Offroad2010

Fellow pathfinder owners. I have a 1987 pathfinder with 181,000 miles. Now it's a 3 liter and is not as reliable as things used to be. I am cut out the body and put roll bars and take it to the dunes. I am wondering if it is possible to put a larger engine in my vehicle, or if there is a practical way to going about charging the dunes in an old clunker