How do I open the files from this assembly?

see link: https://grabcad.com/library/four-cylinder-engine-1/details?folder_id=383185
The files are not in .step version or .prt, how can I convert these to .prt or .step?
4 Answers

How? Just buy Pro/Engineer and open the Modell (just kidding)
I used a conversion tool to create a STEP File (and used 7-zip to compress the file), but its an old version of this tool, so there is no warranty