Sadly; I don't know of any.
What I did try once and it came out okay was this. What is the radiator for? That is first and foremost the thing. Then it's thickness in the model. Then the material. Three come to mind and they all work after a fashion.
Remember if you look closely at a radiator, Straight into it, You can see all the way through it. Hard to replicate in miniature? Nah! First try was with good old window screen. Although out of scale I got four layers into that little space after I flattened the bejaysus out of it!
Second try was different. I had some Tichy Train Group ,Yup, you guessed it. Boxcar Roof Walkways! Did the sanding as per my article for using them for Box Scale Shipmodel Rails. Then stacked them in alternate layers after painting each layer BEFORE assembly. They looked okay.
Lastly and the winner.I had some Etched Brass screen of three different sizes from a 1/96 scale ship. I painted them, overlaid them and Viola"! One beautiful Radiator! There aftermarket parts such as this available .But, I find it more fun to scratch-Build them. Now if you are talking the radiators for say a 1/25 formula Car-use the aftermarket!