Wait a minute guys. The intended use is for a running time of 6 hours on the street, not a few passes down the drag-strip or a run down the salt flats.
Nvr2old, lithium batteries tend to die all at once, as in it can have 12v under load, and then 30 seconds later it only has 8v, and still dropping. If the voltage gets too low, the ignition system can't make enough spark to keep the engine running. I like LiFe batteries for their light weight and high short term starting currents, but lithium batteries in general do not tolerate deep discharge cycles.
A lead acid battery's voltage declines more slowly, and may be more tolerant of discharge/charge cycles. The AGM Steve posted on your other thread might be a good choice, given the price; you could buy 2 of them for less than 1 lithium.
