If you can't hold you hand on it for a minute when it's running, it's too hot.
Best way to figure out pulley size, is keep buying bigger ones until you get to a size where you can't get the pressure up high enough, then go down one size where you get good pressure. This way you won't be burning out your motor or wasting power sending oil through the relief valve.

Well I finished 1 batch of oil yesterday and started another batch this morning. I sure am glad these centrifuge's came thru when they did. Just wish I had one a few years ago and I wouldn't have had to use so many filters. Just finished the second batch, 80+gallons in 2 days. I still think I'll go with a bigger pulley on the pump. I did check the CF temp while I was pulling off the good oil. I was reading 151 degrees.

I changed the pulley size on the pump to 6 1/2" with a 2" on the motor. Working better than ever. Pushing 80 to 100 psi with the bypass closed. While cleaning the CF i noticed the "o" ring was about to come apart. Tomorrow I'll cut and reglue it. Other than that, the only complaint is it's start to vibrate and make a lot of noise. I'm going to isolate it with nylon washers. There isn't any sideplay in the CF to the shaft.

I have a carbonator pump as I have seen with DieselCraft CF and wonder what size of particles in the oil stream affects the longevity of the pump.

Best regards