"In the case of our drag car we use VP fuels C14+ We have tried others with different distillation and oxygenation etc but they create other tuning issues. I have never maxed out the capabilities of the C14+ and changing to other fuel charateristics just mucks up my knowledge base."
This plug is from an engine using 2* 1085 cfm 6 barrel SmartCarby carburetors. The compression ratio of this engine is 15.3 to 1 and the cranking pressure is 300 psi. Fuel is VP C14+ (a leaded fuel). The engine timing is 28 degrees. This is lambda 0.83. Note how the shell has Hydrocarbon deposits on it that are consistent with the strap electrode and the colouration on the porcelain. This is indicating a good consistency of overall mixture with possibly optimum ignition timing. It is a well vaporized rich mixture.
This plug is close to ideal but it’s not right in some ways. This from the same engine as above but at lambda .87. But there is very little colour on the porcelain. This engine is using SmartCarby carburetion. 2 * 6 barrel 1085 CFM carburetors. You will notice the difference in deposit granule size by improved atomization. This is one drag strip run. After 4 runs the porcelain also slightly colored with tan,
So he gets colouration on the porcelain on his race engine on US Race Fuel......He does it on all fuels irrespective of where they come from. It has nothing to do with where the fuel is from and everything to do with Vaporization and Homogization and temperature and pressure of the combustion event.
