Are this run times during very competitive racing or practicing on an open track with no other racers in the way. The reason why I ask is that I noticed a few minute discrepancy between run times per tank in running on an open track in practice to running on a track with 10 other competitors and fighting for position/holding off the competition. With my engine, I can get 8 to 10 minutes per tank on an open track with no other racers pushing the car somewhat hard. However, when you put in the text of competitive racing, that drops to 6 to 8 minutes, give or take a few seconds.