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Tom,
I have a IO 390 installed which has the piston cooling jets installed. My cowl inlets a 4". Modifications on the cowl exit made little change in CHT but up to 10°F change in Oil temp.
My Oil cooler is installed in front of Cyl#2, its the biggest I could fit.
My oiltemps in 75% cruise are 195 to 205° my CHTs are 375max in cruise. Never seen more than 390° even on step climb in summer. Only the Oil gets hot up to 225° but never the CHT's
I'm looking to lower my Oil temps now: little bigger inlets, tighter plenum, better inlet diffusors, ...
Check my Engine data: https://my.savvyanalysis.com/public/ca78361a-b091-4cd6-95f1-a3978b83679f
Hope this helps,
Christian
Am 07.10.2012 um 18:34 schrieb N20087 <n20087@yahoo.com>:
>> 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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