I want to install a coolant temp gauge, but not sure if the radiator hose inner diameter is 30 or 32 mm for the radiator hose adapter.
Also, where would be the best spot to install the adapter?

I have a 2008 Mini Cooper S R56 N14.

 

Get a scan gauge II or III and a mount from craven speed.

You can get coolant temp (engine coolant temp or ECT) from the OBDII port.

The scan gauge also allows you to see and clear codes, and you can pull up voltage and other parameters too!

 

I believe it's a 32mm. I'll double check tomorrow. And I put it below the reservoir. I'll take pictures and get what I ordered for you tomorrow!

 

I am 95% sure it is 32mm. I can't find my receipt for the one I purchased anywhere. But, I do remember doing a ton of research to find the size. I bought the Mishimoto one here: https://www.mishimoto.com/mishimoto-...connector.html
They do offer it in the 30mm as well. So you could get both and return one

And followed the Cravenspeed install instructions here: https://www.cravenspeed.com/water-te...de-mini-gen-2/

Cravenspeed does offer their kit as well and can be found on their website. I decided Mishimoto because it is half the cost and the exact same thing.