What combination of parts contribute to the higher HP factory engines vs. the standard output engines. Are injection pumps different, are injection nozzles different, are pistons different. I'm pretty sure I have seen in the operators manual for my truck where the compression is different HO vs.SO. The reason I ask is that when looking at performance injection nozzles they are usaully listed as 98.5-2002. Okay that is fine, but usually nozzles are designed to match a certain piston as far as spray angle goes. I'm Wondering if any of this could help me understand the performance characteristics of my particular setup better.

 

Bowl pattern is same HO to SO

VP44 is a touch different.

Compression is 1 point higher on the HO than SO