My test stand has a series 2 Renesis and my flying RV6A has a 1986 13B.  Oil cooling was found unsatisfactory at flight power levels with both systems when RX7 oil coolers were used.  On the test stand, various oil cooler configurations were tested.  The same AC evaporator core as used for coolant radiators was found to have less oil pressure drop but oil temperatures were still too high.  Two RX7 coolers were connected in parallel but were still restrictive to oil flow.  The two RX7 coolers were converted to single pass but were still restrictive to oil flow even when connected in parallel.  A water jacket was welded to an RX7 cooler thus converting it to an oil to coolant exchanger.  Oil temperatures were still too high with this setup which suggested to me that the heat exchange on the oil side of the RX7 cooler core was the limiting factor.  A Fluidyne DB-30617 cooler with damaged fittings was purchased on Ebay.  AN 10 male fittings were welded on replacing the original damaged AN 12 ones.  Installing this cooler on the test stand resulted in much lower pressure drop across the core along with much improved oil temperatures.  It was only at this point that the expen$ive new Fluidyne DB-30618 was purchased and installed in the plane.  The positive results of this change has already been discussed.

A Fluidyne oil to coolant exchanger (they only sell one model of these that I know of) was then installed in the plane with good results.  The oil to air cooler was reinstalled purely to retain the redundancy of oil and coolant as cooling systems.

Steve Boese

> On Jun 26, 2018, at 9:40 PM, Andrew Martin andrew@martinag.com.au <flyrotary@lancaironline.net> wrote:
>
> Steve, that sounds same size cooler that I had, was out of a 20b twin turbo cosmo car, pretty sure those cars were only sold by mazda in Japan & Aus being RHD
> That cooler tricked me as it would allow enough oil through to give rated pressure on gauge, but only at low power would cool, as soon as flight was attempted oil overheated quickly and took long time to cool down, second cooler was same frontal area but 75mm thick, better as would cool hot oil down faster but again only at low power. Over 60 psi pressure drop at rpm, but could have been more as that was max of 140psi gauge I had.
> I would highly recommend hooking in a temporary pressure gauge (200psi) prior to the cooler to check its pressure drop, you may be surprised how little rpm you need to build pressure.
> ARE & PWR both in brisbane are only Aus companies I have found to help and getting me quote on coolers similar to Fluidyne. If you want Fluidyne you need third party (someone possibly going to Oshkosh) to carry it back as they will not ship to us.
> But saying all this you have the series 2 renesis which has different oil setup to all other rotaries, Steve B has same so think his setup would be very relevant to you.
> Andrew