Does the INFINITI Q50 have a timing belt or chain?

Even though You didn't specify a year, I can pretty safely say that Your INFINITIQ50 has a timing chain. In fact, I don't know of any model years off the top of my head that used a timing belt -- and an internet search couldn't find any for me, either. With proper care and lubrication, a timing chain should last You 250,000 to 300,000 miles at least -- there's a good chance Your engine will fail before the timing chain does. But... What if something catastrophic happens Well, that's where we get into "what if"s, but it's not good. The cost to replace a chain is much greater than a belt -- You could be looking at up to $3,000. So be sure to take proper care of Your engine with regular oil changes and safe driving -- Your wallet will thank You in the long term.