From a team that has only been around for only a year (and has a limited size), I would recommend using an engine that is not only feasible, but will keep the interest of your team. That may not be the best way to win the competition, but in my opinion it is the best way to get there. I guess that I am with everyone else who says forget having the most power / lightest weight and just build a car that will make it back. Every engine selection has its ups and downs and is arguably the best. In the end it is how well / reliable you build the car, not the engine's weight or horsepower. Last year we used a YFZ-450 because of it's low weight, and we still ended up with a car that weighed 537lbs. Granted it was our first year, but a light engine does not = a light car. This year we are using a 2007 GSXR 600 because of it's tremendous ability to generate horsepower. However, we don't have a single person on the team who has any clue to tune it let alone set it up. In other words, it's about the total package not just the engine alone.