RV-9A w/Rotary 13B

[dlomheim]

I have finally started to get back to working on my 9A w/"alternative engine", and hope to have a first engine start in the coming months. I basically stopped working on project in 2008 due to lack of time and loss of interest, but I finally retired so have at least a couple hrs. / day to now devote to it on a regular basis. Last week I built up required -10 hose w/AN fittings to move the hot oil from the engine to a water/oil intercooler, and from there to the stock Mazda oil cooler. My plan is to pre-cool the oil with the water, and then use airflow to pull it down a bit more. This adds weight of course, but if the water oil cooler works well I might be able to eliminate the Mazda air/oil cooler...TBD.

Doug

RV-3A IRAN / Flown and sold
RV-9A w/86 13B engine / FWF

 

[scottmillhouse]

fluid oil cooler

I tried this in a street/autocross car about 30 years ago and it does not work. Mazda only used it for one year as I recall and found it marginal at best. These engines are essentially oil cooled so a good large oil cooler is necessary. I worked the cooling system over for months and could not keep the engine cool. Installed the stock oil cooler in front of the radiator and never had another problem.

 

[Gearhead51]

IIRC, Mazda only used the water / oil cooler for 1984 and 1985 GS and GSL 12A engines. The '84 and '85 GSL-SE with a 13B retained air / oil coolers. Approximately 1/3 of the cooling is done by oil as oil is used to cool the large surface area inside the rotor faces that are exposed to combustion. In higher performance applications, we always ditched the water / oil cooler in favor of air / oil.

 

[Lufthans]

I'm running an oil/water heat exchanger on my Subaru and it works perfectly for me, even without an additional oil/air unit.

On my RV3B, I am also installing one, WITH additional oil/air cooler this time, but only because the extra horsepower and the limited radiator size that I can fit will give me less thermal headroom than I have in my normally aspirated Jodel.

Obviously, the Subaru is quite a different beast though, and I could see how it would not work on a 13B...