[Steve Sampson]

Now that it has turned cold and the engine is getting a few hours on it I am struggling with the normal O-320/RV4 issue of cold oil. I have almost stopped the airflow through the cooler, but need to do something more to get the temps up. I would rather not totally stop it since, together with the vernatherm, it provides the one bit of variable cooling in the system.

On the last flight with ground temps around 32F apart from the last few minutes of slow flight, moving sheep off the runway, i did not see more that 143F. With the slow circuits it got to 158F. And yes I have put the probe in the spout of the kettle to check its accuracy.

My question is this. Has anyone ever looked at wrapping the filter up in insulation, and with what results? It has quite a large surface area.

Apart from that I just dont see what else to do!

Thanks,

 

[Geico266]

You can block the oil cooler off all the way, I fly with the IO-540 blocked off all the way below -30F. Then start reducing the airflow into the engine. Start slow, and obviously keep an eye on CHT's. In my 0-235 I have the same problem and I don't have an oil cooler.

To answer your question, IMHO the effect of insulating the oil filter would be minimal, but no harm in trying.

 

[vic syracuse]

I think it would help. I have used the Cool CAn oil filter fins to add extra cooling at times, and have found them good for 10-15 degrees, so insulating would probably help in the other direction.

Vic

 

[Steve Sampson]

Warming a -4.

Larry/Vic, thanks for your replies. I was hoping for a few more, but there we go.

Well air to the cooler is reduced to about .5 sq inch hole in the rear baffle wall, and I have wrapped the filter has a little fiberfrax quilt! Together they have made a difference, though I don't know how much to attribute to either.

Yesterday for the first time the oil saw 180F on an 8000' climb and stabilised at that temperature. It dropped on the way back down but did again go over 170F in the circuit.

Temps on the ground were in the 40s and at altitude close to freezing.

 

[Dayton Murdock]

Oil Temp

Hi Steve

On my RV4 the oil cooler is mounted forward of #1 cyc. and my temps are cool also. I have one section of fins expose to the air and my temps are 180F ish. Steve when you force air thru a small hole into a large cavity doesn’t the expanding air loose temperature? I would put tape on the oil cooler face with the full area exposed to the engine plenum
Just my 2cents

 

[Steve Sampson]

Dayton, Thanks for your interest and thoughts.

Thermodynamics is 42 years ago, but I think it works like this. Yes expanding air cools.

(p1*v1)/t1= (p2*v2)/t2

However, the air concerned has just been compressed above ambient pressure as it entered the upper cowl area and it is only decompressing back towards ambient as it runs through to the lower cowl. So at this stage it would appear to still be above the ambient pressure and therefore slightly warmer.

In my case I think it certainly is warmer because the .5sq inch hole is right down behind the fins on #4.

Is yours an O-320 or 360? Reading back through the RV4 archives the O-320 powered -4 in particular, clearly runs too cool. Its just too fast(not a complaint!) and the cooling too efficient. The good news is I am in the temperate UK not N. Finland, Minnesota or Alaska.

I never found any real solutions reading through, except start blocking up behind the prop where the air comes in. One amusing one was to build in leaks so the baffles are less good!

At least the CHT are great at 300F in the cruise!

(The irritating thing is my egt are high, at full power, but that is a separate issue and due to running a little lean. Again, the airbox it too efficient, and I need a larger carb nozzle. Another issue I am working.)

I think the -4 community who worked their way through and solved all these issues have moved on, have learned everything, and lost interest.

 

[Brian Vickers]

Cabin heat?

Steve,
As I recall you are using the oil cooler for cabin heat. I am in the midst of swimming up the same river. Is your cockpit temp tolerable when blocking air flowing through the oil cooler? I live in NW USA. Temps are about the same as your location. Thanks for your comments.

Sincerely,

 

[Steve Barnes]

Awesome Abode

Larry/Vic, thanks for your replies. I was hoping for a few more, but there we go.

Well air to the cooler is reduced to about .5 sq inch hole in the rear baffle wall, and I have wrapped the filter has a little fiberfrax quilt! Together they have made a difference, though I don't know how much to attribute to either.

Yesterday for the first time the oil saw 180F on an 8000' climb and stabilised at that temperature. It dropped on the way back down but did again go over 170F in the circuit.

Temps on the ground were in the 40s and at altitude close to freezing.

Steve, Just played the flick on your first flight. What an awesome place for an RV 4 to be born and first spread its wings.

 

[Steve Sampson]

Steve,
As I recall you are using the oil cooler for cabin heat.

Sincerely,

Brian, Yes that is correct.I have two sources of heat:

1) The oil cooler, but its output is minimal,
and
2) an electric seating element in my seat. Its the same as the seat back of a Mercedes Benz.

I just have the element in the seat back and I have to say I never have felt cold in the plane except when I have forgotten to turn it on. I usually turn it off after airborne because I find I am getting too hot.

For the reasons in the post below the flow of air through the cooler is minimal, however it is enough to keep the area around my feet vaguely warm. I have to say i am puzzled in view of the low OT why I am not having a comfort problem, but I think it is because a lot of energy comes in through the canopy and I really have a good fit with no drafts.

If I was getting cold it would be easy to change to a conventional heat muff on the exhaust but I see no reason for that. I would only be concerned about heat if I had a long flight under a heavy overcast with temps down below 20F.

Electric seats are ideal for the -4 'cos getting heat to the back is difficult. Each element draws a total of 2 amps!

(Steve B. - yes it has some attractions, though my workshop was a pig stye in a previous life! Some people think it still is the way I tidy up!)