation was to also solve the cabin 
heating problem.

I have two coolers in series.  The first one is mounted mid cabin under 
the rear seat. It is a small "Perma Cool" type rated at 180 PSI  at 
300F, high flow.  This has two fans attached. The air is sucked in from 
the cabin and can either be recirculated to heat up the cabin or dumped 
overboard for secondary cooling during the summer.  The second cooler is 
the standard nose mounted cooler.  This provides maximum heat for cabin 
heating by running the oil through the mid cabin heat exchanger first.

I have done a couple of other changes to optimize oil cooling.  Turbo 
charging places an additional burden on oil cooling.

1.)  I removed the diverter flap from the nose cooler duct to insure 
maximum flow through this cooler. It makes a difference.
2.) I have split my lines, the oil flows from the engine up the pilot 
side duct, and back to the engine through the  co-pilots side duct.
3.) I am "not" stealing cylinder cooling air(over head NACA's) for any 
thing (secondary oil cooler, induction air, intercooler, etc..)  I know 
others disagree but I believe oil temperature has a direct connection, 
not one-to-one mind you, with cylinder head temperature. Keeping your 
cylinder temps in the low 300's will dramatically effect your oil temps.

 Scott

Andrew Ellzey wrote:
> Is the second oil cooler in the rear always needed on the IO-540 
> installations? If so what is the proper pluming to make two coolers 
> work? Do you plum them in series with the front cooler plumed first to 
> give you enough heat for winter or what? My IO-540 E1A5 from an Aero 
> Commander was only using one oil cooler.
>  
> Andy
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