|
Interesting idea. Of course the old tractors with low compression ratio can't utilize the octane rating of new gasolines very well. But your description of the benefit is a little backward, as I understand it, higher octane causes the fuel mixture to burn more slowly. Knock is when it burns too fast, or predetonates due to high compression or a hot glowing surface in the head cavity (such as the edge of a carbon deposit). But the tendency of an engine to knock is very dependent on the cylinder pressure at ignition. Low compression engines are not very prone to knock. However, a little diesel or kerosene might be a good mix with modern gasoline in an old low compression engine. I don't think stroke has much to do with it, except that higher compression gasoline engines generally have shorter strokes. The tendency of the diesel component to condense on the cylinder sidewall would be greater on longer stroke engines, and with the cooler running engine. Cylinder temperature at operating conditions is much lower in an old tractor than in a new high compression engine.
| 
