Having said that, what would be a good volumetric compression ratio for a four stroke. In other words do 4 strokes start out at lets say 8 to 1 and I need to raise it to 10 to1 for 0% nitro. I suspect there must be a ratio or formula for deriving best compression ratio for ideal timing and how nitro changes that compression ratio depending on how much it advances the timing. A rule of thumb so to speak. The only 4 stroke I have tried to run on 0% is an old Magnun 120. It ran fine and certainly does not have alot of compression. An old truck of an engine to be sure. Interesting topic.