Tom, Pay close attention to the air inlets and transition. You will want that smooth. I have also seen large oil coolers mounted directly to the back of the baffling excessively dump the pressure on the top of the engine which you need to get effective cooling. Anything you can do to seal up the top of the engine will reduce drag and cool better. You will want the baffling sealed up tight tight tight. Put a shop light under the engine in a dark hangar and seal EVERYTHING with high temp RTV so the only place for your cooling air to go is through the cooling fins. Check the spacing on the baffling that wraps around the cylinders at the bottom. Those can be too tight as well. I would also radius them off instead of 90 degree bends where they are safety wired together too. Also, the suggestion about closing the nose gear slot with a door is a good one and I am planning to do this as well. There is lots of air going in there especially at high angles of attack creating pressure in the lower cowl. This is bad and and it slows you down too.
Lastly, I love my plennum. If they are done right, you will go fast and run cool. 365 degrees are the norm for me in cruise.
Most of this has come from my research and looking carefully at what other guys have done . There may not be a magic bullet here. You may have several factors contributing to bad cooling. You should be able to get cool without having to resort to expensive engine mods...
Look at set ups that are working and keep after it... Good luck..
Randy Snarr N694RS 235/320
Sent from my iPad
Tom,
I have a 360 straight valve with 10:1 pistons,fuel injected with a slightly bigger oil cooler then normal. I increased my inlet air to four inches and a stock RV baffling system sealed tight.My exit air is 3"x 17. If not careful (too lean) on hot days I can go over 400 on takeoff/climb out on a hot day. However if I level off/ reduce power/rpm I can stop the CHTS from going over 400, Once cooled down (stabilized) from the takeoff I can resume full power/climb and manage the temps just fine. I never run my engine over 400 chts.
I recently ran a race in Pogosa Springs Co. it was 150 miles. I ran wide open and 2650rpms, I controlled the chts with fuel and never went over 390. The oil peaked at 210, I averaged 254 mph. I do not have ney nossils nor a Plenum just a tight stock RV baffling system. I expect lower CHTS once I build a nose gear door for the bottom cowl opening that has to be upsetting the exit air from the strut opening. I also see a plenum in the future as I clean-up cooling drag that might allow me to close down inlet and exit air. But for now My cooling is fine
Lycon warns not to go over 400 for break-in. Doing so puts you at great risk of glazing the cylinders and annealing the rings, which will cause blow-by, burning oil. Thus causing the cylinders to run hotter. This is what I would suspect is your results.
Splitting the case and installing Ney nossils is not the answer in my opion. If your baffling system is correctly done with 4" inlets and adequate exit air you should not have a problem, just control the heat on climb out,if you install ney nossils it may help but its the wrong band-aid at a high price.
It sounds to me that you will need to re-ring and hone the cylinders and try the break-in again. Fall is here and cooler outside temps will aid in the break-in just remember do not go over 400 on the break-in.
steve alderman 25SA 360
-----Original Message-----
From: N20087 < n20087@yahoo.com>
To: lml < lml@lancaironline.net>
Sent: Sun, Oct 7, 2012 10:34 am
Subject: [LML] Piston oil cooling jets
> Folks
This is addressed to the hard core engine experts on the forum. I would love
your feedback on this
I am considering having my io360 crankcase modified so that I can install piston
cooling jets which are standard in 200hp engines. The reason being, I have had
to take aircraft out of service twice, once at 80 hrs and now at 160 due to
lousy break-in and high CHTs. I have done all the obvious stuff such as plenum,
timing, plugs, flowed the fuel servo to the rich side, baffles etc.. I am
running 9:1 eci cerminil cylinders and they will hit 430 on climb out. They
went to 450 twice in the initial break-in. They will run 370 in 75% cruise and
340 lop
All this aside, the pistons at 80 hrs (both times) were coated in dark varnish
under the crown and the top of the crowns were heavily carbonized from oil
blowback
I am just getting tired of it and don't want to pul the engine apart again
anytime soon after this downturn
So,,,I am wondering if anybody has any experience or data concerning the cooling
benefits of the piston oil nozzles. Ie is it 5 degrees or 20+
Also, I am debating whether to split the crankcase myself or take the closed
case (jugs and every accessory removed) with con rods still attached to the
local shop and have them split the case, do the machining and reassemble. The
shop is very very reputable but of course the cost will be higher if I get them
to do the breakdown and reassembly
As another cooling remediation measure I was thinking of opening up the cowl
inlets to 4 inches but a little reluctant due to the increased drag and limited
benefit. I added an electric cowl flap by the way and achieved only a 2 degree
CHT improvement in climb at 130 knots Go figure!
Again, any feedback on my plan here would appreciated
Thanks in advance
Tom
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