Thanks again.
I recently installed a MoCal Laminova 43-330 oil/water heat exchanger as a backup to my oil/air cooler. It works as advertised; and will handle roughly ¼ - 1/3 of the heat load for the 20B. That was all I needed to keep my oil temps below max during climb on a hot day.
Setrab still makes a couple of units of lower capacity TOC-150 and TOC-200, but the larger TOC-300 is currently out of production.
Fluidyne no longer makes oil/water units, but some still show up now and then on e-bay.
C&R racing will make a higher capacity unit for you – at a price.
Al