I decided to try an oil cooler. Rally Design have a 16 row with 125mm wide matrix. This makes the unit about 210mm overall wide and 124mm high. This oil cooler fits nicely just in front of the oil filter and in the air flow from the tunnel. This should be an adequate size for a 155bhp engine. The cooler has 2 x 1/2" BSP male threads. RD also sell a sandwich plate for the oil filter take off. RD don't supply DIY Mocal oil pipes, I had to get them from Ebay (Matt Lewis Racing). Mocal do a self assembly pipe and ends. I used 4 rt angle 1/2" BSP fittings (someone should tell RD). I backed up the self assembly fittings with crimp on 'O' Clips.
When the parts arrived The sandwich plate had no adapters to 1/2" BSP male, I ordered what I thought was the correct adapters from RD on line but then discovered the sandwich adapter is 3/4" UNF (female). Now as luck has it 1/2" BSP and 3/4" UNF are very close. The BSP thread is the same pitch but larger diameter. I have a 1/2" BSP tap bought for another project. Cooking with Gas now I think!
Here are the installation pictures:
After a road test (a real test would be Knockhill) I added an air scoop in 0.8mm alloy sheet and Anti-kitty litter filter just in case of stone ingress.
After a track day at Knockhill (reverse) I saw no appreciable difference in oil pressure. I have now added a 120mm 12V fan to the equation. It appears to be an improvement but I will have to invest in another track day to find out. What an imposition.