Originally Posted by DJ_Shakespear

In Bold, that is completely right - to an extent with the crank.
The longer and/or earlier you have the crank opening (within limitations) can determine how much fuel/air mix you can get into the combustion chamber.

With the topic at hand, a friend of mine has a GRP engine, orange head, and at the track we run at, I run about par with him, yet he can do a few laps, start the race and finish with 1/4-3/8 of a tank left! Yet I start racing on a full tank and Im left with maybe 20-40 secs of runtime! Im not entirely sure if it was because I had a bad tuning (issues with my engine, RB T10) but that just shows that you can run more than 5-6 minutes on a single tank.