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Im building a clubman race car with a stock (at this time) NB8A engine. Is it necessary to run an oil cooler? If so what size and what recommendations?

Highly modified, high revving screamers need oil pump and oil cooling mods. I've done 4,000 laps with a stockish motor like yours. Never had an oil cooler and never had any oil issues.

DONE,, no cooler required at this stage. A couple of $ saved. Thanks MB

Yep agree no cooler needed.

Is it needed in a stock engine? Probably not. I too have tracked a stock car, as well as a highly modded dual duty car (115rwkw) without an oil cooler, and with no apparent oiling issues.

I have also tracked a full race engine for a number of years. When I thought it was about time for a refresh of the engine, the engine builder reported that the bearings, bores etc were 'as-new'. He attributed that to high quality oil, and managing oil temperature.

I would suggest an oil temperature gauge for peace of mind, especially if your car is a lotus 7-type clubman as there may be cooling issues in a non-standard installation that are not issues in the donor car. Use the best oil you can afford, and know the operating range (upper and lower) for the oil. If you do put an oil cooler in, don't over-cool the oil.

To put that in perspective, my race engine is kept under 3000rpm until the temperature of the oil hits 80*C, and you might be surprised just how hard it is to get to that temperature without revving the tits off it (especially on a cold Goulburn morning when the car has cold soaked down to about -5* ). To help the process, I run an oil/water heat exchanger where as the coolant warms up, it heats the oil; when the oil temperature exceeds the coolant temperature the coolant heats up and that heat is taken out by the radiator.

If you are doing lots of heavy load track day type stuff you should Monitor your oil temp and pressure.
Then you will be able to identify if a cooler is required.

Green machine you raise a good point about the fact the car is clubman and may heat differently to the MX5. I'll be running a Honda Civic 56mm core (overall thickness 77mm) Aly radiator which is only 422 x 364mm. This is the type of rad most of the clubbie guys are using.
I think for now no oil cooler and run an oil temp gauge for some data. See how she goes from there.

Thanks for the input guys