I was over at the FlightSim library a couple of days ago and found this file, pratt_whitney_r-2800-dc6.zip and downloaded it. (I'm always on the hunt for better sound packs). I have to say this is probably the best one I've found for an aircraft with 4 R-2800s. I converted it for use in a twin engine application and have been using it in the CalClassic C-46 Commando. The only problem I've found with it is that it's a 71.8 MB file and at FlightSim takes a good while to download. But it's definitely worth the wait.