10 RF/t * 20000 ticks = 2 * 10^5 RF in Stirling Engine
20 RF/t * 6000 ticks = 1.2 * 10^5 RF in Combust Engine

Looks a bit weird. Maybe the lava bucket should be banned from burning in Stirling Engine.

It doesn't seem weird at all to me.It just seems that combustion engine sacrifices efficiency for speed.

Asie did say at one point that he wanted to remove the lava + water rf gen in a combustion engine. Anyway, blame Spacetoad \o/ : #1955

Noticed this by accident: I'd preferably kill off the lava + water gen. It makes zero sense. Most of the past BC teams generally agree.

If you want lava power generation, you should consider making a separate engine - however, it is unwanted due to the issues of lag and balance both with BC's pumps and the nether's vast amounts of lava.